@article{Angstrom1900,
annote = {doi: 10.1002/andp.19003081208},
author = {{\AA}ngstr{\"{o}}m, Knut},
doi = {10.1002/andp.19003081208},
issn = {0003-3804},
journal = {Annalen der Physik},
month = {jan},
number = {12},
pages = {720--732},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Ueber die Bedeutung des Wasserdampfes und der Kohlens{\"{a}}ure bei der Absorption der Erdatmosph{\"{a}}re}},
url = {https://doi.org/10.1002/andp.19003081208},
volume = {308},
year = {1900}
}
@article{Aamaas2016,
abstract = {Abstract. For short-lived climate forcers (SLCFs), the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF) values calculated in four different (chemical-transport or coupled chemistry–climate) models. We distinguish between emissions during summer (May–October) and winter (November–April) for emissions in Europe and East Asia, as well as from the global shipping sector and global emissions. The species included in this study are aerosols and aerosol precursors (BC, OC, SO2, NH3), as well as ozone precursors (NOx, CO, VOCs), which also influence aerosols to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH4, have been calculated using global warming potential (GWP) and global temperature change potential (GTP), based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramping period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies.For the aerosols, the emission metric values are larger in magnitude for emissions in Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values for emissions in East Asia and winter for CO and in Europe and summer for VOCs. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of an illustrative mitigation policy package is robust even when accounting for the fact that the magnitude of emission metrics for different species in a given model is correlated. For the ramping emission metrics, the values are generally larger than for pulse or sustained emissions, which holds for all SLCFs. For SLCFs mitigation policies, the dependency of metric values on the region and season of emission should be considered.},
author = {Aamaas, Borgar and Berntsen, Terje K. and Fuglestvedt, Jan S. and Shine, Keith P. and Bellouin, Nicolas},
doi = {10.5194/acp-16-7451-2016},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jun},
number = {11},
pages = {7451--7468},
title = {{Regional emission metrics for short-lived climate forcers from multiple models}},
url = {https://acp.copernicus.org/articles/16/7451/2016/},
volume = {16},
year = {2016}
}
@article{Aamaas2017,
abstract = {Abstract. We calculate the absolute regional temperature change potential (ARTP) of various short-lived climate forcers (SLCFs) based on detailed radiative forcing (RF) calculations from four different models. The temperature response has been estimated for four latitude bands (90–28° S, 28° S–28° N, 28–60° N, and 60–90° N). The regional pattern in climate response not only depends on the relationship between RF and surface temperature, but also on where and when emissions occurred and atmospheric transport, chemistry, interaction with clouds, and deposition. We present four emissions cases covering Europe, East Asia, the global shipping sector, and the entire globe. Our study is the first to estimate ARTP values for emissions during Northern Hemisphere summer (May–October) and winter season (November–April). The species studied are aerosols and aerosol precursors (black carbon, organic carbon, SO2, NH3), ozone precursors (NOx, CO, volatile organic compound), and methane (CH4). For the response to BC in the Arctic, we take into account the vertical structure of the RF in the atmosphere, and an enhanced climate efficacy for BC deposition on snow. Of all SLCFs, BC is the most sensitive to where and when the emissions occur, as well as giving the largest difference in response between the latitude bands. The temperature response in the Arctic per unit BC emission is almost four times larger and more than two times larger than the global average for Northern Hemisphere winter emissions for Europe and East Asia, respectively. The latitudinal breakdown likely gives a better estimate of the global temperature response as it accounts for varying efficacies with latitude. An annual pulse of non-methane SLCF emissions globally (representative of 2008) lead to a global cooling. In contrast, winter emissions in Europe and East Asia give a net warming in the Arctic due to significant warming from BC deposition on snow.},
author = {Aamaas, Borgar and Berntsen, Terje K. and Fuglestvedt, Jan S. and Shine, Keith P. and Collins, William J.},
doi = {10.5194/acp-17-10795-2017},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {sep},
number = {17},
pages = {10795--10809},
title = {{Regional temperature change potentials for short-lived climate forcers based on radiative forcing from multiple models}},
url = {https://acp.copernicus.org/articles/17/10795/2017/},
volume = {17},
year = {2017}
}
@article{Abe-Ouchi2013a,
abstract = {The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere-asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere-asthenosphere response. Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles.},
author = {Abe-Ouchi, Ayako and Saito, Fuyuki and Kawamura, Kenji and Raymo, Maureen E. and Okuno, Jun'Ichi and Takahashi, Kunio and Blatter, Heinz},
doi = {10.1038/nature12374},
isbn = {0028-0836},
issn = {00280836},
journal = {Nature},
number = {7461},
pages = {190--193},
pmid = {23925242},
publisher = {Nature Publishing Group},
title = {{Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume}},
url = {http://dx.doi.org/10.1038/nature12374},
volume = {500},
year = {2013}
}
@article{gmd-8-3621-2015,
author = {Abe-Ouchi, A and Saito, F and Kageyama, M and Braconnot, P and Harrison, S P and Lambeck, K and Otto-Bliesner, B L and Peltier, W R and Tarasov, L and Peterschmitt, J.-Y. and Takahashi, K},
doi = {10.5194/gmd-8-3621-2015},
journal = {Geoscientific Model Development},
number = {11},
pages = {3621--3637},
title = {{Ice-sheet configuration in the CMIP5/PMIP3 Last Glacial Maximum experiments}},
url = {https://gmd.copernicus.org/articles/8/3621/2015/},
volume = {8},
year = {2015}
}
@article{Ackerley2016,
abstract = {Abstract. General circulation models (GCMs) are valuable tools for understanding how the global ocean–atmosphere–land surface system interacts and are routinely evaluated relative to observational data sets. Conversely, observational data sets can also be used to constrain GCMs in order to identify systematic errors in their simulated climates. One such example is to prescribe sea surface temperatures (SSTs) such that 70 {\%} of the Earth's surface temperature field is observationally constrained (known as an Atmospheric Model Intercomparison Project, AMIP, simulation). Nevertheless, in such simulations, land surface temperatures are typically allowed to vary freely, and therefore any errors that develop over the land may affect the global circulation. In this study therefore, a method for prescribing the land surface temperatures within a GCM (the Australian Community Climate and Earth System Simulator, ACCESS) is presented. Simulations with this prescribed land surface temperature model produce a mean climate state that is comparable to a simulation with freely varying land temperatures; for example, the diurnal cycle of tropical convection is maintained. The model is then developed further to incorporate a selection of “proof of concept” sensitivity experiments where the land surface temperatures are changed globally and regionally. The resulting changes to the global circulation in these sensitivity experiments are found to be consistent with other idealized model experiments described in the wider scientific literature. Finally, a list of other potential applications is described at the end of the study to highlight the usefulness of such a model to the scientific community.},
author = {Ackerley, Duncan and Dommenget, Dietmar},
doi = {10.5194/gmd-9-2077-2016},
issn = {1991-9603},
journal = {Geoscientific Model Development},
month = {jun},
number = {6},
pages = {2077--2098},
title = {{Atmosphere-only GCM (ACCESS1.0) simulations with prescribed land surface temperatures}},
url = {https://gmd.copernicus.org/articles/9/2077/2016/},
volume = {9},
year = {2016}
}
@article{Albrecht1989,
abstract = {Increases in aerosol concentrations over the oceans may increase the amount of low-level cloudiness through a reduction in drizzle-a process that regulates the liquid-water content and the energetics of shallow marine clouds. The resulting increase in the global albedo would be in addition to the increase due to enhancement in reflectivity associated with a decrease in droplet size and would contribute to a cooling of the earth's surface.},
author = {Albrecht, B. A.},
doi = {10.1126/science.245.4923.1227},
issn = {0036-8075},
journal = {Science},
month = {sep},
number = {4923},
pages = {1227--1230},
pmid = {17747885},
publisher = {American Association for the Advancement of Science},
title = {{Aerosols, Cloud Microphysics, and Fractional Cloudiness}},
url = {https://www.sciencemag.org/lookup/doi/10.1126/science.245.4923.1227},
volume = {245},
year = {1989}
}
@article{doi:10.1002/env.2140,
abstract = {Predictions of climate change are uncertain mainly because of uncertainties in the emissions of greenhouse gases and how sensitive the climate is to changes in the abundance of the atmospheric constituents. The equilibrium climate sensitivity is defined as the temperature increase because of a doubling of the CO2 concentration in the atmosphere when the climate reaches a new steady state. CO2 is only one out of the several external factors that affect the global temperature, called radiative forcing mechanisms as a collective term. In this paper, we present a model framework for estimating the climate sensitivity. The core of the model is a simple, deterministic climate model based on elementary physical laws such as energy balance. It models yearly hemispheric surface temperature and global ocean heat content as a function of historical radiative forcing. This deterministic model is combined with an empirical, stochastic model and fitted to observations on global temperature and ocean heat content, conditioned on estimates of historical radiative forcing. We use a Bayesian framework, with informative priors on a subset of the parameters and flat priors on the climate sensitivity and the remaining parameters. The model is estimated by Markov Chain Monte Carlo techniques. Copyright {\textcopyright} 2012 John Wiley {\&} Sons, Ltd.},
author = {Aldrin, Magne and Holden, Marit and Guttorp, Peter and Skeie, Ragnhild Bieltvedt and Myhre, Gunnar and Berntsen, Terje Koren},
doi = {10.1002/env.2140},
journal = {Environmetrics},
keywords = {Markov Chain Monte Carlo,climate change,combining computer models and stochastic models,global warming,radiative forcing},
number = {3},
pages = {253--271},
title = {{Bayesian estimation of climate sensitivity based on a simple climate model fitted to observations of hemispheric temperatures and global ocean heat content}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/env.2140},
volume = {23},
year = {2012}
}
@article{Alexeev2005,
abstract = {Polar amplification of surface warming has previously been displayed by one of the authors in a simplified climate system model with no ice-albedo feedbacks. A physical mechanism responsible for this pattern is presented and tested in an energy balance model and two different GCMs through a series of fixed-SST and ``ghost forcing'' experiments. In the first ghost forcing experiment, 4 W/m2 is added uniformly to the mixed layer heat budget and in the second and third, the same forcing is confined to the tropics and extra-tropics, respectively. The result of the uniform forcing is a polar amplified response much like that resulting from a doubling of CO2. Due to an observed linearity this response can be interpreted as the sum of the essentially uniform response to the tropical-only forcing and a more localized response to the extra-tropical-only forcing. The flat response to the tropical forcing comes about due to increased meridional heat transports leading to a warming and moistening of the high-latitude atmosphere. This produces a longwave forcing on the high-latitude surface budget which also has been observed by other investigators. Moreover, the tropical surface budget is found to be more sensitive to SST changes than the extra-tropical surface budget. This strengthens the tendency for the above mechanism to produce polar amplification, since the tropics need to warm less to counter an imposed forcing.},
author = {Alexeev, V A and Langen, P L and Bates, J R},
doi = {10.1007/s00382-005-0018-3},
issn = {1432-0894},
journal = {Climate Dynamics},
month = {jun},
number = {7},
pages = {655--666},
title = {{Polar amplification of surface warming on an aquaplanet in “ghost forcing” experiments without sea ice feedbacks}},
url = {https://doi.org/10.1007/s00382-005-0018-3},
volume = {24},
year = {2005}
}
@article{Alexeev2013,
abstract = {Surface albedo feedback is widely believed to be the principle contributor to polar amplification. However, a number of studies have shown that coupled ocean-atmosphere models without ice albedo feedbacks still produce significant polar amplification in 2 {\{}$\backslash$texttimes{\}} CO2 runs due to atmospheric heat transports and their interaction with surface conditions. In this article, the relative importance of atmospheric heat transport and surface albedo is assessed using a conceptual 2-box energy balance model in a variety of different model climates. While both processes are shown to independently contribute to the polar amplified response of the model, formal feedback analysis indicates that a strong surface albedo response will tend to reduce the effect of atmospheric heat transport in the full model. We identify several scenarios near the present day climate in which, according to this formal feedback analysis, atmospheric heat transport plays no role in shaping the equilibrium warming response to uniform forcing. However, a closer analysis shows that even in these scenarios the presence of atmospheric heat transport feedback does play a significant role in shaping the trajectory by which the climate adjusts to its new equilibrium.},
author = {Alexeev, Vladimir A and Jackson, Craig H},
doi = {10.1007/s00382-012-1601-z},
issn = {1432-0894},
journal = {Climate Dynamics},
month = {jul},
number = {2},
pages = {533--547},
title = {{Polar amplification: is atmospheric heat transport important?}},
url = {https://doi.org/10.1007/s00382-012-1601-z},
volume = {41},
year = {2013}
}
@article{doi:10.1002/2014GL060962,
abstract = {Abstract Combining satellite data, atmospheric reanalyses, and climate model simulations, variability in the net downward radiative flux imbalance at the top of Earth's atmosphere (N) is reconstructed and linked to recent climate change. Over the 1985–1999 period mean N (0.34 ± 0.67 Wm−2) is lower than for the 2000–2012 period (0.62 ± 0.43 Wm−2, uncertainties at 90{\%} confidence level) despite the slower rate of surface temperature rise since 2000. While the precise magnitude of N remains uncertain, the reconstruction captures interannual variability which is dominated by the eruption of Mount Pinatubo in 1991 and the El Ni{\~{n}}o Southern Oscillation. Monthly deseasonalized interannual variability in N generated by an ensemble of nine climate model simulations using prescribed sea surface temperature and radiative forcings and from the satellite-based reconstruction is significantly correlated (r∼0.6) over the 1985–2012 period.},
author = {Allan, Richard P. and Liu, Chunlei and Loeb, Norman G. and Palmer, Matthew and Roberts, Malcolm and Smith, Doug and Vidale, Pier-Luigi},
doi = {10.1002/2014GL060962},
journal = {Geophysical Research Letters},
keywords = {climate model,climate variability,energy balance,radiative flux,satellite data,temperature},
number = {15},
pages = {5588--5597},
title = {{Changes in global net radiative imbalance 1985–2012}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014GL060962},
volume = {41},
year = {2014}
}
@article{Allen2018,
abstract = {While cumulative carbon dioxide (CO2) emissions dominate anthropogenic warming over centuries, temperatures over the coming decades are also strongly affected by short-lived climate pollutants (SLCPs), complicating the estimation of cumulative emission budgets for ambitious mitigation goals. Using conventional Global Warming Potentials (GWPs) to convert SLCPs to “CO2-equivalent” emissions misrepresents their impact on global temperature. Here we show that peak warming under a range of mitigation scenarios is determined by a linear combination of cumulative CO2 emissions to the time of peak warming and non-CO2 radiative forcing immediately prior to that time. This may be understood by expressing aggregate non-CO2 forcing as cumulative CO2 forcing-equivalent (CO2-fe) emissions. We show further that contributions to CO2-fe emissions are well approximated by a new usage of GWP, denoted GWP*, which relates cumulative CO2 emissions to date with the current rate of emission of SLCPs. GWP* accurately indicates the impact of emissions of both long-lived and short-lived pollutants on radiative forcing and temperatures over a wide range of timescales, including under ambitious mitigation when conventional GWPs fail. Measured by GWP*, implementing the Paris Agreement would reduce the expected rate of warming in 2030 by 28{\%} relative to a No Policy scenario. Expressing mitigation efforts in terms of their impact on future cumulative emissions aggregated using GWP* would relate them directly to contributions to future warming, better informing both burden-sharing discussions and long-term policies and measures in pursuit of ambitious global temperature goals.},
author = {Allen, Myles R. and Shine, Keith P. and Fuglestvedt, Jan S. and Millar, Richard J. and Cain, Michelle and Frame, David J. and Macey, Adrian H.},
doi = {10.1038/s41612-018-0026-8},
journal = {npj Climate and Atmospheric Science},
number = {1},
pages = {16},
title = {{A solution to the misrepresentations of CO2-equivalent emissions of short-lived climate pollutants under ambitious mitigation}},
volume = {1},
year = {2018}
}
@article{Allen2016,
abstract = {? 2016 Macmillan Publishers Limited.Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have requested guidance on common greenhouse gas metrics in accounting for Nationally determined contributions (NDCs) to emission reductions. Metric choice can affect the relative emphasis placed on reductions of 'cumulative climate pollutants' such as carbon dioxide versus' short-lived climate pollutants' (SLCPs), including methane and black carbon. Here we show that the widely used 100-year global warming potential (GWP 100) effectively measures the relative impact of both cumulative pollutants and SLCPs on realized warming 20-40 years after the time of emission. If the overall goal of climate policy is to limit peak warming, GWP 100 therefore overstates the importance of current SLCP emissions unless stringent and immediate reductions of all climate pollutants result in temperatures nearing their peak soon after mid-century, which may be necessary to limit warming to "well below 2 ?C" (ref.). The GWP 100 can be used to approximately equate a one-off pulse emission of a cumulative pollutant and an indefinitely sustained change in the rate of emission of an SLCP. The climate implications of traditional CO2 -equivalent targets are ambiguous unless contributions from cumulative pollutants and SLCPs are specified separately.},
author = {Allen, Myles R. and Fuglestvedt, Jan S. and Shine, Keith P. and Reisinger, Andy and Pierrehumbert, Raymond T. and Forster, Piers M.},
doi = {10.1038/nclimate2998},
issn = {17586798},
journal = {Nature Climate Change},
number = {8},
pages = {773--776},
title = {{New use of global warming potentials to compare cumulative and short-lived climate pollutants}},
volume = {6},
year = {2016}
}
@article{Allen2019a,
abstract = {Absorbing aerosols, like black carbon (BC), give rise to rapid adjustments, and the associated perturbation to the atmospheric temperature structure alters the cloud distribution. The level of scientific understanding of these rapid cloud adjustments—otherwise known as semi-direct effects (SDEs)—is considered low, with models indicating a likely negative (−0.44 to +0.1 Wm−2) forcing. Recent studies suggest this negative SDE is primarily driven by decreases in high-level clouds and enhanced longwave cooling. Here, we investigate the SDE using multiple models driven by observationally constrained fine-mode aerosol forcing without dust and sea salt. Unlike aerosol simulations, which yield a relatively vertically uniform aerosol atmospheric heating profile with significant upper-tropospheric heating, observation-based heating peaks in the lower-troposphere and then decays to zero in the mid-troposphere. We find a significant global annual mean decrease in low- and mid-level clouds, and weaker decreases in high-level clouds, which leads to a positive SDE dominated by shortwave radiation. Thus, in contrast to most studies, we find a robust positive SDE, implying cloud adjustments act to warm the climate system. Sensitivity tests with identical average, but vertically uniform observationally constrained aerosol atmospheric heating result in a negative SDE, due to enhanced longwave cooling as a result of large reductions in high-level clouds. Our results therefore suggest that model simulations lead to a negatively biased SDE, due to an aerosol atmospheric heating profile that is too vertically uniform.},
author = {Allen, Robert J. and Amiri-Farahani, Anahita and Lamarque, Jean-Francois and Smith, Chris and Shindell, Drew and Hassan, Taufiq and Chung, Chul E.},
doi = {10.1038/s41612-019-0073-9},
issn = {2397-3722},
journal = {npj Climate and Atmospheric Science},
number = {1},
pages = {1--12},
title = {{Observationally constrained aerosol–cloud semi-direct effects}},
volume = {2},
year = {2019}
}
@article{Allen2013a,
abstract = {Observations from the Global Energy Balance Archive indicate regional decreases in all sky surface solar radiation from approximate to 1950s to 1980s, followed by an increase during the 1990s. These periods are popularly called dimming and brightening, respectively. Removal of the radiative effects of cloud cover variability from all sky surface solar radiation results in a quantity called clear sky proxy radiation, in which multidecadal trends can be seen more distinctly, suggesting aerosol radiative forcing as a likely cause. Prior work has shown climate models from the Coupled Model Intercomparison Project 3 (CMIP3) generally underestimate the magnitude of these trends, particularly over China and India. Here we perform a similar analysis with 173 simulations from 42 climate models participating in the new CMIP5. Results show negligible improvement over CMIP3, as CMIP5 dimming trends over four regionsEurope, China, India, and Japanare all underestimated. This bias is largest for both India and China, where the multimodel mean yields a decrease in clear sky proxy radiation of -1.3 +/- 0.3 and -1.2 +/- 0.2Wm(-2)decade(-1), respectively, compared to observed decreases of -6.5 +/- 0.9 and -8.2 +/- 1.3Wm(-2)decade(-1). Similar underestimation of the observed dimming over Japan exists, with the CMIP5 mean dimming approximate to 20{\%} as large as observed. Moreover, not a single simulation reproduces the magnitude of the observed dimming trend for these three regions. Relative to dimming, CMIP5 models better simulate the observed brightening, but significant underestimation exists for both China and Japan. Overall, no individual model performs particularly well for all four regions. Model biases do not appear to be related to the use of prescribed versus prognostic aerosols or to aerosol indirect effects. However, models exhibit significant correlations between clear sky proxy radiation and several aerosol-related fields, most notably aerosol optical depth (AOD) and absorption AOD. This suggests model underestimation of the observed trends is related to underestimation of aerosol direct radiative forcing and/or deficient aerosol emission inventories.},
address = {Allen, RJ Univ Calif Riverside, Dept Earth Sci, Riverside, CA 92521 USA Univ Calif Riverside, Dept Earth Sci, Riverside, CA 92521 USA Univ Calif Riverside, Dept Earth Sci, Riverside, CA 92521 USA Univ Calif San Diego, Scripps Inst Oceanog, San Diego, CA 9},
annote = {187OY
Times Cited:1
Cited References Count:93},
author = {Allen, R J and Norris, J R and Wild, M},
doi = {10.1002/Jgrd.50426},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {dimming brightening cmip5 surface solar radiation},
language = {English},
number = {12},
pages = {6311--6336},
title = {{Evaluation of multidecadal variability in CMIP5 surface solar radiation and inferred underestimation of aerosol direct effects over Europe, China, Japan, and India}},
volume = {118},
year = {2013}
}
@incollection{IPCC2018,
author = {Allen, M.R. and Dube, O.P. and Solecki, W. and Arag{\'{o}}n-Durand, F. and Cramer, W. and Humphreys, S. and Kainuma, M. and Kala, J. and Mahowald, N. and Mulugetta, Y. and Perez, R. and Wairiu, M. and Zickfeld, K.},
booktitle = {Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change,},
chapter = {1},
editor = {Masson-Delmotte, V. and Zhai, P. and P{\"{o}}rtner, H.-O. and Roberts, D. and Skea, J. and Shukla, P.R. and Pirani, A. and Moufouma-Okia, W. and P{\'{e}}an, C. and Pidcock, R. and Connors, S. and Matthews, J.B.R. and Chen, Y. and Zhou, X. and Gomis, M.I. and Lonnoy, E. and Maycock, T. and Tignor, M. and Waterfield, T.},
pages = {49--92},
publisher = {In Press},
title = {{Framing and Context}},
url = {https://www.ipcc.ch/sr15/chapter/chapter-1},
year = {2018}
}
@article{Allison_2019,
abstract = {Observational estimates of global ocean heat content (OHC) change are used to assess Earth's energy imbalance over the 20th Century. However, intercomparison studies show that the mapping methods used to interpolate sparse ocean temperature profile data are a key source of uncertainty. We present a new approach to assessing OHC mapping methods using ‘synthetic profiles' generated from a state-of-the-art global climate model simulation. Synthetic profiles have the same sampling characteristics as the historical ocean temperature profile data but are based on model simulation data. Mapping methods ingest these data in the same way as they would real observations, but the resultant mapped fields can be compared to a model simulation ‘truth'. We use this approach to assess two mapping methods that are used routinely for climate monitoring and initialisation of decadal forecasts. The introduction of the Argo network of autonomous profiling floats during the 2000s drives clear improvements in the ability of these methods to reconstruct the variability and spatial structure of OHC changes. At depths below 2000 m, both methods underestimate the magnitude of the simulated ocean warming signal. Temporal variability and trends in OHC are better captured in the better-observed northern hemisphere than in the southern hemisphere. At all depths, the sampling characteristics of the historical data introduces some spurious variability in the estimates of global OHC on sub-annual to multi-annual timescales. However, many of the large scale spatial anomalies, especially in the upper ocean, are successfully reconstructed even with sparse observations from the 1960s, demonstrating the potential to construct historical ocean analyses for assessing decadal predictions. The value of using accurate global covariances for data-poor periods is clearly seen. The results of this ‘proof-of-concept' study are encouraging for gaining further insights into the capabilities and limitations of different mapping methods and for quantifying uncertainty in global OHC estimates.},
author = {Allison, L C and Roberts, C D and Palmer, M D and Hermanson, L and Killick, R E and Rayner, N A and Smith, D M and Andrews, M B},
doi = {10.1088/1748-9326/ab2b0b},
journal = {Environmental Research Letters},
month = {aug},
number = {8},
pages = {84037},
publisher = {{\{}IOP{\}} Publishing},
title = {{Towards quantifying uncertainty in ocean heat content changes using synthetic profiles}},
url = {https://doi.org/10.1088{\%}2F1748-9326{\%}2Fab2b0b},
volume = {14},
year = {2019}
}
@article{Allison2020,
abstract = {Time series of global mean surface temperature are widely used to measure the rate of climate change that results from Earth's energy imbalance. However, studies based on climate model simulations suggest that on annual-to-decadal timescales global ocean heat content is a more reliable indicator. Here we examine the observational evidence for this, drawing together multiple datasets that span the past {\~{}}30 years. This observational analysis strongly supports the model-based finding that global ocean heat content and sea level are more reliable than surface temperature for monitoring Earth's energy accumulation on these timescales. Global ocean temperature anomalies in the 0–100 m and 100–250 m layers are negatively correlated (r = −0.36), primarily explained by the influence of the Tropical Pacific, and a clearer heating signal is revealed by integrating over deeper ocean layers. The striking agreement between multiple independent datasets represents unequivocal evidence of ongoing planetary heating.},
author = {Allison, Lesley C and Palmer, Matthew D and Allan, Richard P and Hermanson, Leon and Liu, Chunlei and Smith, Doug M},
doi = {10.1088/2515-7620/abbb39},
issn = {2515-7620},
journal = {Environmental Research Communications},
month = {oct},
number = {10},
pages = {101001},
title = {{Observations of planetary heating since the 1980s from multiple independent datasets}},
url = {https://iopscience.iop.org/article/10.1088/2515-7620/abbb39},
volume = {2},
year = {2020}
}
@article{Alo2017,
abstract = {Recent projections of climate change from general circulation and regional climate models over southern Europe and the Mediterranean basin show strong warming and pronounced decrease in precipitation over large portion of the region, especially in the summer. While the role of vegetation in modulating the region's climate is widely recognized, most, if not all, of these climate change projections do not account for the response of the dynamic biosphere to the potential climate changes. In this study we investigate the role of climate–vegetation interactions in a regional climate model (RegCM3) linked to a dynamic vegetation model (CLM-DGVM). High spatial resolution (20 km) simulations of future climate with static vegetation (i.e. vegetation fixed at the present day state) show surface temperature increases across the entire southern Europe/Mediterranean domain in 2085–2089 relative to 1985–1989 due to the radiative and physiological effects of CO2 increase. In terms of precipitation the simulations exhibit substantial precipitation decreases for most of the domain and both summer and winter seasons. Accounting for the effects of structural vegetation changes significantly alters the simulated climate change effects over these areas, but most substantially over the Mediterranean where vegetation feedback reduces summer warming by 1 K and reverts the 28{\%} precipitation decrease to a 4{\%} increase. These results emphasize the importance of including vegetation feedback in the projections of climate change impacts on the Mediterranean climate including extreme climatic events and storms.},
author = {Alo, Clement Aga and Anagnostou, Emmanouil N.},
doi = {10.1002/joc.4833},
issn = {10970088},
journal = {International Journal of Climatology},
number = {4},
pages = {2037--2050},
title = {{A sensitivity study of the impact of dynamic vegetation on simulated future climate change over Southern Europe and the Mediterranean}},
volume = {37},
year = {2017}
}
@article{Anagnostou2020,
abstract = {Despite recent advances, the link between the evolution of atmospheric CO2 and climate during the Eocene greenhouse remains uncertain. In particular, modelling studies suggest that in order to achieve the global warmth that characterised the early Eocene, warmer climates must be more sensitive to CO2 forcing than colder climates. Here, we test this assertion in the geological record by combining a new high-resolution boron isotope-based CO2 record with novel estimates of Global Mean Temperature. We find that Equilibrium Climate Sensitivity (ECS) was indeed higher during the warmest intervals of the Eocene, agreeing well with recent model simulations, and declined through the Eocene as global climate cooled. These observations indicate that the canonical IPCC range of ECS (1.5 to 4.5 °C per doubling) is unlikely to be appropriate for high-CO2 warm climates of the past, and the state dependency of ECS may play an increasingly important role in determining the state of future climate as the Earth continues to warm.},
author = {Anagnostou, E and John, E H and Babila, T L and Sexton, P F and Ridgwell, A and Lunt, D J and Pearson, P N and Chalk, T B and Pancost, R D and Foster, G L},
doi = {10.1038/s41467-020-17887-x},
issn = {2041-1723},
journal = {Nature Communications},
number = {1},
pages = {4436},
title = {{Proxy evidence for state-dependence of climate sensitivity in the Eocene greenhouse}},
url = {https://doi.org/10.1038/s41467-020-17887-x},
volume = {11},
year = {2020}
}
@article{Anagnostou2016,
abstract = {The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope ($\delta$11 B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the canonical range (1.5 to 4.5 degrees Celsius), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO2 concentrations, and that climate sensitivity was relatively constant throughout this period.},
author = {Anagnostou, Eleni and John, Eleanor H. and Edgar, Kirsty M. and Foster, Gavin L. and Ridgwell, Andy and Inglis, Gordon N. and Pancost, Richard D. and Lunt, Daniel J. and Pearson, Paul N.},
doi = {10.1038/nature17423},
isbn = {1476-4687 (Electronic)$\backslash$r0028-0836 (Linking)},
issn = {14764687},
journal = {Nature},
pages = {380--384},
pmid = {27111509},
publisher = {Nature Publishing Group},
title = {{Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate}},
url = {http://dx.doi.org/10.1038/nature17423},
volume = {533},
year = {2016}
}
@article{Andrews2018,
abstract = {An atmospheric general circulation model (AGCM) is forced with patterns of observed sea surface temperature (SST) change and those output from atmosphere–ocean GCM (AOGCM) climate change simulations to demonstrate a strong dependence of climate feedback on the spatial structure of surface temperature change. Cloud and lapse rate feedbacks are found to vary the most, depending strongly on the pattern of tropical Pacific SST change. When warming is focused in the southeast tropical Pacific—a region of climatological subsidence and extensive marine low cloud cover—warming reduces the lower-tropospheric stability (LTS) and low cloud cover but is largely trapped under an inversion and hence has little remote effect. The net result is a relatively weak negative lapse rate feedback and a large positive cloud feedback. In contrast, when warming is weak in the southeast tropical Pacific and enhanced in the west tropical Pacific—a strong convective region—warming is efficiently transported throughout the free troposphere. The increased atmospheric stability results in a strong negative lapse rate feedback and increases the LTS in low cloud regions, resulting in a low cloud feedback of weak magnitude. These mechanisms help explain why climate feedback and sensitivity change on multidecadal time scales in AOGCM abrupt4xCO 2 simulations and are different from those seen in AGCM experiments forced with observed historical SST changes. From the physical understanding developed here, one should expect unusually negative radiative feedbacks and low effective climate sensitivities to be diagnosed from real-world variations in radiative fluxes and temperature over decades in which the eastern Pacific has lacked warming.},
author = {Andrews, Timothy and Webb, Mark J.},
doi = {10.1175/JCLI-D-17-0087.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Climate change,Climate sensitivity,Clouds,Energy budget/balance,Feedback},
month = {jan},
number = {2},
pages = {641--654},
title = {{The Dependence of Global Cloud and Lapse Rate Feedbacks on the Spatial Structure of Tropical Pacific Warming}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0087.1},
volume = {31},
year = {2018}
}
@article{Andrews2017a,
abstract = {{\textcopyright} 2016, Crown Copyright as represented by the Met Office. The effective radiative forcing (ERF) from the biogeophysical effects of historical land use change is quantified using the atmospheric component of the Met Office Hadley Centre Earth System model HadGEM2-ES. The global ERF at 2005 relative to 1860 (1700) is −0.4 (−0.5) Wm−2, making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. The land use ERF is found to be dominated by increases in the land surface albedo, particularly in North America and Eurasia, and occurs most strongly in the northern hemisphere winter and spring when the effect of unmasking underlying snow, as well as increasing the amount of snow, is at its largest. Increased bare soil fraction enhances the seasonal cycle of atmospheric dust and further enhances the ERF. Clouds are shown to substantially mask the radiative effect of changes in the underlying surface albedo. Coupled atmosphere–ocean simulations forced only with time-varying historical land use change shows substantial global cooling (dT = −0.35 K by 2005) and the climate resistance (ERF/dT = 1.2 Wm−2 K−1) is consistent with the response of the model to increases in CO2alone. The regional variation in land surface temperature change, in both fixed-SST and coupled atmosphere–ocean simulations, is found to be well correlated with the spatial pattern of the forced change in surface albedo. The forcing-response concept is found to work well for historical land use forcing—at least in our model and when the forcing is quantified by ERF. Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period.},
author = {Andrews, T. and Betts, R.A. and Booth, B.B.B. and Jones, C.D. and Jones, G.S.},
doi = {10.1007/s00382-016-3280-7},
journal = {Climate Dynamics},
number = {11-12},
pages = {3489--3505},
title = {{Effective radiative forcing from historical land use change}},
volume = {48},
year = {2017}
}
@article{Andrews2012a,
abstract = {"We quantify forcing and feedbacks across available" "P5 coupled atmosphere-ocean general circulation models" "CMI" "(AOGCMs) by analysing simulations forced by an abrupt" "quadrupling of atmospheric carbon dioxide concentration. This is the first application of the linear forcing-feedback regression analysis of Gregory et al. (2004) to an ensemble" "of AOGCMs. The range of equilibrium climate sensitivity is 2.1–4.7 K. Differences in cloud feedbacks continue to be important contributors to this range. Some models" "show small deviations from a linear dependence of top- of-atmosphere radiative fluxes on global surface temperature change. We show that this phenomenon largely arises from" "shortwave cloud radiative effects over the ocean and is consistent with independent estimates of forcing using fixed sea-surface temperature methods. We suggest that future research should focus more on understanding transient" "climate change, including any time-scale dependence of the forcing and/or feedback, rather than on the equilibrium response to large instantaneous forcing. Citation: Andrews, T.," "J. M. Gregory, M. J."},
author = {Andrews, Timothy and Gregory, Jonathan M. and Webb, Mark J. and Taylor, Karl E.},
doi = {10.1029/2012GL051607},
isbn = {1944-8007},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {AOGCMs,CMIP5,climate feedbacks,climate sensitivity,radiative forcing},
number = {9},
pages = {L09712},
title = {{Forcing, feedbacks and climate sensitivity in CMIP5 coupled atmosphere–ocean climate models}},
volume = {39},
year = {2012}
}
@article{doi:10.1029/2018GL078887,
abstract = {Abstract Eight atmospheric general circulation models (AGCMs) are forced with observed historical (1871–2010) monthly sea surface temperature and sea ice variations using the Atmospheric Model Intercomparison Project II data set. The AGCMs therefore have a similar temperature pattern and trend to that of observed historical climate change. The AGCMs simulate a spread in climate feedback similar to that seen in coupled simulations of the response to CO2 quadrupling. However, the feedbacks are robustly more stabilizing and the effective climate sensitivity (EffCS) smaller. This is due to a pattern effect, whereby the pattern of observed historical sea surface temperature change gives rise to more negative cloud and longwave clear-sky feedbacks. Assuming the patterns of long-term temperature change simulated by models, and the radiative response to them, are credible; this implies that existing constraints on EffCS from historical energy budget variations give values that are too low and overly constrained, particularly at the upper end. For example, the pattern effect increases the long-term Otto et al. (2013, https://doi.org/10.1038/ngeo1836) EffCS median and 5–95{\%} confidence interval from 1.9 K (0.9–5.0 K) to 3.2 K (1.5–8.1 K).},
author = {Andrews, Timothy and Gregory, Jonathan M. and Paynter, David and Silvers, Levi G. and Zhou, Chen and Mauritsen, Thorsten and Webb, Mark J. and Armour, Kyle C. and Forster, Piers M. and Titchner, Holly},
doi = {10.1029/2018GL078887},
journal = {Geophysical Research Letters},
keywords = {climate feedbacks,climate sensitivity,energy budget,pattern effects,temperature change},
number = {16},
pages = {8490--8499},
title = {{Accounting for Changing Temperature Patterns Increases Historical Estimates of Climate Sensitivity}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL078887},
volume = {45},
year = {2018}
}
@article{Andrews2017,
author = {Andrews, Elisabeth and Ogren, John A. and Kinne, Stefan and Samset, Bjorn},
doi = {10.5194/acp-17-6041-2017},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {may},
number = {9},
pages = {6041--6072},
title = {{Comparison of AOD, AAOD and column single scattering albedo from AERONET retrievals and in situ profiling measurements}},
url = {https://www.atmos-chem-phys.net/17/6041/2017/},
volume = {17},
year = {2017}
}
@article{Andrews2015,
abstract = {AbstractExperiments with CO2 instantaneously quadrupled and then held constant are used to show that the relationship between the global-mean net heat input to the climate system and the global-mean surface air temperature change is nonlinear in phase 5 of the Coupled Model Intercomparison Project (CMIP5) atmosphere?ocean general circulation models (AOGCMs). The nonlinearity is shown to arise from a change in strength of climate feedbacks driven by an evolving pattern of surface warming. In 23 out of the 27 AOGCMs examined, the climate feedback parameter becomes significantly (95{\%} confidence) less negative (i.e., the effective climate sensitivity increases) as time passes. Cloud feedback parameters show the largest changes. In the AOGCM mean, approximately 60{\%} of the change in feedback parameter comes from the tropics (30°N?30°S). An important region involved is the tropical Pacific, where the surface warming intensifies in the east after a few decades. The dependence of climate feedbacks on an evolving pattern of surface warming is confirmed using the HadGEM2 and HadCM3 atmosphere GCMs (AGCMs). With monthly evolving sea surface temperatures and sea ice prescribed from its AOGCM counterpart, each AGCM reproduces the time-varying feedbacks, but when a fixed pattern of warming is prescribed the radiative response is linear with global temperature change or nearly so. It is also demonstrated that the regression and fixed-SST methods for evaluating effective radiative forcing are in principle different, because rapid SST adjustment when CO2 is changed can produce a pattern of surface temperature change with zero global mean but nonzero change in net radiation at the top of the atmosphere ({\~{}}?0.5 W m?2 in HadCM3).},
author = {Andrews, Timothy and Gregory, Jonathan M. and Webb, Mark J.},
doi = {10.1175/JCLI-D-14-00545.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {nov},
number = {4},
pages = {1630--1648},
publisher = {American Meteorological Society},
title = {{The Dependence of Radiative Forcing and Feedback on Evolving Patterns of Surface Temperature Change in Climate Models}},
url = {https://doi.org/10.1175/JCLI-D-14-00545.1},
volume = {28},
year = {2015}
}
@article{Andrews2019,
author = {Andrews, Timothy and Andrews, Martin B. and Bodas‐Salcedo, Alejandro and Jones, Gareth S. and Kuhlbrodt, Till and Manners, James and Menary, Matthew B. and Ridley, Jeff and Ringer, Mark A. and Sellar, Alistair A. and Senior, Catherine A. and Tang, Yongming},
doi = {10.1029/2019MS001866},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
month = {dec},
number = {12},
pages = {4377--4394},
title = {{Forcings, Feedbacks, and Climate Sensitivity in HadGEM3‐GC3.1 and UKESM1}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001866},
volume = {11},
year = {2019}
}
@article{Andrews2020,
author = {Andrews, Timothy and Forster, Piers M.},
doi = {https://doi.org/10.1038/s41558-020-0696-1},
journal = {Nature Climate Change},
pages = {313--316},
title = {{Energy budget constraints on historical radiative forcing}},
volume = {10},
year = {2020}
}
@article{Andrews2020a,
abstract = {We describe and evaluate historical simulations which use the third Hadley Centre Global Environment Model in the Global Coupled configuration 3.1 (HadGEM3-GC3.1) model and which form part of the UK's contribution to the sixth Coupled Model Intercomparison Project, CMIP6. These simulations, run at two resolutions, respond to historically evolving forcings such as greenhouse gases, aerosols, solar irradiance, volcanic aerosols, land use, and ozone concentrations. We assess the response of the simulations to these historical forcings and compare against the observational record. This includes the evolution of global mean surface temperature, ocean heat content, sea ice extent, ice sheet mass balance, permafrost extent, snow cover, North Atlantic sea surface temperature and circulation, and decadal precipitation. We find that the simulated time evolution of global mean surface temperature broadly follows the observed record but with important quantitative differences which we find are most likely attributable to strong effective radiative forcing from anthropogenic aerosols and a weak pattern of sea surface temperature response in the low to middle latitudes to volcanic eruptions. We also find evidence that anthropogenic aerosol forcings play a role in driving the Atlantic Multidecadal Variability and the Atlantic Meridional Overturning Circulation, which are key features of the North Atlantic ocean. Overall, the model historical simulations show many features in common with the observed record over the period 1850–2014 and so provide a basis for future in-depth study of recent climate change.},
author = {Andrews, Martin B. and Ridley, Jeff K. and Wood, Richard A. and Andrews, Timothy and Blockley, Edward W. and Booth, Ben and Burke, Eleanor and Dittus, Andrea J. and Florek, Piotr and Gray, Lesley J. and Haddad, Stephen and Hardiman, Steven C. and Hermanson, Leon and Hodson, Dan and Hogan, Emma and Jones, Gareth S. and Knight, Jeff R. and Kuhlbrodt, Till and Misios, Stergios and Mizielinski, Matthew S. and Ringer, Mark A. and Robson, Jon and Sutton, Rowan T.},
doi = {10.1029/2019MS001995},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {AOGCM,CMIP6,HadGEM3-GC3.1,historical simulations},
number = {6},
pages = {1--34},
title = {{Historical Simulations With HadGEM3-GC3.1 for CMIP6}},
volume = {12},
year = {2020}
}
@article{Andrews2021,
abstract = {Effective radiative forcing (ERF) is evaluated in the ACCESS1.0 General Circulation Model (GCM) with fixed land and sea-surface-temperatures as well as sea-ice. The 4xCO2 ERF is 8.0 Wm-2. In contra...},
author = {Andrews, Timothy and Smith, Christopher J and Myhre, Gunnar and Forster, Piers M. and Chadwick, Robin and Ackerley, Duncan},
doi = {10.1029/2020JD033880},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {feb},
number = {4},
pages = {e2020JD033880},
title = {{Effective Radiative Forcing in a GCM With Fixed Surface Temperatures}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020JD033880},
volume = {126},
year = {2021}
}
@article{Annan2006a,
abstract = {Climate sensitivity has been subjectively estimated to be likely to lie in the range of 1.5?4.5°C, and this uncertainty contributes a substantial part of the total uncertainty in climate change projections over the coming century. Objective observationally-based estimates have so far failed to improve on this upper bound, with many estimates even suggesting a significant probability of climate sensitivity exceeding 6°C. In this paper, we show how it is possible to greatly reduce this uncertainty by using Bayes' Theorem to combine several independent lines of evidence. Based on some conservative assumptions regarding the value of independent estimates, we conclude that climate sensitivity is very unlikely ({\textless}5{\%} probability) to exceed 4.5°C. We cannot assign a significant probability to climate sensitivity exceeding 6°C without making what appear to be wholly unrealistic exaggerations about the uncertainties involved. This represents a significant lowering of the previously-estimated bound.},
annote = {doi: 10.1029/2005GL025259},
author = {Annan, J D and Hargreaves, J C},
doi = {10.1029/2005GL025259},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {mar},
number = {6},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Using multiple observationally-based constraints to estimate climate sensitivity}},
url = {https://doi.org/10.1029/2005GL025259},
volume = {33},
year = {2006}
}
@article{Annan2020,
abstract = {We examine what can be learnt about climate sensitivity from variability in the surface air temper- ature record over the instrumental period, from around 1880 to the present. While many previous studies have used trends in observational time series to constrain equilibrium climate sensitivity, it has also been argued that temporal variability may also be a powerful constraint. We explore this question in the context of a simple widely used energy balance model of the climate system. We consider two recently proposed summary measures of variability and also show how the full information content can be optimally used in this idealised scenario. We find that the constraint provided by variability is inherently skewed, and its power is inversely related to the sensitivity itself, discriminating most strongly between low sensitivity values and weakening substantially for higher values. It is only when the sensitivity is very low that the variability can provide a tight constraint. Our investigations take the form of “perfect model” experiments, in which we make the optimistic assumption that the model is structurally perfect and all uncertainties (including the true parameter values and nature of internal variability noise) are correctly characterised. Therefore the results might be interpreted as a best-case scenario for what we can learn from variability, rather than a realistic estimate of this. In these experiments, we find that for a moderate sensitivity of 2.5 ◦C, a 150-year time series of pure internal variability will typically support an estimate with a 5 {\%}–95{\%} range of around 5 ◦C (e.g. 1.9–6.8 ◦C). Total variability including that due to the forced response, as inferred from the detrended observational record, can provide a stronger constraint with an equivalent 5 {\%}–95 {\%} posterior range of around 4 ◦C (e.g. 1.8–6.0 ◦C) even when uncertainty in aerosol forcing is considered. Using a statistical summary of variability based on autocorrelation and the magnitude of residuals after detrending proves somewhat less powerful as a constraint than the full time series in both situations. Our results support the analysis of variability as a potentially useful tool in helping to constrain equilibrium climate sensitivity but suggest caution in the interpretation of precise results.},
author = {Annan, James Douglas and Hargreaves, Julia Catherine and Mauritsen, Thorsten and Stevens, Bjorn},
doi = {10.5194/esd-11-709-2020},
issn = {2190-4987},
journal = {Earth System Dynamics},
keywords = {Autocorrelation,Climate sensitivity,Climatology,Econometrics,Energy balance,Forcing (mathematics),Geology,Magnitude (mathematics),Surface air temperature,Temperature record,Total variability},
pages = {709--719},
title = {{What could we learn about climate sensitivity from variability in the surface temperature record?}},
volume = {11},
year = {2020}
}
@article{cp-9-367-2013,
author = {Annan, J D and Hargreaves, J C},
doi = {10.5194/cp-9-367-2013},
journal = {Climate of the Past},
number = {1},
pages = {367--376},
title = {{A new global reconstruction of temperature changes at the Last Glacial Maximum}},
url = {https://cp.copernicus.org/articles/9/367/2013/},
volume = {9},
year = {2013}
}
@article{Antuna-Marrero2019,
abstract = {The annual trends of the all sky (Eg↓ASky) and clear sky global horizontal irradiances (Eg↓CSky) for the climatologically standard period 1981–2010 at Camag{\"{u}}ey, Cuba, are negative and positive respectively, showing the simultaneous occurrence of dimming and brightening phenomena. Positive cloud cover (CC) annual trend, is among the plausible causes of the Eg↓ASky dimming. The Eg↓CSky annual mean increasing trend could be explained in part by the decreasing broadband aerosol optical depth trend. For the 1981–2016 a period non-standard climatologically the absolute magnitudes of the trends decrease for both Eg↓ASky and Eg↓CSky annual means, with no change in their signs but becoming non-significant statistically. That feature resembles an attenuation process for both dimming and brightening. The series of Eg↓ and CC observations were subject of test for determining in homogeneities identifying change points. For each one of the Eg↓ASky and Eg↓CSky and CC series show no change point statistically significant. The consistency and stability of the Eg↓ASky annual means series were tested using measured and calculated Eg↓ annual means for conditions where the solar disk is empty of clouds. The magnitudes and signs of trends for the measured and calculated Eg↓ annual means are very similar and both are statistically significant at the same level, confirming the series of Eg↓ASky annual means are consistent and stable.},
author = {Antu{\~{n}}a-Marrero, Juan Carlos and Garc{\'{i}}a, Frank and Estevan, Ren{\'{e}} and Barja, Boris and S{\'{a}}nchez-Lorenzo, Arturo},
doi = {10.1016/j.jastp.2019.05.004},
issn = {13646826},
journal = {Journal of Atmospheric and Solar-Terrestrial Physics},
month = {sep},
pages = {45--53},
publisher = {Elsevier Ltd},
title = {{Simultaneous dimming and brightening under all and clear sky at Camag{\"{u}}ey, Cuba (1981–2010)}},
volume = {190},
year = {2019}
}
@article{Armour2016,
abstract = {The Southern Ocean has shown little warming over recent decades, in stark contrast to the rapid warming observed in the Arctic. Along the northern flank of the Antarctic Circumpolar Current, however, the upper ocean has warmed substantially. Here we present analyses of oceanographic observations and general circulation model simulations showing that these patterns—of delayed warming south of the Antarctic Circumpolar Current and enhanced warming to the north—are fundamentally shaped by the Southern Ocean's meridional overturning circulation: wind-driven upwelling of unmodified water from depth damps warming around Antarctica; greenhouse gas-induced surface heat uptake is largely balanced by anomalous northward heat transport associated with the equatorward flow of surface waters; and heat is preferentially stored where surface waters are subducted to the north. Further, these processes are primarily due to passive advection of the anomalous warming signal by climatological ocean currents; changes in ocean circulation are secondary. These findings suggest the Southern Ocean responds to greenhouse gas forcing on the centennial, or longer, timescale over which the deep ocean waters that are upwelled to the surface are warmed themselves. It is against this background of gradual warming that multidecadal Southern Ocean temperature trends must be understood.},
author = {Armour, Kyle C. and Marshall, John and Scott, Jeffery R. and Donohoe, Aaron and Newsom, Emily R.},
doi = {10.1038/ngeo2731},
isbn = {1752-0908},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {jul},
number = {7},
pages = {549--554},
title = {{Southern Ocean warming delayed by circumpolar upwelling and equatorward transport}},
url = {http://www.nature.com/articles/ngeo2731},
volume = {9},
year = {2016}
}
@article{Armour2013,
abstract = {The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback—the global radiative response per degree of global annual mean surface temperature change. While the global climate feedback is often assumed to be constant, its value—diagnosed from global climate models—shows substantial time variation under transient warming. Here a reformulation of the global climate feedback in terms of its contributions from regional climate feedbacks is proposed, providing a clear physical insight into this behavior. Using (i) a state-of-the-art global climate model and (ii) a low-order energy balance model, it is shown that the global climate feedback is fundamentally linked to the geographic pattern of regional climate feedbacks and the geographic pattern of surface warming at any given time. Time variation of the global climate feedback arises naturally when the pattern of surface warming evolves, actuating feedbacks of different strengths in different regions. This result has substantial implications for the ability to constrain future climate changes from observations of past and present climate states. The regional climate feedbacks formulation also reveals fundamental biases in a widely used method for diagnosing climate sensitivity, feedbacks, and radiative forcing—the regression of the global top-of-atmosphere radiation flux on global surface temperature. Further, it suggests a clear mechanism for the “efficacies” of both ocean heat uptake and radiative forcing.},
author = {Armour, Kyle C. and Bitz, Cecilia M. and Roe, Gerard H.},
doi = {10.1175/JCLI-D-12-00544.1},
isbn = {0894-8755},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jul},
number = {13},
pages = {4518--4534},
title = {{Time-Varying Climate Sensitivity from Regional Feedbacks}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-12-00544.1},
volume = {26},
year = {2013}
}
@article{Armour2019,
abstract = {Meridional atmospheric heat transport (AHT) has been investigated through three broad perspectives: a dynamic perspective, linking AHT to the poleward flux of moist static energy (MSE) by atmospheric motions; an energetic perspective, linking AHT to energy input to the atmosphere by top-of-atmosphere radiation and surface heat fluxes; and a diffusive perspective, representing AHT in terms down-gradient energy transport. It is shown here that the three perspectives provide complementary diagnostics of meridional AHT and its changes under greenhouse-gas forcing. When combined, the energetic and diffusive perspectives offer prog-nostic insights: anomalous AHT is constrained to satisfy the net energetic demands of radiative forcing, radiative feedbacks, and ocean heat uptake; in turn, the meridional pattern of warming must adjust to produce those AHT changes, and does so approximately according to diffusion of anomalous MSE. The relationship between temperature and MSE exerts strong constraints on the warming pattern, favoring polar amplification. These conclusions are supported by use of a diffusive moist energy balance model (EBM) that accurately predicts zonal-mean warming and AHT changes within comprehensive general circulation models (GCMs). A dry diffusive EBM predicts similar AHT changes in order to satisfy the same energetic constraints, but does so through tropically-amplified warming-at odds with the GCMs' polar-amplified warming pattern. The results suggest that polar-amplified warming is a near-inevitable consequence of a moist, diffusive at-mosphere's response to greenhouse-gas forcing. In this view, atmospheric circulations must act to satisfy net AHT as constrained by energetics.},
author = {Armour, Kyle C and Siler, Nicholas and Donohoe, Aaron and Roe, Gerard H},
doi = {10.1175/JCLI-D-18-0563.1},
journal = {Journal of Climate},
number = {12},
pages = {3655--3680},
title = {{Meridional Atmospheric Heat Transport Constrained by Energetics and Mediated by Large-Scale Diffusion}},
volume = {32},
year = {2019}
}
@article{Armour2011,
abstract = {Climate commitment—the warming that would still occur given no further human influence—is a fundamental metric for both science and policy. It informs us of the minimum climate change we face and, moreover, depends only on our knowledge of the natural climate system. Studies of the climate commitment due to CO2 find that global temperature would remain near current levels, or even decrease slightly, in the millennium following the cessation of emissions. However, this result overlooks the important role of the non-CO2 greenhouse gases and aerosols. This paper shows that global energetics require an immediate and significant warming following the cessation of emissions as aerosols are quickly washed from the atmosphere, and the large uncertainty in current aerosol radiative forcing implies a large uncertainty in the climate commitment. Fundamental constraints preclude Earth returning to pre-industrial temperatures for the indefinite future. These same constraints mean that observations are currently unable to eliminate the possibility that we are already beyond the point where the ultimate warming will exceed dangerous levels. Models produce a narrower range of climate commitment, but undersample observed forcing constraints.},
author = {Armour, K. C. and Roe, G. H.},
doi = {10.1029/2010GL045850},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {jan},
number = {1},
pages = {L01707},
title = {{Climate commitment in an uncertain world}},
url = {http://doi.wiley.com/10.1029/2010GL045850},
volume = {38},
year = {2011}
}
@article{Armour2017,
abstract = {Global energy budget constraints1, 2, 3 suggest an equilibrium climate sensitivity around 2 °C, which is lower than estimates from palaeoclimate reconstructions4, process-based observational analyses5, 6, 7, and global climate model simulations8, 9. A key assumption is that the climate sensitivity inferred today also applies to the distant future. Yet, global climate models robustly show that feedbacks vary over time, with a strong tendency for climate sensitivity to increase as equilibrium is approached9, 10, 11, 12, 13, 14, 15, 16, 17, 18. Here I consider the implications of inconstant climate feedbacks for energy budget constraints on climate sensitivity. I find that the long-term value of climate sensitivity is, on average, 26{\%} above that inferred during transient warming within global climate models, with a larger discrepancy when climate sensitivity is high. Moreover, model values of climate sensitivity inferred during transient warming are found to be consistent with energy budget observations1, 2, 3, indicating that the models are not overly sensitive. Using model-based estimates of how climate feedbacks will change in the future, in conjunction with recent energy budget constraints1, 19, produces a current best estimate of equilibrium climate sensitivity of 2.9 °C (1.7–7.1 °C, 90{\%} confidence). These findings suggest that climate sensitivity estimated from global energy budget constraints is in agreement with values derived from other methods and simulated by global climate models.},
author = {Armour, Kyle C.},
doi = {10.1038/nclimate3278},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {may},
number = {5},
pages = {331--335},
title = {{Energy budget constraints on climate sensitivity in light of inconstant climate feedbacks}},
url = {http://www.nature.com/articles/nclimate3278},
volume = {7},
year = {2017}
}
@article{Armstrong2019,
abstract = {The Atlantic Meridional Overturning Circulation (AMOC) is an important component of the climate system, however its sensitivity to the terrestrial biosphere has been largely overlooked. Here the HadCM3 coupled climate model is run for millennial timescales to investigate the feedbacks between vegetation and the AMOC at increasing CO2. The impact of agricultural conversion (termed land-use change; LUC) and the role of the simulated ‘background' vegetation (termed land cover change; LCC) are investigated. LUC cools climate in regions of high crop fraction due to increased albedo. LCC is shown to evolve at higher CO2, with a northward migration of the tree line in the Northern Hemisphere and dieback of the Amazon. This generally acts to enhance the impact of climate change primarily due to albedo changes. Density in the Greenland-Iceland-Norwegian (GIN) Seas is crucial in driving the AMOC. Increasing CO2 decreases regional sea surface density, reducing convection and weakening the AMOC. The inclusion of LCC is shown to be responsible for a significant proportion of this weakening; reflecting the amplification effect it has on climate change. This acts to decrease the surface density in the GIN Seas. At elevated CO2 (1400 ppm) the inclusion of dynamic vegetation is shown to drive a reduction in AMOC strength from 6 to 20{\%}. Despite the cooling effect of LUC, the impact on the AMOC is shown to be small reflecting minimal impact it has on GIN Sea density. These results indicate the importance of including dynamic vegetation in future AMOC studies using HadCM3, but LUC may be insignificant. In the context of other climate models however, the importance of vegetation is likely to be overshadowed by other systemic model biases.},
author = {Armstrong, Edward and Valdes, Paul and House, Jo and Singarayer, Joy},
doi = {10.1007/s00382-019-04634-2},
isbn = {0123456789},
issn = {14320894},
journal = {Climate Dynamics},
number = {5-6},
pages = {2485--2500},
publisher = {Springer Berlin Heidelberg},
title = {{Investigating the feedbacks between CO2, vegetation and the AMOC in a coupled climate model}},
volume = {53},
year = {2019}
}
@article{Arora2013,
abstract = {AbstractThe magnitude and evolution of parameters that characterize feedbacks in the coupled carbon–climate system are compared across nine Earth system models (ESMs). The analysis is based on results from biogeochemically, radiatively, and fully coupled simulations in which CO2 increases at a rate of 1{\%} yr−1. These simulations are part of phase 5 of the Coupled Model Intercomparison Project (CMIP5). The CO2 fluxes between the atmosphere and underlying land and ocean respond to changes in atmospheric CO2 concentration and to changes in temperature and other climate variables. The carbon–concentration and carbon–climate feedback parameters characterize the response of the CO2 flux between the atmosphere and the underlying surface to these changes. Feedback parameters are calculated using two different approaches. The two approaches are equivalent and either may be used to calculate the contribution of the feedback terms to diagnosed cumulative emissions. The contribution of carbon–concentration feedback to...},
author = {Arora, Vivek K. and Boer, George J. and Friedlingstein, Pierre and Eby, Michael and Jones, Chris D. and Christian, James R. and Bonan, Gordon and Bopp, Laurent and Brovkin, Victor and Cadule, Patricia and Hajima, Tomohiro and Ilyina, Tatiana and Lindsay, Keith and Tjiputra, Jerry F. and Wu, Tongwen},
doi = {10.1175/JCLI-D-12-00494.1},
isbn = {0894-8755$\backslash$r1520-0442},
issn = {08948755},
journal = {Journal of Climate},
number = {15},
pages = {5289--5314},
pmid = {1331},
title = {{Carbon–concentration and carbon–climate feedbacks in CMIP5 earth system models}},
volume = {26},
year = {2013}
}
@article{Arora2020a,
abstract = {Results from the fully and biogeochemically coupled simulations in which CO2 increases at a rate of 1{\%}yr-1 (1pctCO2) from its preindustrial value are analyzed to quantify the magnitude of carbon-concentration and carbon-climate feedback parameters which measure the response of ocean and terrestrial carbon pools to changes in atmospheric CO2 concentration and the resulting change in global climate, respectively. The results are based on 11 comprehensive Earth system models from the most recent uncertain over land than over ocean as has been seen in existing studies. These values and their spread from 11 CMIP6 models have not changed significantly compared to CMIP5 models. The absolute values of feedback parameters are lower for land with models that include a representation of nitrogen cycle. The transient climate response to cumulative emissions (TCRE) from the 11 CMIP6 models considered here is 1.77±0.37 ° C EgC-1 and is similar to that found in CMIP5 models (1.63±0.48 °C EgC-1) but with somewhat reduced model spread. The expressions for feedback parameters based on the fully and biogeochemically coupled configurations of the 1pctCO2 simulation are simplified when the small temperature change in the biogeochemically coupled simulation is ignored. Decomposition of the terms of these simplified expressions for the feedback parameters is used to gain insight into the reasons for differing responses among ocean and land carbon cycle models.},
author = {Arora, Vivek K. and Katavouta, Anna and Williams, Richard G. and Jones, Chris D. and Brovkin, Victor and Friedlingstein, Pierre and Schwinger, J{\"{o}}rg and Bopp, Laurent and Boucher, Olivier and Cadule, Patricia and Chamberlain, Matthew A. and Christian, James R. and Delire, Christine and Fisher, A. Rosie A. and Hajima, Tomohiro and Ilyina, Tatiana and Joetzjer, Emilie and Kawamiya, Michio and Koven, Charles D. and Krasting, John P. and Law, Rachel M. and Lawrence, David M. and Lenton, Andrew and Lindsay, Keith and Pongratz, Julia and Raddatz, Thomas and S{\'{e}}f{\'{e}}rian, Roland and Tachiiri, Kaoru and Tjiputra, Jerry F. and Wiltshire, Andy and Wu, Tongwen and Ziehn, Tilo},
doi = {10.5194/bg-17-4173-2020},
issn = {17264189},
journal = {Biogeosciences},
month = {aug},
number = {16},
pages = {4173--4222},
publisher = {Copernicus GmbH},
title = {{Carbon–concentration and carbon–climate feedbacks in CMIP6 models and their comparison to CMIP5 models}},
volume = {17},
year = {2020}
}
@article{Arrhenius1896,
author = {Arrhenius, Svante},
doi = {10.1080/14786449608620846},
journal = {The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science},
number = {251},
pages = {237--276},
title = {{On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground}},
url = {https://www.tandfonline.com/doi/abs/10.1080/14786449608620846},
volume = {41},
year = {1896}
}
@article{Ashwin2020,
abstract = {A climate state close to a tipping point will have a degenerate linear response to perturbations, which can be associated with extreme values of the equilibrium climate sensitivity (ECS). In this paper we contrast linearized (‘instantaneous') with fully nonlinear geometric (‘two-point') notions of ECS, in both presence and absence of tipping points. For a stochastic energy balance model of the global mean surface temperature with two stable regimes, we confirm that tipping events cause the appearance of extremes in both notions of ECS. Moreover, multiple regimes with different mean sensitivities are visible in the two-point ECS. We confirm some of our findings in a physics-based multi-box model of the climate system.},
author = {Ashwin, Peter and von der Heydt, Anna S},
doi = {10.1007/s10955-019-02425-x},
issn = {1572-9613},
journal = {Journal of Statistical Physics},
number = {5},
pages = {1531--1552},
title = {{Extreme Sensitivity and Climate Tipping Points}},
url = {https://doi.org/10.1007/s10955-019-02425-x},
volume = {179},
year = {2020}
}
@article{Augustine2013a,
abstract = {Sixteen years of high-quality surface radiation budget (SRB) measurements over seven U.S. stations are summarized. The network average total surface net radiation increases by +8.2 Wm(-2) per decade from 1996 to 2011. A significant upward trend in downwelling shortwave (SW-down) of +6.6 Wm(-2) per decade dominates the total surface net radiation signal. This SW brightening is attributed to a decrease in cloud coverage, and aerosols have only a minor effect. Increasing downwelling longwave (LW-down) of +1.5 Wm (2) per decade and decreasing upwelling LW (LW-up) of -0.9 Wm(-2) per decade produce a +2.3 Wm(-2) per decade increase in surface net-LW, which dwarfs the expected contribution to LW-down from the 30 ppm increase of CO2 during the analysis period. The dramatic surface net radiation excess should have stimulated surface energy fluxes, but, oddly, the temperature trend is flat, and specific humidity decreases. The enigmatic nature of LW-down, temperature, and moisture may be a chaotic result of their large interannual variations. Interannual variation of the El Nino/Southern Oscillation (ENSO) ONI index is shown to be moderately correlated with temperature, moisture, and LW-down. Thus, circulations associated with ENSO events may be responsible for manipulating (e.g., by advection or convection) the excess surface energy available from the SRB increase. It is clear that continued monitoring is necessary to separate the SRB's response to long-term climate processes from natural variability and that collocated surface energy flux measurements at the SRB stations would be beneficial. Citation: Augustine, J.A., and E.G. Dutton (2013), Variability of the surface radiation budget over the United States from 1996 through 2011 from high-quality measurements, J. Geophys. Res. Atmos., 118, 43-53, doi: 10.1029/2012JD018551.},
address = {Augustine, JA NOAA, Earth Syst Res Lab, Global Monitoring Div, Boulder, CO USA NOAA, Earth Syst Res Lab, Global Monitoring Div, Boulder, CO USA NOAA, Earth Syst Res Lab, Global Monitoring Div, Boulder, CO USA},
annote = {129JI
Times Cited:8
Cited References Count:43},
author = {Augustine, J A and Dutton, E G},
doi = {10.1029/2012jd018551},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {climate radiometer network pyrgeometers pyranomete},
language = {English},
number = {1},
pages = {43--53},
title = {{Variability of the surface radiation budget over the United States from 1996 through 2011 from high-quality measurements}},
volume = {118},
year = {2013}
}
@article{Baggenstos2019,
abstract = {The energy imbalance at the top of the atmosphere determines the temporal evolution of the global climate, and vice versa changes in the climate system can alter the planetary energy fluxes. This interplay is fundamental to our understanding of Earth's heat budget and the climate system. However, even today, the direct measurement of global radiative fluxes is difficult, such that most assessments are based on changes in the total energy content of the climate system. We apply the same approach to estimate the long-term evolution of Earth's radiative imbalance in the past. New measurements of noble gas-derived mean ocean temperature from the European Project for Ice Coring in Antarctica Dome C ice core covering the last 40,000 y, combined with recent results from the West Antarctic Ice Sheet Divide ice core and the sea-level record, allow us to quantitatively reconstruct the history of the climate system energy budget. The temporal derivative of this quantity must be equal to the planetary radiative imbalance. During the deglaciation, a positive imbalance of typically +0.2 W{\textperiodcentered}m−2 is maintained for ∼10,000 y, however, with two distinct peaks that reach up to 0.4 W{\textperiodcentered}m−2 during times of substantially reduced Atlantic Meridional Overturning Circulation. We conclude that these peaks are related to net changes in ocean heat uptake, likely due to rapid changes in North Atlantic deep-water formation and their impact on the global radiative balance, while changes in cloud coverage, albeit uncertain, may also factor into the picture.},
author = {Baggenstos, Daniel and H{\"{a}}berli, Marcel and Schmitt, Jochen and Shackleton, Sarah A. and Birner, Benjamin and Severinghaus, Jeffrey P. and Kellerhals, Thomas and Fischer, Hubertus},
doi = {10.1073/pnas.1905447116},
issn = {10916490},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Deglaciation,Energy budget,Ice cores,Noble gases,Paleoclimate},
month = {jul},
number = {30},
pages = {14881--14886},
pmid = {31285336},
publisher = {National Academy of Sciences},
title = {{Earth's radiative imbalance from the Last Glacial Maximum to the present}},
volume = {116},
year = {2019}
}
@article{Balcombe2018,
abstract = {We compare and make recommendations for the use of different climate metrics and time horizons with respect to methane emissions, applying to a case study of LNG as a shipping fuel.},
author = {Balcombe, Paul and Speirs, Jamie F and Brandon, Nigel P. and Hawkes, Adam D},
doi = {10.1039/C8EM00414E},
file = {::},
issn = {2050-7887},
journal = {Environmental Science: Processes {\&} Impacts},
number = {10},
pages = {1323--1339},
title = {{Methane emissions: choosing the right climate metric and time horizon}},
url = {http://xlink.rsc.org/?DOI=C8EM00414E},
volume = {20},
year = {2018}
}
@article{Banerjee2019,
author = {Banerjee, Antara and Chiodo, Gabriel and Previdi, Michael and Ponater, Michael and Conley, Andrew J and Polvani, Lorenzo M},
doi = {10.1007/s00382-019-04721-4},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {3},
pages = {1697--1710},
title = {{Stratospheric water vapor: an important climate feedback}},
url = {https://doi.org/10.1007/s00382-019-04721-4},
volume = {53},
year = {2019}
}
@article{Barreiro2008,
abstract = {A decrease in cloud cover over higher latitudes—a decrease in the extratropical albedo—especially over the Southern Ocean, can result in an extratropical and tropical warming with the intensity of the equatorial cold tongues in the Pacific and Atlantic basins decreasing. These results, obtained by means of a coupled ocean–atmosphere model of intermediate complexity that allow the prescription of atmospheric cloud cover, are relevant to future global warming, and also to conditions during the Pliocene some 3 million years ago. The mechanisms responsible for the response of the tropics to changes in the extra-tropics include atmospheric and oceanic connections. This tropical adjustment can be interpreted from the constraint of a balanced heat budget for the ocean: A change in the albedo of the Southern Hemisphere causes the ocean to lose less heat there, so that it has to gain less heat in the tropics. As a consequence the cold tongues are reduced, particularly in the eastern Pacific where a decrease in the zonal tilt of the equatorial thermocline significantly weakens the east-west sea surface temperature gradient. The total adjustment time scale of the equatorial Pacific to the extratropical perturbation is of the order of interdecadal to centennial time scales, and thus represents a new mechanism of rapid climate change.},
author = {Barreiro, Marcelo and Philander, S. George},
doi = {10.1007/s00382-007-0363-5},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {nov},
number = {6},
pages = {713--729},
title = {{Response of the tropical Pacific to changes in extratropical clouds}},
url = {http://link.springer.com/10.1007/s00382-007-0363-5},
volume = {31},
year = {2008}
}
@article{Bartlein2011,
abstract = {Subfossil pollen and plant macrofossil data derived from 14C-dated sediment profiles can provide quantitative information on glacial and interglacial climates. The data allow climate variables related to growing-season warmth, winter cold, and plant-available moisture to be reconstructed. Continental-scale reconstructions have been made for the mid-Holocene (MH, around 6 ka) and Last Glacial Maximum (LGM, around 21 ka), allowing comparison with palaeoclimate simulations currently being carried out as part of the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change. The synthesis of the available MH and LGM climate reconstructions and their uncertainties, obtained using modern-analogue, regression and model-inversion techniques, is presented for four temperature variables and two moisture variables. Reconstructions of the same variables based on surface-pollen assemblages are shown to be accurate and unbiased. Reconstructed LGM and MH climate anomaly patterns are coherent, consistent between variables, and robust with respect to the choice of technique. They support a conceptual model of the controls of Late Quaternary climate change whereby the first-order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance.},
author = {Bartlein, P J and Harrison, S P and Brewer, S and Connor, S and Davis, B A S and Gajewski, K and Guiot, J and Harrison-Prentice, T I and Henderson, A and Peyron, O and Prentice, I C and Scholze, M and Sepp{\"{a}}, H and Shuman, B and Sugita, S and Thompson, R S and Viau, A E and Williams, J and Wu, H},
doi = {10.1007/s00382-010-0904-1},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {3},
pages = {775--802},
title = {{Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis}},
url = {https://doi.org/10.1007/s00382-010-0904-1},
volume = {37},
year = {2011}
}
@article{doi:10.1002/jgrd.50612,
abstract = {AbstractIce core measurements in conjunction with climate model simulations are of tremendous value when examining anthropogenic and natural aerosol loads and their role in past and future climates. Refractory black carbon (BC) records from the Arctic, the Antarctic, and the Himalayas are analyzed using three transient climate simulations performed with the Goddard Institute for Space Studies ModelE. Simulations differ in aerosol schemes (bulk aerosols vs. aerosol microphysics) and ocean couplings (fully coupled vs. prescribed ocean). Regional analyses for past (1850–2005) and future (2005–2100) carbonaceous aerosol simulations focus on the Antarctic, Greenland, and the Himalayas. Measurements from locations in the Antarctic show clean conditions with no detectable trend over the past 150 years. Historical atmospheric deposition of BC and sulfur in Greenland shows strong trends and is primarily influenced by emissions from early twentieth century agricultural and domestic practices. Models fail to reproduce observations of a sharp eightfold BC increase in Greenland at the beginning of the twentieth century that could be due to the only threefold increase in the North American emission inventory. BC deposition in Greenland is about 10 times greater than in Antarctica and 10 times less than in Tibet. The Himalayas show the most complicated transport patterns, due to the complex terrain and dynamical regimes of this region. Projections of future climate based on the four CMIP5 Representative Concentration Pathways indicate further dramatic advances of pollution to the Tibetan Plateau along with decreasing BC deposition fluxes in Greenland and the Antarctic.},
author = {Bauer, Susanne E and Bausch, Alexandra and Nazarenko, Larissa and Tsigaridis, Kostas and Xu, Baiqing and Edwards, Ross and Bisiaux, Marion and McConnell, Joe},
doi = {10.1002/jgrd.50612},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aerosol,black carbon,deposition},
number = {14},
pages = {7948--7961},
title = {{Historical and future black carbon deposition on the three ice caps: Ice core measurements and model simulations from 1850 to 2100}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/jgrd.50612},
volume = {118},
year = {2013}
}
@article{Beerling2011,
abstract = {Reconstructions of atmospheric carbon dioxide concentrations over the past 65 million years are heading towards consensus. It is time for systematic testing of the proxies, against measurements and against each other.},
author = {Beerling, David J and Royer, Dana L},
doi = {10.1038/ngeo1186},
issn = {1752-0908},
journal = {Nature Geoscience},
number = {7},
pages = {418--420},
title = {{Convergent Cenozoic CO2 history}},
url = {https://doi.org/10.1038/ngeo1186},
volume = {4},
year = {2011}
}
@article{Bellouin2013,
abstract = {Abstract. The Hadley Centre Global Environmental Model (HadGEM) includes two aerosol schemes: the Coupled Large-scale Aerosol Simulator for Studies in Climate (CLASSIC), and the new Global Model of Aerosol Processes (GLOMAP-mode). GLOMAP-mode is a modal aerosol microphysics scheme that simulates not only aerosol mass but also aerosol number, represents internally-mixed particles, and includes aerosol microphysical processes such as nucleation. In this study, both schemes provide hindcast simulations of natural and anthropogenic aerosol species for the period 2000–2006. HadGEM simulations of the aerosol optical depth using GLOMAP-mode compare better than CLASSIC against a data-assimilated aerosol re-analysis and aerosol ground-based observations. Because of differences in wet deposition rates, GLOMAP-mode sulphate aerosol residence time is two days longer than CLASSIC sulphate aerosols, whereas black carbon residence time is much shorter. As a result, CLASSIC underestimates aerosol optical depths in continental regions of the Northern Hemisphere and likely overestimates absorption in remote regions. Aerosol direct and first indirect radiative forcings are computed from simulations of aerosols with emissions for the year 1850 and 2000. In 1850, GLOMAP-mode predicts lower aerosol optical depths and higher cloud droplet number concentrations than CLASSIC. Consequently, simulated clouds are much less susceptible to natural and anthropogenic aerosol changes when the microphysical scheme is used. In particular, the response of cloud condensation nuclei to an increase in dimethyl sulphide emissions becomes a factor of four smaller. The combined effect of different 1850 baselines, residence times, and abilities to affect cloud droplet number, leads to substantial differences in the aerosol forcings simulated by the two schemes. GLOMAP-mode finds a present-day direct aerosol forcing of {\&}minus;0.49 W m{\&}minus;2 on a global average, 72{\%} stronger than the corresponding forcing from CLASSIC. This difference is compensated by changes in first indirect aerosol forcing: the forcing of {\&}minus;1.17 W m{\&}minus;2 obtained with GLOMAP-mode is 20{\%} weaker than with CLASSIC. Results suggest that mass-based schemes such as CLASSIC lack the necessary sophistication to provide realistic input to aerosol-cloud interaction schemes. Furthermore, the importance of the 1850 baseline highlights how model skill in predicting present-day aerosol does not guarantee reliable forcing estimates. Those findings suggest that the more complex representation of aerosol processes in microphysical schemes improves the fidelity of simulated aerosol forcings.},
author = {Bellouin, N. and Mann, G. W. and Woodhouse, M. T. and Johnson, C. and Carslaw, K. S. and Dalvi, M.},
doi = {10.5194/acp-13-3027-2013},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {mar},
number = {6},
pages = {3027--3044},
title = {{Impact of the modal aerosol scheme GLOMAP-mode on aerosol forcing in the Hadley Centre Global Environmental Model}},
url = {https://www.atmos-chem-phys.net/13/3027/2013/},
volume = {13},
year = {2013}
}
@article{Bellouin2013a,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} The European Centre for Medium-range Weather Forecast (ECMWF) provides an aerosol re-analysis starting from year 2003 for the Monitoring Atmospheric Composition and Climate (MACC) project. The re-analysis assimilates total aerosol optical depth retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS) to correct for model departures from observed aerosols. The re-analysis therefore combines satellite retrievals with the full spatial coverage of a numerical model. Re-analysed products are used here to estimate the shortwave direct and first indirect radiative forcing of anthropogenic aerosols over the period 2003–2010, using methods previously applied to satellite retrievals of aerosols and clouds. The best estimate of globally-averaged, all-sky direct radiative forcing is −0.7 ± 0.3 Wm{\textless}sup{\textgreater}{\&}minus;2{\textless}/sup{\textgreater}. The standard deviation is obtained by a Monte-Carlo analysis of uncertainties, which accounts for uncertainties in the aerosol anthropogenic fraction, aerosol absorption, and cloudy-sky effects. Further accounting for differences between the present-day natural and pre-industrial aerosols provides a direct radiative forcing estimate of −0.4 ± 0.3 Wm{\textless}sup{\textgreater}{\&}minus;2{\textless}/sup{\textgreater}. The best estimate of globally-averaged, all-sky first indirect radiative forcing is −0.6 ± 0.4 Wm{\textless}sup{\textgreater}{\&}minus;2{\textless}/sup{\textgreater}. Its standard deviation accounts for uncertainties in the aerosol anthropogenic fraction, and in cloud albedo and cloud droplet number concentration susceptibilities to aerosol changes. The distribution of first indirect radiative forcing is asymmetric and is bounded by −0.1 and −2.0 Wm{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}. In order to decrease uncertainty ranges, better observational constraints on aerosol absorption and sensitivity of cloud droplet number concentrations to aerosol changes are required.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Bellouin, N. and Quaas, J. and Morcrette, J.-J. and Boucher, O.},
doi = {10.5194/acp-13-2045-2013},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {feb},
number = {4},
pages = {2045--2062},
title = {{Estimates of aerosol radiative forcing from the MACC re-analysis}},
url = {https://www.atmos-chem-phys.net/13/2045/2013/},
volume = {13},
year = {2013}
}
@article{Bellouin2019,
author = {Bellouin, N. and Quaas, J. and Gryspeerdt, E. and Kinne, S. and Stier, P. and Watson‐Parris, D. and Boucher, O. and Carslaw, K. S. and Christensen, M. and Daniau, A.‐L. and Dufresne, J.‐L. and Feingold, G. and Fiedler, S. and Forster, P. and Gettelman, A. and Haywood, J. M. and Lohmann, U. and Malavelle, F. and Mauritsen, T. and McCoy, D. T. and Myhre, G. and M{\"{u}}lmenst{\"{a}}dt, J. and Neubauer, D. and Possner, A. and Rugenstein, M. and Sato, Y. and Schulz, M. and Schwartz, S. E. and Sourdeval, O. and Storelvmo, T. and Toll, V. and Winker, D. and Stevens, B.},
doi = {10.1029/2019RG000660},
issn = {8755-1209},
journal = {Reviews of Geophysics},
month = {mar},
number = {1},
pages = {e2019RG000660},
title = {{Bounding Global Aerosol Radiative Forcing of Climate Change}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019RG000660 https://onlinelibrary.wiley.com/doi/10.1029/2019RG000660},
volume = {58},
year = {2020}
}
@article{Bender2010,
abstract = {The radiative flux perturbations and subsequent temperature responses in relation to the eruption of Mount Pinatubo in 1991 are studied in the ten general circulation models incorporated in the Coupled Model Intercomparison Project, phase 3 (CMIP3), that include a parameterization of volcanic aerosol. Models and observations show decreases in global mean temperature of up to 0.5 K, in response to radiative perturbations of up to 10 W m−2, averaged over the tropics. The time scale representing the delay between radiative perturbation and temperature response is determined by the slow ocean response, and is estimated to be centered around 4 months in the models. Although the magniude of the temperature response to a volcanic eruption has previously been used as an indicator of equilibrium climate sensitivity in models, we find these two quantities to be only weakly correlated. This may partly be due to the fact that the size of the volcano-induced radiative perturbation varies among the models. It is found that the magnitude of the modelled radiative perturbation increases with decreasing climate sensitivity, with the exception of one outlying model. Therefore, we scale the temperature perturbation by the radiative perturbation in each model, and use the ratio between the integrated temperature perturbation and the integrated radiative perturbation as a measure of sensitivity to volcanic forcing. This ratio is found to be well correlated with the model climate sensitivity, more sensitive models having a larger ratio. Further, if this correspondence between volcanic sensitivity and sensitivity to CO2 forcing is a feature not only among the models, but also of the real climate system, the alleged linear relation can be used to estimate the real climate sensitivity. The observational value of the ratio signifying volcanic sensitivity is hereby estimated to correspond to an equilibrium climate sensitivity, i.e. equilibrium temperature increase due to a doubling of the CO2 concentration, between 1.7 and 4.1 K. Several sources of uncertainty reside in the method applied, and it is pointed out that additional model output, related to ocean heat storage and radiative forcing, could refine the analysis, as could reduced uncertainty in the observational record, of temperature as well as forcing.},
author = {Bender, Frida A.-M. and Ekman, Annica M.L. and Rodhe, Henning},
doi = {10.1007/s00382-010-0777-3},
isbn = {0930-7575},
issn = {09307575},
journal = {Climate Dynamics},
keywords = {Climate sensitivity,GCM,Volcanic eruption},
number = {5},
pages = {875--886},
title = {{Response to the eruption of Mount Pinatubo in relation to climate sensitivity in the CMIP3 models}},
volume = {35},
year = {2010}
}
@article{Bender2012a,
author = {Bender, F. A.-M. and Ramanathan, V. and Tselioudis, G.},
doi = {https://doi.org/10.1007/s00382-011-1065-6},
journal = {Climate Dynamics},
pages = {2037--2053},
title = {{Changes in extratropical storm track cloudiness 1983–2008: Observational support for a poleward shift}},
volume = {38},
year = {2012}
}
@article{Bender2019,
abstract = {Representing large-scale co-variability between variables related to aerosols, clouds and radiation is one of many aspects of agreement with observations desirable for a climate model. In this study such relations are investigated in terms of temporal correlations on monthly mean scale, to identify points of agreement and disagreement with observations. Ten regions with different meteorological characteristics and aerosol signatures are studied and correlation matrices for the selected regions offer an overview of model ability to represent present day climate variability. Global climate models with different levels of detail and sophistication in their representation of aerosols and clouds are compared with satellite observations and reanalysis assimilating meteorological fields as well as aerosol optical depth from observations. One example of how the correlation comparison can guide model evaluation and development is the often studied relation between cloud droplet number and water content. Reanalysis, with no parameterized aerosol–cloud coupling, shows weaker correlations than observations, indicating that microphysical couplings between cloud droplet number and water content are not negligible for the co-variations emerging on larger scale. These observed correlations are, however, not in agreement with those expected from dominance of the underlying microphysical aerosol–cloud couplings. For instance, negative correlations in subtropical stratocumulus regions show that suppression of precipitation and subsequent increase in water content due to aerosol is not a dominating process on this scale. Only in one of the studied models are cloud dynamics able to overcome the parameterized dependence of rain formation on droplet number concentration, and negative correlations in the stratocumulus regions are reproduced.},
author = {Bender, F. A.-M. and Frey, L. and McCoy, D. T. and Grosvenor, D. P. and Mohrmann, J. K.},
doi = {10.1007/s00382-018-4384-z},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Aerosol–cloud–radiation interaction,GCM-evaluation,Reanalysis,Satellite observations,Volcanic aerosol},
month = {apr},
number = {7-8},
pages = {4371--4392},
publisher = {Springer Verlag},
title = {{Assessment of aerosol–cloud–radiation correlations in satellite observations, climate models and reanalysis}},
volume = {52},
year = {2019}
}
@article{Bender-2011,
author = {Bender, Frida A.-M.},
doi = {10.1007/s00704-011-0411-2},
journal = {Theoretical and Applied Climatology},
number = {3-4},
pages = {529--535},
title = {{Planetary albedo in strongly forced climate, as simulated by the CMIP3 models}},
volume = {105},
year = {2011}
}
@article{Bengtsson2013,
author = {Bengtsson, Lennart and Schwartz, Stephen E.},
doi = {10.3402/tellusb.v65i0.21533},
issn = {1600-0889},
journal = {Tellus B: Chemical and Physical Meteorology},
keywords = {aerosols,climate sensitivity,for his,forcing,greenhouse gases,in honor of the,late professor bert bolin,ocean heat uptake,of a thematic cluster,outstanding contributions to climate,science,temperature change,this paper is part},
month = {dec},
number = {1},
pages = {21533},
title = {{Determination of a lower bound on Earth's climate sensitivity}},
url = {https://www.tandfonline.com/doi/full/10.3402/tellusb.v65i0.21533},
volume = {65},
year = {2013}
}
@article{ISI:000412866400015,
abstract = {For over a decade, several research groups have been developing air-sea heat flux information over the global ocean, including latent (LHF) and sensible (SHF) heat fluxes over the global ocean. This paper aims to provide new insight into the quality and error characteristics of turbulent heat flux estimates at various spatial and temporal scales (from daily upwards). The study is performed within the European Space Agency (ESA) Ocean Heat Flux (OHF) project. One of the main objectives of the OHF project is to meet the recommendations and requirements expressed by various international programs such as the World Research Climate Program (WCRP) and Climate and Ocean Variability, Predictability, and Change (CLIVAR), recognizing the need for better characterization of existing flux errors with respect to the input bulk variables (e.g. surface wind, air and sea surface temperatures, air and surface specific humidities), and to the atmospheric and oceanic conditions (e.g. wind conditions and sea state). The analysis is based on the use of daily averaged LHF and SHF and the associated bulk variables derived from major satellite-based and atmospheric reanalysis products. Inter-comparisons of heat flux products indicate that all of them exhibit similar space and time patterns. However, they also reveal significant differences in magnitude in some specific regions such as the western ocean boundaries during the Northern Hemisphere winter season, and the high southern latitudes. The differences tend to be closely related to large differences in surface wind speed and/or specific air humidity (for LHF) and to air and sea temperature differences (for SHF). Further quality investigations are performed through comprehensive comparisons with daily-averaged LHF and SHF estimated from moorings. The resulting statistics are used to assess the error of each OHF product. Consideration of error correlation between products and observations (e.g., by their assimilation) is also given. This reveals generally high noise variance in all products and a weak signal in common with in situ observations, with some products only slightly better than others. The OHF LHF and SHF products, and their associated error characteristics, are used to compute daily OHF multiproduct-ensemble (OHF/MPE) estimates of LHF and SHF over the ice-free global ocean on a 0.25 degrees x 0.25 degrees grid. The accuracy of this heat multiproduct, determined from comparisons with mooring data, is greater than for any individual product. It is used as a reference for the anomaly characterization of each individual OHF product.},
author = {Bentamy, A and Pioll{\'{e}}, J.F. and Grouazel, A and Danielson, R and Gulev, S and Paul, F and Azelmat, H and Mathieu, P.P. and von Schuckmann, K and Sathyendranath, S and Evers-King, H and Esau, I and Johannessen, J.A. and Clayson, C.A. and Pinker, R.T. and Grodsky, S.A. and Bourassa, M and Smith, S.R. and Haines, K and Valdivieso, M and Merchant, C.J. and Chapron, B and Anderson, A and Hollmann, R and Josey, S.A.},
doi = {10.1016/j.rse.2017.08.016},
issn = {00344257},
journal = {Remote Sensing of Environment},
month = {nov},
pages = {196--218},
title = {{Review and assessment of latent and sensible heat flux accuracy over the global oceans}},
url = {https://linkinghub.elsevier.com/retrieve/pii/S0034425717303826},
volume = {201},
year = {2017}
}
@article{Bilbao2015,
abstract = {Predictions of twenty-first century sea level change show strong regional variation. Regional sea level change observed by satellite altimetry since 1993 is also not spatially homogenous. By comparison with historical and pre-industrial control simulations using the atmosphere–ocean general circulation models (AOGCMs) of the CMIP5 project, we conclude that the observed pattern is generally dominated by unforced (internal generated) variability, although some regions, especially in the Southern Ocean, may already show an externally forced response. Simulated unforced variability cannot explain the observed trends in the tropical Pacific, but we suggest that this is due to inadequate simulation of variability by CMIP5 AOGCMs, rather than evidence of anthropogenic change. We apply the method of pattern scaling to projections of sea level change and show that it gives accurate estimates of future local sea level change in response to anthropogenic forcing as simulated by the AOGCMs under RCP scenarios, implying that the pattern will remain stable in future decades. We note, however, that use of a single integration to evaluate the performance of the pattern-scaling method tends to exaggerate its accuracy. We find that ocean volume mean temperature is generally a better predictor than global mean surface temperature of the magnitude of sea level change, and that the pattern is very similar under the different RCPs for a given model. We determine that the forced signal will be detectable above the noise of unforced internal variability within the next decade globally and may already be detectable in the tropical Atlantic.},
author = {Bilbao, Roberto A.F. and Gregory, Jonathan M. and Bouttes, Nathaelle},
doi = {10.1007/s00382-015-2499-z},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Pattern scaling,Regional sea level change,Times of emergence},
month = {feb},
number = {9-10},
pages = {2647--2666},
publisher = {Springer Verlag},
title = {{Analysis of the regional pattern of sea level change due to ocean dynamics and density change for 1993–2099 in observations and CMIP5 AOGCMs}},
volume = {45},
year = {2015}
}
@incollection{Bindoff2013a,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Bindoff, N.L. and Stott, P.A. and AchutaRao, K.M and Allen, M.R. and Gillett, N. and Gutzler, D. and Hansingo, K. and Hegerl, G. and Hu, Y. and Jain, S. and Mokhov, I.I. and Overland, J. and Perlwitz, J. and Sebbari, R. and Zhang, X.},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {10},
doi = {10.1017/CBO9781107415324.022},
editor = {Stocker, T.F. and Qin, D. and Plattner, G.-K. and Tignor, M. and Allen, S.K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.},
isbn = {9781107415324},
pages = {867--952},
publisher = {Cambridge University Press},
title = {{Detection and Attribution of Climate Change, from Global to Regional}},
year = {2013}
}
@article{Bintanja2013a,
abstract = {Changes in sea ice significantly modulate climate change because of its high reflective and strong insulating nature. In contrast to Arctic sea ice, sea ice surrounding Antarctica has expanded1, with record extent2 in 2010. This ice expansion has previously been attributed to dynamical atmospheric changes that induce atmospheric cooling3. Here we show that accelerated basal melting of Antarctic ice shelves is likely to have contributed significantly to sea-ice expansion. Specifically, we present observations indicating that melt water from Antarctica's ice shelves accumulates in a cool and fresh surface layer that shields the surface ocean from the warmer deeper waters that are melting the ice shelves. Simulating these processes in a coupled climate model we find that cool and fresh surface water from ice-shelf melt indeed leads to expanding sea ice in austral autumn and winter. This powerful negative feedback counteracts Southern Hemispheric atmospheric warming. Although changes in atmospheric dynamics most likely govern regional sea-ice trends4, our analyses indicate that the overall sea-ice trend is dominated by increased ice-shelf melt. We suggest that cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise.},
author = {Bintanja, R. and van Oldenborgh, G. J. and Drijfhout, S. S. and Wouters, B. and Katsman, C. A.},
doi = {10.1038/ngeo1767},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {may},
number = {5},
pages = {376--379},
title = {{Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion}},
url = {http://www.nature.com/articles/ngeo1767},
volume = {6},
year = {2013}
}
@article{Bintanja.ea-2012,
author = {Bintanja, R and {Van Der Linden}, E. C. and Hazeleger, W},
doi = {10.1007/s00382-011-1272-1},
journal = {Climate Dynamics},
keywords = {Arctic amplification,Arctic warming,Boundary-layer inversion,Climate change,Climate feedback,Climate sensitivity},
number = {11},
pages = {2659--2673},
title = {{Boundary layer stability and Arctic climate change: a feedback study using EC-Earth}},
volume = {39},
year = {2012}
}
@article{Bjordal9999,
abstract = {The equilibrium climate sensitivity of Earth is defined as the global mean surface air temperature increase that follows a doubling of atmospheric carbon dioxide. For decades, global climate models have predicted it as between approximately 2 and 4.5 °C. However, a large subset of models participating in the 6th Coupled Model Intercomparison Project predict values exceeding 5 °C. The difference has been attributed to the radiative effects of clouds, which are better captured in these models, but the underlying physical mechanism and thus how realistic such high climate sensitivities are remain unclear. Here we analyse Community Earth System Model simulations and find that, as the climate warms, the progressive reduction of ice content in clouds relative to liquid leads to increased reflectivity and a negative feedback that restrains climate warming, in particular over the Southern Ocean. However, once the clouds are predominantly liquid, this negative feedback vanishes. Thereafter, other positive cloud feedback mechanisms dominate, leading to a transition to a high-sensitivity climate state. Although the exact timing and magnitude of the transition may be model dependent, our findings suggest that the state dependence of the cloud-phase feedbacks is a crucial factor in the evolution of Earth's climate sensitivity with warming.},
author = {Bjordal, Jenny and Storelvmo, Trude and Alterskj{\ae}r, Kari and Carlsen, Tim},
doi = {10.1038/s41561-020-00649-1},
journal = {Nature Geoscience},
pages = {718--721},
title = {{Equilibrium climate sensitivity above 5 °C plausible due to state-dependent cloud feedback}},
volume = {13},
year = {2020}
}
@article{Bloch-Johnson2015,
abstract = {The long-term warming from an anthropogenic increase in atmospheric CO2 is often assumed to be proportional to the forcing associated with that increase. This paper examines this linear approximation using a zero-dimensional energy balance model with a temperature-dependent feedback, with parameter values drawn from physical arguments and general circulation models. For a positive feedback temperature dependence, warming increases Earth's sensitivity, while greater sensitivity makes Earth warm more. These effects can feed on each other, greatly amplifying warming. As a result, for reasonable values of feedback temperature dependence and preindustrial feedback, Earth can jump to a warmer state under only one or two CO2 doublings. The linear approximation breaks down in the long tail of high climate sensitivity commonly seen in observational studies. Understanding feedback temperature dependence is therefore essential for inferring the risk of high warming from modern observations. Studies that assume linearity likely underestimate the risk of high warming.},
author = {Bloch-Johnson, Jonah and Pierrehumbert, Raymond T. and Abbot, Dorian S.},
doi = {10.1002/2015GL064240},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {GCMs,climate sensitivity,long tail,nonlinear feedbacks,observational estimates},
number = {12},
pages = {4973--4980},
title = {{Feedback temperature dependence determines the risk of high warming}},
volume = {42},
year = {2015}
}
@article{BlochJohnson2020,
abstract = {AbstractEquilibrium climate sensitivity - the equilibrium warming per CO2 doubling - increases with CO2 concentration for thirteen of fourteen coupled general circulation models for 0.5 to 8 times the preindustrial concentration. In particular, the abrupt4xCO2 equilibrium warming is more than twice the 2xCO2 warming. We identify three potential causes: nonlogarithmic forcing, feedback CO2 dependence, and feedback temperature dependence. Feedback temperature dependence explains at least half of the sensitivity increase, while feedback CO2 dependence explains a smaller share, and nonlogarithmic forcing decreases sensitivity in as many models as it increases it. Feedback temperature dependence is positive for ten out of fourteen models, primarily due to the longwave clear-sky feedback, while cloud feedbacks drive particularly large sensitivity increases. Feedback temperature dependence increases the risk of extreme or runaway warming, and is estimated to cause six models to warm at least an additional 3K under 8xCO2.},
author = {Bloch‐Johnson, Jonah and Rugenstein, Maria and Stolpe, Martin B. and Rohrschneider, Tim and Zheng, Yiyu and Gregory, Jonathan M.},
doi = {10.1029/2020GL089074},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {CMIP6,climate feedback,climate sensitivity,feedback temperature dependence,nonlinear climate,radiative forcing},
month = {feb},
number = {4},
pages = {e2020GL089074},
publisher = {American Geophysical Union (AGU)},
title = {{Climate Sensitivity Increases Under Higher CO2 Levels Due to Feedback Temperature Dependence}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL089074},
volume = {48},
year = {2020}
}
@article{https://doi.org/10.1002/jame.20041,
abstract = {Radiative feedback mechanisms associated with temperature, water vapor, cloud, and surface albedo change determine climate sensitivity to radiative forcing. Here we use the linearized radiative kernel-technique in combination with a Gregory analysis to determine the strength and structure of feedbacks, as well as direct and adjusted CO2 forcings in the coupled Max Planck Institute Earth System Model at base resolution (MPI-ESM-LR). We show that the combined Kernel-Gregory approach yields an elegant separation of surface temperature-dependent feedbacks from contributions to radiative forcing by fast adjustments. MPI-ESM-LR exhibits a relatively large cloud adjustment of nearly 2 W m−2 in direct response to quadrupled CO2, with positive cloud adjustment evident throughout the tropics, subtropics and over most landmasses whereas midlatitude storm tracks contribute negatively. The model features a nonlinear regression of radiation imbalance to global mean surface temperature change, resulting in a significantly increasing effective climate sensitivity after about 20 years which is approximately at temperatures 4–5 K above preindustrial. This feature is not uncommon among climate models and is relevant for future climate projections. We analyze the contribution of the individual feedback processes to this behavior and discuss possible origins such as differential ocean warming patterns associated with deep-ocean heat uptake or state dependencies of the feedback processes.},
author = {Block, K and Mauritsen, T},
doi = {https://doi.org/10.1002/jame.20041},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {climate change,climate sensitivity,fast adjustments,feedbacks,radiative forcing},
number = {4},
pages = {676--691},
title = {{Forcing and feedback in the MPI-ESM-LR coupled model under abruptly quadrupled CO2}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/jame.20041},
volume = {5},
year = {2013}
}
@article{Bodas-Salcedo2019,
abstract = {Abstract We analyze the atmospheric processes that explain the large changes in radiative feedbacks between the two latest climate configurations of the Hadley Centre Global Environmental model. We use a large set of atmosphere-only climate change simulations (amip and amip-p4K) to separate the contributions to the differences in feedback parameter from all the atmospheric model developments between the two latest model configurations. We show that the differences are mostly driven by changes in the shortwave cloud radiative feedback in the midlatitudes, mainly over the Southern Ocean. Two new schemes explain most of the differences: the introduction of a new aerosol scheme and the development of a new mixed-phase cloud scheme. Both schemes reduce the strength of the preexisting shortwave negative cloud feedback in the midlatitudes. The new aerosol scheme dampens a strong aerosol-cloud interaction, and it also suppresses a negative clear-sky shortwave feedback. The mixed-phase scheme increases the amount of cloud liquid water path (LWP) in the present day and reduces the increase in LWP with warming. Both changes contribute to reducing the negative radiative feedback of the increase of LWP in the warmer climate. The mixed-phase scheme also enhances a strong, preexisting, positive cloud fraction feedback. We assess the realism of the changes by comparing present-day simulations against observations and discuss avenues that could help constrain the relevant processes.},
author = {Bodas-Salcedo, A and Mulcahy, J P and Andrews, T and Williams, K D and Ringer, M A and Field, P R and Elsaesser, G S},
doi = {10.1029/2019MS001688},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {HadGEM3,cloud feedbacks},
month = {jun},
number = {6},
pages = {1735--1758},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Strong Dependence of Atmospheric Feedbacks on Mixed-Phase Microphysics and Aerosol–Cloud Interactions in HadGEM3}},
url = {https://doi.org/10.1029/2019MS001688},
volume = {11},
year = {2019}
}
@article{ISI:000381632100023,
abstract = {The Arctic region is warming at a rate more than double the global average, a trend predicted to continue by all Coupled Model Intercomparison Project 5 (CMIP5) climate models. Despite this consistency, significant intermodel spread exists in the simulated Arctic climate related to differences in the Arctic surface radiation budget. Building upon previous work to characterize and understand surface radiation budget biases in climate models, the annual mean and seasonal cycle of the Arctic surface radiation budget in 17 CMIP5 models using the Historical-forcing scenario is evaluated against state-of-the-art Cloud and Earth's Radiant Energy System Surface Energy Balanced and Filled data. The CMIP5 multimodel ensemble is found to simulate longwave surface fluxes well during the sunlit months (similar to 1Wm(-2) differences in July) but exhibits significant wintertime biases (up to -19Wm(-2)). Shortwave fluxes show substantial across-model spread during summer; the model standard deviation approaches 20Wm(-2) in July. Applying a decomposition analysis to the cloud radiative effect (CRE) seasonal cycles, an unrealistic compensation is uncovered between the model-simulated seasonal cycles of cloud fraction, all-sky/clear-sky flux differences, and surface albedo that enables models to simulate realistic CRE seasonal cycles with unrealistic individual contributions. This unrealistic behavior in models must be constrained to improve Arctic climate simulation; observational uncertainty is sufficient to do so. Lastly, biases in all and clear-sky longwave downwelling fluxes positively correlate with model surface temperature in winter, while in summer surface temperature is most strongly related to clear-sky upwelling radiation biases from surface albedo errors.},
author = {Boeke, Robyn C and Taylor, Patrick C},
doi = {10.1002/2016JD025099},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {jul},
number = {14},
pages = {8525--8548},
title = {{Evaluation of the Arctic surface radiation budget in CMIP5 models}},
volume = {121},
year = {2016}
}
@article{Boeke2018,
abstract = {Rapid and, in many cases, unprecedented Arctic climate changes are having far-reaching impacts on natural and human systems. Despite state-of-the-art climate models capturing the rapid nature of Arctic climate change, termed Arctic amplification, they significantly disagree on its magnitude. Using a regional, process-oriented surface energy budget analysis, we argue that differences in seasonal energy exchanges in sea ice retreat regions via increased absorption and storage of sunlight in summer and increased upward surface turbulent fluxes in fall/winter contribute to the inter-model spread. Models able to more widely disperse energy drawn from the surface in sea ice retreat regions warm more, suggesting that differences in the local Arctic atmospheric circulation response contribute to the inter-model spread. We find that the principle mechanisms driving the inter-model spread in Arctic amplification operate locally on regional scales, requiring an improved understanding of atmosphere-ocean-sea ice interactions in sea ice retreat regions to reduce the spread.},
author = {Boeke, Robyn C. and Taylor, Patrick C.},
doi = {10.1038/s41467-018-07061-9},
issn = {20411723},
journal = {Nature Communications},
month = {dec},
number = {1},
pages = {5017},
publisher = {Nature Publishing Group},
title = {{Seasonal energy exchange in sea ice retreat regions contributes to differences in projected Arctic warming}},
volume = {9},
year = {2018}
}
@article{Boisier2013,
abstract = {Regional cooling resulting from increases in surface albedo has been identified in several studies as the main biogeophysical effect of past land use-induced land cover changes (LCC) on climate. However, the amplitude of this effect remains quite uncertain due to, among other factors, (a) uncertainties in the extent of historical LCC and, (b) differences in the way various models simulate surface albedo and more specifically its dependency on vegetation type and snow cover. We derived monthly albedo climatologies for croplands and four other land cover types from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations. We then reconstructed the changes in surface albedo between preindustrial times and present-day by combining these climatologies with the land cover maps of 1870 and 1992 used by seven land surface models (LSMs) in the context of the LUCID ("Land Use and Climate: identification of robust Impacts") intercomparison project. These reconstructions show surface albedo increases larger than 10{\%} (absolute) in winter, and larger than 2{\%} in summer between 1870 and 1992 over areas that experienced intense deforestation in the northern temperate regions. The historical surface albedo changes estimated with MODIS data were then compared to those simulated by the various climate models participating in LUCID. The inter-model mean albedo response to LCC shows a similar spatial and seasonal pattern to the one resulting from the MODIS-based reconstructions, that is, larger albedo increases in winter than in summer, driven by the presence of snow. However, individual models show significant differences between the simulated albedo changes and the corresponding reconstructions, despite the fact that land cover change maps are the same. Our analyses suggest that the primary reason for those discrepancies is how LSMs parameterize albedo. Another reason, of secondary importance, results from differences in their simulated snow extent. Our methodology is a useful tool not only to infer observations-based historical changes in land surface variables impacted by LCC, but also to point out deficiencies of the models. We therefore suggest that it could be more widely developed and used in conjunction with other tools in order to evaluate LSMs.},
author = {Boisier, J. P. and de Noblet-Ducoudr{\'{e}}, N. and Ciais, P.},
doi = {10.5194/bg-10-1501-2013},
issn = {1726-4189},
journal = {Biogeosciences},
month = {mar},
number = {3},
pages = {1501--1516},
title = {{Inferring past land use-induced changes in surface albedo from satellite observations: a useful tool to evaluate model simulations}},
url = {https://bg.copernicus.org/articles/10/1501/2013/},
volume = {10},
year = {2013}
}
@article{Bonan2018,
abstract = {We employ a moist energy balance model (MEBM), representing atmospheric heat transport as the diffusion of near-surface moist static energy, to evaluate sources of uncertainty in the meridional pattern of surface warming. Given zonal mean patterns of radiative forcing, radiative feedbacks, and ocean heat uptake, the MEBM accurately predicts zonal mean warming as simulated by general circulation models under increased CO 2. Over a wide range of latitudes, the MEBM captures approximately 90{\%} of the variance in zonal mean warming across the general circulation models, with approximately 70{\%} of the variance attributable to differences in radiative feedbacks alone. Partitioning the radiative feedbacks into individual components shows that the majority of the uncertainty in the meridional pattern of warming arises from uncertainty in cloud feedbacks. Isolating feedback uncertainty within specific regions demonstrates that tropical feedback uncertainty leads to surface warming uncertainty that is global and nearly uniform with latitude, whereas polar feedback uncertainty leads to surface warming uncertainty that is largely confined to the poles. Plain Language Summary In response to greenhouse gas forcing, global climate models-which physically describe how the climate system operates-predict a range of surface warming patterns. To better understand the sources of uncertainty in predicted warming patterns, we use an idealized climate model that links regional physical processes to warming responses across latitudes by representing changes in poleward atmospheric heat transport. We find that uncertainty in the spatial pattern of warming primarily arises from uncertainty in climate feedbacks, with uncertainty in climate forcing and ocean heat uptake playing smaller roles. Cloud feedbacks, in particular, contribute the greatest source of warming uncertainty in most regions. By considering the spread of climate feedbacks within distinct geographic regions, we show that feedback uncertainty in the tropics leads to warming uncertainty at all latitudes. However, feedback uncertainty in polar regions leads to warming uncertainty that is confined near the poles. The results suggest that polar warming is particularly difficult to predict because it is influenced by both local and nonlocal feedback processes. On the other hand, improved understanding of tropical cloud feedbacks has the potential to improve warming projections at all latitudes.},
author = {Bonan, D B and Armour, K C and Roe, G H and Siler, N and Feldl, N},
doi = {10.1029/2018GL079429},
journal = {Geophysical Research Letters},
number = {17},
pages = {9131--9140},
title = {{Sources of Uncertainty in the Meridional Pattern of Climate Change}},
volume = {45},
year = {2018}
}
@article{doi:10.1002/jgrd.50171,
abstract = {AbstractBlack carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr−1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m−2 with 90{\%} uncertainty bounds of (+0.08, +1.27) W m−2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m−2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m−2 with 90{\%} uncertainty bounds of +0.17 to +2.1 W m−2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m−2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (−0.50 to +1.08) W m−2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (−0.06 W m−2 with 90{\%} uncertainty bounds of −1.45 to +1.29 W m−2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.},
author = {Bond, T C and Doherty, S J and Fahey, D W and Forster, P M and Berntsen, T and DeAngelo, B J and Flanner, M G and Ghan, S and K{\"{a}}rcher, B and Koch, D and Kinne, S and Kondo, Y and Quinn, P K and Sarofim, M C and Schultz, M G and Schulz, M and Venkataraman, C and Zhang, H and Zhang, S and Bellouin, N and Guttikunda, S K and Hopke, P K and Jacobson, M Z and Kaiser, J W and Klimont, Z and Lohmann, U and Schwarz, J P and Shindell, D and Storelvmo, T and Warren, S G and Zender, C S},
doi = {10.1002/jgrd.50171},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aerosol,black carbon,climate forcing},
number = {11},
pages = {5380--5552},
title = {{Bounding the role of black carbon in the climate system: A scientific assessment}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/jgrd.50171},
volume = {118},
year = {2013}
}
@article{Bony.Colman.ea-jclim-2006,
author = {Bony, S and Colman, R and Kattsov, V M and Allan, R P and Bretherton, C S and Dufresne, J.-L. and Hall, A and Hallegatte, S and Holland, M M and Ingram, W and Randall, D A and Soden, B J and Tselioudis, G and Webb, M J},
journal = {Journal of Climate},
number = {15},
pages = {3445--3482, doi: 10.1175/JCLI3819.1},
title = {{How Well do we Understand and Evaluate Climate Change Feedback Processes?}},
volume = {19},
year = {2006}
}
@article{Bony2016,
abstract = {General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative-convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.},
author = {Bony, Sandrine and Stevens, Bjorn and Coppin, David and Becker, Tobias and Reed, Kevin A. and Voigt, Aiko and Medeiros, Brian},
doi = {10.1073/pnas.1601472113},
issn = {10916490},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Anvil cloud,Climate sensitivity,Cloud feedback,Convective aggregation,Large-scale circulation},
month = {aug},
number = {32},
pages = {8927--8932},
title = {{Thermodynamic control of anvil cloud amount}},
url = {http://www.pnas.org/content/113/32/8927.abstract},
volume = {113},
year = {2016}
}
@article{Bony2015a,
abstract = {Fundamental puzzles of climate science remain unsolved because of our limited understanding of how clouds, circulation and climate interact. One example is our inability to provide robust assessments of future global and regional climate changes. However, ongoing advances in our capacity to observe, simulate and conceptualize the climate system now make it possible to fill gaps in our knowledge. We argue that progress can be accelerated by focusing research on a handful of important scientific questions that have become tractable as a result of recent advances. We propose four such questions below; they involve understanding the role of cloud feedbacks and convective organization in climate, and the factors that control the position, the strength and the variability of the tropical rain belts and the extratropical storm tracks.},
author = {Bony, Sandrine and Stevens, Bjorn and Frierson, Dargan M.W. and Jakob, Christian and Kageyama, Masa and Pincus, Robert and Shepherd, Theodore G. and Sherwood, Steven C. and Siebesma, A. Pier and Sobel, Adam H. and Watanabe, Masahiro and Webb, Mark J.},
doi = {10.1038/ngeo2398},
issn = {17520908},
journal = {Nature Geoscience},
month = {mar},
number = {4},
pages = {261--268},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Clouds, circulation and climate sensitivity}},
url = {http://dx.doi.org/10.1038/ngeo2398 http://10.0.4.14/ngeo2398},
volume = {8},
year = {2015}
}
@article{Bony2005a,
author = {Bony, Sandrine and Dufresne, Jean-Louis},
doi = {10.1029/2005GL023851},
issn = {0094-8276},
journal = {Geophysical Research Letters},
number = {20},
pages = {L20806},
title = {{Marine boundary layer clouds at the heart of tropical cloud feedback uncertainties in climate models}},
url = {http://doi.wiley.com/10.1029/2005GL023851},
volume = {32},
year = {2005}
}
@article{doi:10.1029/2019AV000155,
abstract = {This study analyzes the observed monthly deseasonalized and detrended variability of the tropical radiation budget and suggests that variations of the lower-tropospheric stability and of the spatial organization of deep convection both strongly contribute to this variability. Satellite observations show that on average over the tropical belt, when deep convection is more aggregated, the free troposphere is drier, the deep convective cloud coverage is less extensive, and the emission of heat to space is increased; an enhanced aggregation of deep convection is thus associated with a radiative cooling of the tropics. An increase of the tropical-mean lower-tropospheric stability is also coincident with a radiative cooling of the tropics, primarily because it is associated with more marine low clouds and an enhanced reflection of solar radiation, although the free-tropospheric drying also contributes to the cooling. The contributions of convective aggregation and lower-tropospheric stability to the modulation of the radiation budget are complementary, largely independent of each other, and equally strong. Together, they account for more than sixty percent of the variance of the tropical radiation budget. Satellite observations are thus consistent with the suggestion from modeling studies that the spatial organization of deep convection substantially influences the radiative balance of the Earth. This emphasizes the importance of understanding the factors that control convective organization and lower-tropospheric stability variations, and the need to monitor their changes as the climate warms.},
author = {Bony, S and Semie, A and Kramer, R J and Soden, B and Tompkins, A M and Emanuel, K A},
doi = {10.1029/2019AV000155},
journal = {AGU Advances},
keywords = {convective organization,radiation budget,tropical variability,tropospheric stability},
number = {3},
pages = {e2019AV000155},
title = {{Observed Modulation of the Tropical Radiation Budget by Deep Convective Organization and Lower-Tropospheric Stability}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019AV000155},
volume = {1},
year = {2020}
}
@article{Booth2018,
author = {Booth, Ben B. B. and Harris, Glen R. and Jones, Andy and Wilcox, Laura and Hawcroft, Matt and Carslaw, Ken S. and Booth, Ben B. B. and Harris, Glen R. and Jones, Andy and Wilcox, Laura and Hawcroft, Matt and Carslaw, Ken S.},
doi = {10.1175/JCLI-D-17-0369.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Aerosol indirect effect,Aerosol radiative effect,Aerosol-cloud interaction,Climate models,General circulation models},
month = {nov},
number = {22},
pages = {9407--9412},
publisher = {American Meteorological Society},
title = {{Comments on “Rethinking the Lower Bound on Aerosol Radiative Forcing”}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0369.1},
volume = {31},
year = {2018}
}
@incollection{Boucher2013,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Boucher, O. and Randall, D. and Artaxo, Paulo and Bretherton, C. and Feingold, G. and Forster, P. and Kerminen, V-M V.-M. and Kondo, Y. and Liao, H. and Lohmann, U. and Rasch, P. and Satheesh, S. K. and Sherwood, S. and Stevens, B. and Zhang, X Y and Zhan, X. Y},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
doi = {10.1017/CBO9781107415324.016},
editor = {Stocker, T.F. and Qin, D. and Plattner, G.-K. and Tignor, M. and Allen, S.K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.},
isbn = {9781107661820},
pages = {571--657},
publisher = {Cambridge Univeristy Press},
title = {{Clouds and Aerosols}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Boucher2009,
abstract = {Methane is the second most important anthropogenic greenhouse gas in the atmosphere next to carbon dioxide. Its global warming potential(GWP) for a time horizon of 100years is 25, which makes it an attractive target for climate mitigation policies. Although the methane GWP traditionally includes the methane indirect effects on the concentrations of ozone and stratospheric water vapour, it does not take into account the production of carbon dioxide from methane oxidation. We argue here that this CO2-induced effect should be included for fossil sources of methane, which results in slightly larger GWP values for all time horizons. If the global temperature change potential is used as an alternative climate metric, then the impact of the CO2-induced effect is proportionally much larger. We also discuss what the correction term should be for methane from anthropogenic biogenic sources. {\textcopyright} IOP Publishing Ltd.},
author = {Boucher, O. and Friedlingstein, P. and Collins, B. and Shine, K.P.},
doi = {10.1088/1748-9326/4/4/044007},
journal = {Environmental Research Letters},
number = {4},
pages = {044007},
title = {{The indirect global warming potential and global temperature change potential due to methane oxidation}},
volume = {4},
year = {2009}
}
@article{Boucher2012,
abstract = {There is a controversy on the role methane (and other short-lived species) should play in climate mitigation policies, and there is no consensus on what an optimal methane CO2-equivalence should be. We revisit this question by discussing some aspects of physically-based (i.e. global- warming potential or GWP and global temperature change potential or GTP) and socio-economically-based climate metrics. To this effect we use a simplified global damage potential (GDP) that was introduced by earlier authors and investigate the uncertainties in the methane CO2-equivalence that arise from physical and socio-economic factors. The median value of the methane GDP comes out very close to the widely used methane 100-yr GWP because of various compensating effects. However, there is a large spread in possible methane CO2-equivalences from this metric (1–99{\%} interval: 10.0–42.5; 5–95{\%} interval: 12.5–38.0) that is essentially due to the choice in some socio-economic parameters (i.e. the damage cost function and the discount rate). The main factor differentiating the methane 100-yr GTP from the methane 100-yr GWP and the GDP is the fact that the former metric is an end-point metric, whereas the latter are cumulative metrics. There is some rationale for an increase in the methane CO2-equivalence in the future as global warming unfolds, as implied by a convex damage function in the case of the GDP metric. We also show that a methane CO2-equivalence based on a pulse emission is sufficient to inform multi-year climate policies and emissions reductions, as long as there is enough visibility on CO2 prices and CO2-equivalences for the stakeholders.},
author = {Boucher, O.},
doi = {10.5194/esd-3-49-2012},
issn = {2190-4987},
journal = {Earth System Dynamics},
month = {may},
number = {1},
pages = {49--61},
title = {{Comparison of physically- and economically-based CO2-equivalences for methane}},
url = {https://esd.copernicus.org/articles/3/49/2012/},
volume = {3},
year = {2012}
}
@article{bowerman2013role,
author = {Bowerman, Niel H A and Frame, David J and Huntingford, Chris and Lowe, Jason A and Smith, Stephen M and Allen, Myles R},
doi = {https://doi.org/10.1038/nclimate2034},
journal = {Nature Climate Change},
number = {12},
pages = {1021--1024},
publisher = {Nature Publishing Group},
title = {{The role of short-lived climate pollutants in meeting temperature goals}},
volume = {3},
year = {2013}
}
@article{Brantley1454,
author = {Brantley, Susan L},
doi = {10.1126/science.1161132},
issn = {0036-8075},
journal = {Science},
number = {5895},
pages = {1454--1455},
publisher = {American Association for the Advancement of Science},
title = {{Understanding Soil Time}},
url = {https://science.sciencemag.org/content/321/5895/1454},
volume = {321},
year = {2008}
}
@article{Brenguier2000,
abstract = {Abstract The plane-parallel model for the parameterization of clouds in global climate models is examined in order to estimate the effects of the vertical profile of the microphysical parameters on radiative transfer calculations for extended boundary layer clouds. The vertically uniform model is thus compared to the adiabatic stratified one. The validation of the adiabatic model is based on simultaneous measurements of cloud microphysical parameters in situ and cloud radiative properties from above the cloud layer with a multispectral radiometer. In particular, the observations demonstrate that the dependency of cloud optical thickness on cloud geometrical thickness is larger than predicted with the vertically uniform model and that it is in agreement with the prediction of the adiabatic one. Numerical simulations of the radiative transfer have been performed to establish the equivalence between the two models in terms of the effective radius. They show that the equivalent effective radius of a verticall...},
author = {Brenguier, Jean-Louis and Pawlowska, Hanna and Sch{\"{u}}ller, Lothar and Preusker, Rene and Fischer, J{\"{u}}rgen and Fouquart, Yves and Brenguier, Jean-Louis and Pawlowska, Hanna and Sch{\"{u}}ller, Lothar and Preusker, Rene and Fischer, J{\"{u}}rgen and Fouquart, Yves},
doi = {10.1175/1520-0469(2000)057<0803:RPOBLC>2.0.CO;2},
issn = {0022-4928},
journal = {Journal of the Atmospheric Sciences},
month = {mar},
number = {6},
pages = {803--821},
title = {{Radiative Properties of Boundary Layer Clouds: Droplet Effective Radius versus Number Concentration}},
volume = {57},
year = {2000}
}
@article{Bretherton2015,
abstract = {Cloud feedbacks are a leading source of uncertainty in the climate sensitivity simulated by global climate models (GCMs). Low-latitude boundary-layer and cumulus cloud regimes are particularly problematic, because they are sustained by tight interactions between clouds and unresolved turbulent circulations. Turbulence-resolving models better simulate such cloud regimes and support the GCM consensus that they contribute to positive global cloud feedbacks. Large-eddy simulations using sub-100 m grid spacings over small computational domains elucidate marine boundary-layer cloud response to greenhouse warming. Four observationally supported mechanisms contribute: 'thermodynamic' cloudiness reduction from warming of the atmosphere-ocean column, 'radiative' cloudiness reduction from CO2- and H2O-induced increase in atmospheric emissivity aloft, 'stability-induced' cloud increase from increased lower tropospheric stratification, and 'dynamical' cloudiness increase from reduced subsidence. The cloudiness reduction mechanisms typically dominate, giving positive shortwave cloud feedback. Cloud-resolving models with horizontal grid spacings of a few kilometres illuminate how cumulonimbus cloud systems affect climate feedbacks. Limited-area simulations and superparameterized GCMs show upward shift and slight reduction of cloud cover in a warmer climate, implying positive cloud feedbacks. A global cloud-resolving model suggests tropical cirrus increases in a warmer climate, producing positive longwave cloud feedback, but results are sensitive to subgrid turbulence and ice microphysics schemes.},
author = {Bretherton, Christopher S.},
doi = {10.1098/rsta.2014.0415},
isbn = {0962-8436},
issn = {1364503X},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
keywords = {Climate sensitivity,Cloud feedbacks,Cloud-resolving models,Large-eddy simulation},
number = {2054},
pmid = {26438280},
title = {{Insights into low-latitude cloud feedbacks from high-resolution models}},
volume = {373},
year = {2015}
}
@article{Bretherton2013,
abstract = {Climate change sensitivities of subtropical cloud-topped marine boundary layers are analyzed using large-eddy simulation (LES) of three CGILS cases of well-mixed stratocumulus, cumulus under stratocumulus, and shallow cumulus cloud regimes, respectively. For each case, a steadily forced control simulation on a small horizontally doubly-periodic domain is run 10-20 days into quasi-steady state. The LES is rerun to steady-state with forcings perturbed by changes in temperature, free-tropospheric relative humidity, CO2 concentration, subsidence, inversion stability, and wind speed; cloud responses to combined forcings superpose approximately linearly. For all three cloud regimes and 2×CO2 forcing perturbations estimated from the CMIP3 multimodel mean, the LES predicts positive shortwave cloud feedback, like most CMIP3 global climate models. At both stratocumulus locations, the cloud remains overcast but thins in the warmer, moister, CO2-enhanced climate, due to the combined effects of an increased lower-tropospheric vertical humidity gradient and an enhanced free tropospheric greenhouse effect that reduces the radiative driving of turbulence. Reduced subsidence due to weakening of tropical overturning circulations partly counteracts these two factors by raising the inversion and allowing the cloud layer to deepen. These compensating mechanisms may explain the large scatter in low cloud feedbacks predicted by climate models. CMIP3-predicted changes in wind speed, inversion stability, and free-tropospheric relative humidity have lesser impacts on the cloud thickness. In the shallow cumulus regime, precipitation regulates the simulated boundary layer depth and vertical structure. Cloud droplet (aerosol) concentration limits the boundary layer depth and affects the simulated cloud feedbacks.},
author = {Bretherton, Christopher S. and Blossey, Peter N. and Jones, Christopher R.},
doi = {10.1002/jame.20019},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {LES,boundary-layer cloud,climate sensitivity,cloud feedbacks},
month = {jun},
number = {2},
pages = {316--337},
title = {{Mechanisms of marine low cloud sensitivity to idealized climate perturbations: A single‐LES exploration extending the CGILS cases}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/jame.20019},
volume = {5},
year = {2013}
}
@article{Bretherton2014,
abstract = {Abstract Cloud feedbacks on greenhouse warming are studied in a superparameterized version of the Community Climate System Model (SP-CCSM4) in an atmospheric component SP-CAM4 that explicitly simulates cumulus convection. A 150 year simulation in an abrupt quadrupling of CO2 is branched from a control run. It develops moderate positive global cloud feedback and an implied climate sensitivity of 2.8 K comparable to the conventionally parameterized CCSM4 and the median of other modern climate models. All of SP-CCSM4's positive shortwave cloud feedback is due to a striking decrease in low cloud over land, which is much more pronounced than in most other climate models, including CCSM4. Four other cloud responses ? decreased midlevel cloud, more Arctic water and ice cloud, a slight poleward shift of midlatitude storm track cloud, and an upward shift of high clouds ? are also typical of conventional global climate models. SP-CCSM4 does not simulate the large warming-induced decrease in Southern Ocean cloud found in CCSM4. Two companion uncoupled SP-CAM4 simulations, one with a uniform 4 K sea-surface temperature increase and one with quadrupled CO2 but fixed SST, suggest that SP-CCSM4's global-scale cloud changes are primarily mediated by the warming, rather than by rapid adjustments to increased CO2. SP-CAM4 show spatial patterns of cloud response qualitatively similar to the previous-generation superparameterized SP-CAM3, but with systematically more positive low cloud feedbacks over low-latitude land and ocean.},
author = {Bretherton, Christopher S and Blossey, Peter N and Stan, Cristiana},
doi = {10.1002/2014MS000355},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {climate modeling,cloud feedbacks,cloud-resolving models,superparameterization},
month = {dec},
number = {4},
pages = {1185--1204},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Cloud feedbacks on greenhouse warming in the superparameterized climate model SP-CCSM4}},
url = {https://doi.org/10.1002/2014MS000355},
volume = {6},
year = {2014}
}
@article{Brient2016a,
abstract = {How tropical low clouds change with climate remains the dominant source of uncertainty in global warming projections. An analysis of an ensemble of CMIP5 climate models reveals that a significant part of the spread in the models' climate sensitivity can be accounted by differences in the climatological shallowness of tropical low clouds in weak-subsidence regimes: models with shallower low clouds in weak-subsidence regimes tend to have a higher climate sensitivity than models with deeper low clouds. The dynamical mechanisms responsible for the model differences are analyzed. Competing effects of parameterized boundary-layer turbulence and shallow convection are found to be essential. Boundary-layer turbulence and shallow convection are typically represented by distinct parameterization schemes in current models—parameterization schemes that often produce opposing effects on low clouds. Convective drying of the boundary layer tends to deepen low clouds and reduce the cloud fraction at the lowest levels; turbulent moistening tends to make low clouds more shallow but affects the low-cloud fraction less. The relative importance different models assign to these opposing mechanisms contributes to the spread of the climatological shallowness of low clouds and thus to the spread of low-cloud changes under global warming.},
author = {Brient, Florent and Schneider, Tapio and Tan, Zhihong and Bony, Sandrine and Qu, Xin and Hall, Alex},
doi = {10.1007/s00382-015-2846-0},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Climate sensitivity,Convection,Low-clouds,Tropics,Turbulence},
number = {1-2},
pages = {433--449},
publisher = {Springer Berlin Heidelberg},
title = {{Shallowness of tropical low clouds as a predictor of climate models' response to warming}},
volume = {47},
year = {2016}
}
@article{Brient2016,
abstract = {AbstractPhysical uncertainties in global-warming projections are dominated by uncertainties about how the fraction of incoming shortwave radiation that clouds reflect will change as greenhouse gas concentrations rise. Differences in the shortwave reflection by low clouds over tropical oceans alone account for more than half of the variance of the equilibrium climate sensitivity (ECS) among climate models, which ranges from 2.1 to 4.7 K. Space-based measurements now provide an opportunity to assess how well models reproduce temporal variations of this shortwave reflection on seasonal to interannual time scales. Here such space-based measurements are used to show that shortwave reflection by low clouds over tropical oceans decreases robustly when the underlying surface warms, for example, by −(0.96 ± 0.22){\%} K−1 (90{\%} confidence level) for deseasonalized variations. Additionally, the temporal covariance of low-cloud reflection with temperature in historical simulations with current climate models correlates s...},
author = {Brient, Florent and Schneider, Tapio},
doi = {10.1175/JCLI-D-15-0897.1},
issn = {08948755},
journal = {Journal of Climate},
number = {16},
pages = {5821--5835},
title = {{Constraints on climate sensitivity from space-based measurements of low-cloud reflection}},
volume = {29},
year = {2016}
}
@article{Brierley2015,
author = {Brierley, Chris and Burls, Natalie and Ravelo, Christina and Fedorov, Alexey},
doi = {10.1038/ngeo2444},
issn = {17520908},
journal = {Nature Geoscience},
month = {may},
number = {6},
pages = {419--420},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Pliocene warmth and gradients}},
volume = {8},
year = {2015}
}
@article{Bronselaer2018a,
author = {Bronselaer, Ben and Stouffer, Ronald J. and Winton, Michael and Griffies, Stephen M. and Hurlin, William J. and Russell, Joellen L. and Rodgers, Keith B. and Sergienko, Olga V.},
doi = {10.1038/s41586-018-0712-z},
issn = {0028-0836},
journal = {Nature},
number = {7734},
pages = {53--58},
title = {{Change in future climate due to Antarctic meltwater}},
volume = {564},
year = {2018}
}
@article{doi:10.1029/2009GL037543,
abstract = {In two sensitivity experiments using the Earth System Model of the Max Planck Institute for Meteorology (MPI-ESM), the vegetation cover of the ice-free land surface has been set worldwide to either forest or grassland in order to quantify the quasi-equilibrium response of the atmosphere and ocean components to extreme land surface boundary conditions. After 400 years of model integration, the global mean annual surface temperature increased by 0.7°K and declined by 0.6°K in the forest and grassland simulations, respectively, as compared to the control simulation. Thereafter, the geographic distribution of vegetation has been allowed to respond interactively to climate. After subsequent 500 years of interactive climate-vegetation dynamics, both forest and grassland simulations converged to essentially the same climate state as in the control simulation. This convergence suggests an absence of multiple climate-forest states in the current version of the MPI-ESM.},
author = {Brovkin, Victor and Raddatz, Thomas and Reick, Christian H and Claussen, Martin and Gayler, Veronika},
doi = {10.1029/2009GL037543},
journal = {Geophysical Research Letters},
keywords = {climate modeling,ecosystem modeling,interactions},
number = {7},
pages = {L07405},
title = {{Global biogeophysical interactions between forest and climate}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2009GL037543},
volume = {36},
year = {2009}
}
@article{Brown2018a,
author = {Brown, Patrick T and Stolpe, Martin B and Caldeira, Ken},
doi = {10.1038/s41586-018-0638-5},
issn = {1476-4687},
journal = {Nature},
number = {7729},
pages = {E1--E3},
title = {{Assumptions for emergent constraints}},
url = {https://doi.org/10.1038/s41586-018-0638-5},
volume = {563},
year = {2018}
}
@article{doi:10.1002/2014GL060625,
abstract = {Abstract Much recent work has focused on unforced global mean surface air temperature (T) variability associated with the efficiency of heat transport into the deep ocean. Here the relationship between unforced variability in T and the Earth's top-of-atmosphere (TOA) energy balance is explored in preindustrial control runs of the Coupled Model Intercomparison Project Phase 5 multimodel ensemble. It is found that large decadal scale variations in T tend to be significantly enhanced by the net energy flux at the TOA. This indicates that unforced decadal variability in T is not only caused by a redistribution of heat within the climate system but can also be associated with unforced changes in the total amount of heat in the climate system. It is found that the net TOA radiation imbalances result mostly from changes in albedo associated with the Interdecadal Pacific Oscillation that temporarily counteracts the climate system's outgoing longwave (i.e., Stefan-Boltzmann) response to T change.},
author = {Brown, Patrick T and Li, Wenhong and Li, Laifang and Ming, Yi},
doi = {10.1002/2014GL060625},
journal = {Geophysical Research Letters},
keywords = {Earth's energy balance,global mean temperature,interdecadal Pacific oscillation,internal variability,top of atmosphere radiation,unforced variability},
number = {14},
pages = {5175--5183},
title = {{Top-of-atmosphere radiative contribution to unforced decadal global temperature variability in climate models}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014GL060625},
volume = {41},
year = {2014}
}
@article{Brown2017b,
author = {Brown, Patrick T and Caldeira, Ken},
doi = {10.1038/nature24672},
issn = {0028-0836},
journal = {Nature},
month = {dec},
number = {7683},
pages = {45--50},
publisher = {Macmillan Publishers Limited, part of Springer Nature. All rights reserved.},
title = {{Greater future global warming inferred from Earth's recent energy budget}},
url = {http://dx.doi.org/10.1038/nature24672},
volume = {552},
year = {2017}
}
@article{ISI:000407276600014,
abstract = {The Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), is NASA's latest reanalysis for the satellite era (1980 onward) using the Goddard Earth Observing System, version 5 (GEOS-5), Earth system model. MERRA-2 provides several improvements over its predecessor (MERRA-1), including aerosol assimilation for the entire period. MERRA-2 assimilates bias-corrected aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer and the Advanced Very High Resolution Radiometer instruments. Additionally, MERRA-2 assimilates (non bias corrected) AODfrom the Multiangle Imaging SpectroRadiometer over bright surfaces andAODfrom Aerosol Robotic Network sunphotometer stations. This paper, the second of a pair, summarizes the efforts to assess the quality of the MERRA-2 aerosol products. First, MERRA-2 aerosols are evaluated using independent observations. It is shown that the MERRA-2 absorption aerosol optical depth (AAOD) and ultraviolet aerosol index (AI) compare well with Ozone Monitoring Instrument observations. Next, aerosol vertical structure and surface fine particulate matter (PM2.5) are evaluated using available satellite, aircraft, and ground-based observations. While MERRA-2 generally compares well to these observations, the assimilation cannot correct for all deficiencies in the model (e.g., missing emissions). Such deficiencies can explain many of the biases with observations. Finally, a focus is placed on several major aerosol events to illustrate successes and weaknesses of theAODassimilation: the Mount Pinatubo eruption, a Saharan dust transport episode, the California Rim Fire, and an extreme pollution event over China. The article concludes with a summary that points to best practices for using the MERRA-2 aerosol reanalysis in future studies.},
author = {Buchard, V and Randles, C A and da Silva, A M and Darmenov, A and Colarco, P R and Govindaraju, R and Ferrare, R and Hair, J and Beyersdorf, A J and Ziemba, L D and Yu, H},
doi = {10.1175/JCLI-D-16-0613.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {17},
pages = {6851--6872},
title = {{The MERRA-2 Aerosol Reanalysis, 1980 Onward. Part II: Evaluation and Case Studies}},
volume = {30},
year = {2017}
}
@article{Burke13288,
abstract = {The expected departure of future climates from those experienced in human history challenges efforts to adapt. Possible analogs to climates from deep in Earth{\{}$\backslash$textquoteright{\}}s geological past have been suggested but not formally assessed. We compare climates of the coming decades with climates drawn from six geological and historical periods spanning the past 50 My. Our study suggests that climates like those of the Pliocene will prevail as soon as 2030 CE and persist under climate stabilization scenarios. Unmitigated scenarios of greenhouse gas emissions produce climates like those of the Eocene, which suggests that we are effectively rewinding the climate clock by approximately 50 My, reversing a multimillion year cooling trend in less than two centuries.As the world warms due to rising greenhouse gas concentrations, the Earth system moves toward climate states without societal precedent, challenging adaptation. Past Earth system states offer possible model systems for the warming world of the coming decades. These include the climate states of the Early Eocene (ca. 50 Ma), the Mid-Pliocene (3.3{\{}$\backslash$textendash{\}}3.0 Ma), the Last Interglacial (129{\{}$\backslash$textendash{\}}116 ka), the Mid-Holocene (6 ka), preindustrial (ca. 1850 CE), and the 20th century. Here, we quantitatively assess the similarity of future projected climate states to these six geohistorical benchmarks using simulations from the Hadley Centre Coupled Model Version 3 (HadCM3), the Goddard Institute for Space Studies Model E2-R (GISS), and the Community Climate System Model, Versions 3 and 4 (CCSM) Earth system models. Under the Representative Concentration Pathway 8.5 (RCP8.5) emission scenario, by 2030 CE, future climates most closely resemble Mid-Pliocene climates, and by 2150 CE, they most closely resemble Eocene climates. Under RCP4.5, climate stabilizes at Pliocene-like conditions by 2040 CE. Pliocene-like and Eocene-like climates emerge first in continental interiors and then expand outward. Geologically novel climates are uncommon in RCP4.5 ({\textless}1{\%}) but reach 8.7{\%} of the globe under RCP8.5, characterized by high temperatures and precipitation. Hence, RCP4.5 is roughly equivalent to stabilizing at Pliocene-like climates, while unmitigated emission trajectories, such as RCP8.5, are similar to reversing millions of years of long-term cooling on the scale of a few human generations. Both the emergence of geologically novel climates and the rapid reversion to Eocene-like climates may be outside the range of evolutionary adaptive capacity.},
author = {Burke, K D and Williams, J W and Chandler, M A and Haywood, A M and Lunt, D J and Otto-Bliesner, B L},
doi = {10.1073/pnas.1809600115},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {52},
pages = {13288--13293},
publisher = {National Academy of Sciences},
title = {{Pliocene and Eocene provide best analogs for near-future climates}},
url = {https://www.pnas.org/content/115/52/13288},
volume = {115},
year = {2018}
}
@article{Burls2014,
abstract = {The mean east–west sea surface temperature gradient along the equator is a key feature of tropical climate. Tightly coupled to the atmospheric Walker circulation and the oceanic east–west thermocline tilt, it effec- tively defines tropical climate conditions. In the Pacific, its presence permits the El Ni{\~{}} no–Southern Oscillation phenomenon.What determines this temperature gradient within the fully coupled ocean–atmosphere system is therefore a central question in climate dynamics, critical for understanding past and future climates. Using a comprehensive coupled model [Community Earth System Model (CESM)], the authors demonstrate how the meridional gradient in cloud albedo between the tropics and midlatitudes (Da) sets the mean east–west sea surface temperature gradient inthe equatorialPacific.To changeDain the numerical experiments, the authors change the optical properties of clouds by modifying the atmospheric water path, but only in the shortwave radiation scheme of themodel.WhenDa is varied from approximately20.15 to 0.1, the east–west SST contrast in the equatorial Pacific reduces from 7.58Ctolessthan18C and the Walker circulation nearly collapses. These experiments reveal a near-linear dependence between Da and the zonal temperature gradient, which generally agrees with results from the Coupled Model Intercomparison Project phase 5 (CMIP5) preindustrial control simulations. The authors explain the close relation between the two variables using an energy balance model incorporating the essential dynamics of the warm pool, cold tongue, and Walker circulation complex. 1.},
author = {Burls, N. J. and Fedorov, A. V.},
doi = {10.1175/JCLI-D-13-00255.1},
issn = {08948755},
journal = {Journal of Climate},
number = {7},
pages = {2757--2778},
publisher = {American Meteorological Society},
title = {{What controls the mean east-west sea surface temperature gradient in the equatorial pacific: The role of cloud albedo}},
volume = {27},
year = {2014}
}
@article{doi:10.1002/2014PA002644,
abstract = {AbstractAvailable evidence suggests that during the early Pliocene (4–5 Ma) the mean east-west sea surface temperature (SST) gradient in the equatorial Pacific Ocean was significantly smaller than today, possibly reaching only 1–2°C. The meridional SST gradients were also substantially weaker, implying an expanded ocean warm pool in low latitudes. Subsequent global cooling led to the establishment of the stronger, modern temperature gradients. Given our understanding of the physical processes that maintain the present-day cold tongue in the east, warm pool in the west and hence sharp temperature contrasts, determining the key factors that maintained early Pliocene climate still presents a challenge for climate theories and models. This study demonstrates how different cloud properties could provide a solution. We show that a reduction in the meridional gradient in cloud albedo can sustain reduced meridional and zonal SST gradients, an expanded warm pool and warmer thermal stratification in the ocean, and weaker Hadley and Walker circulations in the atmosphere. Having conducted a range of hypothetical modified cloud albedo experiments, we arrive at our Pliocene simulation, which shows good agreement with proxy SST data from major equatorial and coastal upwelling regions, the tropical warm pool, middle and high latitudes, and available subsurface temperature data. As suggested by the observations, the simulated Pliocene-like climate sustains a robust El Ni{\~{n}}o-Southern Oscillation despite the reduced mean east-west SST gradient. Our results demonstrate that cloud albedo changes may be a critical element of Pliocene climate and that simulating the meridional SST gradient correctly is central to replicating the geographical patterns of Pliocene warmth.},
author = {Burls, N J and Fedorov, A V},
doi = {10.1002/2014PA002644},
journal = {Paleoceanography},
keywords = {Pliocene climate,cloud albedo},
number = {10},
pages = {893--910},
title = {{Simulating Pliocene warmth and a permanent El Ni{\~{n}}o-like state: The role of cloud albedo}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014PA002644},
volume = {29},
year = {2014}
}
@article{Burt2016,
abstract = {As the Arctic sea ice thins and ultimately disappears in a warming climate, its insulating power decreases. This causes the surface air temperature to approach the temperature of the relatively warm ocean water below the ice. The resulting increases in air temperature, water vapor, and cloudiness lead to an increase in the surface downwelling longwave radiation (DLR), which enables a further thinning of the ice. This positive ice–insulation feedback operates mainly in the autumn and winter. A climate change simulation with the Community Earth System Model shows that, averaged over the year, the increase in Arctic DLR is 3 times stronger than the increase in Arctic absorbed solar radiation at the surface. The warming of the surface air over the Arctic Ocean during fall and winter creates a strong thermal contrast with the colder surrounding continents. Sea level pressure falls over the Arctic Ocean, and the high-latitude circulation reorganizes into a shallow “winter monsoon.” The resulting increase in surface wind speed promotes stronger surface evaporation and higher humidity over portions of the Arctic Ocean, thus reinforcing the ice–insulation feedback.},
author = {Burt, Melissa A. and Randall, David A. and Branson, Mark D.},
doi = {10.1175/JCLI-D-15-0147.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Arctic,Atm/Ocean Structure/Phenomena,Climate change,Cloud radiative effects,Geographic location/entity,Monsoons,Physical meteorology and climatology,Sea ice},
month = {jan},
number = {2},
pages = {705--719},
title = {{Dark Warming}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0147.1},
volume = {29},
year = {2016}
}
@article{Caballero2013,
abstract = {Projections of future climate depend critically on refined estimates of climate sensitivity. Recent progress in temperature proxies dramatically increases the magnitude of warming reconstructed from early Paleogene greenhouse climates and demands a close examination of the forcing and feedback mechanisms that maintained this warmth and the broad dynamic range that these paleoclimate records attest to. Here, we show that several complementary resolutions to these questions are possible in the context of model simulations using modern and early Paleogene configurations. We find that (i) changes in boundary conditions representative of slow "Earth system" feedbacks play an important role in maintaining elevated early Paleogene temperatures, (ii) radiative forcing by carbon dioxide deviates significantly from pure logarithmic behavior at concentrations relevant for simulation of the early Paleogene, and (iii) fast or "Charney" climate sensitivity in this model increases sharply as the climate warms. Thus, increased forcing and increased slow and fast sensitivity can all play a substantial role in maintaining early Paleogene warmth. This poses an equifinality problem: The same climate can be maintained by a different mix of these ingredients; however, at present, the mix cannot be constrained directly from climate proxy data. The implications of strongly state-dependent fast sensitivity reach far beyond the early Paleogene. The study of past warm climates may not narrow uncertainty in future climate projections in coming centuries because fast climate sensitivity may itself be state-dependent, but proxies and models are both consistent with significant increases in fast sensitivity with increasing temperature.},
author = {Caballero, R. and Huber, M.},
doi = {10.1073/pnas.1303365110},
isbn = {1091-6490},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {35},
pages = {14162--14167},
pmid = {23918397},
title = {{State-dependent climate sensitivity in past warm climates and its implications for future climate projections}},
url = {http://www.pnas.org/cgi/doi/10.1073/pnas.1303365110},
volume = {110},
year = {2013}
}
@article{cain2019improved,
abstract = {Anthropogenic global warming at a given time is largely determined by the cumulative total emissions (or stock) of long-lived climate pollutants (LLCPs), predominantly carbon dioxide (CO2), and the emission rates (or flow) of short-lived climate pollutants (SLCPs) immediately prior to that time. Under the United Nations Framework Convention on Climate Change (UNFCCC), reporting of greenhouse gas emissions has been standardised in terms of CO2-equivalent (CO2-e) emissions using Global Warming Potentials (GWP) over 100-years, but the conventional usage of GWP does not adequately capture the different behaviours of LLCPs and SLCPs, or their impact on global mean surface temperature. An alternative usage of GWP, denoted GWP*, overcomes this problem by equating an increase in the emission rate of an SLCP with a one-off “pulse” emission of CO2. We show that this approach, while an improvement on the conventional usage, slightly underestimates the impact of recent increases in SLCP emissions on current rates of warming because the climate does not respond instantaneously to radiative forcing. We resolve this with a modification of the GWP* definition, which incorporates a term for each of the short-timescale and long-timescale climate responses to changes in radiative forcing. The amended version allows “CO2-warming-equivalent” (CO2-we) emissions to be calculated directly from reported emissions. Thus SLCPs can be incorporated directly into carbon budgets consistent with long-term temperature goals, because every unit of CO2-we emitted generates approximately the same amount of warming, whether it is emitted as a SLCP or a LLCP. This is not the case for conventionally derived CO2-e.},
author = {Cain, Michelle and Lynch, John and Allen, Myles R. and Fuglestvedt, Jan S. and Frame, David J. and Macey, Adrian H},
doi = {10.1038/s41612-019-0086-4},
issn = {2397-3722},
journal = {NPJ climate and atmospheric science},
number = {1},
pages = {1--7},
publisher = {Nature Publishing Group},
title = {{Improved calculation of warming-equivalent emissions for short-lived climate pollutants}},
volume = {2},
year = {2019}
}
@article{Caldwell2016,
abstract = {AbstractThis study clarifies the causes of intermodel differences in the global-average temperature response to doubled CO2, commonly known as equilibrium climate sensitivity (ECS). The authors begin by noting several issues with the standard approach for decomposing ECS into a sum of forcing and feedback terms. This leads to a derivation of an alternative method based on linearizing the effect of the net feedback. Consistent with previous studies, the new method identifies shortwave cloud feedback as the dominant source of intermodel spread in ECS. This new approach also reveals that covariances between cloud feedback and forcing, between lapse rate and longwave cloud feedbacks, and between albedo and shortwave cloud feedbacks play an important and previously underappreciated role in determining model differences in ECS. Defining feedbacks based on fixed relative rather than specific humidity (as suggested by Held and Shell) reduces the covariances between processes and leads to more straightforward inte...},
author = {Caldwell, Peter M. and Zelinka, Mark D. and Taylor, Karl E. and Marvel, Kate},
doi = {10.1175/JCLI-D-15-0352.1},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Climate models,Climate sensitivity,Feedback,Forcing,Mathematical and statistical techniques,Models and modeling,Physical meteorology and climatology,Statistics},
number = {2},
pages = {513--524},
title = {{Quantifying the sources of intermodel spread in equilibrium climate sensitivity}},
volume = {29},
year = {2016}
}
@article{Caldwell2018,
abstract = {AbstractEmergent constraints are quantities that are observable from current measurements and have skill predicting future climate. This study explores 19 previously proposed emergent constraints related to equilibrium climate sensitivity (ECS; the global-average equilibrium surface temperature response to CO2 doubling). Several constraints are shown to be closely related, emphasizing the importance for careful understanding of proposed constraints. A new method is presented for decomposing correlation between an emergent constraint and ECS into terms related to physical processes and geographical regions. Using this decomposition, one can determine whether the processes and regions explaining correlation with ECS correspond to the physical explanation offered for the constraint. Shortwave cloud feedback is generally found to be the dominant contributor to correlations with ECS because it is the largest source of intermodel spread in ECS. In all cases, correlation results from interaction between a variety of terms, reflecting the complex nature of ECS and the fact that feedback terms and forcing are themselves correlated with each other. For 4 of the 19 constraints, the originally proposed explanation for correlation is borne out by our analysis. These four constraints all predict relatively high climate sensitivity. The credibility of six other constraints is called into question owing to correlation with ECS coming mainly from unexpected sources and/or lack of robustness to changes in ensembles. Another six constraints lack a testable explanation and hence cannot be confirmed. The fact that this study casts doubt upon more constraints than it confirms highlights the need for caution when identifying emergent constraints from small ensembles.},
annote = {doi: 10.1175/JCLI-D-17-0631.1},
author = {Caldwell, Peter M and Zelinka, Mark D and Klein, Stephen A},
doi = {10.1175/JCLI-D-17-0631.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {feb},
number = {10},
pages = {3921--3942},
publisher = {American Meteorological Society},
title = {{Evaluating Emergent Constraints on Equilibrium Climate Sensitivity}},
url = {https://doi.org/10.1175/JCLI-D-17-0631.1},
volume = {31},
year = {2018}
}
@article{Caldwell2014,
abstract = {Several recent efforts to estimate Earth's equilibrium climate sensitivity (ECS) focus on identifying quantities in the current climate which are skillful predictors of ECS yet can be constrained by observations. This study automates the search for observable predictors using data from phase 5 of the Coupled Model Intercomparison Project. The primary focus of this paper is assessing statistical significance of the resulting predictive relationships. Failure to account for dependence between models, variables, locations, and seasons is shown to yield misleading results. A new technique for testing the field significance of data-mined correlations which avoids these problems is presented. Using this new approach, all 41,741 relationships we tested were found to be explainable by chance. This leads us to conclude that data mining is best used to identify potential relationships which are then validated or discarded using physically based hypothesis testing. Key Points Correlation magnitude is not sufficient proof of predictive skill Significance testing is complicated by model nonindependence in ensembles The best predictors of climate change are related to the Southern Ocean {\textcopyright}2014. American Geophysical Union. All Rights Reserved.},
author = {Caldwell, Peter M. and Bretherton, Christopher S. and Zelinka, Mark D. and Klein, Stephen A. and Santer, Benjamin D. and Sanderson, Benjamin M.},
doi = {10.1002/2014GL059205},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {CMIP,climate sensitivity,data mining,ensemble,intercomparison},
number = {5},
pages = {1803--1808},
title = {{Statistical significance of climate sensitivity predictors obtained by data mining}},
volume = {41},
year = {2014}
}
@article{Calisto2014,
author = {Calisto, M and Folini, D and Wild, M and Bengtsson, L},
doi = {10.5194/angeo-32-793-2014},
issn = {1432-0576},
journal = {Annales Geophysicae},
month = {jul},
number = {7},
pages = {793--807},
publisher = {Copernicus Publications},
title = {{Cloud radiative forcing intercomparison between fully coupled CMIP5 models and CERES satellite data}},
url = {https://www.ann-geophys.net/32/793/2014/ https://www.ann-geophys.net/32/793/2014/angeo-32-793-2014.pdf},
volume = {32},
year = {2014}
}
@article{Calogovic2010,
author = {Calogovic, J. and Albert, C. and Arnold, F. and Beer, J. and Desorgher, L. and Flueckiger, E. O.},
doi = {10.1029/2009GL041327},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {feb},
number = {3},
pages = {L03802},
title = {{Sudden cosmic ray decreases: No change of global cloud cover}},
url = {http://doi.wiley.com/10.1029/2009GL041327},
volume = {37},
year = {2010}
}
@article{Cane1997,
author = {Cane, Mark A. and Clement, Amy C. and Kaplan, Alexey and Kushnir, Yochanan and Pozdnyakov, Dmitri and Seager, Richard and Zebiak, Stephen E. and Murtugudde, Ragu},
doi = {10.1126/science.275.5302.957},
journal = {Science},
month = {feb},
number = {5302},
pages = {957--960},
publisher = {American Association for the Advancement of Science (AAAS)},
title = {{Twentieth-Century Sea Surface Temperature Trends}},
volume = {275},
year = {1997}
}
@article{CaoLia15,
abstract = {The decreasing surface albedo caused by continuously retreating sea ice over Arctic plays a critical role in Arctic warming amplification. However, the quantification of the change in radiative forcing at top of atmosphere (TOA) introduced by the decreasing sea ice albedo and its feedback to the climate remain uncertain. In this study, based on the satellite-retrieved long-term surface albedo product CLARA-A1 (Cloud, Albedo, and Radiation dataset, AVHRR-based, version 1) and the radiative kernel method, an estimated 0.20 ± 0.05 W m−2 sea ice radiative forcing (SIRF) has decreased in the Northern Hemisphere (NH) owing to the loss of sea ice from 1982 to 2009, yielding a sea ice albedo feedback (SIAF) of 0.25 W m−2 K−1 for the NH and 0.19 W m−2 K−1 for the entire globe. These results are lower than the estimate from another method directly using the Clouds and the Earth's Radiant Energy System (CERES) broadband planetary albedo. Further data analysis indicates that kernel method is likely to underestimate the change in all-sky SIRF because all-sky radiative kernels mask too much of the effect of sea ice albedo on the variation of cloudy albedo. By applying an adjustment with CERES-based estimate, the change in all-sky SIRF over the NH was corrected to 0.33 ± 0.09 W m−2, corresponding to a SIAF of 0.43 W m−2 K−1 for NH and 0.31 W m−2 K−1 for the entire globe. It is also determined that relative to satellite surface albedo product, two popular reanalysis products, ERA-Interim and MERRA, severely underestimate the changes in NH SIRF in melt season (May–August) from 1982 to 2009 and the sea ice albedo feedback to warming climate.},
author = {Cao, Yunfeng and Liang, Shunlin and Chen, Xiaona and He, Tao},
doi = {10.1175/JCLI-D-14-00389.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {feb},
number = {3},
pages = {1248--1259},
title = {{Assessment of Sea Ice Albedo Radiative Forcing and Feedback over the Northern Hemisphere from 1982 to 2009 Using Satellite and Reanalysis Data}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-14-00389.1},
volume = {28},
year = {2015}
}
@article{Cao2010,
abstract = {An increase in atmospheric carbon dioxide (CO2) concentration influences climate both directly through its radiative effect (i.e., trapping longwave radiation) and indirectly through its physiological effect (i.e., reducing transpiration of land plants). Here we compare the climate response to radiative and physiological effects of increased CO2using the National Center for Atmospheric Research (NCAR) coupled Community Land and Community Atmosphere Model. In response to a doubling of CO2, the radiative effect of CO2causes mean surface air temperature over land to increase by 2.86 ± 0.02 K (±1 standard error), whereas the physiological effects of CO2on land plants alone causes air temperature over land to increase by 0.42 ± 0.02 K. Combined, these two effects cause a land surface warming of 3.33 ± 0.03 K. The radiative effect of doubling CO2increases global runoff by 5.2 ± 0.6{\%}, primarilyby increasing precipitation over the continents. The physiological effect increases runoff by 8.4 ± 0.6{\%}, primarily by diminishing evapotranspiration from the continents. Combined, these two effects cause a 14.9 ± 0.7{\%} increase in runoff. Relative humidity remains roughly constant in response to CO2-radiative forcing, whereas relative humidity over land decreases in response to CO2-physiological forcing as a result of reduced plant transpiration. Our study points to an emerging consensus that the physiological effects of increasing atmospheric CO2on land plants will increase global warming beyond that caused by the radiative effects of CO2.},
author = {Cao, L. and Bala, G. and Caldeira, K. and Nemani, R. and Ban-Weiss, G.},
doi = {10.1073/pnas.0913000107},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
month = {may},
number = {21},
pages = {9513--9518},
title = {{Importance of carbon dioxide physiological forcing to future climate change}},
url = {http://www.pnas.org/cgi/doi/10.1073/pnas.0913000107},
volume = {107},
year = {2010}
}
@article{Ceppi2016,
abstract = {AbstractIncreases in cloud optical depth and liquid water path (LWP) are robust features of global warming model simulations in high latitudes, yielding a negative shortwave cloud feedback, but the mechanisms are still uncertain. Here the importance of microphysical processes for the negative optical depth feedback is assessed by perturbing temperature in the microphysics schemes of two aquaplanet models, both of which have separate prognostic equations for liquid water and ice. It is found that most of the LWP increase with warming is caused by a suppression of ice microphysical processes in mixed-phase clouds, resulting in reduced conversion efficiencies of liquid water to ice and precipitation. Perturbing the temperature-dependent phase partitioning of convective condensate also yields a small LWP increase. Together, the perturbations in large-scale microphysics and convective condensate partitioning explain more than two-thirds of the LWP response relative to a reference case with increased SSTs, and ...},
author = {Ceppi, Paulo and McCoy, Daniel T. and Hartmann, Dennis L.},
doi = {10.1002/2015GL067499},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {climate,climate change,climate feedbacks,clouds},
number = {3},
pages = {1331--1339},
title = {{Observational evidence for a negative shortwave cloud feedback in middle to high latitudes}},
volume = {43},
year = {2016}
}
@article{Ceppi2015a,
author = {Ceppi, Paulo and Hartmann, Dennis L.},
doi = {10.1007/s40641-015-0010-x},
issn = {2198-6061},
journal = {Current Climate Change Reports},
month = {jun},
number = {2},
pages = {94--102},
title = {{Connections Between Clouds, Radiation, and Midlatitude Dynamics: a Review}},
url = {http://link.springer.com/10.1007/s40641-015-0010-x},
volume = {1},
year = {2015}
}
@article{Ceppi2017a,
abstract = {In current climate models, the anticipated amount of warming under greenhouse gas forcing, quantified by the “effective climate sensitivity,” increases as time passes. Consequently, effective climate sensitivity values inferred from the historical record may underestimate the future warming. However, the mechanisms of this increase in effective climate sensitivity are not understood, limiting our confidence in climate model projections of future climate change. Here, we present observational and modeling evidence that the magnitude of effective climate sensitivity partly depends on the evolution of the vertical profile of atmospheric warming. In climate models, as the Earth warms overall, the warming becomes increasingly muted aloft, and this alters the strength of feedbacks controlling the radiative response to greenhouse gas forcing.Climate feedbacks generally become smaller in magnitude over time under CO2 forcing in coupled climate models, leading to an increase in the effective climate sensitivity, the estimated global-mean surface warming in steady state for doubled CO2. Here, we show that the evolution of climate feedbacks in models is consistent with the effect of a change in tropospheric stability, as has recently been hypothesized, and the latter is itself driven by the evolution of the pattern of sea-surface temperature response. The change in climate feedback is mainly associated with a decrease in marine tropical low cloud (a more positive shortwave cloud feedback) and with a less negative lapse-rate feedback, as expected from a decrease in stability. Smaller changes in surface albedo and humidity feedbacks also contribute to the overall change in feedback, but are unexplained by stability. The spatial pattern of feedback changes closely matches the pattern of stability changes, with the largest increase in feedback occurring in the tropical East Pacific. Relationships qualitatively similar to those in the models among sea-surface temperature pattern, stability, and radiative budget are also found in observations on interannual time scales. Our results suggest that constraining the future evolution of sea-surface temperature patterns and tropospheric stability will be necessary for constraining climate sensitivity.},
author = {Ceppi, Paulo and Gregory, Jonathan M.},
doi = {10.1073/pnas.1714308114},
isbn = {0027-8424},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
month = {dec},
number = {50},
pages = {13126--13131},
pmid = {29183969},
title = {{Relationship of tropospheric stability to climate sensitivity and Earth's observed radiation budget}},
url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1714308114},
volume = {114},
year = {2017}
}
@article{Ceppi2019,
abstract = {A commonly-used model of the global radiative budget assumes that the radiative response to forcing, R, is proportional to global surface air temperature T, R= $\lambda$T. Previous studies have highlighted two unresolved issues with this model: first, the feedback parameter $\lambda$ depends on the forcing agent; second, $\lambda$ varies with time. Here, we investigate the factors controlling R in two atmosphere–slab ocean climate models subjected to a wide range of abrupt climate forcings. It is found that R scales not only with T, but also with the large-scale tropospheric stability S (defined here as the estimated inversion strength area-averaged over ocean regions equatorward of 50∘). Positive S promotes negative R, mainly through shortwave cloud and lapse-rate changes. A refined model of the global energy balance is proposed that accounts for both temperature and stability effects. This refined model quantitatively explains (1) the dependence of climate feedbacks on forcing agent (or equivalently, differences in forcing efficacy), and (2) the time evolution of feedbacks in coupled climate model experiments. Furthermore, a similar relationship between R and S is found in observations compared with models, lending confidence that the refined energy balance model is applicable to the real world.},
author = {Ceppi, Paulo and Gregory, Jonathan M.},
doi = {10.1007/s00382-019-04825-x},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Climate change,Climate feedbacks,Climate sensitivity,Clouds,Radiative forcing},
month = {oct},
number = {7-8},
pages = {4781--4797},
publisher = {Springer Verlag},
title = {{A refined model for the Earth's global energy balance}},
volume = {53},
year = {2019}
}
@article{Cesana2019,
author = {Cesana, Gr{\'{e}}gory and {Del Genio}, Anthony D and Ackerman, Andrew S and Kelley, Maxwell and Elsaesser, Gregory and Fridlind, Ann M and Cheng, Ye and Yao, Mao-Sung},
doi = {10.5194/acp-19-2813-2019},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {mar},
number = {5},
pages = {2813--2832},
publisher = {Copernicus Publications},
title = {{Evaluating models' response of tropical low clouds to SST forcings using CALIPSO observations}},
url = {https://www.atmos-chem-phys.net/19/2813/2019/ https://www.atmos-chem-phys.net/19/2813/2019/acp-19-2813-2019.pdf https://acp.copernicus.org/articles/19/2813/2019/},
volume = {19},
year = {2019}
}
@article{Cesana2017,
abstract = {Abstract Whether a cloud is predominantly water or ice strongly influences interactions between clouds and radiation coming down from the Sun or up from the Earth. Being able to simulate cloud phase transitions accurately in climate models based on observational data sets is critical in order to improve confidence in climate projections, because this uncertainty contributes greatly to the overall uncertainty associated with cloud-climate feedbacks. Ultimately, it translates into uncertainties in Earth's sensitivity to higher CO2 levels. While a lot of effort has recently been made toward constraining cloud phase in climate models, more remains to be done to document the radiative properties of clouds according to their phase. Here we discuss the added value of a new satellite data set that advances the field by providing estimates of the cloud radiative effect as a function of cloud phase and the implications for climate projections.},
annote = {doi: 10.1002/2017JD026927},
author = {Cesana, Gregory and Storelvmo, Trude},
doi = {10.1002/2017JD026927},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {climate feedbacks,climate models,cloud phase,cloud radiative effect,radiation,satellite observations},
month = {apr},
number = {8},
pages = {4594--4599},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Improving climate projections by understanding how cloud phase affects radiation}},
url = {https://doi.org/10.1002/2017JD026927},
volume = {122},
year = {2017}
}
@article{ce03000u,
author = {Cess, R D and Potter, G L and Blanchet, J P and Boer, G J and {Del Genio}, A D and Deque, M and Dymnikov, V and Galin, V and Gates, W L and Ghan, S J and Kiehl, J T and Lacis, A A and {Le Treut}, H and Li, Z.-X. and Liang, X.-Z. and McAvaney, B J and Meleshko, V P and Mitchell, J F B and Morcrette, J.-J. and Randall, D A and Rikus, L and Roeckner, E and Royer, J F and Schlese, U and Sheinin, D A and Slingo, A and Sokolov, A P and Taylor, K E and Washington, W M and Wetherald, R T and Yagai, I and Zhang, M.-H.},
doi = {10.1029/JD095iD10p16601},
journal = {Journal of Geophysical Research: Atmospheres},
pages = {16601--16615},
title = {{Intercomparison and interpretation of climate feedback processes in 19 atmospheric general circulation models}},
volume = {95},
year = {1990}
}
@article{Chafik2016,
abstract = {The anomalous decadal warming of the subpolar North Atlantic Ocean (SPNA), and the northward spreading of this warm water, has been linked to rapid Arctic sea ice loss and more frequent cold European winters. Recently, variations in this heat transport have also been reported to covary with global warming slowdown/acceleration periods via a Pacific climate response.We here examine the role of SPNA temperature variability in this Atlantic-Pacific climate connectivity.We find that the evolution of ocean heat content anomalies from the subtropics to the subpolar region, likely due to ocean circulation changes, coincides with a basin-wide Atlantic warming/cooling. This induces an Atlantic-Pacific sea surface temperature seesaw, which in turn, strengthens/weakens theWalker circulation and amplifies the Pacific decadal variability that triggers pronounced global-scale atmospheric circulation anomalies.We conclude that the decadal oceanic variability in the SPNA is an essential component of the tropical interactions between the Atlantic and Pacific Oceans.},
author = {Chafik, L. and H{\"{a}}kkinen, S. and England, M. H. and Carton, J. A. and Nigam, S. and Ruiz-Barradas, A. and Hannachi, A. and Miller, L.},
doi = {10.1002/2016GL071134},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {Atlantic climate,Pacific climate,Walker circulation,decadal variability,subpolar North Atlantic,teleconnections},
month = {oct},
number = {20},
pages = {10909--10919},
pmid = {22139199},
publisher = {Blackwell Publishing Ltd},
title = {{Global linkages originating from decadal oceanic variability in the subpolar North Atlantic}},
volume = {43},
year = {2016}
}
@article{Chandan2018,
abstract = {We present results from our investigation into the physical mechanisms through which the mid-Pliocene, with an atmospheric pCO2 of only {\~{}}{\&}thinsp;400{\&}thinsp;ppmv, could have supported the same magnitude of global warmth as that which has been projected for the climate at the end of the 21st century when pCO2 is expected to be three times higher. These mechanisms explore changes to the radiative properties of the surface, the clouds, greenhouse gases and changes to the meridional heat transport. Furthermore, we provide a mid-Pliocene perspective on ongoing efforts to understand the climate system's sensitivity at various timescales and using multiple lines of evidence. The similarities in the boundary conditions between the mid-Pliocene and the present day, together with the globally elevated temperatures, make the mid-Pliocene an ideal palaeo time period from which to derive inferences of climate sensitivity and assess the impacts of various timescale-dependent feedback processes. We assess a hierarchy of climate sensitivities of increasing complexity in order to explore the response of the climate over a very large range of timescales. The various sensitivities that we calculate provide insight on not only how the climate responds to a given forcing over a short timescale, but also on intermediate and very-long timescales. The latter category includes the impact of the feedback from the glacial isostatic adjustment of the Earth's surface in response to the melting of the polar ice sheets. Our inference of the intermediate timescale climate sensitivity suggests that the projected warming by 2300{\&}thinsp;CE, inferred using Earth System Models of Intermediate Complexity on the basis of an extension to the RCP4.5 emission scenario in which atmospheric pCO2 stabilizes at roughly twice the PI level in year 2150{\&}thinsp;CE, could be underestimated by {\~{}}{\&}thinsp;1{\&}thinsp;{\&}deg;C due to the absence of ice sheet based feedbacks.},
author = {Chandan, Deepak and Peltier, R. W.},
doi = {10.5194/cp-14-825-2018},
issn = {18149332},
journal = {Climate of the Past},
number = {6},
pages = {825--856},
title = {{On the mechanisms of warming the mid-Pliocene and the inference of a hierarchy of climate sensitivities with relevance to the understanding of climate futures}},
volume = {14},
year = {2018}
}
@book{NAP12181,
address = {Washington, DC, USA},
author = {Charney, Jule G. and Arakawa, Akio and Baker, D. James and Bolin, Bert and Dickinson, Robert E. and Goody, Richard M. and Leith, Cecil E. and Stommel, Henry M. and Wunsch, Carl I.},
doi = {10.17226/12181},
pages = {34},
publisher = {National Research Council (NRC). The National Academies Press},
title = {{Carbon Dioxide and Climate: A Scientific Assessment}},
url = {https://www.nap.edu/catalog/12181/carbon-dioxide-and-climate-a-scientific-assessment},
year = {1979}
}
@article{Checa-Garcia2018,
abstract = {{\textcopyright}2018. American Geophysical Union. All Rights Reserved. We calculate ozone radiative forcing (RF) and stratospheric temperature adjustments for the period 1850–2014 using the newly available Coupled Model Intercomparison Project phase 6 (CMIP6) ozone data set. The CMIP6 total ozone RF (1850s to 2000s) is 0.28 ± 0.17 W m−2(which is 80{\%} higher than our CMIP5 estimation), and 0.30 ± 0.17 W m−2out to the present day (2014). The total ozone RF grows rapidly until the 1970s, slows toward the 2000s, and shows a renewed growth thereafter. Since the 1990s the shortwave RF exceeds the longwave RF. Global stratospheric ozone RF is positive between 1930 and 1970 and then turns negative but remains positive in the Northern Hemisphere throughout. Derived stratospheric temperature changes show a localized cooling in the subtropical lower stratosphere due to tropospheric ozone increases and cooling in the upper stratosphere due to ozone depletion by more than 1 K already prior to the satellite era (1980) and by more than 2 K out to the present day (2014).},
author = {Checa-Garcia, R. and Hegglin, M.I. and Kinnison, D. and Plummer, D.A. and Shine, K.P.},
doi = {10.1002/2017GL076770},
journal = {Geophysical Research Letters},
number = {7},
pages = {3264--3273},
title = {{Historical Tropospheric and Stratospheric Ozone Radiative Forcing Using the CMIP6 Database}},
volume = {45},
year = {2018}
}
@article{ChenLC16a,
author = {Chen, Xiaona and Liang, Shunlin and Cao, Yunfeng},
doi = {10.1088/1748-9326/11/8/084002},
issn = {1748-9326},
journal = {Environmental Research Letters},
month = {aug},
number = {8},
pages = {084002},
title = {{Satellite observed changes in the Northern Hemisphere snow cover phenology and the associated radiative forcing and feedback between 1982 and 2013}},
url = {http://stacks.iop.org/1748-9326/11/i=8/a=084002 https://iopscience.iop.org/article/10.1088/1748-9326/11/8/084002},
volume = {11},
year = {2016}
}
@article{Chen2014b,
abstract = {The levels of aerosols in the atmosphere affect cloud reflectivity and the Earth's radiative balance. A comprehensive analysis of satellite observations shows that thermodynamics and precipitation govern cloud responses to aerosols.},
author = {Chen, Yi-Chun and Christensen, Matthew W. and Stephens, Graeme L. and Seinfeld, John H.},
doi = {10.1038/ngeo2214},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {sep},
number = {9},
pages = {643--646},
publisher = {Nature Publishing Group},
title = {{Satellite-based estimate of global aerosol–cloud radiative forcing by marine warm clouds}},
volume = {7},
year = {2014}
}
@article{Chenge1601545,
abstract = {Earth's energy imbalance (EEI) drives the ongoing global warming and can best be assessed across the historical record (that is, since 1960) from ocean heat content (OHC) changes. An accurate assessment of OHC is a challenge, mainly because of insufficient and irregular data coverage. We provide updated OHC estimates with the goal of minimizing associated sampling error. We performed a subsample test, in which subsets of data during the data-rich Argo era are colocated with locations of earlier ocean observations, to quantify this error. Our results provide a new OHC estimate with an unbiased mean sampling error and with variability on decadal and multidecadal time scales (signal) that can be reliably distinguished from sampling error (noise) with signal-to-noise ratios higher than 3. The inferred integrated EEI is greater than that reported in previous assessments and is consistent with a reconstruction of the radiative imbalance at the top of atmosphere starting in 1985. We found that changes in OHC are relatively small before about 1980; since then, OHC has increased fairly steadily and, since 1990, has increasingly involved deeper layers of the ocean. In addition, OHC changes in six major oceans are reliable on decadal time scales. All ocean basins examined have experienced significant warming since 1998, with the greatest warming in the southern oceans, the tropical/subtropical Pacific Ocean, and the tropical/subtropical Atlantic Ocean. This new look at OHC and EEI changes over time provides greater confidence than previously possible, and the data sets produced are a valuable resource for further study.},
author = {Cheng, Lijing and Trenberth, Kevin E. and Fasullo, John and Boyer, Tim and Abraham, John and Zhu, Jiang},
doi = {10.1126/sciadv.1601545},
isbn = {2375-2548},
issn = {23752548},
journal = {Science Advances},
number = {3},
pages = {e1601545},
publisher = {American Association for the Advancement of Science},
title = {{Improved estimates of ocean heat content from 1960 to 2015}},
url = {http://advances.sciencemag.org/content/3/3/e1601545},
volume = {3},
year = {2017}
}
@article{Cheng2018a,
author = {Cheng, Lijing and Trenberth, Kevin E. and Fasullo, John and Abraham, John and Boyer, Tim P. and von Schuckmann, Karina and Zhu, Jiang},
doi = {10.1029/2017eo081839},
issn = {23249250},
journal = {Eos, Transactions, American Geophysical Union},
number = {1},
pages = {14--16},
title = {{Taking the pulse of the planet}},
volume = {99},
year = {2018}
}
@article{Chepfer2014,
abstract = {Climate models predict that the geographic distribution of clouds will change in response to anthropogenic warming, though uncertainties in the existing satellite record are larger than the magnitude of the predicted effects. Here we argue that cloud vertical distribution, observable by active spaceborne sensors, is a more robust signature of climate change. Comparison of Atmospheric Model Intercomparison Project present day and +4 K runs from Coupled Model Intercomparison Project Phase 5 shows that cloud radiative effect and total cloud cover do not represent robust signatures of climate change, as predicted changes fall within the range of variability in the current observational record. However, the predicted forced changes in cloud vertical distribution (directly measurable by spaceborne active sensors) are much larger than the currently observed variability and are expected to first appear at a statistically significant level in the upper troposphere, at all latitudes.},
author = {Chepfer, H. and Noel, V. and Winker, D. and Chiriaco, M.},
doi = {10.1002/2014GL061792},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {climate,clouds,remote sensing,spaceborne lidar},
number = {23},
pages = {8387--8395},
title = {{Where and when will we observe cloud changes due to climate warming?}},
volume = {41},
year = {2014}
}
@article{Cherian2014,
abstract = {An increasing trend in surface solar radiation (solar brightening) has been observed over Europe since the 1990s, linked to economic developments and air pollution regulations and their direct as well as cloud-mediated effects on radiation. Here, we find that the all-sky solar brightening trend (1990–2005) over Europe from seven out of eight models (historical simulations in the Fifth Coupled Model Intercomparison Project) scales well with the regional and global mean effective forcing by anthropogenic aerosols (idealized “present-day” minus “preindustrial” runs). The reason for this relationship is that models that simulate stronger forcing efficiencies and stronger radiative effects by aerosol-cloud interactions show both a stronger aerosol forcing and a stronger solar brightening. The all-sky solar brightening is the observable from measurements (4.06±0.60Wm−2 decade −1 ), which then allows to infer a global mean total aerosol effective forcing at about−1.30Wm−2 with standard deviation±0.40Wm−2},
author = {Cherian, Ribu and Quaas, Johannes and Salzmann, Marc and Wild, Martin},
doi = {10.1002/2013GL058715},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {mar},
number = {6},
pages = {2176--2181},
title = {{Pollution trends over Europe constrain global aerosol forcing as simulated by climate models}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2013GL058715},
volume = {41},
year = {2014}
}
@article{RePEc:eee:enscpo:v:64:y:2016:i:c:p:129-140,
abstract = {Life-cycle assessment and carbon footprint studies are widely used by decision makers to identify climate change mitigation options and priorities at corporate and public levels. These applications, including the vast majority of emission accounting schemes and policy frameworks, traditionally quantify climate impacts of human activities by aggregating greenhouse gas emissions into the so-called CO2-equivalents using the 100-year Global Warming Potential (GWP100) as the default emission metric. The practice was established in the early nineties and has not been coupled with progresses in climate science, other than simply updating numerical values for GWP100. We review the key insights from the literature surrounding climate science that are at odds with existing climate impact methods and we identify possible improvement options. Issues with the existing approach lie in the use of a single metric that cannot represent the climate system complexity for all possible research and policy contexts, and in the default exclusion of near-term climate forcers such as aerosols or ozone precursors and changes in the Earth's energy balance associated with land cover changes. Failure to acknowledge the complexity of climate change drivers and the spatial and temporal heterogeneities of their climate system responses can lead to the deployment of suboptimal, and potentially even counterproductive, mitigation strategies. We argue for an active consideration of these aspects to bridge the gap between climate impact methods used in environmental impact analysis and climate science.},
author = {Cherubini, Francesco and Fuglestvedt, Jan and Gasser, Thomas and Reisinger, Andy and Cavalett, Ot{\'{a}}vio and Huijbregts, Mark A J and Johansson, Daniel J A and J{\o}rgensen, Susanne V and Raugei, Marco and Schivley, Greg},
doi = {10.1016/j.envsci.2016.06.},
journal = {Environmental Science {\&} Policy},
keywords = {Climate change; Emission metrics; Life cycle asses},
number = {C},
pages = {129--140},
title = {{Bridging the gap between impact assessment methods and climate science}},
url = {https://ideas.repec.org/a/eee/enscpo/v64y2016icp129-140.html},
volume = {64},
year = {2016}
}
@article{Christensen2016,
abstract = {High amounts of acrylamide in some foods result in an estimated daily mean intake of 50 mu g for a western style diet. Animal studies have shown the carcinogenicity of acrylamide upon oral exposure. However, only sparse human toxicokinetic data is available for acrylamide, which is needed for the extrapolation of human cancer risk from animal data. We evaluated the toxicokinetics of acrylamide in six young healthy volunteers after the consumption of a meal containing 0.94 mg of acrylamide. Urine was collected up to 72 hours thereafter. Unchanged acrylamide, its mercapturic acid metabolite N-acetyl-S-(2-carbamoylethyl)cysteine (AAMA), its epoxy derivative glycidamide, and the respective metabolite of glycidamide, N-acetyl-S-(2-hydroxy2-carbamoylethyl)cysteine (GAMA), were quantified in the urine by liquid chromatography-mass spectrometry. Toxicokinetic variables were obtained by noncompartmental Introduction methods. Overall, 60.3 +/- 11.2{\%} of the dose was recovered in the urine. Although no glycidamide was found, unchanged acrylamide, AAMA, and GAMA accounted for urinary excretion of (mean +/- SD) 4.4 +/- 1.5{\%}, 50.0 +/- 9.4{\%}, and 5.9 +/- 1.2{\%} of the dose, respectively. Apparent terminal elimination half-lives for the substances were 2.4 +/- 0.4, 17.4 +/- 3.9, and 25.1 +/- 6.4 hours. The ratio of GAMA/AAMA amounts excreted was 0.12 +/- 0.02. In conclusion, most of the acrylamide ingested with food is absorbed in humans. Conjugation with glutathione exceeds the formation of the reactive metabolite glycidamide. The data suggests an at least 2-fold and 4-fold lower relative internal exposure for glycidamide from dietary acrylamide in humans compared with rats or mice, respectively. This should be considered for quantitative cancer risk assessment.},
author = {Christensen, Matthew W. and Chen, Yi‐Chun and Stephens, Graeme L.},
doi = {10.1002/2016JD025245},
isbn = {2169-8996},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {dec},
number = {24},
pages = {14636--14650},
title = {{Aerosol indirect effect dictated by liquid clouds}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2016JD025245},
volume = {121},
year = {2016}
}
@article{Christensen2011,
author = {Christensen, Matthew W. and Stephens, Graeme L.},
doi = {10.1029/2010JD014638},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
month = {feb},
number = {D3},
pages = {D03201},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Microphysical and macrophysical responses of marine stratocumulus polluted by underlying ships: Evidence of cloud deepening}},
volume = {116},
year = {2011}
}
@article{Christensen2017a,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Increased concentrations of aerosol can enhance the albedo of warm low-level cloud. Accurately quantifying this relationship from space is challenging due in part to contamination of aerosol statistics near clouds. Aerosol retrievals near clouds can be influenced by stray cloud particles in areas assumed to be cloud-free, particle swelling by humidification, shadows and enhanced scattering into the aerosol field from (3-D radiative transfer) clouds. To screen for this contamination we have developed a new cloud–aerosol pairing algorithm (CAPA) to link cloud observations to the nearest aerosol retrieval within the satellite image. The distance between each aerosol retrieval and nearest cloud is also computed in CAPA. {\textless}br{\textgreater}{\textless}/br{\textgreater} Results from two independent satellite imagers, the Advanced Along-Track Scanning Radiometer (AATSR) and Moderate Resolution Imaging Spectroradiometer (MODIS), show a marked reduction in the strength of the intrinsic aerosol indirect radiative forcing when selecting aerosol pairs that are located farther away from the clouds (−0.28±0.26{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}W{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}) compared to those including pairs that are within 15{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}km of the nearest cloud (−0.49±0.18{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}W{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}). The larger aerosol optical depths in closer proximity to cloud artificially enhance the relationship between aerosol-loading, cloud albedo, and cloud fraction. These results suggest that previous satellite-based radiative forcing estimates represented in key climate reports may be exaggerated due to the inclusion of retrieval artefacts in the aerosol located near clouds.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Christensen, Matthew W. and Neubauer, David and Poulsen, Caroline A. and Thomas, Gareth E. and McGarragh, Gregory R. and Povey, Adam C. and Proud, Simon R. and Grainger, Roy G.},
doi = {10.5194/acp-17-13151-2017},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {nov},
number = {21},
pages = {13151--13164},
title = {{Unveiling aerosol–cloud interactions – Part 1: Cloud contamination in satellite products enhances the aerosol indirect forcing estimate}},
url = {https://www.atmos-chem-phys.net/17/13151/2017/},
volume = {17},
year = {2017}
}
@article{ISI:000380345200003,
author = {Christensen, Matthew W and Behrangi, Ali and L'ecuyer, Tristan S and Wood, Norman B and Lebsock, Matthew D and Stephens, Graeme L},
doi = {10.1175/BAMS-D-14-00273.1},
issn = {0003-0007},
journal = {Bulletin of the American Meteorological Society},
month = {jun},
number = {6},
pages = {907--915},
title = {{Arctic Observation and Reanalysis Integrated System: A New Data Product for Validation and Climate Study}},
volume = {97},
year = {2016}
}
@article{Chung2010,
abstract = {We analyze the radiative damping of climatological variations in surface temperature based on relationships between surface temperature and top-of-atmosphere radiative fluxes for both satellite observations and climate model simulations. The observed damping rates are generally consistent with positive radiative feedbacks over the tropical oceans, in agreement with climate model simulations. The model-simulated radiative damping rates are shown to be much more robust when analyzed at global scales, rather than tropical-means. Moreover, the model-simulated values of global-mean radiative damping rates deduced from interannual variability are shown to be modestly correlated to the climate sensitivity of the model in response to increasing CO2.},
author = {Chung, Eui-Seok and Soden, Brian J. and Sohn, Byung-Ju},
doi = {10.1029/2010GL043051},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {may},
number = {10},
pages = {L10703},
title = {{Revisiting the determination of climate sensitivity from relationships between surface temperature and radiative fluxes}},
url = {http://doi.wiley.com/10.1029/2010GL043051},
volume = {37},
year = {2010}
}
@article{Soden2015a,
abstract = {Because the radiative forcing is rarely computed separately when performing climate model$\backslash$nsimulations, several alternative methods have been developed to estimate both the instantaneous (or$\backslash$ndirect) forcing and the adjusted forcing. The adjusted forcing accounts for the radiative impact$\backslash$narising from the adjustment of climate variables to the instantaneous forcing, independent of any$\backslash$nsurface warming. Using climate model experiments performed for CMIP5, we find the adjusted forcing$\backslash$nfor 4 × CO 2 ranges from roughly 5.5–9 W m −2 in current models. This range is shown to be$\backslash$nconsistent between different methods of estimating the adjusted forcing. Decomposition using$\backslash$nradiative kernels and offline double-call radiative transfer calculations indicates that the spread$\backslash$nreceives a substantial contribution (roughly 50{\%}) from intermodel differences in the instantaneous$\backslash$ncomponent of the radiative forcing. Moreover, nearly all of the spread in adjusted forcing can be$\backslash$naccounted for by differences in the instantaneous forcing and stratospheric adjustment, implying$\backslash$nthat tropospheric adjustments to CO 2 play only a secondary role. This suggests that differences in$\backslash$nmodeling radiative transfer are responsible for substantial differences in the projected climate$\backslash$nresponse and underscores the need to archive double-call radiative transfer calculations of the$\backslash$ninstantaneous forcing as a routine diagnostic.},
author = {Chung, Eui-Seok and Soden, Brian J},
doi = {10.1088/1748-9326/10/7/074004},
isbn = {1748-9326},
issn = {1748-9326},
journal = {Environmental Research Letters},
keywords = {article is available online,climate models,model spread,radiative forcing,radiative kernel method,radiative transfer,rapid adjustment,supplementary material for this},
number = {7},
pages = {074004},
publisher = {IOP Publishing},
title = {{An assessment of methods for computing radiative forcing in climate models}},
volume = {10},
year = {2015}
}
@article{Chung2018b,
abstract = {Intermodel compensation between cloud feedback and rapid cloud adjustment has important implications for the range of model-inferred climate sensitivity. Although this negative intermodel correlation exists in both realistic (e.g., coupled ocean–atmosphere models) and idealized (e.g., aqua-planet) model configurations, the compensation appears to be stronger in the latter. The cause of the compensation between feedback and adjustment, and its dependence on model configuration remain poorly understood. In this study, we examine the characteristics of the cloud feedback and adjustment in model simulations with differing complexity, and analyze the causes responsible for their compensation. We show that in all model configurations, the intermodel compensation between cloud feedback and cloud adjustment largely results from offsetting changes in marine boundary-layer clouds. The greater prevalence of these cloud types in aqua-planet models is a likely contributor to the larger correlation between feedback and adjustment in those configurations. It is also shown that differing circulation changes in the aqua-planet configuration of some models act to amplify the intermodel range and sensitivity of the cloud radiative response by about a factor of 2.},
author = {Chung, Eui-Seok and Soden, Brian J},
doi = {10.1007/s00382-017-3682-1},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {3},
pages = {1267--1276},
title = {{On the compensation between cloud feedback and cloud adjustment in climate models}},
url = {https://doi.org/10.1007/s00382-017-3682-1},
volume = {50},
year = {2018}
}
@article{Chung11636,
author = {Chung, Eui-Seok and Soden, Brian and Sohn, B J and Shi, Lei},
doi = {10.1073/pnas.1409659111},
journal = {Proceedings of the National Academy of Sciences},
number = {32},
pages = {11636--11641},
publisher = {National Academy of Sciences},
title = {{Upper-tropospheric moistening in response to anthropogenic warming}},
volume = {111},
year = {2014}
}
@article{Chung2019,
abstract = {A strengthening of the Pacific Walker circulation (PWC) over recent decades triggered an intense debate on the validity of model-projected weakening of the PWC in response to anthropogenic warming. However, limitations of in situ observations and reanalysis datasets have hindered an unambiguous attribution of PWC changes to either natural or anthropogenic causes. Here, by conducting a comprehensive analysis based on multiple independent observational records, including satellite observations along with a large ensemble of model simulations, we objectively determine the relative contributions of internal variability and anthropogenic warming to the emergence of long-term PWC trends. Our analysis shows that the satellite-observed changes differ considerably from the model ensemble-mean changes, but they also indicate substantially weaker strengthening than implied by the reanalyses. Furthermore, some ensemble members are found to reproduce the observed changes in the tropical Pacific. These findings clearly reveal a dominant role of internal variability on the recent strengthening of the PWC.},
author = {Chung, Eui-Seok and Timmermann, Axel and Soden, Brian J. and Ha, Kyung Ja and Shi, Lei and John, Viju O.},
doi = {10.1038/s41558-019-0446-4},
issn = {17586798},
journal = {Nature Climate Change},
month = {may},
number = {5},
pages = {405--412},
publisher = {Nature Publishing Group},
title = {{Reconciling opposing Walker circulation trends in observations and model projections}},
volume = {9},
year = {2019}
}
@incollection{Church2013,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Church, J. A. and Clark, P. U. and Cazenave, A. and Gregory, J. M. and Jevrejeva, S. and Levermann, A. and Merrifield, M. A. and Milne, G. A. and Nerem, R.S and Nunn, P.D. and Payne, A.J. and Pfeffer, W.T. and Stammer, D. and Unnikrishnan, A.S.},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
doi = {10.1017/CB09781107415315.026},
editor = {Stocker, T.F. and Qin, D. and Plattner, G.-K. and Tignor, M. and Allen, S.K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.},
isbn = {9781107661820},
pages = {1137--1216},
publisher = {Cambridge University Press},
title = {{Sea Level Change}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Clark2016a,
abstract = {Most of the policy debate surrounding the actions needed to mitigate and adapt to anthropogenic climate change has been framed by observations of the past 150 years as well as climate and sea-level projections for the twenty-first century. The focus on this 250-year window, however, obscures some of the most profound problems associated with climate change. Here, we argue that the twentieth and twenty-first centuries, a period during which the overwhelming majority of human-caused carbon emissions are likely to occur, need to be placed into a long-term context that includes the past 20 millennia, when the last Ice Age ended and human civilization developed, and the next ten millennia, over which time the projected impacts of anthropogenic climate change will grow and persist. This long-term perspective illustrates that policy decisions made in the next few years to decades will have profound impacts on global climate, ecosystems and human societies-not just for this century, but for the next ten millennia and beyond.},
author = {Clark, Peter U. and Shakun, Jeremy D. and Marcott, Shaun A. and Mix, Alan C. and Eby, Michael and Kulp, Scott and Levermann, Anders and Milne, Glenn A. and Pfister, Patrik L. and Santer, Benjamin D. and Schrag, Daniel P. and Solomon, Susan and Stocker, Thomas F. and Strauss, Benjamin H. and Weaver, Andrew J. and Winkelmann, Ricarda and Archer, David and Bard, Edouard and Goldner, Aaron and Lambeck, Kurt and Pierrehumbert, Raymond T. and Plattner, Gian Kasper},
doi = {10.1038/nclimate2923},
issn = {17586798},
journal = {Nature Climate Change},
month = {feb},
number = {4},
pages = {360--369},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Consequences of twenty-first-century policy for multi-millennial climate and sea-level change}},
url = {https://doi.org/10.1038/nclimate2923 http://10.0.4.14/nclimate2923 https://www.nature.com/articles/nclimate2923{\#}supplementary-information},
volume = {6},
year = {2016}
}
@incollection{Clarke2014,
address = {Cambridge, United Kingdom and New York, USA},
author = {Clarke, L. and Jiang, K. and Akimoto, K. and Babiker, M. and Blanford, G. and {Fisher-Vanden, K. Hourcade}, J.-C. and Krey, V. and Kriegler, E. and L{\"{o}}schel, A. and McCollum, D. and Paltsev, S. and Rose, S. and Shukla, P.R. and Tavoni, M. and van {Zwaan, B. van der Vuuren}, D.},
booktitle = {Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
doi = {10.1017/CBO9781107415416.012},
editor = {Edenhofer, O and Pichs-Madruga, R and Sokona, Y and Farahani, E and Kadner, S and Seyboth, K and Adler, A and Baum, I and Brunner, S and Eickemeier, P and Kriemann, B and Savolainen, J and Schl{\"{o}}mer, S and von Stechow, C and Zwickel, T and Minx, J C},
isbn = {9781107058217},
pages = {413--510},
publisher = {Cambridge University Press},
title = {{Assessing Transformation Pathways}},
url = {https://www.ipcc.ch/report/ar5/wg3},
year = {2014}
}
@article{cp-16-699-2020,
author = {Cleator, S F and Harrison, S P and Nichols, N K and Prentice, I C and Roulstone, I},
doi = {10.5194/cp-16-699-2020},
journal = {Climate of the Past},
number = {2},
pages = {699--712},
title = {{A new multivariable benchmark for Last Glacial Maximum climate simulations}},
url = {https://cp.copernicus.org/articles/16/699/2020/},
volume = {16},
year = {2020}
}
@article{Clement1996,
abstract = {The role of ocean dynamics is the regulation of tropical sea surface temperatures is investigated using the Zebiak-Cane coupled ocean-atmosphere model. The model is forced with a uniform heating, or cooling, varying between +- 40 W/m{\^{}}2 into the ocean surface. A new climatological SST pattern is established for which the area-averaged temperature change is smaller in magnitude than the imposed forcing. The forcing is balanced almost equally by a change in the heat flux out of the ocean and by vertical advection of heat in the ocean through anomalous equatorial ocean upwelling. The generation of anomalous upwelling is identified here as a possible mechanism capable of regulating tropical SSTs. The ocean dynamical thermostat mechanism has a seasonally varying efficiency that causes amplification (weakening) of the seasonal cycle for the heating (cooling). The internal variability also changes under the imposed forcing. The results suggest that the role of ocean dynamics should be included in any discussion of the regulation of the tropical climate.},
author = {Clement, Amy C. and Seager, Richard and Cane, Mark A. and Zebiak, Stephen E.},
doi = {10.1175/1520-0442(1996)009<2190:AODT>2.0.CO;2},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {9},
pages = {2190--2196},
title = {{An Ocean Dynamical Thermostat}},
url = {http://journals.ametsoc.org/doi/10.1175/1520-0442(1996)009{\%}3C2190:AODT{\%}3E2.0.CO;2},
volume = {9},
year = {1996}
}
@article{Coats2017,
abstract = {Historical trends in the tropical Pacific zonal sea surface temperature gradient (SST gradient) are analyzed herein using 41 climate models (83 simulations) and 5 observational data sets. A linear inverse model is trained on each simulation and observational data set to assess if trends in the SST gradient are significant relative to the stationary statistics of internal variability, as would suggest an important role for external forcings such as anthropogenic greenhouse gasses. None of the 83 simulations have a positive trend in the SST gradient, a strengthening of the climatological SST gradient with more warming in the western than eastern tropical Pacific, as large as the mean trend across the five observational data sets. If the observed trends are anthropogenically forced, this discrepancy suggests that state-of-the-art climate models are not capturing the observed response of the tropical Pacific to anthropogenic forcing, with serious implications for confidence in future climate projections. There are caveats to this interpretation, however, as some climate models have a significant strengthening of the SST gradient between 1900 and 2013 Common Era, though smaller in magnitude than the observational data sets, and the strengthening in three out of five observational data sets is insignificant. When combined with observational uncertainties and the possibility of centennial time scale internal variability not sampled by the linear inverse model, this suggests that confident validation of anthropogenic SST gradient trends in climate models will require further emergence of anthropogenic trends. Regardless, the differences in SST gradient trends between climate models and observational data sets are concerning and motivate the need for process-level validation of the atmosphere-ocean dynamics relevant to climate change in the tropical Pacific.},
author = {Coats, S. and Karnauskas, K. B.},
doi = {10.1002/2017GL074622},
journal = {Geophysical Research Letters},
keywords = {Pacific,SST,anthropogenic,climate,historical,trends},
month = {oct},
number = {19},
pages = {9928--9937},
publisher = {Blackwell Publishing Ltd},
title = {{Are Simulated and Observed Twentieth Century Tropical Pacific Sea Surface Temperature Trends Significant Relative to Internal Variability?}},
volume = {44},
year = {2017}
}
@article{Coddington2016,
abstract = {We present a new climate data record for total solar irradiance and solar spectral irradiance between 1610 and the present day with associated wavelength and timedependent uncertainties and quarterly updates. The data record, which is part of the National Oceanic and Atmospheric Administration's (NOAA) Climate Data Record (CDR) program, provides a robust, sustainable, and scientifically defensible record of solar irradiance that is of sufficient length, consistency, and continuity for use in studies of climate variability and climate change on multiple time scales and for user groups spanning climate modeling, remote sensing, and natural resource and renewable energy industries. The data record, jointly developed by the University of Colorado's Laboratory for Atmospheric and Space Physics (LASP) and the Naval Research Laboratory (NRL), is constructed from solar irradiance models that determine the changes with respect to quiet sun conditions when facular brightening and sunspot darkening features are present on the solar disk where the magnitude of the changes in irradiance are determined from the linear regression of a proxy magnesium (Mg) II index and sunspot area indices against the approximately decade-long solar irradiance measurements of the Solar Radiation and Climate Experiment (SORCE). To promote long-term data usage and sharing for a broad range of users, the source code, the dataset itself, and supporting documentation are archived at NOAA's National Centers for Environmental Information (NCEI). In the future, the dataset will also be available through the LASP Interactive Solar Irradiance Data Center (LISIRD) for userspecified time periods and spectral ranges of interest.},
author = {Coddington, Odele and Lean, J. L. and Pilewskie, P. and Snow, M. and Lindholm, D.},
doi = {10.1175/BAMS-D-14-00265.1},
issn = {00030007},
journal = {Bulletin of the American Meteorological Society},
month = {jul},
number = {7},
pages = {1265--1282},
publisher = {American Meteorological Society},
title = {{A solar irradiance climate data record}},
url = {www.wmo.int},
volume = {97},
year = {2016}
}
@article{Cohan2002,
abstract = {[1] Scattering and absorption of sunlight by anthropogenic aerosols reduce the photosynthetically active radiation (PAR) incident upon the Earth's surface, but increase the fraction of the PAR that is diffuse. These alterations to irradiance may elicit conflicting responses in terrestrial plants: photosynthesis and net primary productivity (NPP) are slowed by reductions in total PAR, but enhanced by increases in diffuse PAR. In this paper, we use two canopy photosynthesis models to estimate the net effect of aerosols on carbon assimilation by green plants during summertime at midlatitudes. The model calculations indicate that the net effect of PAR scattering and absorption by atmospheric aerosols on NPP can be positive, neutral, or negative. Two parameters that strongly influence the net effect are the aerosol optical depth (integral of light extinction with height) and the cloud cover. On cloudless days NPP peaks under moderately thick aerosol loadings. On overcast days, aerosols slow NPP. The implications of these results for various regions of the globe and possible directions for future studies on the effect of aerosols on plant growth are discussed.},
author = {Cohan, Daniel S. and Xu, Jin and Greenwald, Roby and Bergin, Michael H. and Chameides, William L.},
doi = {10.1029/2001gb001441},
journal = {Global Biogeochemical Cycles},
number = {4},
pages = {37--1--37--12},
title = {{Impact of atmospheric aerosol light scattering and absorption on terrestrial net primary productivity}},
volume = {16},
year = {2002}
}
@incollection{Collins2013d,
author = {Collins, Matthew and Knutti, Reto and Arblaster, Julie and Dufresne, J.-L. Jean-Louis and Fichefet, Thierry and Friedlingstein, Pierre and Gao, Xuejie and Gutowski, William J. and Johns, Tim and Krinner, Gerhard and Shongwe, Mxolisi and Tebaldi, Claudia and Weaver, Andrew J. and Wehner, Michael},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {12},
doi = {10.1017/CBO9781107415324.024},
editor = {Stocker, T F and Qin, D and Plattner, G.-K. and Tignor, M and Allen, S K and Boschung, J and Nauels, A and Xia, Y and Bex, V and Midgley, P M},
isbn = {9781107661820},
pages = {1029--1136},
publisher = {Cambridge University Press},
title = {{Long-term Climate Change: Projections, Commitments and Irreversibility}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Collins2011,
abstract = {Abstract. We describe here the development and evaluation of an Earth system model suitable for centennial-scale climate prediction. The principal new components added to the physical climate model are the terrestrial and ocean ecosystems and gas-phase tropospheric chemistry, along with their coupled interactions. The individual Earth system components are described briefly and the relevant interactions between the components are explained. Because the multiple interactions could lead to unstable feedbacks, we go through a careful process of model spin up to ensure that all components are stable and the interactions balanced. This spun-up configuration is evaluated against observed data for the Earth system components and is generally found to perform very satisfactorily. The reason for the evaluation phase is that the model is to be used for the core climate simulations carried out by the Met Office Hadley Centre for the Coupled Model Intercomparison Project (CMIP5), so it is essential that addition of the extra complexity does not detract substantially from its climate performance. Localised changes in some specific meteorological variables can be identified, but the impacts on the overall simulation of present day climate are slight. This model is proving valuable both for climate predictions, and for investigating the strengths of biogeochemical feedbacks.},
author = {Collins, W. J. and Bellouin, N. and Doutriaux-Boucher, M. and Gedney, N. and Halloran, P. and Hinton, T. and Hughes, J. and Jones, C. D. and Joshi, M. and Liddicoat, S. and Martin, G. and O{\&}apos;Connor, F. and Rae, J. and Senior, C. and Sitch, S. and Totterdell, I. and Wiltshire, A. and Woodward, S.},
doi = {10.5194/gmd-4-1051-2011},
isbn = {1991-962X},
issn = {1991-9603},
journal = {Geoscientific Model Development},
pages = {1051--1075},
title = {{Development and evaluation of an Earth-System model – HadGEM2}},
volume = {4},
year = {2011}
}
@article{Collins2013,
abstract = {We examine the climate effects of the emissions of near-term climate forcers (NTCFs) from 4 continental regions (East Asia, Europe, North America and South Asia) using radiative forcing from the task force on hemispheric transport of air pollution source-receptor global chemical transport model simulations. These simulations model the transport of 3 aerosol species (sulphate, particulate organic matter and black carbon) and 4 ozone precursors (methane, nitric oxides (NOx), volatile organic compounds and carbon monoxide). From the equilibrium radiative forcing results we calculate global climate metrics, global warming potentials (GWPs) and global temperature change potentials (GTPs) and show how these depend on emission region, and can vary as functions of time. For the aerosol species, the GWP(100) values are −37±12, −46±20, and 350±200 for SO2, POM and BC respectively for the direct effects only. The corresponding GTP(100) values are −5.2±2.4, −6.5±3.5, and 50±33. This analysis is further extended by examining the temperature-change impacts in 4 latitude bands. This shows that the latitudinal pattern of the temperature response to emissions of the NTCFs does not directly follow the pattern of the diagnosed radiative forcing. For instance temperatures in the Arctic latitudes are particularly sensitive to NTCF emissions in the northern mid-latitudes. At the 100-yr time horizon the ARTPs show NOx emissions can have a warming effect in the northern mid and high latitudes, but cooling in the tropics and Southern Hemisphere. The northern mid-latitude temperature response to northern mid-latitude emissions of most NTCFs is approximately twice as large as would be implied by the global average.},
author = {Collins, W. J. and Fry, M. M. and Yu, H. and Fuglestvedt, J. S. and Shindell, D. T. and West, J. J.},
doi = {10.5194/acp-13-2471-2013},
isbn = {1680-7316},
issn = {16807316},
journal = {Atmospheric Chemistry and Physics},
pages = {2471--2485},
title = {{Global and regional temperature-change potentials for near-term climate forcers}},
volume = {13},
year = {2013}
}
@article{Collins2018b,
abstract = {Recently, it was recognized that widely used calculations of methane radiative forcing systematically underestimated its global value by 15{\%} by omitting its shortwave effects. We show that shortwave forcing by methane can be accurately calculated despite considerable uncertainty and large gaps in its shortwave spectroscopy. We demonstrate that the forcing is insensitive, even when confronted with much more complete methane absorption spectra extending to violet light wavelengths derived from observations of methane-rich Jovian planets. We undertake the first spatially resolved global calculations of this forcing and find that it is dependent on bright surface features and clouds. Localized annual mean forcing from preindustrial to present-day methane increases approaches +0.25 W/m 2 , 10 times the global annualized shortwave forcing and 43{\%} of the total direct CH 4 forcing. Shortwave forcing by anthropogenic methane is sufficiently large and accurate to warrant its inclusion in historical analyses, projections, and mitigation strategies for climate change.},
author = {Collins, William D. and Feldman, Daniel R. and Kuo, Chaincy and Nguyen, Newton H.},
doi = {10.1126/sciadv.aas9593},
issn = {2375-2548},
journal = {Science Advances},
month = {sep},
number = {9},
pages = {eaas9593},
title = {{Large regional shortwave forcing by anthropogenic methane informed by Jovian observations}},
url = {https://www.science.org/doi/10.1126/sciadv.aas9593},
volume = {4},
year = {2018}
}
@article{Collins2002,
abstract = {Oxidation by hydroxyl radicals is the main removal process for organic compounds in the troposphere. This oxidation acts as a source of ozone and as a removal process for hydroxyl and peroxy radicals, thereby reducing the efficiency of methane oxidation and promoting the build-up of methane. Emissions of organic compounds may therefore lead to the build-up of two important radiatively-active trace gases: Methane and ozone. Emission pulses of 10 organic compounds were followed in a global 3-D Lagrangian chemistry-transport model to quantify their indirect greenhouse gas impacts through changes induced in the tropospheric distributions of methane and ozone. The main factors influencing the global warming potentials of the 10 organic compounds were found to be their spatial emission patterns, chemical reactivity and transport, molecular complexity and oxidation products formed. The indirect radiative forcing impacts of organic compounds may be large enough that ozone precursors should be considered in the basket of trace gases through which policy-makers aim to combat global climate change.},
author = {Collins, W. J. and Derwent, R. G. and Johnson, C. E. and Stevenson, D. S.},
doi = {10.1023/A:1014221225434},
issn = {01650009},
journal = {Climatic Change},
pages = {453--479},
title = {{The oxidation of organic compounds in the troposphere and their global warming potentials}},
volume = {52},
year = {2002}
}
@article{Collins,
abstract = {Multi-gas climate agreements rely on a methodology (widely referred to as 'metrics') to place emissions of different gases on a CO2-equivalent scale. There has been an ongoing debate on the extent to which existing metrics serve current climate policy. Endpoint metrics (such as global temperature change potential GTP) are the most closely related to policy goals based on temperature limits (such as Article 2 of the Paris Agreement). However, for short-lived climate forcers (SLCFs), endpoint metrics vary strongly with time horizon making them difficult to apply in practical situations. We show how combining endpoint metrics for a step change in SLCF emissions with a pulse emission of CO2 leads to an endpoint metric that only varies slowly over time horizons of interest. We therefore suggest that these combined step-pulse metrics (denoted combined global warming potential CGWP and combined global temperature change potential CGTP) can be a useful way to include short and long-lived species in the same basket in policy applications-this assumes a single basket approach is preferred by policy makers. The advantage of a combined step-pulse metric for SLCFs is that for species with a lifetime less than 20 years a single time horizon of around 75 years can cover the range of timescales appropriate to the Paris Agreement. These metrics build on recent work using the traditional global warming potential (GWP) metric in a new way, called GWP*. We show how the GWP∗ relates to CGWP and CGTP and that it systematically underestimates the temperature effects of SLCFs by up to 20{\%}. These step-pulse metrics are all more appropriate than the conventional GWP for comparing the relative contributions of different species to future temperature targets and for SLCFs they are much less dependent on time horizon than GTP.},
author = {Collins, William J. and Frame, David J. and Fuglestvedt, Jan S. and Shine, Keith P.},
doi = {10.1088/1748-9326/ab6039},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {carbon budgets,climate metrics,climate targets,non-CO2 greenhouse gases,short-lived climate forcers},
month = {dec},
number = {2},
title = {{Stable climate metrics for emissions of short and long-lived species-combining steps and pulses}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/ab6039},
volume = {15},
year = {2020}
}
@article{gmd-10-585-2017,
abstract = {The Aerosol Chemistry Model Intercomparison Project (AerChemMIP) is endorsed by the Coupled-Model Intercomparison Project 6 (CMIP6) and is designed to quantify the climate and air quality impacts of aerosols and chemically reactive gases. These are specifically near-term climate forcers (NTCFs: methane, tropospheric ozone and aerosols, and their precursors), nitrous oxide and ozone-depleting halocarbons. The aim of AerChemMIP is to answer four scientific questions. 1. How have anthropogenic emissions contributed to global radiative forcing and affected regional climate over the historical period? 2. How might future policies (on climate, air quality and land use) affect the abundances of NTCFs and their climate impacts? 3.How do uncertainties in historical NTCF emissions affect radiative forcing estimates? 4. How important are climate feedbacks to natural NTCF emissions, atmospheric composition, and radiative effects? These questions will be addressed through targeted simulations with CMIP6 climate models that include an interactive representation of tropospheric aerosols and atmospheric chemistry. These simulations build on the CMIP6 Diagnostic, Evaluation and Characterization of Klima (DECK) experiments, the CMIP6 historical simulations, and future projections performed elsewhere in CMIP6, allowing the contributions from aerosols and/or chemistry to be quantified. Specific diagnostics are requested as part of the CMIP6 data request to highlight the chemical composition of the atmosphere, to evaluate the performance of the models, and to understand differences in behaviour between them.},
author = {Collins, William J. and Lamarque, Jean Fran{\c{c}}ois and Schulz, Michael and Boucher, Olivier and Eyring, Veronika and Hegglin, I. Michaela and Maycock, Amanda and Myhre, Gunnar and Prather, Michael and Shindell, Drew and Smith, J. Steven and Collins, J. William and Lamarque, Jean Fran{\c{c}}ois and Schulz, Michael and Boucher, Olivier and Eyring, Veronika and Hegglin, I. Michaela and Maycock, Amanda and Myhre, Gunnar and Prather, Michael and Shindell, Drew and Smith, J. Steven},
doi = {10.5194/gmd-10-585-2017},
issn = {19919603},
journal = {Geoscientific Model Development},
month = {feb},
number = {2},
pages = {585--607},
publisher = {Copernicus GmbH},
title = {{AerChemMIP: Quantifying the effects of chemistry and aerosols in CMIP6}},
url = {https://gmd.copernicus.org/articles/10/585/2017/},
volume = {10},
year = {2017}
}
@article{Colman2017,
abstract = {Using the method of radiative ‘kernels', an analysis is made of feedbacks in models participating in the World Climate Research Program Coupled Model Intercomparison Project phase 5. Feedbacks are calculated for RCP8.5 and abrupt4xCO2 experiments as well as for interannual and decadal variability from pre-industrial runs. Regressions across models are used to elicit relationships across experiments/timescales. Feedbacks between RCP8.5 and abrupt4xCO2 experiments show strong relationships, as expected from surface temperature response similarities arising from the two experiments. The analysis also reveals significant relationships between RCP8.5 and decadal and interannual lapse rate feedback, decadal water vapour and interannual total cloud—the latter confirming results elsewhere. To reveal the impact of warming pattern differences, ‘synthetic' feedbacks are also generated, based on RCP8.5, whereby local feedbacks determined from that experiment are scaled by relative temperature changes (per degree of global warming) from the others. The synthetic feedbacks indicate that the (sometimes strongly) differing temperature response patterns themselves should not preclude strong correlations between variability and climate change feedbacks—indeed such correlations would be close if local feedbacks were a robust feature of the climate. Although such close correlations are not manifest, the synthetic feedbacks predict the interannual and decadal feedbacks to some extent (are correlated across models), and reveal the consistency, to a first approximation, of the mean model strength of variability feedbacks. Although cloud feedbacks at interannual timescales are correlated with those from RCP8.5, and show consistency with the strength of synthetic feedbacks, separate long and short wave components reveal very different, compensating, latitudinal patterns, suggesting the close correlation may be fortuitous.},
author = {Colman, Robert A. and Hanson, Lawson},
doi = {10.1007/s00382-016-3441-8},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Climate feedbacks,Climate sensitivity,Climate variability,Feedback},
number = {5-6},
pages = {2115--2129},
publisher = {Springer Berlin Heidelberg},
title = {{On the relative strength of radiative feedbacks under climate variability and change}},
volume = {49},
year = {2017}
}
@article{Colman2009,
abstract = {An atmospheric general circulation model, coupled to a mixed layer ocean, is subjected to a broad range of forcing away from the current climate between 1/16 to 32 times current CO2 in halving/doubling steps. As climate warms climate sensitivity weakens (although not monotonically), albedo feedback weakens (driving much of the sensitivity weakening), water vapour feedback strengthens (at a rate slightly larger than it would if relative humidity remained unchanged), and lapse rate feedback increases (negatively); this latter change essentially offsetting the water vapour increases. Longwave cloud feedbacks are relatively stable (moderate and positive) across the full range; shortwave cloud feedback remains relatively weak, apart from under the coldest climates. Cloud optical property related components (from total water content, water/ice fraction and cloud thickness) remain remarkably stable. Cloud ‘amount' feedbacks show the greatest trends: weakening as temperatures increase. Although cloud feedbacks show an overall consistency of features in different latitudes, precise patterns of changes differ substantially for different baseline climates.},
author = {Colman, Robert A. and McAvaney, Bryant},
doi = {10.1029/2008GL036268},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate feedbacks,doi:10.1029/2008GL036268,http://dx.doi.org/10.1029/2008GL036268},
number = {1},
pages = {1--5},
pmid = {8939599},
title = {{Climate feedbacks under a very broad range of forcing}},
volume = {36},
year = {2009}
}
@article{Colman2015,
abstract = {{\textcopyright} 2015. American Geophysical Union. All Rights Reserved. Climate radiative feedbacks are traditionally defined at top of atmosphere (TOA); however, strong radiative feedbacks also occur at the surface, with profound effect on the surface heat budget and hydrological cycle. “Rapid responses” to radiative forcing also occur and may also be expected to affect the surface. This study evaluates surface radiation changes, using a combined Partial Radiative Perturbation-Gregory approach, under abrupt increases in CO2in a climate model. We find significant surface rapid radiative response from changes in clouds, relative humidity, and latent heat flux. As surface temperature increases, strong water vapor feedback exceeds net cooling from atmospheric and surface temperature changes, resulting in increased surface evaporation. Feedbacks fromclouds are smaller, with complex horizontal and vertical structures. Surface longwave feedback structures differ widely from those of the TOA and are dominated by lower troposphere changes. Lapse rate, cloud, and albedo feedbacks are small equatorward of around 50° of latitude but stronger at high latitudes. The approach here allows precise evaluation of the rich structure of surface radiative feedbacks.},
author = {Colman, R.A.},
doi = {10.1002/2014JD022896},
journal = {Journal of Geophysical Research:Atmospheres},
number = {8},
pages = {3173--3182},
title = {{Climate radiative feedbacks and adjustments at the Earth's surface}},
volume = {120},
year = {2015}
}
@article{Covey2000,
abstract = {We examine the seasonal cycle of near-surface air temperature simulated by 17 coupled ocean-atmosphere general circulation models participating in the Coupled Model Intercomparison Project (CMIP). Nine of the models use ad hoc “flux adjustment” at the ocean surface to bring model simulations close to observations of the present-day climate. We group flux-adjusted and non-flux-adjusted models separately and examine the behavior of each class. When averaged over all of the flux-adjusted model simulations, near-surface air temperature falls within 2 K of observed values over the oceans. The corresponding average over non-flux-adjusted models shows errors up to ∼6 K in extensive ocean areas. Flux adjustments are not directly applied over land, and near-surface land temperature errors are substantial in the average over flux-adjusted models, which systematically underestimates (by ∼5 K) temperature in areas of elevated terrain. The corresponding average over non-flux-adjusted models forms a similar error pattern (with somewhat increased amplitude) over land. We use the temperature difference between July and January to measure seasonal cycle amplitude. Zonal means of this quantity from the individual flux-adjusted models form a fairly tight cluster (all within ∼30{\%} of the mean) centered on the observed values. The non-flux-adjusted models perform nearly as well at most latitudes. In Southern Ocean mid-latitudes, however, the non-flux-adjusted models overestimate the magnitude of January-minus-July temperature differences by ∼5 K due to an overestimate of summer (January) near-surface temperature. This error is common to five of the eight non-flux-adjusted models. Also, over Northern Hemisphere mid-latitude land areas, zonal mean differences between July and January temperatures simulated by the non-flux-adjusted models show a greater spread (positive and negative) about observed values than results from the flux-adjusted models. Elsewhere, differences between the two classes of models are less obvious. At no latitude is the zonal mean difference between averages over the two classes of models greater than the standard deviation over models. The ability of coupled GCMs to simulate a reasonable seasonal cycle is a necessary condition for confidence in their prediction of long-term climatic changes (such as global warming), but it is not a sufficient condition unless the seasonal cycle and long-term changes involve similar climatic processes. To test this possible connection, we compare seasonal cycle amplitude with equilibrium warming under doubled atmospheric carbon dioxide for the models in our data base. A small but positive correlation exists between these two quantities. This result is predicted by a simple conceptual model of the climate system, and it is consistent with other modeling experience, which indicates that the seasonal cycle depends only weakly on climate sensitivity.},
author = {Covey, C and Abe-Ouchi, A and Boer, G J and Boville, B A and Cubasch, U and Fairhead, L and Flato, G M and Gordon, H and Guilyardi, E and Jiang, X and Johns, T C and {Le Treut}, H and Madec, G and Meehl, G A and Miller, R and Noda, A and Power, S B and Roeckner, E and Russell, G and Schneider, E K and Stouffer, R J and Terray, L and von Storch, J.-S.},
doi = {10.1007/s003820000081},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {10},
pages = {775--787},
title = {{The seasonal cycle in coupled ocean–atmosphere general circulation models}},
url = {https://doi.org/10.1007/s003820000081},
volume = {16},
year = {2000}
}
@article{Cox2018,
abstract = {Equilibrium climate sensitivity (ECS) is the long-term change in global mean surface temperature predicted to occur in response to an instantaneous doubling of atmospheric carbon dioxide concentrations. It is an inherently artificial metric, but is nonetheless an important tool when comparing climate models, and a key point of policy discussion. The seemingly intractable range of ECS estimates complicates policy making because the response of the real climate system to the lowest and highest predicted temperature change would translate into radically different policy options. Peter Cox and colleagues now constrain climate models by their ability to simulate observed variations in climate, and conclude that ECS has a central estimate of 2.8 degrees Celsius (°C), which sits towards the middle to lower end of current estimates, and a range of 2.2–3.4 °C. Importantly, their approach allows them to almost exclude ECS estimates above 4.5 °C or below 1.5 °C.},
author = {Cox, Peter M and Huntingford, Chris and Williamson, Mark S},
doi = {10.1038/nature25450},
isbn = {1476-4687 (Electronic) 0028-0836 (Linking)},
issn = {14764687},
journal = {Nature},
number = {7688},
pages = {319--322},
pmid = {29345639},
publisher = {Nature Publishing Group},
title = {{Emergent constraint on equilibrium climate sensitivity from global temperature variability}},
url = {http://dx.doi.org/10.1038/nature25450},
volume = {553},
year = {2018}
}
@article{Cox2018a,
author = {Cox, Peter M and Williamson, Mark S and Nijsse, Femke J M M and Huntingford, Chris},
doi = {10.1038/s41586-018-0641-x},
issn = {1476-4687},
journal = {Nature},
number = {7729},
pages = {E10--E15},
title = {{Cox et al. reply}},
url = {https://doi.org/10.1038/s41586-018-0641-x},
volume = {563},
year = {2018}
}
@article{Crook2014,
author = {Crook, Julia A. and Forster, Piers M.},
doi = {10.1002/2014GL059280},
issn = {00948276},
journal = {Geophysical Research Letters},
pages = {1717--1723},
title = {{Comparison of surface albedo feedback in climate models and observations}},
url = {http://onlinelibrary.wiley.com/doi/10.1002/2014GL059280/full},
volume = {41},
year = {2014}
}
@article{Crook2011,
abstract = {Spatial patterns of local climate feedback and equilibrium partial temperature responses are produced from eight general circulation models with slab oceans forced by doubling carbon dioxide (CO2). The analysis is extended to other forcing mechanisms with the Met Office Hadley Centre slab ocean climate model version 3 (HadSM3). In agreement with previous studies, the greatest intermodel differences are in the tropical cloud feedbacks. However, the greatest intermodel spread in the equilibrium temperature response comes from the water vapor plus lapse rate feedback, not clouds, disagreeing with a previous study. Although the surface albedo feedback contributes most in the annual mean to the greater warming of high latitudes, compared to the tropics (polar amplification), its effect is significantly ameliorated by shortwave cloud feedback. In different seasons the relative importance of the contributions varies considerably, with longwave cloudy-sky feedback and horizontal heat transport plus ocean heat release playing a major role during winter and autumn when polar amplification is greatest. The greatest intermodel spread in annual mean polar amplification is due to variations in horizontal heat transport and shortwave cloud feedback. Spatial patterns of local climate feedback for HadSM3 forced with 2 x CO2, +2{\%} solar, low-level scattering aerosol and high-level absorbing aerosol are more similar than those for different models forced with 2 x CO2. However, the equilibrium temperature response to high-level absorbing aerosol shows considerably enhanced polar amplification compared to the other forcing mechanisms, largely due to differences in horizontal heat transport and water vapor plus lapse rate feedback, with the forcing itself acting to reduce amplification. Such variations in high-latitude response between models and forcing mechanisms make it difficult to infer specific causes of recent Arctic temperature change.},
author = {Crook, Julia A. and Forster, Piers M. and Stuber, Nicola},
doi = {10.1175/2011JCLI3863.1},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Aerosols/particulates,Feedback,Fluxes,Ocean models,Temperature},
number = {14},
pages = {3575--3592},
pmid = {62851043},
title = {{Spatial patterns of modeled climate feedback and contributions to temperature response and polar amplification}},
volume = {24},
year = {2011}
}
@article{Cuesta-Valero9999,
abstract = {Abstract. Energy exchanges among climate subsystems are of critical importance to determine the climate sensitivity of the Earth's system to greenhouse gases, to quantify the magnitude and evolution of the Earth's energy imbalance, and to project the evolution of future climate. Thus, ascertaining the magnitude of and change in the Earth's energy partition within climate subsystems has become urgent in recent years. Here, we provide new global estimates of changes in ground surface temperature, ground surface heat flux, and continental heat storage derived from geothermal data using an expanded database and new techniques. Results reveal markedly higher changes in ground heat flux and heat storage within the continental subsurface than previously reported, with land temperature changes of 1 K and continental heat gains of around 12 ZJ during the last part of the 20th century relative to preindustrial times. Half of the heat gain by the continental subsurface since 1960 has occurred in the last 20 years.},
author = {Cuesta-Valero, Francisco Jos{\'{e}} and Garc{\'{i}}a-Garc{\'{i}}a, Almudena and Beltrami, Hugo and Gonz{\'{a}}lez-Rouco, J. Fidel and Garc{\'{i}}a-Bustamante, Elena},
doi = {10.5194/cp-17-451-2021},
issn = {1814-9332},
journal = {Climate of the Past},
month = {feb},
number = {1},
pages = {451--468},
title = {{Long-term global ground heat flux and continental heat storage from geothermal data}},
url = {https://cp.copernicus.org/articles/17/451/2021/},
volume = {17},
year = {2021}
}
@article{Cui2017a,
abstract = {The additions of straw and biochar have been suggested to increase soil fertility, carbon sequestration, and crop productivity of agricultural lands. To our knowledge, there is little information on the effects of straw and biochar addition on soil nitrogen form, carbon storage, and super rice yield in cold waterlogged paddy soils. We performed field trials with four treatments including conventional fertilization system (CK), straw amendment 6 t ha−1 (S), biochar amendment 2 t ha−1 (C1), and biochar amendment 40 t ha−1 (C2). The super japonica rice variety, Shennong 265, was selected as the test crop. The results showed that the straw and biochar amendments improved total nitrogen and organic carbon content of the soil, reduced N2O emissions, and had little influence on nitrogen retention, nitrogen density, and CO2 emissions. The S and C1 increased NH4+-N content, and C2 increased NO3−-N content. Both S and C1 had little influence on soil organic carbon density (SOCD) and C/N ratio. However, C2 greatly increased SOCD and C/N ratio. C1 and C2 significantly improved the soil carbon sequestration (SCS) by 62.9 and 214.0{\%} (P{\textless}0.05), respectively, while S had no influence on SCS. C1 and C2 maintained the stability of super rice yield, and significantly reduced CH4 emissions, global warming potential (GWP), and greenhouse gas intensity (GHGI), whereas S had the opposite and negative effects. In summary, the biochar amendments in cold waterlogged paddy soils of North China increased soil nitrogen and carbon content, improved soil carbon sequestration, and reduced GHG emission without affecting the yield of super rice.},
author = {Cui, Y. F. and Meng, J. and Wang, Q. X. and Zhang, W. M. and Cheng, X. Y. and Chen, W. F.},
doi = {10.1016/S2095-3119(16)61578-2},
file = {::},
issn = {20953119},
journal = {Journal of Integrative Agriculture},
keywords = {biochar,carbon sequestration,greenhouse gas emission,nitrogen form,paddy field,rice yield,straw},
month = {may},
number = {5},
pages = {1064--1074},
publisher = {Chinese Academy of Agricultural Sciences},
title = {{Effects of straw and biochar addition on soil nitrogen, carbon, and super rice yield in cold waterlogged paddy soils of North China}},
volume = {16},
year = {2017}
}
@article{Dai2019,
abstract = {Warming in the Arctic has been much faster than the rest of the world in both observations and model simulations, a phenomenon known as the Arctic amplification (AA) whose cause is still under debate. By analyzing data and model simulations, here we show that large AA occurs only from October to April and only over areas with significant sea-ice loss. AA largely disappears when Arctic sea ice is fixed or melts away. Periods with larger AA are associated with larger sea-ice loss, and models with bigger sea-ice loss produce larger AA. Increased outgoing longwave radiation and heat fluxes from the newly opened waters cause AA, whereas all other processes can only indirectly contribute to AA by melting sea-ice. We conclude that sea-ice loss is necessary for the existence of large AA and that models need to simulate Arctic sea ice realistically in order to correctly simulate Arctic warming under increasing CO2.},
author = {Dai, Aiguo and Luo, Dehai and Song, Mirong and Liu, Jiping},
doi = {10.1038/s41467-018-07954-9},
issn = {2041-1723},
journal = {Nature Communications},
number = {1},
pages = {121},
title = {{Arctic amplification is caused by sea-ice loss under increasing CO2}},
url = {https://doi.org/10.1038/s41467-018-07954-9},
volume = {10},
year = {2019}
}
@article{Daniel2012,
abstract = {Numerous policy options exist to reduce future greenhouse gas emissions. A single-basket approach, which controls aggregate emissions, was adopted by the Kyoto Protocol. Such an approach allows emissions reductions of one gas to be traded with those of other gases in the "basket", with the trade "price" determined by some weighting metric like the Global Warming Potential. To reduce stratospheric ozone depletion, the Montreal Protocol also dealt with controlling many compounds, but did so employing an alternative, multi-basket scheme. Trading was allowed within each basket, but not among baskets. While the Montreal Protocol has been highly successful using this approach, we show that if a single-basket approach had been adopted the short-term success could have been at risk due to the non-unique relationship between controls and environmental impacts when using a single basket. Using climate policy as an example, and without considering technological and economic constraints, we further show that the magnitude of the ambiguities in impacts associated with a single-basket approach depends on the rapidity of the emission phaseout. Fast phaseouts lead to less ambiguity than do slow ones. These results suggest that for each set of greenhouse gas control policies considered, the benefit of additional flexibility associated with a single-basket approach should be weighed against the associated increased uncertainties in the impacts to ascertain whether a single- or a multi-basket approach has the greater chance of successfully mitigating climate change. {\textcopyright} 2011 U.S. Government.},
author = {Daniel, John S. and Solomon, Susan and Sanford, Todd J. and McFarland, Mack and Fuglestvedt, Jan S. and Friedlingstein, Pierre},
doi = {10.1007/s10584-011-0136-3},
issn = {01650009},
journal = {Climatic Change},
month = {mar},
number = {2},
pages = {241--248},
publisher = {Springer Netherlands},
title = {{Limitations of single-basket trading: Lessons from the Montreal Protocol for climate policy}},
url = {http://link.springer.com/10.1007/s10584-011-0136-3},
volume = {111},
year = {2012}
}
@article{Davies2017,
abstract = {Abstract Davies and Molloy (2012) reported a decrease in the global effective cloud height over the first 10?years of Multiangle Imaging Spectroradiometer (MISR) measurements on the Terra satellite. We have reexamined their time series for possible artefacts that might especially affect the initial portion of the record when the heights appeared anomalously high. While variations in sampling were shown to be inconsequential, an artefact due to the change in equator crossing time that affected the first 2?years was discovered, and this has now been corrected. That correction, together with the extension of the time series by five more years, yields no significant overall trend in global heights during the first 15?years of Terra operation. The time series is dominated by large interannual fluctuations associated with La Ni{\~{n}}a events that mask any overall trend on a global scale. On a regional basis, the cloud heights showed significant interannual variations of much larger amplitude, sometimes with fairly direct cancellation between regions. There were unexplained differences between the two hemispheres in the timing of height anomalies. These differences persisted over a large range of extratropical latitudes, suggestive of teleconnections. Within the tropics, there were very strong changes associated with the Central Pacific and Indonesian Maritime Continent regions that oscillated out of phase with each other, with interannual amplitudes that exceeded 1?km.},
annote = {doi: 10.1002/2017JD026456},
author = {Davies, Roger and Jovanovic, Veljko M and Moroney, Catherine M},
doi = {10.1002/2017JD026456},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {ENSO,MISR stereo heights,effective cloud height,equatorial clouds,global time series,teleconnections},
month = {apr},
number = {7},
pages = {3975--3986},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Cloud heights measured by MISR from 2000 to 2015}},
url = {https://doi.org/10.1002/2017JD026456},
volume = {122},
year = {2017}
}
@article{doi:10.1002/2014GB004949,
abstract = {Abstract Climate change is projected to cause substantial alterations in vegetation distribution, but these have been given little attention in comparison to land use in the Representative Concentration Pathway (RCP) scenarios. Here we assess the climate-induced land cover changes (CILCC) in the RCPs and compare them to land use land cover change (LULCC). To do this, we use an ensemble of simulations with and without LULCC in Earth System Model HadGEM2-ES (Hadley Centre Global Environmental Model 2) - for RCP2.6, RCP4.5, and RCP8.5. We find that climate change causes an expansion poleward of vegetation that affects more land area than LULCC in all of the RCPs considered here. The terrestrial carbon changes from CILCC are also larger than for LULCC. When considering only forest, the LULCC is larger, but the CILCC is highly variable with the overall radiative forcing of the scenario. The CILCC forest increase compensates 90{\%} of the global anthropogenic deforestation by 2100 in RCP8.5 but just 3{\%} in RCP2.6. Overall, bigger land cover changes tend to originate from LULCC in the shorter term or lower radiative forcing scenarios and from CILCC in the longer term and higher radiative forcing scenarios. The extent to which CILCC could compensate for LULCC raises difficult questions regarding global forest and biodiversity offsetting, especially at different time scales. This research shows the importance of considering the relative size of CILCC to LULCC, especially with regard to the ecological effects of the different RCPs.},
author = {Davies-Barnard, T and Valdes, P J and Singarayer, J S and Wiltshire, A J and Jones, C D},
doi = {10.1002/2014GB004949},
journal = {Global Biogeochemical Cycles},
keywords = {Representative Concentration Pathways,climate change impacts,deforestation,land use change,vegetation shifts},
number = {6},
pages = {842--853},
title = {{Quantifying the relative importance of land cover change from climate and land use in the representative concentration pathways}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014GB004949},
volume = {29},
year = {2015}
}
@article{DelaVega2020a,
abstract = {The Piacenzian stage of the Pliocene (2.6 to 3.6 Ma) is the most recent past interval of sustained global warmth with mean global temperatures markedly higher (by {\~{}}2–3 °C) than today. Quantifying CO2 levels during the mid-Piacenzian Warm Period (mPWP) provides a means, therefore, to deepen our understanding of Earth System behaviour in a warm climate state. Here we present a new high-resolution record of atmospheric CO2 using the $\delta$11B-pH proxy from 3.35 to 3.15 million years ago (Ma) at a temporal resolution of 1 sample per 3–6 thousand years (kyrs). Our study interval covers both the coolest marine isotope stage of the mPWP, M2 ({\~{}}3.3 Ma) and the transition into its warmest phase including interglacial KM5c (centered on {\~{}}3.205 Ma) which has a similar orbital configuration to present. We find that CO2 ranged from {\$}{\$}{\{}389{\}}{\_}{\{}-8{\}}{\^{}}{\{}+38{\}}{\$}{\$}389−8+38ppm to {\$}{\$}{\{}331{\}}{\_}{\{}-11{\}}{\^{}}{\{}+13{\}},{\$}{\$}331−11+13,ppm, with CO2 during the KM5c interglacial being {\$}{\$}{\{}371{\}}{\_}{\{}-29{\}}{\^{}}{\{}+32{\}}$\backslash$,{\$}{\$}371−29+32ppm (at 95{\%} confidence). Our findings corroborate the idea that changes in atmospheric CO2 levels played a distinct role in climate variability during the mPWP. They also facilitate ongoing data-model comparisons and suggest that, at present rates of human emissions, there will be more CO2 in Earth's atmosphere by 2025 than at any time in at least the last 3.3 million years.},
author = {de la Vega, Elwyn and Chalk, Thomas B and Wilson, Paul A and Bysani, Ratna Priya and Foster, Gavin L},
doi = {10.1038/s41598-020-67154-8},
issn = {2045-2322},
journal = {Scientific Reports},
number = {1},
pages = {11002},
title = {{Atmospheric CO2 during the Mid-Piacenzian Warm Period and the M2 glaciation}},
url = {https://doi.org/10.1038/s41598-020-67154-8},
volume = {10},
year = {2020}
}
@article{doi:10.1029/2007GC001931,
abstract = {Geochemical sea surface temperature (SST) proxies such as the magnesium to calcium ratio (Mg/Ca) in foraminifera and the alkenone unsaturation index (UK′37) are becoming widely used in pre-Pleistocene climate records. This study quantitatively compares previously published Mg/Ca and UK′37 data from Ocean Drilling Program (ODP) site 847 in the eastern equatorial Pacific to assess the utility of these proxies to reconstruct tropical SST over the last 5 Ma. Foraminiferal Mg/Ca–SST calibrations that include a dissolution correction are most appropriate at this location because they provide SST estimates for the youngest sample that are close to modern mean annual SST. The long-term trends in the two records are remarkably similar and confirm a ∼3.5°C cooling trend from the early Pliocene warm period to the late Pleistocene noted in previous work. Absolute temperature estimates are similar for both proxies when errors in the dissolution correction used to estimate SST from Mg/Ca are taken into account. Comparing the two SST records at ODP site 847 to other records in the region shows that the eastern equatorial Pacific was 2–4°C warmer during the early Pliocene compared to today.},
author = {Dekens, Petra S and Ravelo, Ana Christina and McCarthy, Matthew D and Edwards, Christopher A},
doi = {10.1029/2007GC001931},
journal = {Geochemistry, Geophysics, Geosystems},
keywords = {Mg/Ca,Pliocene,SST proxy,alkenone},
number = {10},
pages = {Q10001},
title = {{A 5 million year comparison of Mg/Ca and alkenone paleothermometers}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2007GC001931},
volume = {9},
year = {2008}
}
@article{Denison_2019,
abstract = {Many nationally determined contributions (NDCs) under the Paris Agreement follow the established practice of specifying emissions levels in tonnes of CO2 equivalent emissions. The Global Warming Potential (GWP) is the emissions metric used most often to aggregate contributions from different greenhouse gases (GHGs). However, the climate impact of pathways expressed in this way is known to be ambiguous. For this reason, alternatives have been proposed but the ambiguity has not been quantified in the context of the Paris Agreement. Here we assess the variation in temperature using pathways consistent with the ambition of limiting temperature increases to well below 2 °C. These are taken from the IPCC Special Report on Global Warming of 1.5 °C (SR15). The CO2 emission levels are adjusted so that the pathways all have the same total CO2 equivalent emissions for a given emissions metric but have different proportions of short-lived and long-lived pollutants. We show that this difference affects projections by up to 0.17 °C when GWP100 is used. Options of reducing this ambiguity include using a different emissions metric or adding supplementary information in NDCs about the emissions levels of individual GHGs. We suggest the latter on the grounds of simplicity and because it does not require agreement on the use of a different emissions metric.},
author = {Denison, Steve and Forster, Piers M and Smith, Christopher J},
doi = {10.1088/1748-9326/ab4df4},
journal = {Environmental Research Letters},
month = {nov},
number = {12},
pages = {124002},
publisher = {{\{}IOP{\}} Publishing},
title = {{Guidance on emissions metrics for nationally determined contributions under the Paris Agreement}},
url = {https://doi.org/10.1088{\%}2F1748-9326{\%}2Fab4df4},
volume = {14},
year = {2019}
}
@article{Deser2012b,
author = {Deser, Clara and Knutti, Reto and Solomon, Susan and Phillips, Adam S},
doi = {10.1038/nclimate1562},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {nov},
number = {11},
pages = {775--779},
title = {{Communication of the role of natural variability in future North American climate}},
url = {http://www.nature.com/articles/nclimate1562},
volume = {2},
year = {2012}
}
@article{Dessler2018,
abstract = {Our climate is constrained by the balance between solar energy absorbed by the Earth and terrestrial energy radiated to space. This energy balance has been widely used to infer equilibrium climate sensitivity (ECS) from observations of 20th-century warming. Such estimates yield lower values than other methods and these have been influential in pushing down the consensus ECS range in recent assessments. Here we test the method using a 100-member ensemble of the MPI-ESM1.1 climate model simulations of the period 1850{\&}ndash;2005 with known forcing. We calculate ECS in each ensemble member using energy balance, yielding values ranging from 2.1 to 3.9{\&}thinsp;K. The spread in the ensemble is related to the central hypothesis in the energy budget framework: that global average surface temperature anomalies are indicative of anomalies in outgoing energy (either of terrestrial origin or reflected solar energy). We find that assumption is not well supported over the historical temperature record in the model ensemble or more recent satellite observations. We find that framing energy balance in terms of 500-hPa tropical temperature better describes the planet's energy balance.},
author = {Dessler, Andrew E. and Mauritsen, Thorsten and Stevens, Bjorn},
doi = {10.5194/acp-18-5147-2018},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
number = {7},
pages = {5147--5155},
title = {{The influence of internal variability on Earth's energy balance framework and implications for estimating climate sensitivity}},
volume = {18},
year = {2018}
}
@article{Dessler2018a,
abstract = {Abstract Estimating the equilibrium climate sensitivity (ECS; the equilibrium warming in response to a doubling of CO2) from observations is one of the big problems in climate science. Using observations of interannual climate variations covering the period 2000 to 2017 and a model‐derived relationship between interannual variations and forced climate change, we estimate ECS is likely 2.4‐4.6 K (17‐83{\%} confidence interval), with a mode and median value of 2.9 and 3.3 K, respectively. This analysis provides no support for low values of ECS (below 2 K) suggested by other analyses. The main uncertainty in our estimate is not observational uncertainty, but rather uncertainty in converting observations of short‐term, mainly unforced climate variability to an estimate of the response of the climate system to long‐term forced warming.},
author = {Dessler, A. E. and Forster, P. M.},
doi = {10.1029/2018JD028481},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
number = {16},
pages = {8634--8645},
title = {{An estimate of equilibrium climate sensitivity from interannual variability}},
volume = {123},
year = {2018}
}
@article{Dessler2011,
abstract = {The question of whether clouds are the cause of surface temperature changes, rather than acting as a feedback in response to those temperature changes, is explored using data obtained between 2000 and 2010. An energy budget calculation shows that the radiative impact of clouds accounts for little of the observed climate variations. It is also shown that observations of the lagged response of top-of-atmosphere (TOA) energy fluxes to surface temperature variations are not evidence that clouds are causing climate change.},
author = {Dessler, A. E.},
doi = {10.1029/2011GL049236},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {oct},
number = {19},
pages = {L19701},
title = {{Cloud variations and the Earth's energy budget}},
url = {http://doi.wiley.com/10.1029/2011GL049236},
volume = {38},
year = {2011}
}
@article{Dessler18087,
abstract = {We show observational evidence for a stratospheric water vapor feedback{\{}$\backslash$textemdash{\}}a warmer climate increases stratospheric water vapor, and because stratospheric water vapor is itself a greenhouse gas, this leads to further warming. An estimate of its magnitude from a climate model yields a value of +0.3 W/(m2.K), suggesting that this feedback plays an important role in our climate system.We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry{\{}$\backslash$textendash{\}}climate model to be +0.3 W/(m2.K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause.},
author = {Dessler, A E and Schoeberl, M R and Wang, T and Davis, S M and Rosenlof, K H},
doi = {10.1073/pnas.1310344110},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {45},
pages = {18087--18091},
publisher = {National Academy of Sciences},
title = {{Stratospheric water vapor feedback}},
url = {https://www.pnas.org/content/110/45/18087},
volume = {110},
year = {2013}
}
@article{Dessler2013a,
abstract = {Feedbacks in response to climate variations during the period 2000–10 have been calculated using reanalysis meteorological fields and top-of-atmosphere flux measurements. Over this period, the climate was stabilized by a strongly negative temperature feedback ({\~{}}−3 W m−2 K−1); climate variations were also amplified by a strong positive water vapor feedback ({\~{}}+1.2 W m−2 K−1) and smaller positive albedo and cloud feedbacks ({\~{}}+0.3 and +0.5 W m−2 K−1, respectively). These observations are compared to two climate model ensembles, one dominated by internal variability (the control ensemble) and the other dominated by long-term global warming (the A1B ensemble). The control ensemble produces global average feedbacks that agree within uncertainties with the observations, as well as producing similar spatial patterns. The most significant discrepancy was in the spatial pattern for the total (shortwave + longwave) cloud feedback. Feedbacks calculated from the A1B ensemble show a stronger negative temperature feedback (due to a stronger lapse-rate feedback), but that is cancelled by a stronger positive water vapor feedback. The feedbacks in the A1B ensemble tend to be more smoothly distributed in space, which is consistent with the differences between El Ni{\~{n}}o–Southern Oscillation (ENSO) climate variations and long-term global warming. The sum of all of the feedbacks, sometimes referred to as the thermal damping rate, is −1.15 ± 0.88 W m−2 K−1 in the observations and −0.60 ± 0.37 W m−2 K−1 in the control ensemble. Within the control ensemble, models that more accurately simulate ENSO tend to produce thermal damping rates closer to the observations. The A1B ensemble average thermal damping rate is −1.26 ± 0.45 W m−2 K−1.},
author = {Dessler, A. E.},
doi = {10.1175/JCLI-D-11-00640.1},
isbn = {10.1175/JCLI-D-11-00640.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jan},
number = {1},
pages = {333--342},
title = {{Observations of Climate Feedbacks over 2000–10 and Comparisons to Climate Models}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-11-00640.1},
volume = {26},
year = {2013}
}
@article{Devaraju2015,
abstract = {Land-use changes since the start of the industrial era account for nearly one-third of the cumulative anthropogenic CO2 emissions. In addition to the greenhouse effect of CO2 emissions, changes in land use also affect climate via changes in surface physical properties such as albedo, evapotranspiration and roughness length. Recent modelling studies suggest that these biophysical components may be comparable with biochemical effects. In regard to climate change, the effects of these two distinct processes may counterbalance one another both regionally and, possibly, globally. In this article, through hypothetical large-scale deforestation simulations using a global climate model, we contrast the implications of afforestation on ameliorating or enhancing anthropogenic contributions from previously converted (agricultural) land surfaces. Based on our review of past studies on this subject, we conclude that the sum of both biophysical and biochemical effects should be assessed when large-scale afforestation is used for countering global warming, and the net effect on global mean temperature change depends on the location of deforestation/afforestation. Further, although biochemical effects trigger global climate change, biophysical effects often cause strong local and regional climate change. The implication of the biophysical effects for adaptation and mitigation of climate change in agriculture and agroforestry sectors is discussed.},
author = {Devaraju, Narayanappa and Bala, G. and Nemani, R.},
doi = {10.1111/pce.12488},
issn = {13653040},
journal = {Plant, Cell and Environment},
keywords = {Atmospheric circulation,Biochemical and biophysical processes,Climate change},
month = {sep},
number = {9},
pages = {1931--1946},
publisher = {Blackwell Publishing Ltd},
title = {{Modelling the influence of land-use changes on biophysical and biochemical interactions at regional and global scales}},
volume = {38},
year = {2015}
}
@article{Diamond2020a,
abstract = {The influence of aerosol particles on cloud reflectivity remains one of the largest sources of uncertainty in our understanding anthropogenic climate change. Commercial shipping constitutes a large and concentrated aerosol perturbation in a meteorological regime where clouds have a disproportionally large effect on climate. Yet, to date, studies have been unable to detect climatologically-relevant cloud radiative effects from shipping, despite models indicating that the cloud response should produce a sizable negative radiative forcing (perturbation to Earth's energy balance). We attribute a significant increase in cloud reflectivity to enhanced cloud droplet number concentrations within a major shipping corridor in the southeast Atlantic. Prevailing winds constrain emissions around the corridor, which cuts through a climatically-important region of expansive low-cloud cover. We use universal kriging, a classic geostatistical method, to estimate what cloud properties would have been in the absence of ship...},
author = {Diamond, Michael and Director, Hannah M. and Eastman, Ryan and Possner, Anna and Wood, Robert},
doi = {10.1029/2019av000111},
file = {::},
issn = {2576-604X},
journal = {AGU Advances},
keywords = {10.1029/2019AV000111 and cloud,aerosol,climate,cloud,radiative forcing,shipping},
month = {mar},
number = {1},
pages = {e2019AV000111},
publisher = {American Geophysical Union (AGU)},
title = {{Substantial Cloud Brightening From Shipping in Subtropical Low Clouds}},
url = {https://doi.org/},
volume = {1},
year = {2020}
}
@article{Dickinson1975,
abstract = {Abstract Mechanisms possibly connecting solar activity to meteorology of the lower atmosphere are reviewed. Besides direct variations of solar visible emission, solar-related fluctuations in some aspect of cloudiness could be important. Any such variations in cloudiness are likely to be related to variations in production of ionization near the tropopause by galactic cosmic rays, the only geophysical phenomena unconnected with upper atmospheric processes known to have a striking (negative) correlation with solar activity. Such a connection might involve a dependence of sulfate aerosol formation on ionization and in turn a dependence of cloud radiative properties on variations of the aerosol particles' action as cloud condensation nuclei.},
author = {Dickinson, Robert E.},
doi = {10.1175/1520-0477(1975)056<1240:svatla>2.0.co;2},
issn = {0003-0007},
journal = {Bulletin of the American Meteorological Society},
month = {dec},
number = {12},
pages = {1240--1248},
publisher = {American Meteorological Society},
title = {{Solar Variability and the Lower Atmosphere}},
volume = {56},
year = {1975}
}
@article{DiNezio2009,
author = {DiNezio, Pedro N. and Clement, Amy C. and Vecchi, Gabriel A. and Soden, Brian J. and Kirtman, Benjamin P. and Lee, Sang-Ki},
doi = {10.1175/2009jcli2982.1},
journal = {Journal of Climate},
month = {apr},
number = {18},
pages = {4873--4892},
publisher = {American Meteorological Society},
title = {{Climate Response of the Equatorial Pacific to Global Warming}},
volume = {22},
year = {2009}
}
@article{Dinh2019,
abstract = {Abstract General Circulation Models (GCMs) predict that clouds in the atmosphere rapidly adjust to the radiative perturbation of an abrupt increase in atmospheric CO2 concentration on a short time scale of about 10 days. This rapid adjustment consists of an increase of clouds in the boundary layer and a decrease of clouds in the free troposphere. Our focus is the mechanism for the decrease of clouds in the free troposphere, which is the dominating component of cloud rapid adjustment in most GCMs. We propose that the decrease in clouds in the free troposphere arises from the causal relationship between the moist diabatic circulation and the production of condensates that forms clouds in moist processes. As CO2 concentration increases, tropospheric radiative cooling is reduced, resulting in weakening of the moist diabatic circulation and a decrease in precipitation. As the hydrologic cycle weakens and the moist processes involving phase change of water vapour to form the condensates in the atmosphere lessen, the mass of cloud condensates decreases. This decrease in cloud condensates can be predicted from the decrease in the radiative subsidence mass flux, which is a metric for the strength of the moist diabatic circulation in the free troposphere.},
annote = {doi: 10.1029/2019MS001853},
author = {Dinh, T and Fueglistaler, S},
doi = {10.1029/2019MS001853},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {circulation,clouds,hydrologic cycle,radiative forcing,rapid adjustment},
month = {nov},
number = {11},
pages = {3836--3851},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{On the Causal Relationship between the Moist Diabatic Circulation and Cloud Rapid Adjustment to Increasing CO2}},
url = {https://doi.org/10.1029/2019MS001853},
volume = {11},
year = {2019}
}
@article{Dohrty13,
author = {Doherty, Sarah J and Grenfell, Thomas C and Forsstr{\"{o}}m, Sanja and Hegg, Dean L and Brandt, Richard E and Warren, Stephen G},
doi = {10.1002/jgrd.50235},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {jun},
number = {11},
pages = {5553--5569},
title = {{Observed vertical redistribution of black carbon and other insoluble light-absorbing particles in melting snow}},
url = {http://dx.doi.org/10.1002/jgrd.50235 http://doi.wiley.com/10.1002/jgrd.50235},
volume = {118},
year = {2013}
}
@article{ISI:000351458300030,
abstract = {A large degree of uncertainty in global climate models (GCMs) can be attributed to the representation of clouds and how they interact with incoming solar and outgoing longwave radiation. In this study, the simulated total cloud fraction (CF), cloud water path (CWP), top of the atmosphere (TOA) radiation budgets and cloud radiative forcings (CRFs) from 28 CMIP5 AMIP models are evaluated and compared with multiple satellite observations from CERES, MODIS, ISCCP, CloudSat, and CALIPSO. The multimodel ensemble mean CF (57.6 {\%}) is, on average, underestimated by nearly 8 {\%} (between 65 degrees N/S) when compared to CERES-MODIS (CM) and ISCCP results while an even larger negative bias (17.1 {\%}) exists compared to the CloudSat/CALIPSO results. CWP bias is similar in comparison to the CF results, with a negative bias of 16.1 gm(-2) compared to CM. The model simulated and CERES EBAF observed TOA reflected SW and OLR fluxes on average differ by 1.8 and -0.9 Wm(-2), respectively. The averaged SW, LW, and net CRFs from CERES EBAF are -50.1, 27.6, and -22.5 Wm(-2), respectively, indicating a net cooling effect of clouds on the TOA radiation budget. The differences in SW and LW CRFs between observations and the multimodel ensemble means are only -1.3 and -1.6 Wm(-2), respectively, resulting in a larger net cooling effect of 2.9 Wm(-2) in the model simulations. A further investigation of cloud properties and CRFs reveals that the GCM biases in atmospheric upwelling (15 degrees S-15 degrees N) regimes are much less than in their downwelling (15 degrees-45 degrees N/S) counterparts over the oceans. Sensitivity studies have shown that the magnitude of SW cloud radiative cooling increases significantly with increasing CF at similar rates (similar to-1.25 Wm(-2) {\%}(-1)) in both regimes. The LW cloud radiative warming increases with increasing CF but is regime dependent, suggested by the different slopes over the upwelling and downwelling regimes (0.81 and 0.22 Wm(-2) {\%}(-1), respectively). Through a comprehensive error analysis, we found that CF is a primary modulator of warming (or cooling) in the atmosphere. The comparisons and statistical results from this study may provide helpful insight for improving GCM simulations of clouds and TOA radiation budgets in future versions of CMIP.},
address = {233 SPRING ST, NEW YORK, NY 10013 USA},
author = {Dolinar, Erica K and Dong, Xiquan and Xi, Baike and Jiang, Jonathan H and Su, Hui},
doi = {10.1007/s00382-014-2158-9},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {Cloud fraction,Error analys,TOA radiation budget},
month = {apr},
number = {7-8},
pages = {2229--2247},
publisher = {SPRINGER},
title = {{Evaluation of CMIP5 simulated clouds and TOA radiation budgets using NASA satellite observations}},
type = {Article},
volume = {44},
year = {2015}
}
@article{Dong2019a,
abstract = {Global radiative feedbacks have been found to vary in global climate model (GCM) simulations. Atmospheric GCMs (AGCMs) driven with historical patterns of sea surface temperatures (SSTs) and sea ice concentrations produce radiative feedbacks that trend toward more negative values, implying low climate sensitivity, over recent decades. Freely evolving coupled GCMs driven by increasing CO2 produce radiative feedbacks that trend toward more positive values, implying increasing climate sensitivity, in the future. While this time variation in feedbacks has been linked to evolving SST patterns, the role of particular regions has not been quantified. Here, a Green's function is derived from a suite of simulations within an AGCM (NCAR's CAM4), allowing an attribution of global feedback changes to surface warming in each region. The results highlight the radiative response to surface warming in ascent regions of the western tropical Pacific as the dominant control on global radiative feedback changes. Historical warming from the 1950s to 2000s preferentially occurred in the western Pacific, yielding a strong global outgoing radiative response at the top of the atmosphere (TOA) and thus a strongly negative global feedback. Long-term warming in coupled GCMs occurs preferentially in tropical descent regions and in high latitudes, where surface warming yields small global TOA radiation change but large global surface air temperature change, and thus a less-negative global feedback. These results illuminate the importance of determining mechanisms of warm pool warming for understanding how feedbacks have varied historically and will evolve in the future.},
author = {Dong, Yue and Proistosescu, Cristian and Armour, Kyle C. and Battisti, David S.},
doi = {10.1175/JCLI-D-18-0843.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {17},
pages = {5471--5491},
title = {{Attributing Historical and Future Evolution of Radiative Feedbacks to Regional Warming Patterns using a Green's Function Approach: The Preeminence of the Western Pacific}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-18-0843.1},
volume = {32},
year = {2019}
}
@article{Dong2017,
abstract = {A striking trend of the Indian Ocean interhemispheric gradient in sea surface temperatures (SSTs) developed during the recent global warming hiatus. The contributions of external forcing and internal variability to this trend are examined in forced climate model experiments. Results indicate that the observed negative trend was strong by historical standards and most likely due to internal variability rather than to external forcing. Anthropogenic aerosol forcing favors negative gradient trends, but its effects are countered by greenhouse gas forcing, and both are weak relative to internal variability. The observed interhemispheric gradient trend occurred in parallel with a negative phase of the interdecadal Pacific oscillation (IPO), a linkage that is also found in climate models. However, the physical mechanisms responsible for these gradient trends in models differ from those in ocean reanalysis products. In particular, oceanic processes via an increased Indonesian Throughflow (ITF) transport into the Indian Ocean forced by stronger Pacific trade winds are the principal cause of the observed negative SST gradient trend during 2000–13. In contrast, atmospheric processes via changing surface wind stress over the southern Indian Ocean remotely forced by the IPO appear to play a dominant role in changing the interhemispheric SST gradients in climate models. The models underestimate the magnitude of the IPO and produce changes in the ITF that are too weak owing to their coarse spatial resolution. These model deficiencies may account for the differences between the simulations and observations.},
author = {Dong, Lu and McPhaden, Michael J.},
doi = {10.1175/JCLI-D-17-0138.1},
isbn = {0894-8755
1520-0442},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Atmosphere-ocean interaction,Decadal variability,Indian Ocean,Numerical analysis/modeling,Pacific decadal oscillation,Sea surface temperature},
month = {nov},
number = {22},
pages = {9077--9095},
publisher = {American Meteorological Society},
title = {{The effects of external forcing and internal variability on the formation of interhemispheric sea surface temperature gradient trends in the Indian Ocean}},
volume = {30},
year = {2017}
}
@article{Dong9999,
abstract = {It is widely known that radiative feedbacks which set climate sensitivity depend on the spatial 28 patterns of sea-surface temperatures (SSTs) and thus can change over time as SST patterns evolve 29-the so-called 'pattern effect'. Here we investigate the causes of inter-model differences in the 30 magnitude of the pattern effect and the degree to which these differences contribute to the spread 31 in equilibrium climate sensitivity (ECS) within CMIP5 and CMIP6 models. We find that, although 32 ECS is on average higher in CMIP6 than CMIP5, the model-mean ECS bias relative to historical 33 estimates owing to time-varying feedbacks, is reduced from 9.5{\%} (CMIP5) to 5.3{\%} (CMIP6). The 34 feedback time-variation is generally smaller in CMIP6 models, primarily due to surface-albedo 35 feedback, which results from a stronger hemispheric asymmetry in SST patterns in CMIP6 models. 36},
author = {Dong, Yue and Armour, Kyle C and Zelinka, Mark D and Proistosescu, Cristian and Battisti, David S and Zhou, Chen and Andrews, Timothy},
doi = {10.1175/JCLI-D-19-1011.1},
journal = {Journal of Climate},
pages = {7755--7775},
title = {{Inter-model spread in the sea-surface temperature pattern effect and its contribution to climate sensitivity in CMIP5 and CMIP6 models}},
volume = {33},
year = {2020}
}
@article{Donohoe2014a,
abstract = {In response to increasing concentrations of atmospheric CO2, highend general circulation models (GCMs) simulate an accumulation of energy at the top of the atmosphere not through a reduction in outgoing longwave radiation (OLR)—as one might expect from greenhouse gas forcing—but through an enhancement of net absorbed solar radiation (ASR). A simple linear radiative feedback framework is used to explain this counterintuitive behavior. It is found that the timescale over which OLR returns to its initial value after a CO2 perturbation depends sensitively on the magnitude of shortwave (SW) feedbacks. If SW feedbacks are sufficiently positive, OLR recovers within merely several decades, and any subsequent global energy accumulation is because of enhanced ASR only. In the GCM mean, this OLR recovery timescale is only 20 y because of robust SW water vapor and surface albedo feedbacks. However, a large spread in the net SW feedback across models (because of clouds) produces a range of OLR responses; in those few models with a weak SW feedback, OLR takes centuries to recover, and energy accumulation is dominated by reduced OLR. Observational constraints of radiative feedbacks—from satellite radiation and surface temperature data—suggest an OLR recovery timescale of decades or less, consistent with the majority of GCMs. Altogether, these results suggest that, although greenhouse gas forcing predominantly acts to reduce OLR, the resulting global warming is likely caused by enhanced ASR.},
author = {Donohoe, Aaron and Armour, Kyle C. and Pendergrass, Angeline G. and Battisti, David S.},
doi = {10.1073/pnas.1412190111},
isbn = {0027-8424},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {47},
pages = {16700--16705},
pmid = {25385628},
title = {{Shortwave and longwave radiative contributions to global warming under increasing CO2}},
volume = {111},
year = {2014}
}
@article{doi:10.1175/2011JCLI3946.1,
abstract = {AbstractThe planetary albedo is partitioned into a component due to atmospheric reflection and a component due to surface reflection by using shortwave fluxes at the surface and top of the atmosphere in conjunction with a simple radiation model. The vast majority of the observed global average planetary albedo (88{\%}) is due to atmospheric reflection. Surface reflection makes a relatively small contribution to planetary albedo because the atmosphere attenuates the surface contribution to planetary albedo by a factor of approximately 3. The global average planetary albedo in the ensemble average of phase 3 of the Coupled Model Intercomparison Project (CMIP3) preindustrial simulations is also primarily (87{\%}) due to atmospheric albedo. The intermodel spread in planetary albedo is relatively large and is found to be predominantly a consequence of intermodel differences in atmospheric albedo, with surface processes playing a much smaller role despite significant intermodel differences in surface albedo. The CMIP3 models show a decrease in planetary albedo under a doubling of carbon dioxide—also primarily due to changes in atmospheric reflection (which explains more than 90{\%} of the intermodel spread). All models show a decrease in planetary albedo due to the lowered surface albedo associated with a contraction of the cryosphere in a warmer world, but this effect is small compared to the spread in planetary albedo due to model differences in the change in clouds.},
author = {Donohoe, Aaron and Battisti, David S.},
doi = {10.1175/2011JCLI3946.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Albedo,Model comparison,Radiation budgets,Shortwave radiation},
number = {16},
pages = {4402--4418},
title = {{Atmospheric and Surface Contributions to Planetary Albedo}},
url = {https://doi.org/10.1175/2011JCLI3946.1},
volume = {24},
year = {2011}
}
@article{Donohoe2020,
abstract = {Meridional heat transport (MHT) in ensembles of coupled climate models simulating climate states ranging from the Last Glacial Maximum (LGM) to quadrupled CO 2 is partitioned here into atmospheric (AHT) and implied oceanic (OHT) heat transports. In turn, AHT is subdivided into dry and moist energy transport by the meridional overturning circulation (MOC), transient eddy energy transport (TE) and stationary eddy energy transport (SE) using a novel technique that requires only the monthly averaged model output that is typically archived. In all climate models examined, the maximum total MHT (AHT+OHT) is nearly climate-state invariant, except for a modest (4{\%}, 0.3PW) enhancement of MHT in the Northern Hemisphere (NH) during the LGM. However, the partitioning of MHT changes markedly between climate state and differs considerably among different climate models. In response to CO 2 quadrupling, poleward implied OHT decreases while AHT increases by a nearly compensating amount. The increase in annual-mean AHT is a smooth function of latitude but is due to a spatially inhomogeneous blend of changes in SE and TE acting in different seasons. During the LGM, the increase in wintertime SE flux in the NH mid-latitudes exceeds the decrease in TE resulting in enhanced total AHT. Total AHT changes in the SH are not significant.These results suggest that the net top of atmosphere radiative constraints on total MHT are relatively invariant to climate forcing due to nearly compensating changes in absorbed solar radiation and outgoing longwave radiation. However, the partitioning of MHT depends on detailed regional and seasonal factors.},
author = {Donohoe, Aaron and Armour, Kyle C and Roe, Gerard H and Battisti, David S and Hahn, Lily},
doi = {10.1175/JCLI-D-19-0797.1},
journal = {Journal of Climate},
pages = {4141--4165},
title = {{The partitioning of meridional heat transport from the Last Glacial Maximum to CO2 quadrupling in coupled climate models}},
volume = {33},
year = {2020}
}
@article{Donohoe2012a,
abstract = {The annual mean maximum meridional heat transport (MHTMAX) differs by$\backslash$napproximately 20{\%} among coupled climate models. The value of MHTMAX can$\backslash$nbe expressed as the difference between the equator-to-pole contrast in$\backslash$nabsorbed solar radiation (ASR{\{}*{\}}) and outgoing longwave radiation$\backslash$n(OLR{\{}*{\}}). As an example, in the Northern Hemisphere observations, the$\backslash$nextratropics (defined as the region with a net radiative deficit)$\backslash$nreceive an 8.2-PW deficit of net solar radiation (ASR{\{}*{\}}) relative to$\backslash$nthe global average that is balanced by a 2.4-PW deficit of outgoing$\backslash$nlongwave radiation (OLR{\{}*{\}}) and 5.8 PW of energy import via the$\backslash$natmospheric and oceanic circulation (MHTMAX). The intermodel spread of$\backslash$nMHTMAX in the Coupled Model Intercomparison Project Phase 3 (CMIP3)$\backslash$nsimulations of the preindustrial climate is primarily (R-2 = 0.72) due$\backslash$nto differences in ASR{\{}*{\}} while model differences in OLR{\{}*{\}} are$\backslash$nuncorrelated with the MHTMAX spread. The net solar radiation (ASR{\{}*{\}}) is$\backslash$npartitioned into contributions from (i) the equator-to-pole contrast in$\backslash$nincident radiation acting on the global average albedo and (ii) the$\backslash$nequator-to-pole contrast of planetary albedo, which is further$\backslash$nsubdivided into components due to atmospheric and surface reflection. In$\backslash$nthe observations, 62{\%} of ASR{\{}*{\}} is due to the meridional distribution$\backslash$nof incident radiation, 33{\%} is due to atmospheric reflection, and 5{\%} is$\backslash$ndue to surface reflection. The intermodel spread in ASR{\{}*{\}} is due to$\backslash$nmodel differences in the equator-to-pole gradient in planetary albedo,$\backslash$nwhich are primarily a consequence of atmospheric reflection differences$\backslash$n(92{\%} of the spread), and is uncorrelated with differences in surface$\backslash$nreflection. As a consequence, the spread in MHTMAX in climate models is$\backslash$nprimarily due to the spread in cloud reflection properties.},
author = {Donohoe, Aaron and Battisti, David S.},
doi = {10.1175/JCLI-D-11-00257.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Albedo,Climate models,Cloud radiative effects,Energy budget/balance,Energy transport,Ensembles},
number = {11},
pages = {3832--3850},
title = {{What determines meridional heat transport in climate models?}},
volume = {25},
year = {2012}
}
@article{Dorheim2020,
abstract = {Simple climate models (SCMs) are computationally efficient and capable of emulating global mean output of more complex Earth system models (ESMs). In doing so, SCMs can play a critical role in climate research as stand-ins for the computationally more expensive models, especially in studies involving low, spatial, and/or temporal resolution, providing more computationally efficient sources of climate data. Here we use Hector v2.5.0 to emulate the multiforcing historical and RCP scenario output for 31 concentration and seven emission-driven ESMs. When calibrating Hector, sufficient calibration data must be used to constrain the model; otherwise, climate and/or carbon parameters affecting physical processes may be able to trade off with one another, allowing for solutions to use physically unreasonable fitted parameter values as well as limiting the application of the SCM as an emulator. We also present a novel methodology that uses the ESM range as a calibration data, which can be adopted when faced with missing variable output from a specific model.},
author = {Dorheim, Kalyn and Link, Robert and Hartin, Corinne and Kravitz, Ben and Snyder, Abigail},
doi = {10.1029/2019EA000980},
issn = {2333-5084},
journal = {Earth and Space Science},
month = {nov},
number = {11},
pages = {e2019EA000980},
publisher = {Blackwell Publishing Ltd},
title = {{Calibrating Simple Climate Models to Individual Earth System Models: Lessons Learned From Calibrating Hector}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2019EA000980},
volume = {7},
year = {2020}
}
@article{Doutriaux-Boucher2009,
abstract = {We performed an ensemble of twelve five-year experiments using a coupled climate-carbon-cycle model with scenarios of prescribed atmospheric carbon dioxide concentration; CO2 was instantaneously doubled or quadrupled at the start of the experiments. Within these five years, climate feedback is not significantly influenced by the effects of climate change on the carbon system. However, rapid changes take place, within much less than a year, due to the physiological effect of CO2 on plant stomatal conductance, leading to adjustment in the shortwave cloud radiative effect over land, due to a reduction in low cloud cover. This causes a 10{\%} enhancement to the radiative forcing due to CO2, which leads to an increase in the equilibrium warming of 0.4 and 0.7 K for doubling and quadrupling. The implications for calibration of energy-balance models are discussed.},
author = {Doutriaux-Boucher, M. and Webb, M. J. and Gregory, J. M. and Boucher, O.},
doi = {10.1029/2008GL036273},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
number = {2},
pages = {1--5},
pmid = {262748200004},
title = {{Carbon dioxide induced stomatal closure increases radiative forcing via a rapid reduction in low cloud}},
volume = {36},
year = {2009}
}
@article{Dowsett2012a,
abstract = {In light of mounting empirical evidence that planetary warming is well underway, the climate research community looks to palaeoclimate research for a ground-truthing measure with which to test the accuracy of future climate simulations. Model experiments that attempt to simulate climates of the past serve to identify both similarities and differences between two climate states and, when compared with simulations run by other models and with geological data, to identify model-specific biases. Uncertainties associated with both the data and the models must be considered in such an exercise. The most recent period of sustained global warmth similar to what is projected for the near future occurred about 3.3–3.0 million years ago, during the Pliocene epoch. Here, we present Pliocene sea surface temperature data, newly characterized in terms of level of confidence, along with initial experimental results from four climate models. We conclude that, in terms of sea surface temperature, models are in good agreement with estimates of Pliocene sea surface temperature in most regions except the North Atlantic. Our analysis indicates that the discrepancy between the Pliocene proxy data and model simulations in the mid-latitudes of the North Atlantic, where models underestimate warming shown by our highest-confidence data, may provide a new perspective and insight into the predictive abilities of these models in simulating a past warm interval in Earth history. This is important because the Pliocene has a number of parallels to present predictions of late twenty-first century climate.},
author = {Dowsett, Harry J and Robinson, Marci M and Haywood, Alan M and Hill, Daniel J and Dolan, Aisling M and Stoll, Danielle K and Chan, Wing-Le and Abe-Ouchi, Ayako and Chandler, Mark A and Rosenbloom, Nan A and Otto-Bliesner, Bette L and Bragg, Fran J and Lunt, Daniel J and Foley, Kevin M and Riesselman, Christina R},
doi = {10.1038/nclimate1455},
issn = {1758-6798},
journal = {Nature Climate Change},
number = {5},
pages = {365--371},
title = {{Assessing confidence in Pliocene sea surface temperatures to evaluate predictive models}},
url = {https://doi.org/10.1038/nclimate1455},
volume = {2},
year = {2012}
}
@article{ISI:000403872200001,
abstract = {Although global warming has been attributed to increases in atmospheric greenhouses gases, the mechanisms underlying spatiotemporal patterns of warming trends remain under debate. Herein, we analyzed surface and air warming observations recorded at 1977 stations in China from 1960 to 2003. Our results showed a significant spatial pattern for the warming of the daily maximum surface (Ts-max) and air (Ta-max) temperatures, and the pattern was stronger in northwest and northeast China and weaker or negative in South China and the North China Plain. These warming spatial patterns were attributed to surface shortwave solar radiation (R-s) and precipitation (P), which play a key role in the surface energy budget. During the study period, R-s decreased by -1.50 +/- 0.42 W m(-2) 10 yr(-1) in China, which reduced the trends of Ts-max and Ta-max by about 0.139 and 0.053 degrees C 10 yr(-1), respectively. More importantly, the decreasing rates in South China and the North China Plain were stronger than those in other parts of China. The spatial contrasts in the trends of Ts-max and Ta-max in China were significantly reduced after adjusting for the effect of R-s and P. For example, after adjusting for the effect of R-s and P, the difference in the Ts-max and Ta-max values between the North China Plain and the Loess Plateau was reduced by 97.8 and 68.3 {\%}, respectively; the seasonal contrast in Ts-max and Ta-max decreased by 45.0 and 17.2 {\%}, respectively; and the daily contrast in the warming rates of the surface and air temperature decreased by 33.0 and 29.1 {\%}, respectively. This study shows that the land energy budget plays an essential role in the identification of regional warming patterns.},
author = {Du, Jizeng and Wang, Kaicun and Wang, Jiankai and Ma, Qian},
doi = {10.5194/acp-17-4931-2017},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
month = {apr},
number = {8},
pages = {4931--4944},
title = {{Contributions of surface solar radiation and precipitation to the spatiotemporal patterns of surface and air warming in China from 1960 to 2003}},
volume = {17},
year = {2017}
}
@article{Duan2018,
abstract = {Abstract Geoengineering has been proposed as a backup approach to rapidly cool the Earth and avoid damages associated with anthropogenic climate change. In this study, we use the NCAR Community Earth System Model to conduct a series of slab-ocean and prescribed sea surface temperature simulations to investigate the climate response to three proposed radiation management geoengineering schemes: stratospheric aerosol increase (SAI), marine cloud brightening (MCB), and cirrus cloud thinning (CCT). Our simulations show that different amounts of radiative forcing are needed for these three schemes to compensate global mean warming induced by a doubling of atmospheric CO2. With radiative forcing defined in terms of top-of-atmosphere energy imbalances in prescribed sea surface temperature simulations with land temperature adjustments, radiative forcing efficacy for SAI is about 15{\%} smaller than that of CO2, and the efficacy for MCB and CCNCCT is about 10{\%} larger than that of CO2. In our simulations, different forcing efficacies are associated with different feedback processes for these forcing agents. Also, these geoengineering schemes produce different land-ocean temperature change contrasts. The apparent hydrological sensitivity, that is, change in equilibrium global mean precipitation per degree of equilibrium temperature change, differs substantially between CO2, SAI, MCB, and CCNCCT forcings, which is mainly a result of different precipitation responses during fast adjustment. After removing the component of fast adjustment, the northward movement of the Intertropical Convergence Zone in response to these forcing agents is tightly related with changes in the interhemispheric energy exchange and hemispheric temperature gradient.},
author = {Duan, Lei and Cao, Long and Bala, Govindasamy and Caldeira, Ken},
doi = {10.1029/2018JD029034},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
number = {21},
pages = {11980--12001},
title = {{Comparison of the Fast and Slow Climate Response to Three Radiation Management Geoengineering Schemes}},
volume = {123},
year = {2018}
}
@article{doi:10.1029/2018JD029093,
abstract = {Abstract In this study, we use the National Center for Atmospheric Research Community Earth System Model to investigate the contribution of sea ice and land snow to the climate sensitivity in response to increased atmospheric carbon dioxide content. We focus on the overall effect arising from the presence or absence of sea ice and/or land snow. We analyze our results in terms of the radiative forcing and climate feedback parameter. We find that the presence of sea ice and land snow decreases the climate feedback parameter (and thus increases climate sensitivity). Adjusted radiative forcing from added carbon dioxide is comparatively less sensitive to the presence of sea ice or land snow. The effect of sea ice on the climate feedback parameter decreases as sea ice cover diminishes at higher CO2 concentration. However, the influence of both sea ice and land snow on the climate feedback parameter remains substantial under the CO2 concentration range considered here (to eight times preindustrial CO2 content). Approximately, one quarter of the effect of sea ice and land snow on the climate feedback parameter is a consequence of the effect of these components on longwave feedback that is mainly associated with cloud change. Polar warming in response to added CO2 is approximately doubled by the presence of sea ice and land snow. Relative to the case in which sea ice and land snow are absent in the model, in response to increased CO2 concentrations, the presence of sea ice and land snow results in an increase in global mean warming by over 40{\%}.},
author = {Duan, Lei and Cao, Long and Caldeira, Ken},
doi = {10.1029/2018JD029093},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {climate feedback parameter,climate sensitivity,polar amplification,sea ice and land snow},
number = {1},
pages = {199--208},
title = {{Estimating Contributions of Sea Ice and Land Snow to Climate Feedback}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD029093},
volume = {124},
year = {2019}
}
@article{Dufresne.SaintLu-bams-2016,
author = {Dufresne, J-L and Saint-Lu, M},
doi = {10.1175/BAMS-D-14-00022.1},
journal = {Bulletin of the American Meteorological Society},
number = {5},
pages = {755--765},
title = {{Positive feedback in climate: stabilization or runaway, illustrated by a simple experiment}},
volume = {97},
year = {2016}
}
@article{Dufresne2008,
abstract = {Climate feedback analysis constitutes a useful framework for comparing the global mean surface temperature responses to an external forcing predicted by general circulation models (GCMs). Nevertheless, the contributions of the different radiative feedbacks to global warming (in equilibrium or transient conditions) and their comparison with the contribution of other processes (e.g., the ocean heat uptake) have not been quantified explicitly. Here these contributions from the classical feedback analysis framework are defined and quantified for an ensemble of 12 third phase of the Coupled Model Intercomparison Project (CMIP3)/Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) coupled atmosphere–ocean GCMs. In transient simulations, the multimodel mean contributions to global warming associated with the combined water vapor–lapse-rate feedback, cloud feedback, and ocean heat uptake are comparable. However, intermodel differences in cloud feedbacks constitute by far the mo...},
author = {Dufresne, Jean-Louis and Bony, Sandrine},
doi = {10.1175/2008JCLI2239.1},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
number = {19},
pages = {5135--5144},
title = {{An assessment of the primary sources of spread of global warming estimates from coupled atmosphere–ocean models}},
volume = {21},
year = {2008}
}
@article{Dunne2016,
abstract = {Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast, gas-phase chemistry models have been based on laboratory kinetics measurements for decades. We built a global model of aerosol formation by using extensive laboratory measurements of rates of nucleation involving sulfuric acid, ammonia, ions, and organic compounds conducted in the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present-day atmosphere involves ammonia or biogenic organic compounds, in addition to sulfuric acid. A considerable fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied, variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere.},
author = {Dunne, Eimear M. and Gordon, Hamish and K{\"{u}}rten, Andreas and Almeida, Jo{\~{a}}o and Duplissy, Jonathan and Williamson, Christina and Ortega, Ismael K. and Pringle, Kirsty J. and Adamov, Alexey and Baltensperger, Urs and Barmet, Peter and Benduhn, Francois and Bianchi, Federico and Breitenlechner, Martin and Clarke, Antony and Curtius, Joachim and Dommen, Josef and Donahue, Neil M. and Ehrhart, Sebastian and Flagan, Richard C. and Franchin, Alessandro and Guida, Roberto and Hakala, Jani and Hansel, Armin and Heinritzi, Martin and Jokinen, Tuija and Kangasluoma, Juha and Kirkby, Jasper and Kulmala, Markku and Kupc, Agnieszka and Lawler, Michael J. and Lehtipalo, Katrianne and Makhmutov, Vladimir and Mann, Graham and Mathot, Serge and Merikanto, Joonas and Miettinen, Pasi and Nenes, Athanasios and Onnela, Antti and Rap, Alexandru and Reddington, Carly L.S. and Riccobono, Francesco and Richards, Nigel A.D. and Rissanen, Matti P. and Rondo, Linda and Sarnela, Nina and Schobesberger, Siegfried and Sengupta, Kamalika and Simon, Mario and Sipil{\"{a}}, Mikko and Smith, James N. and Stozkhov, Yuri and Tom{\'{e}}, Antonio and Tr{\"{o}}stl, Jasmin and Wagner, Paul E. and Wimmer, Daniela and Winkler, Paul M. and Worsnop, Douglas R. and Carslaw, Kenneth S.},
doi = {10.1126/science.aaf2649},
issn = {10959203},
journal = {Science},
month = {dec},
number = {6316},
pages = {1119--1124},
publisher = {American Association for the Advancement of Science},
title = {{Global atmospheric particle formation from CERN CLOUD measurements}},
volume = {354},
year = {2016}
}
@article{Durack2014b,
author = {Durack, Paul J and Gleckler, Peter J and Landerer, Felix W and Taylor, Karl E},
doi = {https://doi.org/10.1038/nclimate2389},
journal = {Nature Climate Change},
month = {oct},
pages = {999--1005},
publisher = {Nature Publishing Group},
title = {{Quantifying underestimates of long-term upper-ocean warming}},
volume = {4},
year = {2014}
}
@article{Eastman2013a,
abstract = {An archive of land-based, surface-observed cloud reports has been updated and now spans 39 years from 1971 through 2009. Cloud-type information at weather stations is available in individual reports or in longterm, seasonal, and monthly averages. A shift to a new data source and the automation of cloud reporting in some countries has reduced the number of available stations; however, this dataset still represents most of the global land area. Global-average trends of cloud cover suggest a small decline in total cloud cover, on the order of 0.4{\%} per decade. Declining clouds in middle latitudes at high and middle levels appear responsible for this trend. An analysis of zonal cloud cover changes suggests poleward shifts of the jet streams in both hemispheres. The observed displacement agrees with other studies. Changes seen in cloud types associated with the Indian monsoon are consistent with previous work suggesting that increased pollution (black carbon) may be affecting monsoonal precipitation, causing drought in northern India. A similar analysis over northern China does not show an obvious aerosol connection. Past reports claiming a shift from stratiform to cumuliform cloud types over Russia were apparently partially based on spurious data. When the faulty stations are removed, a trade-off of stratiform and cumuliform cloud cover is still observed, but muted, over much of northern Eurasia. {\textcopyright} 2013 American Meteorological Society.},
author = {Eastman, Ryan and Warren, Stephen G.},
doi = {10.1175/JCLI-D-12-00280.1},
issn = {08948755},
journal = {Journal of Climate},
number = {4},
pages = {1286--1303},
title = {{A 39-yr survey of cloud changes from land stations worldwide 1971–2009: Long-term trends, relation to aerosols, and expansion of the tropical belt}},
volume = {26},
year = {2013}
}
@article{Ebmeier2014,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} The impact of volcanic emissions, especially from passive degassing and minor explosions, is a source of uncertainty in estimations of aerosol indirect effects. Observations of the impact of volcanic aerosol on clouds contribute to our understanding of both present-day atmospheric properties and of the pre-industrial baseline necessary to assess aerosol radiative forcing. We present systematic measurements over several years at multiple active and inactive volcanic islands in regions of low present-day aerosol burden. The time-averaged indirect aerosol effects within 200 km downwind of island volcanoes are observed using Moderate Resolution Imaging Spectroradiometer (MODIS, 2002–2013) and Advanced Along-Track Scanning Radiometer (AATSR, 2002–2008) data. Retrievals of aerosol and cloud properties at Kīlauea (Hawai'i), Yasur (Vanuatu) and Piton de la Fournaise (la R{\'{e}}union) are rotated about the volcanic vent to be parallel to wind direction, so that upwind and downwind retrievals can be compared. The emissions from all three volcanoes – including those from passive degassing, Strombolian activity and minor explosions – lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference ranging from 2–8 $\mu$m at the different volcanoes in different seasons. Estimations of the difference in Top of Atmosphere upward Short Wave flux upwind and downwind of the active volcanoes from NASA's Clouds and the Earth's Radiant Energy System (CERES) suggest a downwind elevation of between 10 and 45 Wm{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater} at distances of 150–400 km from the volcano, with much greater local ({\textless} 80 km) effects. Comparison of these observations with cloud properties at isolated islands without degassing or erupting volcanoes suggests that these patterns are not purely orographic in origin. Our observations of unpolluted, isolated marine settings may capture processes similar to those in the pre-industrial marine atmosphere.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Ebmeier, S. K. and Sayer, A. M. and Grainger, R. G. and Mather, T. A. and Carboni, E.},
doi = {10.5194/acp-14-10601-2014},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {oct},
number = {19},
pages = {10601--10618},
title = {{Systematic satellite observations of the impact of aerosols from passive volcanic degassing on local cloud properties}},
url = {https://www.atmos-chem-phys.net/14/10601/2014/},
volume = {14},
year = {2014}
}
@article{Edwards2014a,
abstract = {Energy technologies emit greenhouse gases with differing radiative efficiencies and atmospheric lifetimes. Standard practice for evaluating technologies, which uses the global warming potential (GWP) to compare the integrated radiative forcing of emitted gases over a fixed time horizon, does not acknowledge the importance of a changing background climate relative to climate change mitigation targets. Here we demonstrate that the GWP misvalues the impact of CH 4 -emitting technologies as mid-century approaches, and we propose a new class of metrics to evaluate technologies based on their time of use. The instantaneous climate impact (ICI) compares gases in an expected radiative forcing stabilization year, and the cumulative climate impact (CCI) compares their time-integrated radiative forcing up to a stabilization year. Using these dynamic metrics, we quantify the climate impacts of technologies and show that high-CH 4 -emitting energy sources become less advantageous over time. The impact of natural gas for transportation, with CH 4 leakage, exceeds that of gasoline within 1-2 decades for a commonly cited 3 W m a ̂'2 stabilization target. The impact of algae biodiesel overtakes that of corn ethanol within 2-3 decades, where algae co-products are used to produce biogas and corn co-products are used for animal feed. The proposed metrics capture the changing importance of CH 4 emissions as a climate threshold is approached, thereby addressing a major shortcoming of the GWP for technology evaluation. {\textcopyright} 2014 Macmillan Publishers Limited. All rights reserved.},
author = {Edwards, Morgan R. and Trancik, Jessika E.},
doi = {10.1038/nclimate2204},
issn = {17586798},
journal = {Nature Climate Change},
pages = {347--352},
title = {{Climate impacts of energy technologies depend on emissions timing}},
volume = {4},
year = {2014}
}
@article{2018A&A...615A..85E,
archivePrefix = {arXiv},
arxivId = {astro-ph.SR/1804.00287},
author = {Egorova, T. and Schmutz, W. and Rozanov, E. and Shapiro, A. I. and Usoskin, I. and Beer, J. and Tagirov, R. V. and Peter, T.},
doi = {10.1051/0004-6361/201731199},
eprint = {1804.00287},
journal = {Astronomy {\&} Astrophysics},
keywords = {Astrophysics - Solar and Stellar Astrophysics,Sun: UV radiation,Sun: atmosphere,Sun: faculae,line: formation,plages,radiative transfer,solar-terrestrial relations},
month = {jul},
pages = {A85},
primaryClass = {astro-ph.SR},
title = {{Revised historical solar irradiance forcing}},
volume = {615},
year = {2018}
}
@article{doi:10.1002/andp.19053220806,
author = {Einstein, A},
doi = {10.1002/andp.19053220806},
journal = {Annalen der Physik},
number = {8},
pages = {549--560},
title = {{{\"{U}}ber die von der molekularkinetischen Theorie der W{\"{a}}rme geforderte Bewegung von in ruhenden Fl{\"{u}}ssigkeiten suspendierten Teilchen}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/andp.19053220806},
volume = {322},
year = {1905}
}
@article{Elagib2013a,
abstract = {The magnitude and variability of warming of air and the solar dimming/brightening phenomenon are investigated for Bahrain. The temperature records show highly significant warming trends through six months of the year (April-September) for absolute maximum (AbsTx), and through five months (April-July and October) for absolute minimum (AbsTn). Greater warming overwhelms the daytime extremes over the nocturnal ones and the hot, dry part of the year than the cool, wet season, leading to significant widening range between AbsTx and AbsTn. The highest recorded temperature reveals an alarming warming rate of 0.60 degrees C decade(-1). Almost exclusively above-average values characterise the last 15 years, with the year 2010 set as the hottest within the study period. Accompanying this warming climate has been increasing variability of the within-year monthly temperatures. Although two statistical tests agree on significant solar dimming only for July and November, the data do reveal a return to decreased sunshine since 2002/2003. Adoption of serious measures would be needed to overcome the anticipated future environmental insecurity resulting from climate warming.},
address = {Elagib, NA CUAS, Inst Technol {\&} Resources Management Trop {\&} Subtro, Betzdorfer Str 2, D-50679 Cologne, Deutz, Germany CUAS, Inst Technol {\&} Resources Management Trop {\&} Subtro, Betzdorfer Str 2, D-50679 Cologne, Deutz, Germany CUAS, Inst Technol {\&} Resources},
annote = {095WL
Times Cited:0
Cited References Count:39},
author = {Elagib, N A and Alvi, S H},
doi = {https://doi.org/10.1504/IJGW.2013.051487},
issn = {1758-2083},
journal = {International Journal of Global Warming},
keywords = {solar dimming solar brightening climate warming te},
language = {English},
number = {1},
pages = {96--107},
title = {{Moderate solar dimming in an accelerating warming climate of Bahrain}},
volume = {5},
year = {2013}
}
@article{Emanuel2014,
abstract = {AbstractRadiative-moist-convective equilibrium (RCE) is a simple paradigm for the statistical equilibrium the earth's climate would exhibit in the absence of lateral energy transport. It has generally been assumed that for a given solar forcing and long-lived greenhouse gas concentration, such a state would be unique, but recent work suggests that more than one stable equilibrium may be possible. Here we show that above a critical specified sea surface temperature, the ordinary RCE state becomes linearly unstable to large-scale overturning circulations. The instability migrates the RCE state toward one of the two stable equilibria first found by Raymond and Zeng (2000). It occurs when the clear-sky infrared opacity of the lower troposphere becomes so large, owing to high water vapor concentration, that variations of the radiative cooling of the lower troposphere are governed principally by variations in upper tropospheric water vapor. We show that the instability represents a subcritical bifurcation of the ordinary RCE state, leading to either a dry state with large-scale descent, or to a moist state with mean ascent; these states may be accessed by finite amplitude perturbations to ordinary RCE in the subcritical state, or spontaneously in the supercritical state. As first suggested by Raymond (2000) and Sobel et al. (2007), the latter corresponds to the phenomenon of self-aggregation of moist convection, taking the form of cloud clusters or tropical cyclones. We argue that the nonrobustness of self-aggregation in cloud system resolving models may be an artifact of running such models close to the critical temperature for instability.},
author = {Emanuel, Kerry and Wing, Allison A and Vincent, Emmanuel M},
doi = {10.1002/2013MS000270},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {convection,radiation,self-aggregation},
month = {mar},
number = {1},
pages = {75--90},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Radiative–convective instability}},
url = {https://doi.org/10.1002/2013MS000270},
volume = {6},
year = {2014}
}
@article{England2014a,
abstract = {Despite ongoing increases in atmospheric greenhouse gases, the Earth[rsquor]s global average surface air temperature has remained more or less steady since 2001. A variety of mechanisms have been proposed to account for this slowdown in surface warming. A key component of the global hiatus that has been identified is cool eastern Pacific sea surface temperature, but it is unclear how the ocean has remained relatively cool there in spite of ongoing increases in radiative forcing. Here we show that a pronounced strengthening in Pacific trade winds over the past two decades[mdash]unprecedented in observations/reanalysis data and not captured by climate models[mdash]is sufficient to account for the cooling of the tropical Pacific and a substantial slowdown in surface warming through increased subsurface ocean heat uptake. The extra uptake has come about through increased subduction in the Pacific shallow overturning cells, enhancing heat convergence in the equatorial thermocline. At the same time, the accelerated trade winds have increased equatorial upwelling in the central and eastern Pacific, lowering sea surface temperature there, which drives further cooling in other regions. The net effect of these anomalous winds is a cooling in the 2012 global average surface air temperature of 0.1-0.2 [deg]C, which can account for much of the hiatus in surface warming observed since 2001. This hiatus could persist for much of the present decade if the trade wind trends continue, however rapid warming is expected to resume once the anomalous wind trends abate.},
author = {England, Matthew H. and McGregor, Shayne and Spence, Paul and Meehl, Gerald A. and Timmermann, Axel and Cai, Wenju and Gupta, Alex Sen and Mcphaden, Michael J. and Purich, Ariaan and Santoso, Agus},
doi = {10.1038/nclimate2106},
isbn = {1758-678X$\backslash$r1758-6798},
issn = {17586798},
journal = {Nature Climate Change},
number = {3},
pages = {222--227},
title = {{Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus}},
volume = {4},
year = {2014}
}
@article{Erfani2019,
abstract = {Variability in the strength of low-cloud feedbacks across climate models is the primary contributor to the spread in their estimates of equilibrium climate sensitivity (ECS). This raises the question: What are the regional implications for key features of tropical climate of globally weak versus strong low-cloud feedbacks in response to greenhouse gas–induced warming? To address this question and formalize our understanding of cloud controls on tropical climate, we perform a suite of idealized fully coupled and slab-ocean climate simulations across which we systematically scale the strength of the low-cloud-cover feedback under abrupt 2 × CO2 forcing within a single model, thereby isolating the impact of low-cloud feedback strength. The feedback strength is varied by modifying the stratus cloud fraction so that it is a function of not only local conditions but also global temperature in a series of abrupt 2 × CO2 sensitivity experiments. The unperturbed decrease in low cloud cover (LCC) under 2 × CO2 is greatest in the mid- and high-latitude oceans, and the subtropical eastern Pacific and Atlantic, a pattern that is magnified as the feedback strength is scaled. Consequently, sea surface temperature (SST) increases more in these regions as well as the Pacific cold tongue. As the strength of the low-cloud feedback increases this results in not only increased ECS, but also an enhanced reduction of the large-scale zonal and meridional SST gradients (structural climate sensitivity), with implications for the atmospheric Hadley and Walker circulations, as well as the hydrological cycle. The relevance of our results to simulating past warm climate is also discussed.},
author = {Erfani, Ehsan and Burls, Natalie J.},
doi = {10.1175/JCLI-D-18-0551.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {may},
number = {9},
pages = {2497--2516},
title = {{The Strength of Low-Cloud Feedbacks and Tropical Climate: A CESM Sensitivity Study}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-18-0551.1},
volume = {32},
year = {2019}
}
@article{Etminan2016a,
abstract = {New calculations of the radiative forcing (RF) are presented for the three main well-mixed greenhouse gases, methane, nitrous oxide, and carbon dioxide. Methane's RF is particularly impacted because of the inclusion of the shortwave forcing; the 1750–2011 RF is about 25{\%} higher (increasing from 0.48 W m −2 to 0.61 W m −2 ) compared to the value in the Intergovernmental Panel on Climate Change (IPCC) 2013 assessment; the 100 year global warming potential is 14{\%} higher than the IPCC value. We present new simplified expressions to calculate RF. Unlike previous expressions used by IPCC, the new ones include the overlap between CO 2 and N 2 O; for N 2 O forcing, the CO 2 overlap can be as important as the CH 4 overlap. The 1750–2011 CO 2 RF is within 1{\%} of IPCC's value but is about 10{\%} higher when CO 2 amounts reach 2000 ppm, a value projected to be possible under the extended RCP8.5 scenario.},
author = {Etminan, M. and Myhre, G. and Highwood, E. J. and Shine, K. P.},
doi = {10.1002/2016GL071930},
isbn = {1944-8007},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {methane,radiative forcing},
number = {24},
pages = {12614--12623},
title = {{Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing}},
volume = {43},
year = {2016}
}
@article{Exarchou2014a,
abstract = {AbstractThe quasi-equilibrium heat balances, as well as the responses to 4 ? CO2 perturbation, are compared among three global climate models with the aim to identify and explain intermodel differences in ocean heat uptake (OHU) processes. It is found that, in quasi equilibrium, convective and mixed layer processes, as well as eddy-related processes, cause cooling of the subsurface ocean. The cooling is balanced by warming caused by advective and diapycnally diffusive processes. It is also found that in the CO2-perturbed climates the largest contribution to OHU comes from changes in vertical mixing processes and the mean circulation, particularly in the extratropics, caused both by changes in wind forcing and by changes in high-latitude buoyancy forcing. There is a substantial warming in the tropics: a significant part of which occurs because of changes in horizontal advection in extratropics. Diapycnal diffusion makes only a weak contribution to the OHU, mainly in the tropics, because of increased stratification. There are important qualitative differences in the contribution of eddy-induced advection and isopycnal diffusion to the OHU among the models. The former is related to the different values of the coefficients used in the corresponding scheme. The latter is related to the different tapering formulations of the isopycnal diffusion scheme. These differences affect the OHU in the deep ocean, which is substantial in two of the models, with the dominant region of deep warming being the Southern Ocean. However, most of the OHU takes place above 2000 m, and the three models are quantitatively similar in their global OHU efficiency and its breakdown among processes and as a function of latitude.},
author = {Exarchou, Eleftheria and Kuhlbrodt, Till and Gregory, Jonathan M and Smith, Robin S},
doi = {10.1175/JCLI-D-14-00235.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {2},
pages = {887--908},
publisher = {American Meteorological Society},
title = {{Ocean Heat Uptake Processes: A Model Intercomparison}},
url = {https://doi.org/10.1175/JCLI-D-14-00235.1},
volume = {28},
year = {2014}
}
@article{doi:10.1029/2019GL083574,
abstract = {Abstract Climate sensitivity is a key metric used to assess the magnitude of global warming given increased CO2 concentrations. The geological past can provide insights into climate sensitivity; however, on timescales of millions of years, factors other than CO2 can drive climate, including paleogeographic forcing and solar luminosity. Here, through an ensemble of climate model simulations covering the period 150–35 million years ago, we show that climate sensitivity to CO2 doubling varies between ∼3.5 and 5.5 °C through this time. These variations can be explained as a nonlinear response to solar luminosity, evolving surface albedo due to changes in ocean area, and changes in ocean circulation. The work shows that the modern climate sensitivity is relatively low in the context of the geological record, as a result of relatively weak feedbacks due to a relatively low CO2 baseline, and the presence of ice and relatively small ocean area in the modern continental configuration.},
author = {Farnsworth, A and Lunt, D J and O'Brien, C L and Foster, G L and Inglis, G N and Markwick, P and Pancost, R D and Robinson, S A},
doi = {10.1029/2019GL083574},
journal = {Geophysical Research Letters},
keywords = {climate sensitivity,paleoclimate modeling},
number = {16},
pages = {9880--9889},
title = {{Climate Sensitivity on Geological Timescales Controlled by Nonlinear Feedbacks and Ocean Circulation}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083574},
volume = {46},
year = {2019}
}
@article{Fedorov2015a,
abstract = {The climate of the tropics and surrounding regions is defined by pronounced zonal (east-west) and meridional (equator to mid-latitudes) gradients in sea surface temperature. These gradients control zonal and meridional atmospheric circulations, and thus the Earth[rsquor]s climate. Global cooling over the past five million years, since the early Pliocene epoch, was accompanied by the gradual strengthening of these temperature gradients. Here we use records from the Atlantic and Pacific oceans, including a new alkenone palaeotemperature record from the South Pacific, to reconstruct changes in zonal and meridional sea surface temperature gradients since the Pliocene, and assess their connection using a comprehensive climate model. We find that the reconstructed zonal and meridional temperature gradients vary coherently over this time frame, showing a one-to-one relationship between their changes. In our model simulations, we systematically reduce the meridional sea surface temperature gradient by modifying the latitudinal distribution of cloud albedo or atmospheric CO2 concentration. The simulated zonal temperature gradient in the equatorial Pacific adjusts proportionally. These experiments and idealized modelling indicate that the meridional temperature gradient controls upper-ocean stratification in the tropics, which in turn controls the zonal gradient along the equator, as well as heat export from the tropical oceans. We conclude that this tight linkage between the two sea surface temperature gradients posits a fundamental constraint on both past and future climates.},
author = {Fedorov, Alexey V. and Burls, Natalie J. and Lawrence, Kira T. and Peterson, Laura C.},
doi = {https://doi.org/10.1038/ngeo2577},
issn = {17520908},
journal = {Nature Geoscience},
pages = {975--980},
title = {{Tightly linked zonal and meridional sea surface temperature gradients over the past five million years}},
volume = {8},
year = {2015}
}
@article{Fedorov2013,
abstract = {About five to four million years ago, in the early Pliocene epoch, Earth had a warm, temperate climate. The gradual cooling that followed led to the establishment of modern temperature patterns, possibly in response to a decrease in atmospheric CO 2 concentration, of the order of 100 parts per million, towards preindustrial values. Here we synthesize the available geochemical proxy records of sea surface temperature and show that, compared with that of today, the early Pliocene climate had substantially lower meridional and zonal temperature gradients but similar maximum ocean temperatures. Using an Earth system model, we show that none of the mechanisms currently proposed to explain Pliocene warmth can simultaneously reproduce all three crucial features. We suggest that a combination of several dynamical feedbacks underestimated in the models at present, such as those related to ocean mixing and cloud albedo, may have been responsible for these climate conditions. {\textcopyright} 2013 Macmillan Publishers Limited. All rights reserved.},
author = {Fedorov, A. V. and Brierley, C. M. and Lawrence, K. T. and Liu, Z. and Dekens, P. S. and Ravelo, A. C.},
doi = {10.1038/nature12003},
issn = {00280836},
journal = {Nature},
month = {apr},
number = {7443},
pages = {43--49},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Patterns and mechanisms of early Pliocene warmth}},
url = {http://dx.doi.org/10.1038/nature12003 http://10.0.4.14/nature12003 https://www.nature.com/articles/nature12003{\#}supplementary-information},
volume = {496},
year = {2013}
}
@article{Feldl2017,
abstract = {AbstractProjections of amplified climate change in the Arctic are attributed to positive feedbacks associated with the retreat of sea ice and changes in the lapse rate of the polar atmosphere. Here, a set of idealized aquaplanet experiments are performed to understand the coupling between high-latitude feedbacks, polar amplification, and the large-scale atmospheric circulation. Results are compared to CMIP5. Simulated climate responses are characterized by a wide range of polar amplification (from none to nearly 15 K warming, relative to the low latitudes) under CO2 quadrupling. Notably, the high-latitude lapse rate feedback varies in sign among the experiments. The aquaplanet simulation with the greatest polar amplification, representing a transition from perennial to ice-free conditions, exhibits a marked decrease in dry static energy flux by transient eddies. Partly compensating the reduced poleward energy flux is a contraction of the Ferrel cell and an increase in latent energy flux. Enhanced eddy energy flux is consistent with the upper-tropospheric warming that occurs in all experiments and provides a remote influence on the polar lapse rate feedback. Main conclusions are that (i) given a large, localized change in meridional surface temperature gradient, the midlatitude circulation exhibits strong compensation between changes in dry and latent energy fluxes and (ii) atmospheric eddies mediate the nonlinear interaction between surface albedo and lapse rate feedbacks, rendering the high-latitude lapse rate feedback less positive than it would be otherwise. Consequently, the variability of the circulation response, and particularly the partitioning of energy fluxes, offers insights into understanding the magnitude of polar amplification.},
author = {Feldl, Nicole and Anderson, Bruce T. and Bordoni, Simona},
doi = {10.1175/JCLI-D-16-0706.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Climate sensitivity,Energy transport,Feedback,Hydrologic cycle,Large-scale motions},
number = {22},
pages = {9213--9224},
title = {{Atmospheric eddies mediate lapse rate feedback and arctic amplification}},
volume = {30},
year = {2017}
}
@article{Feldl2013,
abstract = {The climate feedback framework partitions the radiative response to climate forcing into contributions from individual atmospheric processes. The goal of this study is to understand the closure of the energy budget in as much detail and precision as possible, within as clean an experimental setup as possible. Radiative kernels and radiative forcing are diagnosed for an aquaplanet simulation under perpetual equinox conditions. The role of the meridional structure of feedbacks, heat transport, and nonlinearities in controlling the local climate response is characterized. Results display a combination of positive subtropical feedbacks and polar amplified warming. These two factors imply a critical role for transport and nonlinear effects, with the latter acting to substantially reduce global climate sensitivity. At the hemispheric scale, a rich picture emerges: anomalous divergence of heat flux away from positive feedbacks in the subtropics; nonlinear interactions among and within clear-sky feedbacks, which reinforce the pattern of tropical cooling and high-latitude warming tendencies; and strong ice-line feedbacks that drive further amplification of polar warming. These results have implications for regional climate predictability, by providing an indication of how spatial patterns in feedbacks combine to affect both the local and nonlocal climate response, and how constraining uncertainty in those feedbacks may constrain the climate response.},
author = {Feldl, Nicole and Roe, Gerard H.},
doi = {10.1175/JCLI-D-12-00631.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Energy budget/balance,Energy transport,Feedback,Radiation budgets,Radiative forcing},
month = {nov},
number = {21},
pages = {8289--8304},
title = {{The Nonlinear and Nonlocal Nature of Climate Feedbacks}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-12-00631.1},
volume = {26},
year = {2013}
}
@article{Feldl2017a,
abstract = {The response of atmospheric heat transport to anthropogenic warming is determined by the anomalous meridional energy gradient. Feedback analysis offers a characterization of that gradient and hence reveals how uncertainty in physical processes may translate into uncertainty in the circulation response. However, individual feedbacks do not act in isolation. Anomalies associated with one feedback may be compensated by another, as is the case for the positive water vapor and negative lapse rate feedbacks in the tropics. Here a set of idealized experiments are performed in an aquaplanet model to evaluate the coupling between the surface albedo feedback and other feedbacks, including the impact on atmospheric heat transport. In the tropics, the dynamical response manifests as changes in the intensity and structure of the overturning Hadley circulation. Only half of the range of Hadley cell weakening exhibited in these experiments is found to be attributable to imposed, systematic variations in the surface albedo feedback. Changes in extratropical clouds that accompany the albedo changes explain the remaining spread. The feedback-driven circulation changes are compensated by eddy energy flux changes, which reduce the overall spread among experiments. These findings have implications for the efficiency with which the climate system, including tropical circulation and the hydrological cycle, adjusts to high-latitude feedbacks over climate states that range from perennial or seasonal ice to ice-free conditions in the Arctic.},
author = {Feldl, Nicole and Bordoni, Simona and Merlis, Timothy M.},
doi = {10.1175/JCLI-D-16-0324.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Climate change,Climate sensitivity,Energy transport,Feedback},
number = {1},
pages = {189--201},
publisher = {American Meteorological Society},
title = {{Coupled high-latitude climate feedbacks and their impact on atmospheric heat transport}},
volume = {30},
year = {2017}
}
@article{Feldl2020,
abstract = {Arctic amplification of anthropogenic climate change is widely attributed to the sea-ice albedo feedback, with its attendant increase in absorbed solar radiation, and to the effect of the vertical structure of atmospheric warming on Earth's outgoing longwave radiation. The latter lapse rate feedback is subject, at high latitudes, to a myriad of local and remote influences whose relative contributions remain unquantified. The distinct controls on the high-latitude lapse rate feedback are here partitioned into “upper” and “lower” contributions originating above and below a characteristic climatological isentropic surface that separates the high-latitude lower troposphere from the rest of the atmosphere. This decomposition clarifies how the positive high-latitude lapse rate feedback over polar oceans arises primarily as an atmospheric response to local sea ice loss and is reduced in subpolar latitudes by an increase in poleward atmospheric energy transport. The separation of the locally driven component of the high-latitude lapse rate feedback further reveals how it and the sea-ice albedo feedback together dominate Arctic amplification as a coupled mechanism operating across the seasonal cycle.},
author = {Feldl, Nicole and Po-Chedley, Stephen and Singh, Hansi K.A. and Hay, Stephanie and Kushner, Paul J.},
doi = {10.1038/s41612-020-00146-7},
issn = {23973722},
journal = {npj Climate and Atmospheric Science},
month = {dec},
number = {1},
pages = {41},
publisher = {Nature Research},
title = {{Sea ice and atmospheric circulation shape the high-latitude lapse rate feedback}},
volume = {3},
year = {2020}
}
@article{ISI:000461606600011,
abstract = {Surface incident solar radiation (R-s) is a key parameter of energy and water cycles of the Earth. Reanalyses represent important sources of information on R-s. However, reanalyses R-s may have important bias due to their imperfect parameterizations and input errors of cloud and aerosol. NASA's Global Modelling and Assimilation Office has recently released Version 2 of the Modern-Era Retrospective Analysis for Research and Applications (MERRA2), which incorporates a reanalysis of atmospheric optical depth for the first time. In this study, we evaluate R-s from MERRA2 and its predecessor (MERRA) in China from 1980 to 2014. We first compare three possible reference data sources: (a) observed R-s at 122 stations, (b) satellite retrievals of R-s and (c) R-s values derived from sunshine durations measured at 2,400 weather stations. We find sunshine duration derived R-s is a reliable reference and use it to evaluate MERRA and MERRA2. Our results show that both MERRA and MERRA2 have a high mean bias of 38.63 and 43.86 W/m(2) over China due to their underestimation of cloud fraction, which is greater in southern China. MERRA2 displays improved capability in reproducing monthly and annual variability, and national mean trend of R-s. MERRA overestimates the trend of R-s by 3.23 W/m(2) in eastern China. MERRA2 reduced this trend bias over the North China Plain likely due to its aerosol assimilation. However, MERRA2 show a negative bias in trend of R-s (-3.44 W/m(2)) in the south China likely due to its overestimation of atmospheric aerosols loading and aerosol-cloud interaction. The results provide guidance for future development of reanalysis and its scientific applications for ecological and hydrological models.},
author = {Feng, Fei and Wang, Kaicun},
doi = {10.1002/joc.5881},
issn = {0899-8418},
journal = {International Journal of Climatology},
month = {mar},
number = {3},
pages = {1305--1318},
title = {{Does the modern-era retrospective analysis for research and applications-2 aerosol reanalysis introduce an improvement in the simulation of surface solar radiation over China?}},
volume = {39},
year = {2019}
}
@article{doi:10.1029/2019GL083960,
abstract = {Abstract Forcings and feedbacks controlling the seasonally sea ice-free Arctic Ocean during the mid-Piacenzian Warm period (3.264–3.025 Ma, MPWP), a period when CO2 level, geography, and topography were similar to present day, remain unclear given that many complex Earth System Models with comparatively higher skills at simulating twentieth century Arctic sea ice tend to produce perennial Arctic sea ice for this period. We demonstrate that explicitly simulating aerosol-cloud interactions and the exclusion of industrial pollutants from model forcing conditions is key to simulating seasonally sea ice-free Arctic Ocean of MPWP. The absence of industrial pollutants leads to fewer and larger cloud droplets over the high-latitude Northern Europe and North Pacific, which allows greater absorption of solar radiation at the surface during the early summer. This enhanced absorption triggers the seasonally runaway sea ice surface albedo feedback that gives rise to September sea ice-free Arctic Ocean and strongly amplified northern high-latitude surface warmth.},
author = {Feng, Ran and Otto-Bliesner, Bette L and Xu, Yangyang and Brady, Esther and Fletcher, Tamara and Ballantyne, Ashley},
doi = {10.1029/2019GL083960},
journal = {Geophysical Research Letters},
number = {16},
pages = {9920--9929},
title = {{Contributions of aerosol–cloud interactions to mid-Piacenzian seasonally sea ice-free Arctic Ocean}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083960},
volume = {46},
year = {2019}
}
@article{Feng2020b,
abstract = {Three new equilibrium mid-Pliocene (MP) simulations are implemented with the Community Climate System Model version 4 (CCSM4) and Community Earth System Model versions 1.2 (CESM1.2) and 2 (CESM2). All simulations are carried out with the same boundary and forcing conditions following the protocol of Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). These simulations reveal amplified MP climate change relative to the preindustrial going from CCSM4 to CESM2, seen in global and polar averages of surface warming, sea ice reduction in both the Arctic and the Antarctic, and weakened Hadley circulation. The enhanced global mean warming arises from enhanced Earth system sensitivity (ESS) to not only CO2 change but also changes in boundary conditions primarily from vegetation and ice sheets. ESS is amplified by up to 70{\%} in CCSM4 and up to 100{\%} in CESM1.2 and CESM2 relative to the equilibrium climate sensitivity of respective models. Simulations disagree on several climate metrics. Different from CCSM4, both CESM1.2 and CESM2 show reduction of cloud cover, and weakened Walker circulation accompanied by an El Ni{\~{n}}o-like mean state of the tropical Pacific in MP simulations relative to the preindustrial. This El Ni{\~{n}}o-like mean state is consistent with paleo-observational sea surface temperatures, suggesting an improvement upon CCSM4. The performances of MP simulations are assessed with a new compilation of observational MP sea surface temperature. The model-data comparison suggests that CCSM4 is not sensitivity enough to the MP forcings, but CESM2 is likely too sensitive, especially in the tropics.},
author = {Feng, Ran and Otto-Bliesner, Bette L. and Brady, Esther C. and Rosenbloom, Nan},
doi = {10.1029/2019MS002033},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {AMOC,Earth System Sensitivity,PMIP4,PlioMIP2,mid-Pliocene,tropical circulation},
number = {8},
pages = {e2019MS002033},
title = {{Increased Climate Response and Earth System Sensitivity From CCSM4 to CESM2 in Mid-Pliocene Simulations}},
volume = {12},
year = {2020}
}
@article{Fiedler2017,
author = {Fiedler, S. and Stevens, B. and Mauritsen, T.},
doi = {10.1002/2017MS000932},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
month = {jun},
number = {2},
pages = {1325--1341},
title = {{On the sensitivity of anthropogenic aerosol forcing to model-internal variability and parameterizing a Twomey effect}},
url = {http://doi.wiley.com/10.1002/2017MS000932},
volume = {9},
year = {2017}
}
@article{Fiedler2019,
abstract = {This study assesses the change in anthropogenic aerosol forcing from the mid-1970s to the mid-2000s. Both decades had similar global-mean anthropogenic aerosol optical depths but substantially different global distributions. For both years, we quantify (i) the forcing spread due to modelinternal variability and (ii) the forcing spread among models. Our assessment is based on new ensembles of atmosphereonly simulations with five state-of-the-art Earth system models. Four of these models will be used in the sixth Coupled Model Intercomparison Project (CMIP6; Eyring et al., 2016). Here, the complexity of the anthropogenic aerosol has been reduced in the participating models. In all our simulations, we prescribe the same patterns of the anthropogenic aerosol optical properties and associated effects on the cloud droplet number concentration. We calculate the instantaneous radiative forcing (RF) and the effective radiative forcing (ERF). Their difference defines the net contribution from rapid adjustments. Our simulations show a model spread in ERF from-0:4 to-0:9 W m-2. The standard deviation in annual ERF is 0.3 W m-2, based on 180 individual estimates from each participating model. This result implies that identifying the model spread in ERF due to systematic differences requires averaging over a sufficiently large number of years. Moreover, we find almost identical ERFs for the mid-1970s and mid-2000s for individual models, although there are major model differences in natural aerosols and clouds. The modelensemble mean ERF is-0:54 W m-2 for the pre-industrial era to the mid-1970s and-0:59 W m-2 for the pre-industrial era to the mid-2000s. Our result suggests that comparing ERF changes between two observable periods rather than absolute magnitudes relative to a poorly constrained preindustrial state might provide a better test for a model's ability to represent transient climate changes.},
author = {Fiedler, Stephanie and Kinne, Stefan and {Ting Katty Huang}, Wan and R{\"{a}}is{\"{a}}nen, Petri and O'Donnell, Declan and Bellouin, Nicolas and Stier, Philip and Merikanto, Joonas and {Van Noije}, Twan and Makkonen, Risto and Lohmann, Ulrike},
doi = {10.5194/acp-19-6821-2019},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
month = {may},
number = {10},
pages = {6821--6841},
publisher = {Copernicus GmbH},
title = {{Anthropogenic aerosol forcing-insights from multiple estimates from aerosol–climate models with reduced complexity}},
volume = {19},
year = {2019}
}
@article{ISI:000403682600007,
abstract = {The fate of the terrestrial biosphere is highly uncertain given recent and projected changes in climate. This is especially acute for impacts associated with changes in drought frequency and intensity on the distribution and timing of water availability. The development of effective adaptation strategies for these emerging threats to food and water security are compromised by limitations in our understanding of how natural and managed ecosystems are responding to changing hydrological and climatological regimes. ThiFisher, J. B., Melton, F., Middleton, E., Hain, C., Anderson, M., Allen, R., et al. (2017). The future of evapotranspiration: Global requirements for ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources. WATER Resour. Res. 53, 2618–2626. doi:10.1002/2016WR020175.s information gap is exacerbated by insufficient monitoring capabilities from local to global scales. Here, we describe how evapotranspiration (ET) represents the key variable in linking ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources, and highlight both the outstanding science and applications questions and the actions, especially from a space-based perspective, necessary to advance them.},
address = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
author = {Fisher, Joshua B and Melton, Forrest and Middleton, Elizabeth and Hain, Christopher and Anderson, Martha and Allen, Richard and McCabe, Matthew F and Hook, Simon and Baldocchi, Dennis and Townsend, Philip A and Kilic, Ayse and Tu, Kevin and Miralles, Diego D and Perret, Johan and Lagouarde, Jean-Pierre and Waliser, Duane and Purdy, Adam J and French, Andrew and Schimel, David and Famiglietti, James S and Stephens, Graeme and Wood, Eric F},
doi = {10.1002/2016WR020175},
issn = {0043-1397},
journal = {Water Resources Research},
month = {apr},
number = {4},
pages = {2618--2626},
publisher = {AMER GEOPHYSICAL UNION},
title = {{The future of evapotranspiration: Global requirements for ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources}},
type = {Editorial Material},
volume = {53},
year = {2017}
}
@article{FlZ06,
author = {Flanner, Mark G and Zender, Charles S},
doi = {10.1029/2005JD006834},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
number = {D12},
pages = {D12208},
title = {{Linking snowpack microphysics and albedo evolution}},
url = {http://dx.doi.org/10.1029/2005JD006834 http://doi.wiley.com/10.1029/2005JD006834},
volume = {111},
year = {2006}
}
@article{FlS11,
author = {Flanner, M G and Shell, K M and Barlage, M and Perovich, D K and Tschudi, M A},
doi = {10.1038/ngeo1062},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {mar},
number = {3},
pages = {151--155},
title = {{Radiative forcing and albedo feedback from the Northern Hemisphere cryosphere between 1979 and 2008}},
url = {http://www.nature.com/articles/ngeo1062},
volume = {4},
year = {2011}
}
@article{Flannery1984,
abstract = {Standard latitudinally resolved energy balance models describe conservation of energy on a sphere subject to solar heating, cooling by infrared radiation and diffusive redistribution of energy according to a Fourier type heat flow with flux proportional to the gradient of temperature. The model determines the distribution of temperature with latitude T(x). Here we consider a similar model, the two phase model, in which we allow for transport of both thermal energy of air and latent heat associated with water vapor. We use the two phase model to calculate climate change, i.e., $\Delta$T(x), as a function of varying insolation and changing concentration of atmospheric CO2 under the assumption that relative humidity does not change. We compare the results with calculations from standard energy balance models and general circulation models. The distribution of warming with latitude for doubled atmospheric CO2 found with the two phase model agrees far better with the pattern of warming found in GCM studies than do results found with the standard model. In particular, the two phase model, like the GCM, shows greater manning at the poles than at the equator. In the two phase model, polar amplification can be explained in terms of a temperature dependent effective diffusion coefficient that increases with warming. Amplification of warming toward the poles occurs in the two phase model because the ability of the system to transport heat increases as the system warms.},
author = {Flannery, Brian P.},
doi = {10.1175/1520-0469(1984)041<0414:EBMITO>2.0.CO;2},
issn = {0022-4928},
journal = {Journal of the Atmospheric Sciences},
month = {feb},
number = {3},
pages = {414--421},
title = {{Energy Balance Models Incorporating Transport of Thermal and Latent Energy}},
url = {http://journals.ametsoc.org/doi/10.1175/1520-0469(1984)041{\%}3C0414:EBMITO{\%}3E2.0.CO;2},
volume = {41},
year = {1984}
}
@incollection{IPCC-AR5-Ch09,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Flato, G and Marotzke, J. and Abiodun, B. and Braconnot, P. and Chou, S.C. C and Collins, W. and Cox, P. and Driouech, F. and Emori, S. and Eyring, V. and Forest, C. and Gleckler, P. and Guilyardi, E. and Jakob, C. and Kattsov, V. and Reason, C. and Rummukainen, M.},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {9},
doi = {10.1017/CBO9781107415324.020},
editor = {Stocker, T.F. and Qin, D. and Plattner, G.-K. and Tignor, M. and Allen, S.K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.},
isbn = {9781107661820},
pages = {741--866},
publisher = {Cambridge University Press},
title = {{Evaluation of Climate Models}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Flynn2020,
abstract = {Abstract. The Earth's equilibrium climate sensitivity (ECS) to a doubling of atmospheric CO2, along with the transient climate response (TCR) and greenhouse gas emissions pathways, determines the amount of future warming. Coupled climate models have in the past been important tools to estimate and understand ECS. ECS estimated from Coupled Model Intercomparison Project Phase 5 (CMIP5) models lies between 2.0 and 4.7 K (mean of 3.2 K), whereas in the latest CMIP6 the spread has increased to 1.8–5.5 K (mean of 3.7 K), with 5 out of 25 models exceeding 5 K. It is thus pertinent to understand the causes underlying this shift. Here we compare the CMIP5 and CMIP6 model ensembles and find a systematic shift between CMIP eras to be unexplained as a process of random sampling from modeled forcing and feedback distributions. Instead, shortwave feedbacks shift towards more positive values, in particular over the Southern Ocean, driving the shift towards larger ECS values in many of the models. These results suggest that changes in model treatment of mixed-phase cloud processes and changes to Antarctic sea ice representation are likely causes of the shift towards larger ECS. Somewhat surprisingly, CMIP6 models exhibit less historical warming than CMIP5 models, despite an increase in TCR between CMIP eras (mean TCR increased from 1.7 to 1.9 K). The evolution of the warming suggests, however, that several of the CMIP6 models apply too strong aerosol cooling, resulting in too weak mid-20th century warming compared to the instrumental record.},
author = {Flynn, Clare Marie and Mauritsen, Thorsten},
doi = {10.5194/acp-20-7829-2020},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
number = {13},
pages = {7829--7842},
title = {{On the climate sensitivity and historical warming evolution in recent coupled model ensembles}},
volume = {20},
year = {2020}
}
@article{Folini2015a,
author = {Folini, D and Wild, M},
doi = {10.1002/2014JD022851},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {mar},
number = {6},
pages = {2261--2279},
title = {{The effect of aerosols and sea surface temperature on China's climate in the late twentieth century from ensembles of global climate simulations}},
url = {http://doi.wiley.com/10.1002/2014JD022851},
volume = {120},
year = {2015}
}
@article{doi:10.1002/2015GL064215,
abstract = {Abstract The tropical Pacific thermocline strength, depth, and tilt are critical to tropical mean state and variability. During the early Pliocene ({\~{}}3.5 to 4.5 Ma), the Eastern Equatorial Pacific (EEP) thermocline was deeper and the cold tongue was warmer than today, which resulted in a mean state with a reduced zonal sea surface temperature gradient or El Padre. However, it is unclear whether the deep thermocline was a local feature of the EEP or a basin-wide condition with global implications. Our measurements of Mg/Ca of Globorotalia tumida in a western equatorial Pacific site indicate Pliocene subsurface temperatures warmer than today; thus, El Padre included a basin-wide thermocline that was relatively warm, deep, and weakly tilted. At {\~{}}4 Ma, thermocline steepening was coupled to cooling of the cold tongue. Since {\~{}}4 Ma, the basin-wide thermocline cooled/shoaled gradually, with implications for thermocline feedbacks in tropical dynamics and the interpretation of TEX86-derived temperatures.},
author = {Ford, Heather L and Ravelo, A Christina and Dekens, Petra S and LaRiviere, Jonathan P and Wara, Michael W},
doi = {10.1002/2015GL064215},
journal = {Geophysical Research Letters},
keywords = {Mg/Ca,Pliocene,thermocline},
number = {12},
pages = {4878--4887},
title = {{The evolution of the equatorial thermocline and the early Pliocene El Padre mean state}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2015GL064215},
volume = {42},
year = {2015}
}
@article{Forest2002,
author = {Forest, C. E.},
doi = {10.1126/science.1064419},
issn = {00368075},
journal = {Science},
month = {jan},
number = {5552},
pages = {113--117},
title = {{Quantifying Uncertainties in Climate System Properties with the Use of Recent Climate Observations}},
url = {http://www.sciencemag.org/cgi/doi/10.1126/science.1064419},
volume = {295},
year = {2002}
}
@article{Forest2018,
abstract = {This review summarizes the inverse methods used to estimate the net aerosol forcing inferred from the historical climate change records for the Earth.},
author = {Forest, Chris E},
doi = {10.1007/s40641-018-0085-2},
issn = {2198-6061},
journal = {Current Climate Change Reports},
month = {mar},
number = {1},
pages = {11--22},
title = {{Inferred Net Aerosol Forcing Based on Historical Climate Changes: a Review}},
url = {https://doi.org/10.1007/s40641-018-0085-2},
volume = {4},
year = {2018}
}
@article{Forster2013,
abstract = {We utilize energy budget diagnostics from the Coupled Model Intercomparison Project phase 5 (CMIP5) to evaluate the models' climate forcing since preindustrial times employing an established regression technique. The climate forcing evaluated this way, termed the adjusted forcing (AF), includes a rapid adjustment term associated with cloud changes and other tropospheric and land-surface changes. We estimate a 2010 total anthropogenic and natural AF from CMIP5 models of 1.9?0.9Wm?2 (5–95{\%} range). The projected AF of the Representative Concentration Pathway simulations are lower than their expected radiative forcing (RF) in 2095 but agree well with efficacy weighted forcings from integrated assessment models. The smaller AF, compared to RF, is likely due to cloud adjustment. Multimodel time series of temperature change and AF from 1850 to 2100 have large intermodel spreads throughout the period. The intermodel spread of temperature change is principally driven by forcing differences in the present day and climate feedback differences in 2095, although forcing differences are still important for model spread at 2095. We find no significant relationship between the equilibrium climate sensitivity (ECS) of a model and its 2003 AF, in contrast to that found in older models where higher ECS models generally had less forcing. Given the large present-day model spread, there is no indication of any tendency by modelling groups to adjust their aerosol forcing in order to produce observed trends. Instead, some CMIP5 models have a relatively large positive forcing and overestimate the observed temperature change.},
author = {Forster, Piers M. and Andrews, Timothy and Good, Peter and Gregory, Jonathan M. and Jackson, Lawrence S. and Zelinka, Mark},
doi = {10.1002/jgrd.50174},
isbn = {2169-8996},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {CMIP5,climate sensitivity,forcing,model spread,rapid adjustment},
number = {3},
pages = {1139--1150},
title = {{Evaluating adjusted forcing and model spread for historical and future scenarios in the CMIP5 generation of climate models}},
volume = {118},
year = {2013}
}
@article{Forster2016a,
abstract = {The usefulness of previous Coupled Model Intercomparison Project (CMIP) exercises has been hampered by a lack of radiative forcing information. This has made it difficult to understand reasons for differences between model responses. Effective radiative forcing (ERF) is easier to diagnose than traditional radiative forcing in global climate models (GCMs) and is more representative of the eventual temperature response. Here we examine the different methods of computing ERF in two GCMs. We find that ERF computed from a fixed sea-surface temperature (SST) method (ERF{\_}fSST) has much more certainty than regression based methods. Thirty-year integrations are sufficient to reduce the 5-95{\%} confidence interval in global ERF{\_}fSST to 0.1 W m-2. For 2xCO2 ERF, 30 year integrations are needed to ensure that the signal is larger than the local confidence interval over more than 90{\%} of the globe. Within the ERF{\_}fSST method there are various options for prescribing SSTs and sea-ice. We explore these and find that ERF is only weakly dependent on the methodological choices. Prescribing the monthly-averaged seasonally varying model's preindustrial climatology is recommended for its smaller random error and easier implementation. As part of CMIP6, the Radiative Forcing Model Intercomparison Project (RFMIP) asks models to conduct 30-year ERF{\_}fSST experiments using the model's own preindustrial climatology of SST and sea-ice. The Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) will also mainly use this approach. We propose this as a standard method for diagnosing ERF and recommend that it be used across the climate modelling community to aid future comparisons.},
author = {Forster, Piers M. and Richardson, Thomas and Maycock, Amanda C. and Smith, Christopher J. and Samset, Bjorn H. and Myhre, Gunnar and Andrews, Timothy and Pincus, Robert and Schulz, Michael},
doi = {10.1002/2016JD025320},
isbn = {2169-9291},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {oct},
number = {20},
pages = {12460--12475},
title = {{Recommendations for diagnosing effective radiative forcing from climate models for CMIP6}},
url = {http://doi.wiley.com/10.1002/2016JD025320},
volume = {121},
year = {2016}
}
@article{Forster2016,
abstract = {Recent attempts to diagnose equilibrium climate sensitivity (ECS) from changes in Earth's energy budget point toward values at the low end of the Intergovernmental Panel on Climate Change Fifth Assessment Report (AR5)'s likely range (1.5–4.5 K). These studies employ observations but still require an element of modeling to infer ECS. Their diagnosed effective ECS over the historical period of around 2 K holds up to scrutiny, but there is tentative evidence that this underestimates the true ECS from a doubling of carbon dioxide. Different choices of energy imbalance data explain most of the difference between published best estimates, and effective radiative forcing dominates the overall uncertainty. For decadal analyses the largest source of uncertainty comes from a poor understanding of the relationship between ECS and decadal feedback. Considerable progress could be made by diagnosing effective radiative forcing in models.},
author = {Forster, Piers M.},
doi = {10.1146/annurev-earth-060614-105156},
issn = {0084-6597},
journal = {Annual Review of Earth and Planetary Sciences},
keywords = {aerosol,ocean heat uptake,radiative forcing,simple climate models,transient climate response},
month = {jun},
number = {1},
pages = {85--106},
publisher = {Annual Reviews},
title = {{Inference of Climate Sensitivity from Analysis of Earth's Energy Budget}},
url = {http://www.annualreviews.org/doi/10.1146/annurev-earth-060614-105156},
volume = {44},
year = {2016}
}
@article{Forster2019,
author = {Forster, Piers M. and Maycock, Amanda C. and McKenna, Christine M. and Smith, Christopher J.},
doi = {10.1038/s41558-019-0660-0},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {jan},
number = {1},
pages = {7--10},
publisher = {Nature Research},
title = {{Latest climate models confirm need for urgent mitigation}},
url = {http://www.nature.com/articles/s41558-019-0660-0},
volume = {10},
year = {2020}
}
@article{Forster2005,
abstract = {Releases of halocarbons into the atmosphere over the last 50 years are among the factors that have contributed to changes in the Earth's climate since pre-industrial times. Their individual and collective potential to contribute directly to surface climate change is usually gauged through calculation of their radiative efficiency, radiative forcing, and/or Global Warming Potential (GWP). For those halocarbons that contain chlorine and bromine, indirect effects on temperature via ozone layer depletion represent another way in which these gases affect climate. Further, halocarbons can also affect the temperature in the stratosphere. In this paper, we use a narrow-band radiative transfer model together with a range of climate models to examine the role of these gases on atmospheric temperatures in the stratosphere and troposphere. We evaluate in detail the halocarbon contributions to temperature changes at the tropical tropopause, and find that they have contributed a significant warming of ∼0.4 K over the last 50 years, dominating the effect of the other well-mixed greenhouse gases at these levels. The fact that observed tropical temperatures have not warmed strongly suggests that other mechanisms may be countering this effect. In a climate model this warming of the tropopause layer is found to lead to a 6{\%} smaller climate sensitivity for halocarbons on a globally averaged basis, compared to that for carbon dioxide changes. Using recent observations together with scenarios we also assess their past and predicted future direct and indirect roles on the evolution of surface temperature. We find that the indirect effect of stratospheric ozone depletion could have offset up to approximately half of the predicted past increases in surface temperature that would otherwise have occurred as a result of the direct effect of halocarbons. However, as ozone will likely recover in the next few decades, a slightly faster rate of warming should be expected from the net effect of halocarbons, and we find that together halocarbons could bring forward next century's expected warming by ∼20 years if future emissions projections are realized. In both the troposphere and stratosphere CFC-12 contributes most to the past temperature changes and the emissions projection considered suggest that HFC-134a could contribute most of the warming over the coming century. {\textcopyright} Springer 2005.},
author = {Forster, Piers M. and Joshi, Manoj},
doi = {10.1007/s10584-005-5955-7},
issn = {0165-0009},
journal = {Climatic Change},
month = {jul},
number = {1-2},
pages = {249--266},
title = {{The Role Of Halocarbons In The Climate Change Of The Troposphere And Stratosphere}},
url = {http://link.springer.com/10.1007/s10584-005-5955-7},
volume = {71},
year = {2005}
}
@incollection{IPCC2018,
author = {Forster, P.M. and Huppmann, D. and Kriegler, E. and Mundaca, L. and Smith, C. and Rogelj, J. and S{\'{e}}f{\'{e}}rian, R.},
booktitle = {Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change,},
chapter = {2},
editor = {Masson-Delmotte, V. and Zhai, P. and P{\"{o}}rtner, H.-O. and Roberts, D. and Skea, J. and Shukla, P.R. and Pirani, A. and Moufouma-Okia, W. and P{\'{e}}an, C. and Pidcock, R. and Connors, S. and Matthews, J.B.R. and Chen, Y. and Zhou, X. and Gomis, M.I. and Lonnoy, E. and Maycock, T. and Tignor, M. and Waterfield, T.},
pages = {2SM: 1--50},
publisher = {In Press},
title = {{Mitigation Pathways Compatible with 1.5°C in the Context of Sustainable Development Supplementary Material}},
url = {https://www.ipcc.ch/sr15/chapter/chapter-2},
year = {2018}
}
@incollection{Forster2007a,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Forster, PM and Ramaswamy, V and Artaxo, P and Berntsen, T and Betts, R and Fahey, D W and Haywood, J and Lean, J and Lowe, D C and Myhre, G and Nganga, J and Prinn, R and Raga, G and Schulz, M and {Van Dorland}, R},
booktitle = {Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {2},
editor = {Solomon, S. and Qin, D. and Manning, M. and Chen, Z. and Marquis, M. and Averyt, K.B. and Tignor, M. and Miller, H.L.},
isbn = {9780521880091},
pages = {129--234},
publisher = {Cambridge University Press},
title = {{Changes in Atmospheric Constituents and in Radiative Forcing}},
url = {https://www.ipcc.ch/report/ar4/wg1},
year = {2007}
}
@article{Foster2016a,
abstract = {In order to better understand the effect of CO2 on the Earth system in the future, geologists may look to CO2-induced environmental change in Earth's past. Here we describe how CO2 can be reconstructed using the boron isotopic composition ($\delta$11B) of marine calcium carbonate. We review the chemical principles that underlie the proxy, summarize the available calibration data, and detail how boron isotopes can be used to estimate ocean pH and ultimately atmospheric CO2 in the past. $\delta$11B in a variety of marine carbonates shows a coherent relationship with seawater pH, in broad agreement with simple models for this proxy. Offsets between measured and predicted $\delta$11B may in part be explained by physiological influences, though the exact mechanisms of boron incorporation into carbonate remain unknown. Despite these uncertainties, we demonstrate that $\delta$11B may provide crucial constraints on past ocean acidification and atmospheric CO2.},
author = {Foster, Gavin L. and Rae, James W.B.},
doi = {10.1146/annurev-earth-060115-012226},
isbn = {0084-6597},
issn = {0084-6597},
journal = {Annual Review of Earth and Planetary Sciences},
keywords = {boron isotopes,marine carbonates,p co 2,ph},
number = {1},
pages = {207--237},
title = {{Reconstructing Ocean pH with Boron Isotopes in Foraminifera}},
url = {http://www.annualreviews.org/doi/10.1146/annurev-earth-060115-012226},
volume = {44},
year = {2016}
}
@article{Foster2008,
author = {Foster, Grant and Annan, James D. and Schmidt, Gavin A. and Mann, Michael E.},
doi = {10.1029/2007JD009373},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
month = {aug},
number = {D15},
pages = {D15102},
title = {{Comment on “Heat capacity, time constant, and sensitivity of Earth's climate system” by S. E. Schwartz}},
url = {http://doi.wiley.com/10.1029/2007JD009373},
volume = {113},
year = {2008}
}
@article{Frame2006,
abstract = {Studies attempting to constrain climate sensitivity, or equilibrium surface warming in response to a doubling of atmospheric carbon dioxide, by comparing models with observations report a wide range of distributions, particularly regarding the upper bound. There is, by contrast, a considerable consensus surrounding the transient climate response, in large part because it is directly related to observed warming attributable to greenhouse gases. We argue that scenarios which can exploit this consensus may be preferable to stabilization scenarios for practical policy-making purposes. The difficulty of ruling out a high equilibrium warming response to elevated carbon dioxide levels may provide an opportunity for reassessment of the stabilization scenario as the centerpiece of climate policy in favour of scenarios that are more directly constrained by the transient response.},
author = {Frame, D. J. and Stone, D. A. and Stott, P. A. and Allen, M. R.},
doi = {10.1029/2006GL025801},
isbn = {0094-8276},
issn = {0094-8276},
journal = {Geophysical Research Letters},
number = {14},
pages = {L14707},
title = {{Alternatives to stabilization scenarios}},
url = {http://doi.wiley.com/10.1029/2006GL025801},
volume = {33},
year = {2006}
}
@article{doi:10.1029/2004GL022241,
abstract = {Any attempt to estimate climate sensitivity using observations requires a set of models or model-versions that simultaneously predict both climate sensitivity and some observable quantity(-ies) given a range of values of unknown climate system properties, represented by choices of parameters, subsystems or even entire models. The choices researchers make with respect to these unknown properties play a crucial role in conditioning their climate forecasts. We show that any probabilistic estimate of climate sensitivity, and hence of the risk that a given greenhouse gas stabilisation level might result in a “dangerous” equilibrium warming, is critically dependent on subjective prior assumptions of the investigators, not simply on constraints provided by actual climate observations. This apparent arbitrariness can be resolved by focussing on the intended purpose of the forecast: while uncertainty in long-term equilibrium warming remains high, an objectively determined 10–90{\%} (5–95{\%}) range of uncertainty in climate sensitivity that is relevant to forecasts of 21st century transient warming under nearly all current emission scenarios is 1.4–4.1°C with a median of 2.4°C, in good agreement with the “traditional” range.},
author = {Frame, D. J. and Booth, B. B. B. and Kettleborough, J. A. and Stainforth, D. A. and Gregory, J. M. and Collins, M. and Allen, M. R.},
doi = {10.1029/2004GL022241},
issn = {0094-8276},
journal = {Geophysical Research Letters},
number = {9},
pages = {L09702},
title = {{Constraining climate forecasts: The role of prior assumptions}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2004GL022241 http://doi.wiley.com/10.1029/2004GL022241},
volume = {32},
year = {2005}
}
@article{Frey2018,
abstract = {Global coupled climate models have large long-standing cloud and radiation biases, calling into question their ability to simulate climate and climate change. This study assesses the impact of reducing shortwave radiation biases on climate sensitivity within the Community Earth System Model (CESM). The model is modified by increasing supercooled cloud liquid to better match absorbed shortwave radiation observations over the Southern Ocean while tuning to reduce a compensating tropical shortwave bias. With a thermodynamic mixed-layer ocean, equilibrium warming in response to doubled CO2 increases from 4.1 K in the control to 5.6 K in the modified model. This 1.5 K increase in equilibrium climate sensitivity is caused by changes in two extratropical shortwave cloud feedbacks. First, reduced conversion of cloud ice to liquid at high southern latitudes decreases the magnitude of a negative cloud phase feedback. Second, warming is amplified in the mid-latitudes by a larger positive shortwave cloud feedback. The positive cloud feedback, usually associated with the subtropics, arises when sea surface warming increases the moisture gradient between the boundary layer and free troposphere. The increased moisture gradient enhances the effectiveness of mixing to dry the boundary layer, which decreases cloud amount and optical depth. When a full-depth ocean with dynamics and thermodynamics is included, ocean heat uptake preferentially cools the mid-latitude Southern Ocean, partially inhibiting the positive cloud feedback and slowing warming. Overall, the results highlight strong connections between Southern Ocean mixed-phase cloud partitioning, cloud feedbacks, and ocean heat uptake in a climate forced by greenhouse gas changes.},
author = {Frey, William R and Kay, Jennifer E},
doi = {10.1007/s00382-017-3796-5},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {7},
pages = {3097--3116},
title = {{The influence of extratropical cloud phase and amount feedbacks on climate sensitivity}},
url = {https://doi.org/10.1007/s00382-017-3796-5},
volume = {50},
year = {2018}
}
@article{Friberg2015,
author = {Friberg, J. and Martinsson, B. G. and Sporre, M. K. and Andersson, S. M. and Brenninkmeijer, C. A. M. and Hermann, M. and van Velthoven, P. F. J. and Zahn, A},
doi = {10.1002/2015EA000110.},
journal = {Earth and Space Science},
pages = {285--300},
title = {{Influence of volcanic eruptions on midlatitude upper tropospheric aerosol and consequences for cirrus clouds}},
volume = {2},
year = {2015}
}
@article{Friedrich2016a,
abstract = {Global mean surface temperatures are rising in response to anthropogenic greenhouse gas emissions. The magnitude of this warming at equilibrium for a given radiative forcing—referred to as specific equilibrium climate sensitivity ( S )—is still subject to uncertainties. We estimate global mean temperature variations and S using a 784,000-year-long field reconstruction of sea surface temperatures and a transient paleoclimate model simulation. Our results reveal that S is strongly dependent on the climate background state, with significantly larger values attained during warm phases. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, we find that the range of paleo-based estimates of Earth's future warming by 2100 CE overlaps with the upper range of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Furthermore, we find that within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years. On the basis of temperature data from eight glacial cycles, our results provide an independent validation of the magnitude of current CMIP5 warming projections.},
author = {Friedrich, Tobias and Timmermann, Axel and Tigchelaar, Michelle and Timm, Oliver Elison and Ganopolski, Andrey},
doi = {10.1126/sciadv.1501923},
issn = {23752548},
journal = {Science Advances},
number = {11},
pages = {e1501923},
title = {{Nonlinear climate sensitivity and its implications for future greenhouse warming}},
volume = {2},
year = {2016}
}
@article{FRIEDRICH2020115911,
abstract = {Future greenhouse warming projections conducted with coupled climate models still exhibit a substantial spread in response to a given anthropogenic greenhouse gas concentration scenario. In order to constrain this spread and to provide robust warming projections, our understanding of Earth's global-mean surface temperature response to radiative forcing (referred to as climate sensitivity) needs to be further refined. Here we estimate an averaged glacial/interglacial climate sensitivity using 25 transient Earth system model simulations of the Last Glacial Cycle and a global-mean sea surface temperature (SST) reconstruction derived from 64 globally-distributed paleo-proxies of SST. Our results document that Earth's averaged Late Pleistocene equilibrium climate sensitivity is in the order of ∼4.2 K per CO2 doubling. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, this value translates into a global-mean surface warming of ∼5.0 K by the year 2100 relative to pre-industrial levels. This estimate is in excellent agreement with the ensemble-mean projection of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Our uncertainty analysis reveals further that the lack of robust reconstructions of glacial aerosol forcing is a key contributor to the overall uncertainty of paleo-based estimates of climate sensitivity.},
author = {Friedrich, Tobias and Timmermann, Axel},
doi = {https://doi.org/10.1016/j.epsl.2019.115911},
issn = {0012-821X},
journal = {Earth and Planetary Science Letters},
keywords = {climate sensitivity,glacial cycles,global warming,paleo modeling},
pages = {115911},
title = {{Using Late Pleistocene sea surface temperature reconstructions to constrain future greenhouse warming}},
url = {http://www.sciencedirect.com/science/article/pii/S0012821X1930603X},
volume = {530},
year = {2020}
}
@article{Frouin2002,
abstract = {[1] Oceanic phytoplankton may exert a warming influence on the planet by decreasing surface albedo. Compared with the case of pure seawater, the globally and annually averaged outgoing radiative flux is decreased by a probable value of 0.25 Wm-2. This value corresponds to about 20{\%} of the combined radiative forcing by greenhouse gases and anthropogenic aerosols since preindustrial times, including indirect effects. The relative importance of phytoplankton is greater on regional and seasonal scales, with forcing values reaching -1.5 Wm-2 in coastal zones and high-latitude regions during summer. The annual amplitude of radiative forcing by phytoplankton is large in subpolar regions, owing to the conjugate action of cloud amount and biomass level. Spatial and temporal variability of the forcing is affected by phytoplankton type, some reflective species increasing the outgoing radiative flux. The effects of space- and time-varying phytoplankton on surface albedo should be taken into account explicitly in the numerical modeling of climate change. Copyright 2002 by the American Geophysical Union.},
author = {Frouin, R. and Iacobellis, Sam F},
doi = {10.1029/2001JD000562},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {Albedo,Climate,Ocean color,Phytoplankton,Radiative budget},
month = {oct},
number = {D19},
pages = {4377},
publisher = {Blackwell Publishing Ltd},
title = {{Influence of phytoplankton on the global radiation budget}},
url = {http://doi.wiley.com/10.1029/2001JD000562},
volume = {107},
year = {2002}
}
@article{Fu2020,
abstract = {Short-lived climate forcers (SLCFs) like methane, ozone and aerosols have a shorter atmospheric lifetime than CO2 and are often assumed to have a short-term effect on the climate system: should their emissions cease, so would their radiative forcing (RF). However, via their climate impact, SLCFs can affect carbon sinks and atmospheric CO2, causing additional climate change. Here, we use a compact Earth system model to attribute CO2 RF to direct CO2 emissions and to climate–carbon feedbacks since the pre-industrial era. We estimate the climate–carbon feedback contributed 93 ± 50 mW m−2 ({\~{}}5{\%}) to total RF of CO2 in 2010. Of this, SLCF impacts were −13 ± 50 mW m−2, made up of cooling (−115 ± 43 mW m−2) and warming (102 ± 26 mW m−2) terms that largely cancel. This study illustrates the long-term impact that short-lived species have on climate and indicates that past (and future) change in atmospheric CO2 cannot be attributed only to CO2 emissions.},
author = {Fu, Bo and Gasser, Thomas and Li, Bengang and Tao, Shu and Ciais, Philippe and Piao, Shilong and Balkanski, Yves and Li, Wei and Yin, Tianya and Han, Luchao and Li, Xinyue and Han, Yunman and An, Jie and Peng, Siyuan and Xu, Jing},
doi = {10.1038/s41558-020-0841-x},
issn = {17586798},
journal = {Nature Climate Change},
keywords = {Attribution,Climate and Earth system modelling},
month = {sep},
number = {9},
pages = {851--855},
publisher = {Nature Research},
title = {{Short-lived climate forcers have long-term climate impacts via the carbon–climate feedback}},
url = {https://doi.org/10.1038/s41558-020-0841-x},
volume = {10},
year = {2020}
}
@article{Fueglistaler2019,
abstract = {Tropical average shortwave cloud radiative effect (SWCRE) anomalies observed by CERES/EBAF v4 are explained by observed average sea surface temperature ((Formula presented.)) and the difference between the warmest 30{\%} where deep convection occurs and (Formula presented.)). Observed tropospheric temperatures show variations in boundary layer capping strength over time consistent with the evolution of SST{\#}. The CERES/EBAF v4 data confirm that associated cloud fraction changes over the colder waters dominate SWCRE. This observational evidence for the “pattern effect” noted in General Circulation Model simulations suggests that SST{\#} captures much of this effect. The observed sensitivities (dSWCRE/d (Formula presented.) W{\textperiodcentered}m−2{\textperiodcentered}K−1, dSWCRE/dSST{\#}≈−4.8W{\textperiodcentered}m−2{\textperiodcentered}K−1) largely reflect El Ni{\~{n}}o–Southern Oscillation. As El Ni{\~{n}}o develops, (Formula presented.) increases and SST{\#} decreases (both increasing SWCRE). Only after the El Ni{\~{n}}o peak, SST{\#} increases and SWCRE decreases. SST{\#} is also relevant for the tropical temperature trend profile controversy and the discrepancy between observed and modeled equatorial Pacific SST trends. Causality and implications for future climates are discussed.},
author = {Fueglistaler, S.},
doi = {10.1029/2019GL083990},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {ENSO,climate sensitivity,cloud albedo,sea surface temperatures,tropical convection},
month = {aug},
number = {16},
pages = {9890--9898},
publisher = {Blackwell Publishing Ltd},
title = {{Observational Evidence for Two Modes of Coupling Between Sea Surface Temperatures, Tropospheric Temperature Profile, and Shortwave Cloud Radiative Effect in the Tropics}},
volume = {46},
year = {2019}
}
@article{Fueglistaler2021,
abstract = {Abstract General Circulation Model (GCM) simulations with prescribed observed Sea Surface Temperature (SST) over the historical period show systematic global Shortwave Cloud Radiative Effect (SWCRE) variations uncorrelated with global surface temperature (known as ?pattern effect?). Here, we show that a single parameter that quantifies the difference in SSTs between regions of tropical deep convection and the tropical or global average (?conv) captures the time-varying ?pattern effect? in the simulations using the PCMDI/AMIPII SST recommended for CMIP6. In particular, a large positive trend in the 1980s-1990s in ?conv explains the change of sign to a strongly negative SWCRE feedback since the late 1970s. In these decades, the regions of deep convection warm about +50{\%} more than the tropical average. Such an amplification is rarely observed in forced coupled atmosphere-ocean GCM simulations, where the amplified warming is typically about +10{\%}. During the post-2000 global warming hiatus ?conv shows little change, and the more recent period of resumed global warming is too short to robustly detect trends. In the prescribed SST simulations, ?conv is forced by the SST difference between warmer and colder regions. An index thereof (SST{\#}) evaluated for 6 SST reconstructions shows similar trends for the satellite era, but the difference between the pre- and the satellite era is substantially larger in the PCMDI/AMIPII SSTs than in the other reconstructions. Quantification of the cloud feedback depends critically on small changes in the shape of the SST probability density distribution. These sensitivities underscore how essential highly accurate, persistent, and stable global climate records are to determine the cloud feedback. This article is protected by copyright. All rights reserved.},
author = {Fueglistaler, S. and Silvers, L.G.},
doi = {10.1029/2020JD033629},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {climate change,cloud feedback,sea surface temperature},
month = {feb},
number = {4},
pages = {e2020JD033629},
publisher = {American Geophysical Union (AGU)},
title = {{The Peculiar Trajectory of Global Warming}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020JD033629},
volume = {126},
year = {2021}
}
@article{Fuglestvedt2018,
abstract = {The main goal of the Paris Agreement as stated in Article 2 is ‘holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C'. Article 4 points to this long-term goal and the need to achieve ‘balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases'. This statement on ‘greenhouse gas balance' is subject to interpretation, and clarifications are needed to make it operational for national and international climate policies. We study possible interpretations from a scientific perspective and analyse their climatic implications. We clarify how the implications for individual gases depend on the metrics used to relate them. We show that the way in which balance is interpreted, achieved and maintained influences temperature outcomes. Achieving and maintaining net-zero CO2-equivalent emissions conventionally calculated using GWP100 (100-year global warming potential) and including substantial positive contributions from short-lived climate-forcing agents such as methane would result in a sustained decline in global temperature. A modified approach to the use of GWP100 (that equates constant emissions of short-lived climate forcers with zero sustained emission of CO2) results in global temperatures remaining approximately constant once net-zero CO2-equivalent emissions are achieved and maintained. Our paper provides policymakers with an overview of issues and choices that are important to determine which approach is most appropriate in the context of the Paris Agreement. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.},
author = {Fuglestvedt, J.S. and Rogelj, J. and Millar, R. J. and Allen, M. and Boucher, O. and Cain, M. and Forster, P. M. and Kriegler, E. and Shindell, D.},
doi = {10.1098/rsta.2016.0445},
issn = {1364503X},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
keywords = {CO 2 equivalence,Emission metrics,Greenhouse gas balance,Net-zero emissions,Paris agreement},
number = {2119},
pages = {20160445},
pmid = {29610378},
title = {{Implications of possible interpretations of ‘greenhouse gas balance' in the Paris Agreement}},
volume = {376},
year = {2018}
}
@article{Fuglestvedt2003,
abstract = {In this paper, we review existing and alternative metrics of climate change, with particular emphasis on radiative forcing and global warming potentials (GWPs), in terms of their scientific performance. Radiative forcing is assessed in terms of questions such as the utility of the concept, uncertainties and sensitivity to key assumptions. The assessment of emission indices focuses on the climate and other resulting impacts (end points) against which emissions are weighted; the extent to which (and how) time dependence is included, with regard to both emission control and impact; how cost issues are dealt with; and the sensitivity of the metrics to various assumptions. It is concluded that the radiative forcing concept is a robust and useful metric of the potential climatic impact of various agents and that there are prospects for improvement by weighing different forcings according to their effectiveness. We also find that although the GWP concept is associated with serious shortcomings, it retains advantages over any of the proposed alternatives in terms of political feasibility. Alternative metrics, however, make a significant contribution to addressing important issues, and this contribution should be taken into account in the further development of refined metrics of climate change.},
author = {Fuglestvedt, J.S. and Berntsen, T.K. and Godal, O. and Sausen, R. and Shine, K.P. and Skodvin, T.},
doi = {10.1023/A:1023905326842},
journal = {Climatic Change},
number = {3},
pages = {267--331},
title = {{Metrics of climate change: Assessing radiative forcing and emission indices}},
volume = {58},
year = {2003}
}
@article{Fyke2018a,
abstract = {Abstract Ice sheet response to forced changes ? such as that from anthropogenic climate forcing ? is closely regulated by two?way interactions with other components of the Earth system. These interactions encompass the ice sheet response to Earth system forcing, the Earth system response to ice sheet change, and feedbacks resulting from coupled ice?sheet/Earth system evolution. Motivated by the impact of Antarctic and Greenland ice sheet change on future sea level rise, here we review the state of knowledge of ice?sheet/Earth system interactions and feedbacks. We also describe emerging observation and model?based methods that can improve understanding of ice?sheet/Earth system interactions and feedbacks. We particularly focus on the development of Earth System Models that incorporate current understanding of Earth system processes, ice dynamics and ice?sheet/Earth system couplings. Such models will be critical tools for projecting future sea level rise from anthropogenically forced ice sheet mass loss.},
author = {Fyke, Jeremy and Sergienko, Olga and L{\"{o}}fverstr{\"{o}}m, Marcus and Price, Stephen and Lenaerts, Jan T.M.},
doi = {10.1029/2018RG000600},
issn = {19449208},
journal = {Reviews of Geophysics},
number = {2},
pages = {361--408},
title = {{An Overview of Interactions and Feedbacks Between Ice Sheets and the Earth System}},
volume = {56},
year = {2018}
}
@article{Gan2014a,
abstract = {Long-term data sets of all-sky and clear-sky downwelling shortwave (SW) radiation, cloud cover fraction, and aerosol optical depth (AOD) were analyzed together with surface concentrations from several networks (e. g., Surface Radiation Budget Network (SURFRAD), Clean Air Status and Trend Network (CASTNET), Interagency Monitoring of Protection Visual Environments (IMPROVE) and Atmospheric Radiation Measurement (ARM)) in the United States (US). Seven states with varying climatology were selected to better understand the effects of aerosols and clouds on SW radiation. This analysis aims to assess the effects of reductions in anthropogenic aerosol burden resulting from substantial reductions in emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) over the past 16 yr across the US, based on trends in SW radiation. The SO2 and NOx emission data show decreasing trends from 1995 to 2010, which indirectly validates the effects of the Clean Air Act (CAA) in the US. Meanwhile, the total column AOD and surface total PM2.5 observations also show decreasing trends in the eastern US but slightly increasing trends in the western US. Moreover, measured surface concentrations of several other pollutants (i.e., SO2, SO4 and NOx) have similar behavior to AOD and total PM2.5. Analysis of the observed data shows strong increasing trends in all-sky downwelling SW radiation with decreasing trends in cloud cover. However, since observations of both all-sky direct and diffuse SW radiation show increasing trends, there may be other factors contributing to the radiation trends in addition to the decreasing trends in overall cloud cover. To investigate the role of direct radiative effects of aerosols, clear-sky downwelling radiation is analyzed so that cloud effects are eliminated. However, similar increasing trends in clear-sky total and diffuse SW radiation are observed. While significantly decreasing trends in AOD and surface PM2.5 concentrations along with increasing SW radiation (both all-sky and clear-sky) in the eastern US during 1995-2010 imply the occurrence of direct aerosol mediated "brightening", the increasing trends of both all-sky and clear-sky diffuse SW radiation contradicts this conclusion since diffuse radiation would be expected to decrease as aerosols direct effects decrease and cloud cover decreases. After investigating several confounding factors, the increasing trend in clear-sky diffuse SW may be due to more high-level cirrus from increasing air traffic over the US. The clear-sky radiation observations in the western US also show indications of "brightening" even though the AOD, PM2.5 and surface concentration do not vary drastically. This outcome was not unexpected because the CAA controls were mainly aimed at reducing air pollutant emissions in the eastern US and air pollutant levels in the western US were much lower at the onset. This suggests other factors affect the "brightening" especially in the western US.},
address = {Gan, Cm US EPA, Atmospher Modeling {\&} Anal Div, Natl Exposure Res Lab, Res Triangle Pk, Res Triangle Pk, NC 27711 USA US EPA, Atmospher Modeling {\&} Anal Div, Natl Exposure Res Lab, Res Triangle Pk, Res Triangle Pk, NC 27711 USA US EPA, Atmospher Modeling {\&}},
annote = {Ac2zn
Times Cited:2
Cited References Count:42},
author = {Gan, C M and Pleim, J and Mathur, R and Hogrefe, C and Long, C N and Xing, J and Roselle, S and Wei, C},
doi = {10.5194/Acp-14-1701-2014},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
keywords = {surface solar-radiation budget network optical dep},
language = {English},
number = {3},
pages = {1701--1715},
title = {{Assessment of the effect of air pollution controls on trends in shortwave radiation over the United States from 1995 through 2010 from multiple observation networks}},
volume = {14},
year = {2014}
}
@article{Garcia2014a,
abstract = {This paper presents the reconstruction of the 80-year time series of daily global solar radiation (GSR) at the subtropical high-mountain Izana Atmospheric Observatory (IZO) located in Tenerife (The Canary Islands, Spain). For this purpose, we combine GSR estimates from sunshine duration (SD) data using the Angstrom-Prescott method over the 1933/1991 period, and GSR observations directly performed by pyranometers between 1992 and 2013. Since GSR measurements have been used as a reference, a strict quality control has been applied based on principles of physical limits and comparison with LibRadtran model. By comparing with high quality GSR measurements, the precision and consistency over time of GSR estimations from SD data have been successfully documented. We obtain an overall root mean square error (RMSE) of 9.2{\%} and an agreement between the variances of GSR estimations and GSR measurements within 92{\%}. Nonetheless, this agreement significantly increases when the GSR estimation is done considering different daily fractions of clear sky (FCS). In that case, RMSE is reduced by half, to about 4.5 {\%}, when considering percentages of FCS {\textgreater} 40{\%} (similar to 90{\%} of days in the testing period). Furthermore, we prove that the GSR estimations can monitor the GSR anomalies in consistency with GSR measurements and, then, can be suitable for reconstructing solar radiation time series. The reconstructed IZO GSR time series between 1933 and 2013 confirms change points and periods of increases/decreases of solar radiation at Earth's surface observed at a global scale, such as the early brightening, dimming and brightening. This fact supports the consistency of the IZO GSR time series presented in this work, which may be a reference for solar radiation studies in the subtropical North Atlantic region.},
address = {Garcia, RD Agencia Estatal Meteorol AEMET, IARC, Madrid, Spain Agencia Estatal Meteorol AEMET, IARC, Madrid, Spain Agencia Estatal Meteorol AEMET, IARC, Madrid, Spain Univ Valladolid, Atmospher Opt Grp, Valladolid, Spain Inst Astrofis Canarias, Santa Cruz},
annote = {Aq8wr
Times Cited:0
Cited References Count:72},
author = {Garcia, R D and Cuevas, E and Garcia, O E and Cachorro, V E and Palle, P and Bustos, J J and Romero-Campos, P M and de Frutos, A M},
doi = {10.5194/Amt-7-3139-2014},
issn = {1867-1381},
journal = {Atmospheric Measurement Techniques},
keywords = {stokes sunshine recorder surface radiation free tr},
language = {English},
number = {9},
pages = {3139--3150},
title = {{Reconstruction of global solar radiation time series from 1933 to 2013 at the Izana Atmospheric Observatory}},
volume = {7},
year = {2014}
}
@article{Garuba2018,
abstract = {The temporal evolution of the effective climate sensitivity is shown to be influenced by the changing pattern of sea surface temperature (SST) and ocean heat uptake (OHU), which in turn have been attributed to ocean circulation changes. A set of novel experiments are performed to isolate the active role of the ocean by comparing a fully coupled CO 2 quadrupling community Earth System Model (CESM) simulation against a partially coupled one, where the effect of the ocean circulation change and its impact on surface fluxes are disabled. The active OHU is responsible for the reduced effective climate sensitivity and weaker surface warming response in the fully coupled simulation. The passive OHU excites qualitatively similar feedbacks to CO 2 quadrupling in a slab ocean model configuration due to the similar SST spatial pattern response in both experiments. Additionally, the nonunitary forcing efficacy of the active OHU (1.7) explains the very different net feedback parameters in the fully and partially coupled responses.},
author = {Garuba, Oluwayemi A. and Lu, Jian and Liu, Fukai and Singh, Hansi A.},
doi = {10.1002/2017GL075633},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {Air-sea interactions,Climate sensitivity,Ocean circulation change,Ocean heat uptake,Radiative Feedbacks},
month = {jan},
number = {1},
pages = {306--315},
title = {{The Active Role of the Ocean in the Temporal Evolution of Climate Sensitivity}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2017GL075633},
volume = {45},
year = {2018}
}
@article{Gasso2008,
author = {Gass{\'{o}}, Santiago},
doi = {10.1029/2007JD009106},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aerosols,clouds,volcanoes},
month = {apr},
number = {D14},
pages = {D14S19},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Satellite observations of the impact of weak volcanic activity on marine clouds}},
url = {http://doi.wiley.com/10.1029/2007JD009106},
volume = {113},
year = {2008}
}
@article{Gasser2017,
abstract = {Most emission metrics have previously been inconsistently estimated by including the climate{\&}ndash;carbon feedback for the reference gas (i.e. CO2) but not the other species (e.g. CH4). In the fifth assessment report of the IPCC, a first attempt was made to consistently account for the climate{\&}ndash;carbon feedback in emission metrics. This attempt was based on only one study, and therefore the IPCC concluded that more research was needed. Here, we carry out this research. First, using the simple Earth system model OSCAR v2.2, we establish a new impulse response function for the climate{\&}ndash;carbon feedback. Second, we use this impulse response function to provide new estimates for the two most common metrics: global warming potential (GWP) and global temperature-change potential (GTP). We find that, when the climate-carbon feedback is correctly accounted for, the emission metrics of non-CO2 species increase, but in most cases not as much as initially indicated by IPCC. We also find that, when the feedback is removed for both the reference and studied species, these relative metric values only have modest changes compared to when the feedback is included (absolute metrics change more markedly). Including or excluding the climate-carbon feedback ultimately depends on the user's goal, but consistency should be ensured in either case.},
author = {Gasser, Thomas and Peters, Glen P. and Fuglestvedt, Jan S. and Collins, William J. and Shindell, Drew T. and Ciais, Philippe},
doi = {10.5194/esd-8-235-2017},
issn = {21904987},
journal = {Earth System Dynamics},
number = {2},
pages = {235--253},
title = {{Accounting for the climate–carbon feedback in emission metric}},
volume = {8},
year = {2017}
}
@article{Gasser2020,
abstract = {Emissions from land use and land cover change are a key component of the global carbon cycle. However, models are required to disentangle these emissions from the land carbon sink, as only the sum of both can be physically observed. Their assessment within the yearly communitywide effort known as the "Global Carbon Budget"remains a major difficulty, because it combines two lines of evidence that are inherently inconsistent: bookkeeping models and dynamic global vegetation models. Here, we propose a unifying approach that relies on a bookkeeping model, which embeds processes and parameters calibrated on dynamic global vegetation models, and the use of an empirical constraint. We estimate that the global CO 2 emissions from land use and land cover change were 1:36±0:42 PgC yr -1 (1$\sigma$ range) on average over the 2009-2018 period and reached a cumulative total of 206±57 PgC over the 1750-2018 period. We also estimate that land cover change induced a global loss of additional sink capacity - that is, a foregone carbon removal, not part of the emissions - of 0:68±0:57 PgC yr -1 and 32±23 PgC over the same periods, respectively. Additionally, we provide a breakdown of our results' uncertainty, including aspects such as the land use and land cover change data sets used as input and the model's biogeochemical parameters. We find that the biogeochemical uncertainty dominates our global and regional estimates with the exception of tropical regions in which the input data dominates. Our analysis further identifies key sources of uncertainty and suggests ways to strengthen the robustness of future Global Carbon Budget estimates.},
author = {Gasser, Thomas and Crepin, Le{\'{a}} and Quilcaille, Yann and Houghton, Richard A. and Ciais, Philippe and Obersteiner, Michael},
doi = {10.5194/bg-17-4075-2020},
issn = {17264189},
journal = {Biogeosciences},
month = {aug},
number = {15},
pages = {4075--4101},
publisher = {Copernicus GmbH},
title = {{Historical CO2 emissions from land use and land cover change and their uncertainty}},
volume = {17},
year = {2020}
}
@article{Gasser2017a,
abstract = {This paper provides a comprehensive description of OSCAR v2.2, a simple Earth system model. The general philosophy of development is first explained, followed by a complete description of the model's drivers and various modules. All components of the Earth system necessary to simulate future climate change are represented in the model: the oceanic and terrestrial carbon cycles - including a book-keeping module to endogenously estimate land-use change emissions - so as to simulate the change in atmospheric carbon dioxide; the tropospheric chemistry and the natural wetlands, to simulate that of methane; the stratospheric chemistry, for nitrous oxide; 37 halogenated compounds; changing tropospheric and stratospheric ozone; the direct and indirect effects of aerosols; changes in surface albedo caused by black carbon deposition on snow and land-cover change; and the global and regional response of climate - in terms of temperature and precipitation - to all these climate forcers. Following the probabilistic framework of the model, an ensemble of simulations is made over the historical period (1750-2010). We show that the model performs well in reproducing observed past changes in the Earth system such as increased atmospheric concentration of greenhouse gases or increased global mean surface temperature.},
author = {Gasser, Thomas and Ciais, Philippe and Boucher, Olivier and Quilcaille, Yann and Tortora, Maxime and Bopp, Laurent and Hauglustaine, Didier},
doi = {10.5194/gmd-10-271-2017},
issn = {19919603},
journal = {Geoscientific Model Development},
month = {jan},
number = {1},
pages = {271--319},
publisher = {Copernicus GmbH},
title = {{The compact Earth system model OSCAR v2.2: Description and first results}},
volume = {10},
year = {2017}
}
@article{Gebbie70,
abstract = {Earth{\{}$\backslash$textquoteright{\}}s climate cooled considerably across the transition from the Medieval Warm Period to the Little Ice Age about 700 years ago. Theoretically, owing to how the ocean circulates, this cooling should be recorded in Pacific deep-ocean temperatures, where water that was on the surface then is found today. Gebbie and Huybers used an ocean circulation model and observations from both the end of the 19th century and the end of the 20th century to detect and quantify this trend. The ongoing deep Pacific is cooling, which revises Earth{\{}$\backslash$textquoteright{\}}s overall heat budget since 1750 downward by 35{\%}.Science, this issue p. 70Proxy records show that before the onset of modern anthropogenic warming, globally coherent cooling occurred from the Medieval Warm Period to the Little Ice Age. The long memory of the ocean suggests that these historical surface anomalies are associated with ongoing deep-ocean temperature adjustments. Combining an ocean model with modern and paleoceanographic data leads to a prediction that the deep Pacific is still adjusting to the cooling going into the Little Ice Age, whereas temperature trends in the surface ocean and deep Atlantic reflect modern warming. This prediction is corroborated by temperature changes identified between the HMS Challenger expedition of the 1870s and modern hydrography. The implied heat loss in the deep ocean since 1750 CE offsets one-fourth of the global heat gain in the upper ocean.},
author = {Gebbie, Geoffrey and Huybers, Peter},
doi = {10.1126/science.aar8413},
issn = {0036-8075},
journal = {Science},
number = {6422},
pages = {70--74},
pmid = {30606843},
publisher = {American Association for the Advancement of Science},
title = {{The Little Ice Age and 20th Century Deep Pacific Cooling}},
url = {http://science.sciencemag.org/content/363/6422/70},
volume = {363},
year = {2019}
}
@article{Geoffroy2012a,
abstract = {Energy-balance models (EBM) constitute a useful framework for summarizing the first-order physical properties driving the magnitude of the global mean surface air temperature response to an externally imposed radiative perturbation. Here the contributions of these properties to the spread of the temperature responses of an ensemble of coupled Atmosphere-ocean General Circulation Models (AOGCM) of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) are evaluated within the framework of a state-of-the-art EBM. These partial contributions are quantified (in equilibrium and transient conditions) using the analysis of variance method. The radiative properties, particularly the strength of the radiative feedback to the global equilibrium surface warming, appear to constitute the most primary source of the spread. Moreover, the adjusted radiative forcing is found to play an important role in the spread of the transient response.},
author = {Geoffroy, O. and Saint-Martin, D. and Ribes, A.},
doi = {10.1029/2012GL054172},
isbn = {1944-8007},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {analysis of variance,climate sensitivity,forcing adjustment,inter-model spread,ocean heat uptake,radiative feedbacks},
month = {dec},
number = {24},
pages = {L24703},
publisher = {Wiley-Blackwell},
title = {{Quantifying the sources of spread in climate change experiments}},
url = {https://doi.org/10.1029/2012GL054172},
volume = {39},
year = {2012}
}
@article{Geoffroy2013,
abstract = {AbstractIn this second part of a series of two articles analyzing the global thermal properties of atmosphere?ocean coupled general circulation models (AOGCMs) within the framework of a two-layer energy-balance model (EBM), the role of the efficacy of deep-ocean heat uptake is investigated. Taking into account such an efficacy factor is shown to amount to representing the effect of deep-ocean heat uptake on the local strength of the radiative feedback in the transient regime. It involves an additional term in the formulation of the radiative imbalance at the top of the atmosphere (TOA), which explains the nonlinearity between radiative imbalance and the mean surface temperature observed in some AOGCMs. An analytical solution of this system is given and this simple linear EBM is calibrated for the set of 16 AOGCMs of phase 5 of the Coupled Model Intercomparison Project (CMIP5) studied in Part I. It is shown that both the net radiative fluxes at TOA and the global surface temperature transient response are well represented by the simple EBM over the available period of simulations. Differences between this two-layer EBM and the previous version without an efficacy factor are analyzed and relationships between parameters are discussed. The simple model calibration applied to AOGCMs constitutes a new method for estimating their respective equilibrium climate sensitivity and adjusted radiative forcing amplitude from short-term step-forcing simulations and more generally a method to compute their global thermal properties.},
author = {Geoffroy, Olivier and Saint-Martin, D. and Bellon, G. and Voldoire, A. and Olivi{\'{e}}, D. J.L. L and Tyt{\'{e}}ca, S.},
doi = {10.1175/JCLI-D-12-00196.1},
isbn = {0894-8755},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {6},
pages = {1859--1876},
publisher = {American Meteorological Society},
title = {{Transient Climate Response in a Two-Layer Energy-Balance Model. Part II: Representation of the Efficacy of Deep-Ocean Heat Uptake and Validation for CMIP5 AOGCMs}},
url = {https://doi.org/10.1175/JCLI-D-12-00196.1},
volume = {26},
year = {2013}
}
@article{Geoffroy2013a,
abstract = {This is the first part of a series of two articles analyzing the global thermal properties of atmosphere–ocean coupled general circulation models (AOGCMs) within the framework of a two-layer energy-balance model (EBM). In this part, the general analytical solution of the system is given and two idealized climate change scenarios, one with a step forcing and one with a linear forcing, are discussed. These solutions give a didactic description of the contributions from the equilibrium response and of the fast and slow transient responses during a climate transition. Based on these analytical solutions, a simple and physically based procedure to calibrate the two-layer model parameters using an AOGCM step-forcing experiment is introduced. Using this procedure, the global thermal properties of 16 AOGCMs participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) are determined. It is shown that, for a given AOGCM, the EBM tuned with only the abrupt 4×CO2 experiment is able to reproduce with a very good accuracy the temperature evolution in both a step-forcing and a linear-forcing experiment. The role of the upper-ocean and deep-ocean heat uptakes in the fast and slow responses is also discussed. One of the main weaknesses of the simple EBM discussed in this part is its ability to represent the evolution of the top-of-the-atmosphere radiative imbalance in the transient regime. This issue is addressed in Part II by taking into account the efficacy factor of deep-ocean heat uptake.},
archivePrefix = {arXiv},
arxivId = {arXiv:cond-mat/0402594v3},
author = {Geoffroy, Olivier and Saint-Martin, D. and Olivi{\'{e}}, D. J. L. and Voldoire, A. and Bellon, G. and Tyt{\'{e}}ca, S.},
doi = {10.1175/JCLI-D-12-00195.1},
eprint = {0402594v3},
isbn = {0894-8755},
issn = {0894-8755},
journal = {Journal of Climate},
month = {mar},
number = {6},
pages = {1841--1857},
primaryClass = {arXiv:cond-mat},
publisher = {American Meteorological Society},
title = {{Transient Climate Response in a Two-Layer Energy-Balance Model. Part I: Analytical Solution and Parameter Calibration Using CMIP5 AOGCM Experiments}},
url = {https://doi.org/10.1175/JCLI-D-12-00195.1 http://journals.ametsoc.org/doi/10.1175/JCLI-D-12-00195.1},
volume = {26},
year = {2013}
}
@article{Gettelman2012,
abstract = {The major evolution of the National Center for Atmospheric Research Community Atmosphere Model (CAM) is used to diagnose climate feedbacks, understand how climate feedbacks change with different physical parameterizations, and identify the processes and regions that determine climate sensitivity. In the evolution of CAM from version 4 to version 5, the water vapor, temperature, surface albedo, and lapse rate feedbacks are remarkably stable across changes to the physical parameterization suite. However, the climate sensitivity increases from 3.2 K in CAM4 to 4.0 K in CAM5. The difference is mostly due to (i) more positive cloud feedbacks and (ii) higher CO2 radiative forcing in CAMS. The intermodel differences in cloud feedbacks are largest in the tropical trade cumulus regime and in the midlatitude storm tracks. The subtropical stratocumulus regions do not contribute strongly to climate feedbacks owing to their small area coverage. A "modified Cess" configuration for atmosphere-only model experiments is shown to reproduce slab ocean model results. Several parameterizations contribute to changes in tropical cloud feedbacks between CAM4 and CAM5, but the new shallow convection scheme causes the largest midlatitude feedback differences and the largest change in climate sensitivity. Simulations with greater cloud forcing in the mean state have lower climate sensitivity. This work provides a methodology for further analysis of climate sensitivity across models and a framework for targeted comparisons with observations that can help constrain climate sensitivity to radiative forcing.},
author = {Gettelman, A. and Kay, J. E. and Shell, K. M.},
doi = {10.1175/JCLI-D-11-00197.1},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Climate models,Climate sensitivity,Cloud forcing,Cloud radiative effects,Feedback},
number = {5},
pages = {1453--1469},
title = {{The evolution of climate sensitivity and climate feedbacks in the Community Atmosphere Model}},
volume = {25},
year = {2012}
}
@article{Gettelman2019,
abstract = {Abstract The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long-term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5?4.5 K, is plausible.},
author = {Gettelman, A and Hannay, C and Bacmeister, J T and Neale, R B and Pendergrass, A G and Danabasoglu, G and Lamarque, J.-F. and Fasullo, J T and Bailey, D A and Lawrence, D M and Mills, M J},
doi = {10.1029/2019GL083978},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {climate models,climate sensitivity},
month = {jul},
number = {14},
pages = {8329--8337},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)}},
url = {https://doi.org/10.1029/2019GL083978},
volume = {46},
year = {2019}
}
@article{Gettelman2016a,
abstract = {Cloud feedback on global climate is determined by the combined action of multiple processes that have different relevance in different cloud regimes. This review lays out the framework for cloud feedback and highlights recent advances and outstanding issues. A consensus is emerging on large-scale controls on cloud feedback. Recent work has made significant progress in the understanding and observationally constraining the local response of shallow clouds. But significant uncertainties remain in microphysical mechanisms for cloud feedback. Important microphysical mechanisms include cloud phase changes, precipitation processes and even aerosol distributions. The treatment of these processes varies across climate models and may contribute to greater spread in feedbacks across models as models advance. Future work will need to try to bound the range of possible cloud microphysical feedback mechanisms and seek observational constraints on them.},
author = {Gettelman, A and Sherwood, S C},
doi = {10.1007/s40641-016-0052-8},
issn = {2198-6061},
journal = {Current Climate Change Reports},
number = {4},
pages = {179--189},
title = {{Processes Responsible for Cloud Feedback}},
url = {https://doi.org/10.1007/s40641-016-0052-8},
volume = {2},
year = {2016}
}
@article{Gettelman2015a,
author = {Gettelman, Andrew and Schmidt, Anja and Kristj{\'{a}}nsson, J{\'{o}}n Egill},
doi = {10.1038/ngeo2376},
issn = {17520908},
journal = {Nature Geoscience},
number = {4},
pages = {243},
publisher = {Nature Publishing Group},
title = {{Icelandic volcanic emissions and climate}},
volume = {8},
year = {2015}
}
@article{Ghan2016,
abstract = {A large number of processes are involved in the chain from emissions of aerosol precursor gases and primary particles to impacts on cloud radiative forcing. Those processes are manifest in a number of relationships that can be expressed as factors dlnX/dlnY driving aerosol effects on cloud radiative forcing. These factors include the relationships between cloud condensation nuclei (CCN) concentration and emissions, droplet number and CCN concentration, cloud fraction and droplet number, cloud optical depth and droplet number, and cloud radiative forcing and cloud optical depth. The relationship between cloud optical depth and droplet number can be further decomposed into the sum of two terms involving the relationship of droplet effective radius and cloud liquid water path with droplet number. These relationships can be constrained using observations of recent spatial and temporal variability of these quantities. However, we are most interested in the radiative forcing since the preindustrial era. Because few relevant measurements are available from that era, relationships from recent variability have been assumed to be applicable to the preindustrial to present-day change. Our analysis of Aerosol Comparisons between Observations and Models (AeroCom) model simulations suggests that estimates of relationships from recent variability are poor constraints on relationships from anthropogenic change for some terms, with even the sign of some relationships differing in many regions. Proxies connecting recent spatial/temporal variability to anthropogenic change, or sustained measurements in regions where emissions have changed, are needed to constrain estimates of anthropogenic aerosol impacts on cloud radiative forcing.},
author = {Ghan, Steven and Wang, Minghuai and Zhang, Shipeng and Ferrachat, Sylvaine and Gettelman, Andrew and Griesfeller, Jan and Kipling, Zak and Lohmann, Ulrike and Morrison, Hugh and Neubauer, David and Partridge, Daniel G and Stier, Philip and Takemura, Toshihiko and Wang, Hailong and Zhang, Kai},
doi = {10.1073/pnas.1514036113},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
keywords = {aerosol radiative forcing,cloud−aerosol interactions,constraints,factors},
month = {may},
number = {21},
pages = {5804--5811},
publisher = {National Academy of Sciences},
title = {{Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing using present-day spatiotemporal variability}},
url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1514036113},
volume = {113},
year = {2016}
}
@article{Ghimire2014,
abstract = {Widespread anthropogenic land-cover change over the last five centuries has influenced the global climate system through both biogeochemical and biophysical processes. Models indicate that warming from carbon emissions associated with land-cover conversion have been partially offset by cooling from elevated albedo, but considerable uncertainty remains partly because of uncertainty in model treatments of albedo. This study incorporates a new spatially and temporally explicit, land-cover specific albedo product derived from MODIS with a historical land-use dataset (Land Use Harmonization product) to provide more precise, observationally derived estimates of albedo impacts from anthropogenic land-cover change with a complete range of dataset specific uncertainty. The mean annual global albedo increase due to land-cover change during 1700–2005 was estimated as 0.00106 ± 0.00008 (mean ± standard deviation), mainly driven by snow exposure due to land-cover transitions from natural vegetation to agriculture. This translates to a top-of-atmosphere (TOA) radiative cooling of −0.15 ± 0.1 W m−2 (mean ± standard deviation). Our estimate was in the middle of the IPCC AR5 range of −0.05 to −0.25 W m−2, and incorporates variability in albedo within land-cover classes.},
author = {Ghimire, Bardan and Williams, Christopher A. and Masek, Jeffrey and Gao, Feng and Wang, Zhuosen and Schaaf, Crystal and He, Tao},
doi = {10.1002/2014GL061671},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {MODIS,albedo,global climate system,land cover change,radiative forcing},
month = {dec},
number = {24},
pages = {9087--9096},
title = {{Global albedo change and radiative cooling from anthropogenic land cover change, 1700 to 2005 based on MODIS, land use harmonization, radiative kernels, and reanalysis}},
url = {http://doi.wiley.com/10.1002/2014GL061671},
volume = {41},
year = {2014}
}
@article{acp-18-10521-2018,
author = {Gilgen, A and Huang, W T K and Ickes, L and Neubauer, D and Lohmann, U},
doi = {10.5194/acp-18-10521-2018},
journal = {Atmospheric Chemistry and Physics},
number = {14},
pages = {10521--10555},
title = {{How important are future marine and shipping aerosol emissions in a warming Arctic summer and autumn?}},
url = {https://www.atmos-chem-phys.net/18/10521/2018/},
volume = {18},
year = {2018}
}
@article{Gillett2012,
abstract = {Projections of 21st century warming may be derived by using regression-based methods to scale a model's projected warming up or down according to whether it under- or over-predicts the response to anthropogenic forcings over the historical period. Here we apply such a method using near surface air temperature observations over the 18512010 period, historical simulations of the response to changing greenhouse gases, aerosols and natural forcings, and simulations of future climate change under the Representative Concentration Pathways from the second generation Canadian Earth System Model (CanESM2). Consistent with previous studies, we detect the influence of greenhouse gases, aerosols and natural forcings in the observed temperature record. Our estimate of greenhouse-gas-attributable warming is lower than that derived using only 19001999 observations. Our analysis also leads to a relatively low and tightly-constrained estimate of Transient Climate Response of 1.31.8C, and relatively low projections of 21st-century warming under the Representative Concentration Pathways. Repeating our attribution analysis with a second model (CNRM-CM5) gives consistent results, albeit with somewhat larger uncertainties.},
author = {Gillett, N. P. and Arora, V. K. and Flato, G. M. and Scinocca, J. F. and {Von Salzen}, K.},
doi = {10.1029/2011GL050226},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {Representative Concentration Pathway,Transient Climate Response,detection and attribution,observationally-constrained projection},
number = {1},
pages = {1--5},
title = {{Improved constraints on 21st-century warming derived using 160 years of temperature observations}},
volume = {39},
year = {2012}
}
@article{Gillett2013,
abstract = {The ratio of warming to cumulative emissions of carbon dioxide has been shown to be approximately independent of time and emissions scenarios and directly relates emissions to temperature. It is therefore a potentially important tool for climate mitigation policy. The transient climate response to cumulative carbon emissions (TCRE), defined as the ratio of global-mean warming to cumulative emissions at CO2 doubling in a 1{\%}yr21CO2 increase experiment, ranges from 0.8 to 2.4KEgC21 in 15 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5)—a somewhat broader range than that found in a previous generation of carbon–climate models. Using newly available simulations and a new observational temperature dataset to 2010,TCREis estimated from observations by dividing an observationally constrained estimate of CO2-attributable warming by an estimate of cumulative carbon emissions to date, yielding an observationally constrained 5{\%}–95{\%} range of 0.7–2.0K EgC21.},
author = {Gillett, Nathan P. and Arora, Vivek K. and Matthews, Damon and Allen, Myles R.},
doi = {10.1175/JCLI-D-12-00476.1},
isbn = {10.1175/JCLI-D-12-00476.1},
issn = {08948755},
journal = {Journal of Climate},
number = {18},
pages = {6844--6858},
title = {{Constraining the ratio of global warming to cumulative CO2 emissions using CMIP5 simulations}},
volume = {26},
year = {2013}
}
@article{Gillett2010,
abstract = {Greenhouse gases other than CO 2 make a significant contribution to human-induced climate change, and multi-gas mitigation strategies are cheaper to implement than those which limit CO 2 emissions alone. Most practical multi-gas mitigation strategies require metrics to relate the climate warming effects of CO 2 and other greenhouse gases. Global warming potential (GWP), defined as the ratio of time-integrated radiative forcing of a particular gas to that of CO 2 following a unit mass emission, is the metric used in the Kyoto Protocol, and we define mean global temperature change potential (MGTP) as an equivalent metric of the temperature response. Here we show that carbon--climate feedbacks inflate the GWPs and MGTPs of methane and nitrous oxide by {\~{}} 20{\%} in coupled carbon--climate model simulations of the response to a pulse of 50 × 1990 emissions, due to a warming-induced release of CO 2 from the land biosphere and ocean. The magnitude of this effect is expected to be dependent on the model, but it is not captured at all by the analytical models usually used to calculate metrics such as GWP. We argue that the omission of carbon cycle dynamics has led to a low bias of uncertain but potentially substantial magnitude in metrics of the global warming effect of other greenhouse gases, and we suggest that the carbon--climate feedback should be considered when greenhouse gas metrics are calculated and applied.},
author = {Gillett, Nathan P. and Matthews, H. Damon},
doi = {10.1088/1748-9326/5/3/034011},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {Carbon feedback,Global temperature change potential,Global warming potential,Metrics},
number = {3},
pages = {034011},
title = {{Accounting for carbon cycle feedbacks in a comparison of the global warming effects of greenhouse gases}},
volume = {5},
year = {2010}
}
@article{doi:10.1002/jame.20038,
abstract = {The new Max-Planck-Institute Earth System Model (MPI-ESM) is used in the Coupled Model Intercomparison Project phase 5 (CMIP5) in a series of climate change experiments for either idealized CO2-only forcing or forcings based on observations and the Representative Concentration Pathway (RCP) scenarios. The paper gives an overview of the model configurations, experiments related forcings, and initialization procedures and presents results for the simulated changes in climate and carbon cycle. It is found that the climate feedback depends on the global warming and possibly the forcing history. The global warming from climatological 1850 conditions to 2080–2100 ranges from 1.5°C under the RCP2.6 scenario to 4.4°C under the RCP8.5 scenario. Over this range, the patterns of temperature and precipitation change are nearly independent of the global warming. The model shows a tendency to reduce the ocean heat uptake efficiency toward a warmer climate, and hence acceleration in warming in the later years. The precipitation sensitivity can be as high as 2.5{\%} K−1 if the CO2 concentration is constant, or as small as 1.6{\%} K−1, if the CO2 concentration is increasing. The oceanic uptake of anthropogenic carbon increases over time in all scenarios, being smallest in the experiment forced by RCP2.6 and largest in that for RCP8.5. The land also serves as a net carbon sink in all scenarios, predominantly in boreal regions. The strong tropical carbon sources found in the RCP2.6 and RCP8.5 experiments are almost absent in the RCP4.5 experiment, which can be explained by reforestation in the RCP4.5 scenario.},
author = {Giorgetta, Marco A and Jungclaus, Johann and Reick, Christian H and Legutke, Stephanie and Bader, J{\"{u}}rgen and B{\"{o}}ttinger, Michael and Brovkin, Victor and Crueger, Traute and Esch, Monika and Fieg, Kerstin and Glushak, Ksenia and Gayler, Veronika and Haak, Helmuth and Hollweg, Heinz-Dieter and Ilyina, Tatiana and Kinne, Stefan and Kornblueh, Luis and Matei, Daniela and Mauritsen, Thorsten and Mikolajewicz, Uwe and Mueller, Wolfgang and Notz, Dirk and Pithan, Felix and Raddatz, Thomas and Rast, Sebastian and Redler, Rene and Roeckner, Erich and Schmidt, Hauke and Schnur, Reiner and Segschneider, Joachim and Six, Katharina D and Stockhause, Martina and Timmreck, Claudia and Wegner, J{\"{o}}rg and Widmann, Heinrich and Wieners, Karl-H. and Claussen, Martin and Marotzke, Jochem and Stevens, Bjorn},
doi = {10.1002/jame.20038},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {CMIP5,MPI-ESM,carbon cycle,climate,climate change},
number = {3},
pages = {572--597},
title = {{Climate and carbon cycle changes from 1850 to 2100 in MPI-ESM simulations for the Coupled Model Intercomparison Project phase 5}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/jame.20038},
volume = {5},
year = {2013}
}
@article{Goelzer2011,
abstract = {We use the Earth system model of intermediate complexity LOVECLIM to show the effect of coupling interactive ice sheets on the climate sensitivity of the model on a millennial time scale. We compare the response to a 2xCO(2) warming scenario between fully coupled model versions including interactive Greenland and Antarctic ice sheet models and model versions with fixed ice sheets. For this purpose an ensemble of different parameter sets have been defined for LOVECLIM, covering a wide range of the model's sensitivity to greenhouse warming, while still simulating the present-day climate and the climate evolution over the last millennium within observational uncertainties. Additional freshwater fluxes from the melting ice sheets have a mitigating effect on the model's temperature response, leading to generally lower climate sensitivities of the fully coupled model versions. The mitigation is effectuated by changes in heat exchange within the ocean and at the sea-air interface, driven by freshening of the surface ocean and amplified by sea-ice-related feedbacks. The strength of the effect depends on the response of the ice sheets to the warming and on the model's climate sensitivity itself. The effect is relatively strong in model versions with higher climate sensitivity due to the relatively large polar amplification of LOVECLIM. With the ensemble approach in this study we cover a wide range of possible model responses.},
author = {Goelzer, H. and Huybrechts, P. and Loutre, M. F. and Goosse, H. and Fichefet, T. and Mouchet, A.},
doi = {10.1007/s00382-010-0885-0},
isbn = {0930-7575; 1432-0894},
issn = {09307575},
journal = {Climate Dynamics},
number = {5},
pages = {1005--1018},
title = {{Impact of Greenland and Antarctic ice sheet interactions on climate sensitivity}},
volume = {37},
year = {2011}
}
@article{Golaz2013,
abstract = {Climate models incorporate a number of adjustable parameters in their cloud formulations. They arise from uncertainties in cloud processes. These parameters are tuned to achieve a desired radiation balance and to best reproduce the observed climate. A given radiation balance can be achieved by multiple combinations of parameters.We investigate the impact of cloud tuning in the CMIP5 GFDL CM3 coupled climate model by constructing two alternate configurations. They achieve the desired radiation balance using different, but plausible, combinations of parameters. The present-day climate is nearly indistinguishable among all configurations. However, the magnitude of the aerosol indirect effects differs by as much as 1.2 Wm− 2, resulting in significantly different temperature evolution over the 20th century.},
author = {Golaz, J. C. and Golaz, Jean Christophe and Levy, Hiram},
doi = {10.1002/grl.50232},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {20th century warming,climate modeling,clouds,indirect effects},
number = {10},
pages = {2246--2251},
title = {{Cloud tuning in a coupled climate model: Impact on 20th century warming}},
volume = {40},
year = {2013}
}
@article{Golaz2019,
abstract = {This work documents the first version of the U.S. Department of Energy (DOE) new Energy Exascale Earth System Model (E3SMv1). We focus on the standard resolution of the fully coupled physical model designed to address DOE mission-relevant water cycle questions. Its components include atmosphere and land (110-km grid spacing), ocean and sea ice (60 km in the midlatitudes and 30 km at the equator and poles), and river transport (55 km) models. This base configuration will also serve as a foundation for additional configurations exploring higher horizontal resolution as well as augmented capabilities in the form of biogeochemistry and cryosphere configurations. The performance of E3SMv1 is evaluated by means of a standard set of Coupled Model Intercomparison Project Phase 6 (CMIP6) Diagnosis, Evaluation, and Characterization of Klima simulations consisting of a long preindustrial control, historical simulations (ensembles of fully coupled and prescribed SSTs) as well as idealized CO2 forcing simulations. The model performs well overall with biases typical of other CMIP-class models, although the simulated Atlantic Meridional Overturning Circulation is weaker than many CMIP-class models. While the E3SMv1 historical ensemble captures the bulk of the observed warming between preindustrial (1850) and present day, the trajectory of the warming diverges from observations in the second half of the twentieth century with a period of delayed warming followed by an excessive warming trend. Using a two-layer energy balance model, we attribute this divergence to the model's strong aerosol-related effective radiative forcing (ERFari+aci = −1.65 W/m2) and high equilibrium climate sensitivity (ECS = 5.3 K).},
author = {Golaz, Jean Christophe and Caldwell, Peter M. and {Van Roekel}, Luke P. and Petersen, Mark R. and Tang, Qi and Wolfe, Jonathan D. and Abeshu, Guta and Anantharaj, Valentine and Asay-Davis, Xylar S. and Bader, David C. and Baldwin, Sterling A. and Bisht, Gautam and Bogenschutz, Peter A. and Branstetter, Marcia and Brunke, Michael A. and Brus, Steven R. and Burrows, Susannah M. and Cameron-Smith, Philip J. and Donahue, Aaron S. and Deakin, Michael and Easter, Richard C. and Evans, Katherine J. and Feng, Yan and Flanner, Mark and Foucar, James G. and Fyke, Jeremy G. and Griffin, Brian M. and Hannay, C{\'{e}}cile and Harrop, Bryce E. and Hoffman, Mattthew J. and Hunke, Elizabeth C. and Jacob, Robert L. and Jacobsen, Douglas W. and Jeffery, Nicole and Jones, Philip W. and Keen, Noel D. and Klein, Stephen A. and Larson, Vincent E. and Leung, L. Ruby and Li, Hong Yi and Lin, Wuyin and Lipscomb, William H. and Ma, Po Lun and Mahajan, Salil and Maltrud, Mathew E. and Mametjanov, Azamat and McClean, Julie L. and McCoy, Renata B. and Neale, Richard B. and Price, Stephen F. and Qian, Yun and Rasch, Philip J. and {Reeves Eyre}, J. E.Jack and Riley, William J. and Ringler, Todd D. and Roberts, Andrew F. and Roesler, Erika L. and Salinger, Andrew G. and Shaheen, Zeshawn and Shi, Xiaoying and Singh, Balwinder and Tang, Jinyun and Taylor, Mark A. and Thornton, Peter E. and Turner, Adrian K. and Veneziani, Milena and Wan, Hui and Wang, Hailong and Wang, Shanlin and Williams, Dean N. and Wolfram, Phillip J. and Worley, Patrick H. and Xie, Shaocheng and Yang, Yang and Yoon, Jin Ho and Zelinka, Mark D. and Zender, Charles S. and Zeng, Xubin and Zhang, Chengzhu and Zhang, Kai and Zhang, Yuying and Zheng, Xue and Zhou, Tian and Zhu, Qing},
doi = {10.1029/2018MS001603},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
number = {7},
pages = {2089--2129},
title = {{The DOE E3SM Coupled Model Version 1: Overview and Evaluation at Standard Resolution}},
volume = {11},
year = {2019}
}
@article{Goldner2014,
abstract = {Two main hypotheses compete to explain global cooling and the abrupt growth of the Antarctic ice sheet across the Eocene–Oligocene trans-ition about 34 million years ago: thermal isolation of Antarctica due to southern ocean gateway opening 1–4 , and declining atmospheric CO 2 (refs 5, 6). Increases in ocean thermal stratification and circulation in proxies across the Eocene–Oligocene transition have been interpreted as a unique signature of gateway opening 2,4 , but at present both mecha-nisms remain possible. Here, using a coupled ocean–atmosphere model, we show that the rise of Antarctic glaciation, rather than altered pa-laeogeography, is best able to explain the observed oceanographic changes. We find that growth of the Antarctic ice sheet caused en-hanced northward transport of Antarctic intermediate water and invigorated the formation of Antarctic bottom water, fundament-ally reorganizing ocean circulation. Conversely, gateway openings had much less impact on ocean thermal stratification and circula-tion. Our results support available evidence that CO 2 drawdown— not gateway opening—caused Antarctic ice sheet growth, and fur-ther show that these feedbacks in turn altered ocean circulation. The precise timing and rate of glaciation, and thus its impacts on ocean circulation, reflect the balance between potentially positive feed-backs (increases in sea ice extent and enhanced primary productiv-ity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The Antarctic ice sheet had a complex, dynamic role in ocean circulation and heat fluxes during its initiation, and these processes are likely to operate in the future. Two main conceptual models have been advanced to explain the pattern of cooling 7 , enhanced Antarctic circumpolar circulation 1 , bio-spheric transitions 8 and glaciation across the Eocene–Oligocene trans-ition (EOT) (,34.1–33.6 Myr ago). These are Southern Ocean gateway opening and CO 2 drawdown. The first model, supported by proxy inter-pretations and numerical ocean modelling, posits that opening of Sou-thern Ocean gateways caused a fundamental reorganization of ocean structure and circulation 1–4},
author = {Goldner, A. and Herold, N. and Huber, M.},
doi = {10.1038/nature13597},
isbn = {0028-0836},
issn = {14764687},
journal = {Nature},
number = {7511},
pages = {574--577},
pmid = {25079555},
title = {{Antarctic glaciation caused ocean circulation changes at the Eocene–Oligocene transition}},
volume = {511},
year = {2014}
}
@article{cp-10-523-2014,
author = {Goldner, A and Herold, N and Huber, M},
doi = {10.5194/cp-10-523-2014},
journal = {Climate of the Past},
number = {2},
pages = {523--536},
title = {{The challenge of simulating the warmth of the mid-Miocene climatic optimum in CESM1}},
url = {https://cp.copernicus.org/articles/10/523/2014/},
volume = {10},
year = {2014}
}
@article{Golledge2019a,
abstract = {Government policies currently commit us to surface warming of three to four degrees Celsius above pre-industrial levels by 2100, which will lead to enhanced ice-sheet melt. Ice-sheet discharge was not explicitly included in Coupled Model Intercomparison Project phase 5, so effects on climate from this melt are not currently captured in the simulations most commonly used to inform governmental policy. Here we show, using simulations of the Greenland and Antarctic ice sheets constrained by satellite-based measurements of recent changes in ice mass, that increasing meltwater from Greenland will lead to substantial slowing of the Atlantic overturning circulation, and that meltwater from Antarctica will trap warm water below the sea surface, creating a positive feedback that increases Antarctic ice loss. In our simulations, future ice-sheet melt enhances global temperature variability and contributes up to 25 centimetres to sea level by 2100. However, uncertainties in the way in which future changes in ice dynamics are modelled remain, underlining the need for continued observations and comprehensive multi-model assessments.},
author = {Golledge, Nicholas R and Keller, Elizabeth D and Gomez, Natalya and Naughten, Kaitlin A and Bernales, Jorge and Trusel, Luke D and Edwards, Tamsin L},
doi = {10.1038/s41586-019-0889-9},
issn = {1476-4687},
journal = {Nature},
number = {7742},
pages = {65--72},
title = {{Global environmental consequences of twenty-first-century ice-sheet melt}},
volume = {566},
year = {2019}
}
@article{Gong2017,
abstract = {During the past three decades, the most rapid warming at the surface has occurred during the Arctic winter. By analyzing daily ERA-Interim data, it is found that the majority of the winter warming trend north of 70°N can be explained by the trend in the downward infrared radiation (IR). This downward IR trend can be attributed to an enhanced poleward flux of moisture and sensible heat into the Arctic by poleward-propagating Rossby waves, which increases the total column water and temperature within this region. This enhanced moisture flux is mostly due to changes in the planetary-scale atmospheric circulation rather than an increase in moisture in lower latitudes. The results of this study lead to the question of whether Arctic amplification has mostly arisen through changes in the Rossby wave response to greenhouse gas forcing and its impact on moisture transport into the Arctic.},
author = {Gong, Tingting and Feldstein, Steven and Lee, Sukyoung},
doi = {10.1175/JCLI-D-16-0180.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Atmospheric,Dynamics,Large-scale motions,Teleconnections,Waves},
month = {jul},
number = {13},
pages = {4937--4949},
title = {{The Role of Downward Infrared Radiation in the Recent Arctic Winter Warming Trend}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-16-0180.1},
volume = {30},
year = {2017}
}
@article{Good2015,
abstract = {When considering adaptation measures and global climate mitigation goals, stakeholders need regional-scale climate projections, including the range of plausible warming rates. To assist these stakeholders, it is important to understand whether some locations may see disproportionately high or low warming from additional forcing above targets such as 2 K (ref.1). There is a need to narrow uncertainty2 in this nonlinear warming, which requires understanding how climate changes as forcings increase from medium to high levels. However, quantifying and understanding regional nonlinear processes is challenging. Here we show that regional-scale warming can be strongly superlinear to successive CO2 doublings, using five different climate models. Ensemble-mean warming is superlinear over most land locations. Further, the inter-model spread tends to be amplified at higher forcing levels, as nonlinearities grow - especially when considering changes per kelvin of global warming. Regional nonlinearities in surface warming arise from nonlinearities in global-mean radiative balance, the Atlantic meridional overturning circulation, surface snow/ice cover and evapotranspiration. For robust adaptation and mitigation advice, therefore, potentially avoidable climate change (the difference between business-as-usual and mitigation scenarios) and unavoidable climate change (change under strong mitigation scenarios) may need different analysis methods.},
author = {Good, Peter and Lowe, Jason A. and Andrews, Timothy and Wiltshire, Andrew and Chadwick, Robin and Ridley, Jeff K. and Menary, Matthew B. and Bouttes, Nathaelle and Dufresne, Jean Louis and Gregory, Jonathan M. and Schaller, Nathalie and Shiogama, Hideo},
doi = {10.1038/nclimate2498},
issn = {17586798},
journal = {Nature Climate Change},
number = {2},
pages = {138--142},
title = {{Nonlinear regional warming with increasing CO2 concentrations}},
volume = {5},
year = {2015}
}
@article{Good2016,
abstract = {nonlinMIP provides experiments that account for state-dependent regional and global climate responses. The experiments have two main applications: (1) to focus understanding of responses to CO2 forcing on states relevant to specific policy or scientific questions (e.g. change under low-forcing scenarios, the benefits of mitigation, or from past cold climates to the present day), or (2) to understand the state dependence (non-linearity) of climate change – i.e. why doubling the forcing may not double the response. State dependence (non-linearity) of responses can be large at regional scales, with important implications for understanding mechanisms and for general circulation model (GCM) emulation techniques (e.g. energy balance models and pattern-scaling methods). However, these processes are hard to explore using traditional experiments, which explains why they have had so little attention in previous studies. Some single model studies have established novel analysis principles and some physical mechanisms. There is now a need to explore robustness and uncertainty in such mechanisms across a range of models (point 2 above), and, more broadly, to focus work on understanding the response to CO2 on climate states relevant to specific policy/science questions (point 1). nonlinMIP addresses this using a simple, small set of CO2-forced experiments that are able to separate linear and non-linear mechanisms cleanly, with a good signal-to-noise ratio – while being demonstrably traceable to realistic transient scenarios. The design builds on the CMIP5 (Coupled Model Intercomparison Project Phase 5) and CMIP6 DECK (Diagnostic, Evaluation and Characterization of Klima) protocols, and is centred around a suite of instantaneous atmospheric CO2 change experiments, with a ramp-up–ramp-down experiment to test traceability to gradual forcing scenarios. In all cases the models are intended to be used with CO2 concentrations rather than CO2 emissions as the input. The understanding gained will help interpret the spread in policy-relevant scenario projections. Here we outline the basic physical principles behind nonlinMIP, and the method of establishing traceability from abruptCO2 to gradual forcing experiments, before detailing the experimental design, and finally some analysis principles. The test of traceability from abruptCO2 to transient experiments is recommended as a standard analysis within the CMIP5 and CMIP6 DECK protocols.},
author = {Good, Peter and Andrews, Timothy and Chadwick, Robin and Dufresne, Jean Louis and Gregory, Jonathan M. and Lowe, Jason A. and Schaller, Nathalie and Shiogama, Hideo},
doi = {10.5194/gmd-9-4019-2016},
issn = {19919603},
journal = {Geoscientific Model Development},
number = {11},
pages = {4019--4028},
title = {{NonlinMIP contribution to CMIP6: Model intercomparison project for non-linear mechanisms: Physical basis, experimental design and analysis principles (v1.0)}},
volume = {9},
year = {2016}
}
@article{Good2013a,
abstract = {A fast simple climate modelling approach is developed for predicting and helping to understand general circulation model (GCM) simulations. We show that the simple model reproduces the GCM results accurately, for global mean surface air temperature change and global-mean heat uptake projections from 9 GCMs in the fifth coupled model inter-comparison project (CMIP5). This implies that understanding gained from idealised CO2 step experiments is applicable to policy-relevant scenario projections. Our approach is conceptually simple. It works by using the climate response to a CO2 step change taken directly from a GCM experiment. With radiative forcing from non-CO2 constituents obtained by adapting the Forster and Taylor method, we use our method to estimate results for CMIP5 representative concentration pathway (RCP) experiments for cases not run by the GCMs. We estimate differences between pairs of RCPs rather than RCP anomalies relative to the pre-industrial state. This gives better results because it makes greater use of available GCM projections. The GCMs exhibit differences in radiative forcing, which we incorporate in the simple model. We analyse the thus-completed ensemble of RCP projections. The ensemble mean changes between 1986–2005 and 2080–2099 for global temperature (heat uptake) are, for RCP8.5: 3.8 K (2.3 × 1024 J); for RCP6.0: 2.3 K (1.6 × 1024 J); for RCP4.5: 2.0 K (1.6 × 1024 J); for RCP2.6: 1.1 K (1.3 × 1024 J). The relative spread (standard deviation/ensemble mean) for these scenarios is around 0.2 and 0.15 for temperature and heat uptake respectively. We quantify the relative effect of mitigation action, through reduced emissions, via the time-dependent ratios (change in RCPx)/(change in RCP8.5), using changes with respect to pre-industrial conditions. We find that the effects of mitigation on global-mean temperature change and heat uptake are very similar across these different GCMs.},
author = {Good, Peter and Gregory, Jonathan M and Lowe, Jason A and Andrews, Timothy},
doi = {10.1007/s00382-012-1410-4},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {3},
pages = {1041--1053},
title = {{Abrupt CO2 experiments as tools for predicting and understanding CMIP5 representative concentration pathway projections}},
url = {https://doi.org/10.1007/s00382-012-1410-4},
volume = {40},
year = {2013}
}
@article{Good2011a,
abstract = {We propose a new simple climate modelling (SCM) framework for making fast climate projections and for interpreting global climate model (GCM) projections. This SCM is derived from CO2 step GCM experiments (a core integration in the fifth Climate Model Intercomparison Project CMIP5), and is similar to linear impulse-response theory. Its results are therefore traceable to GCM physics and closely related to a commonly-used method of analysing GCMs. Its formulation needs no tuning and permits clear validation. After discussing theoretical properties, we show that this SCM can work well, using the HadCM3 GCM for global temperature, precipitation, heat uptake and outgoing radiation under a range of forcing scenarios. The validation reveals interesting deviations from impulse-response linearity in surface temperature, radiative response and precipitation. These non-linearities emerge not just in climate feedback (as previously reported), but also in the rapid adjustment to forcing change. Some commonality is found between mechanisms by which temperature and precipitation depart from impulse-response linearity. Our results suggest that in support of the 4xCO2 experiments within CMIP5, additional 2xCO2 integrations from other GCMs could be very valuable. We also show how our framework can help understand time-dependent scenario projections, and suggest that this approach could be used as part of a process where GCM understanding and SCM formulation develop together.},
author = {Good, Peter and Gregory, Jonathan M and Lowe, Jason A},
doi = {10.1029/2010GL045208},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate,feedback,mitigation,projections,scm,simple climate model},
month = {jan},
number = {1},
pages = {L01703},
publisher = {Wiley-Blackwell},
title = {{A step-response simple climate model to reconstruct and interpret AOGCM projections}},
url = {https://doi.org/10.1029/2010GL045208 http://doi.wiley.com/10.1029/2010GL045208},
volume = {38},
year = {2011}
}
@article{doi:10.1002/joc.4654,
abstract = {ABSTRACT The limited historical observational sampling of the ocean gives rise to uncertainty in time series of global ocean temperature anomalies calculated from those observations. Without knowledge of the true global state of the oceans, it is difficult to characterize the errors caused by these sampling issues. One way to quantify them is to use climate model data. Pseudo observational time series can be constructed from the model data using knowledge of where observations occurred. Comparison of these with time series constructed from the full model fields yields information about how observational sampling impacts time series of the temperature change in the modelled world. This can then be related back to the time series generated from the real observations. In this study, climate model data were used to investigate sampling errors in 0–700 m global average ocean temperature anomaly time series calculated using a straightforward gridding approach. The sampling had two impacts. First, sampling causes issues with constructing a climatology that is representative of the long-term average state of the ocean. Climatology errors were shown to have the potential to cause systematically changing errors in anomaly time series. Second, some regions of the ocean were poorly observed prior to improvements brought about by the Argo project. This was found to cause spurious variability, both year to year and over multi-year time scales. The latter had similar magnitude to the actual multi-year variability seen in the model data but was smaller than the model's long-term temperature change. The features of these errors depend on the ocean state and therefore varied between climate model runs. More sophisticated methods used to calculate ocean temperature time series are expected to be less impacted by sampling. Nevertheless, sampling errors will still occur and therefore this type of study is recommended even for those techniques.},
author = {Good, Simon A},
doi = {10.1002/joc.4654},
journal = {International Journal of Climatology},
keywords = {observations,ocean heat content,ocean temperature,sampling,time series,uncertainty},
number = {5},
pages = {2260--2268},
title = {{The impact of observational sampling on time series of global 0–700 m ocean average temperature: a case study}},
url = {https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.4654},
volume = {37},
year = {2017}
}
@article{Goodwin2018,
abstract = {The Earth's climate sensitivity to radiative forcing remains a key source of uncertainty in future warming projections. There is a growing realization in recent literature that research must go beyond an equilibrium and CO 2 -only viewpoint, toward considering how climate sensitivity will evolve over time in response to anthropogenic and natural radiative forcing from multiple sources. Here the transient behavior of climate sensitivity is explored using a modified energy balance model, in which multiple climate feedbacks evolve independently over time to multiple sources of radiative forcing, combined with constraints from observations and from the Climate Model Intercomparison Project phase 5 (CMIP5). First, a large initial ensemble of 10 7 simulations is generated, with a distribution of climate feedback strengths from subannual to 10 2 -year timescales constrained by the CMIP5 ensemble, including the Planck feedback, the combined water vapor lapse rate feedback, snow and sea ice albedo feedback, fast cloud feedbacks, and the cloud response to sea surface temperature adjustment feedback. These 10 7 simulations are then tested against observational metrics representing decadal trends in warming, heat and carbon uptake, leaving only 4.6 × 10 3 history-matched simulations consistent with both the CMIP5 ensemble and historical observations. The results reveal an annual timescale climate sensitivity of 2.1 °C (ranging from 1.6 to 2.8 °C at 95{\%} uncertainty), rising to 2.9 °C (from 1.9 to 4.6 °C) on century timescales. These findings provide a link between lower estimates of climate sensitivity, based on the current transient state of the climate system, and higher estimates based on long-term behavior of complex models and palaeoclimate evidence.},
author = {Goodwin, Philip},
doi = {10.1029/2018EF000889},
issn = {23284277},
journal = {Earth's Future},
keywords = {climate feedback,climate projections,climate sensitivity,equilibrium climate sensitivity,future warming},
month = {sep},
number = {9},
pages = {1336--1348},
publisher = {John Wiley and Sons Inc},
title = {{On the Time Evolution of Climate Sensitivity and Future Warming}},
volume = {6},
year = {2018}
}
@article{Goodwin2016,
abstract = {Projections of future climate made by model-ensembles have credibility because the historic simulations by these models are consistent with, or near-consistent with, historic observations. However, it is not known how small inconsistencies between the ranges of observed and simulated historic climate change affects the future projections made by a model ensemble. Here, the impact of historical simulation–observation inconsistencies on future warming projections is quantified in a 4-million member Monte Carlo ensemble from a new efficient Earth System Model (ESM). Of the 4-million ensemble members, a subset of 182,500 are consistent with historic ranges of warming, heat uptake and carbon uptake simulated by the Climate Model Intercomparison Project 5 (CMIP5) ensemble. This simulation–consistent subset projects similar future warming ranges to the CMIP5 ensemble for all four RCP scenarios, indicating the new ESM represents an efficient tool to explore parameter space for future warming projections based on historic performance. A second subset of 14,500 ensemble members are consistent with historic observations for warming, heat uptake and carbon uptake. This observation–consistent subset projects a narrower range for future warming, with the lower bounds of projected warming still similar to CMIP5, but the upper warming bounds reduced by 20–35 {\%}. These findings suggest that part of the upper range of twenty-first century CMIP5 warming projections may reflect historical simulation–observation inconsistencies. However, the agreement of lower bounds for projected warming implies that the likelihood of warming exceeding dangerous levels over the twenty-first century is unaffected by small discrepancies between CMIP5 models and observations.},
author = {Goodwin, Philip},
doi = {10.1007/s00382-015-2960-z},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Climate ensemble,Climate projections,Future warming uncertainty},
month = {oct},
number = {7-8},
pages = {2219--2233},
publisher = {Springer Verlag},
title = {{How historic simulation–observation discrepancy affects future warming projections in a very large model ensemble}},
volume = {47},
year = {2016}
}
@article{Goosse2018a,
abstract = {The concept of feedback is key in assessing whether a perturbation to a system is amplified or damped by mechanisms internal to the system. In polar regions, climate dynamics are controlled by both radiative and non-radiative interactions between the atmosphere, ocean, sea ice, ice sheets and land surfaces. Precisely quantifying polar feedbacks is required for a process-oriented evaluation of climate models, a clear understanding of the processes responsible for polar climate changes, and a reduction in uncertainty associated with model projections. This quantification can be performed using a simple and consistent approach that is valid for a wide range of feedbacks, offering the opportunity for more systematic feedback analyses and a better understanding of polar climate changes.},
author = {Goosse, Hugues and Kay, Jennifer E. and Armour, Kyle C. and Bodas-Salcedo, Alejandro and Chepfer, Helene and Docquier, David and Jonko, Alexandra and Kushner, Paul J. and Lecomte, Olivier and Massonnet, Fran{\c{c}}ois and Park, Hyo-Seok and Pithan, Felix and Svensson, Gunilla and Vancoppenolle, Martin},
doi = {10.1038/s41467-018-04173-0},
issn = {2041-1723},
journal = {Nature Communications},
month = {dec},
number = {1},
pages = {1919},
title = {{Quantifying climate feedbacks in polar regions}},
url = {http://www.nature.com/articles/s41467-018-04173-0},
volume = {9},
year = {2018}
}
@article{Gordon2013,
abstract = {The increase in atmospheric concentrations of water vapor with global warming is a large positive feedback in the climate system. Thus, even relatively small errors in its magnitude can lead to large uncertainties in predicting climate response to anthropogenic forcing. This study incorporates observed variability of water vapor over 2002-2009 from the Atmospheric Infrared Sounder (AIRS) instrument into a radiative transfer scheme to provide constraints on this feedback. We derive a short-term water vapor feedback of 2.2 ± 0.4 Wm −2K−1. Based on the relationship between feedbacks derived over short and long timescales in 20th century simulations of 14 climate models we estimate a range of likely values for the long-term 20th century water vapor feedback of 1.9 to 2.8 Wm −2K−1. We use the 20th century simulations to determine the record length necessary for the short-term feedback to approach the long-term value. In most of the climate models we analyze, the short-term feedback converges to within 15{\%} of its long-term value after 25 years, implying that a longer observational record is necessary to accurately estimate the water vapor feedback.},
author = {Gordon, N. D. and Jonko, A. K. and Forster, P. M. and Shell, K. M.},
doi = {10.1002/2013JD020184},
isbn = {2169-8996},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {climate feedback,water vapor},
number = {22},
pages = {12435--12443},
title = {{An observationally based constraint on the water-vapor feedback}},
volume = {118},
year = {2013}
}
@article{Gordon2017,
author = {Gordon, Hamish and Kirkby, Jasper and Baltensperger, Urs and Bianchi, Federico and Breitenlechner, Martin and Curtius, Joachim and Dias, Antonio and Dommen, Josef and Donahue, Neil M. and Dunne, Eimear M. and Duplissy, Jonathan and Ehrhart, Sebastian and Flagan, Richard C. and Frege, Carla and Fuchs, Claudia and Hansel, Armin and Hoyle, Christopher R. and Kulmala, Markku and K{\"{u}}rten, Andreas and Lehtipalo, Katrianne and Makhmutov, Vladimir and Molteni, Ugo and Rissanen, Matti P. and Stozkhov, Yuri and Tr{\"{o}}stl, Jasmin and Tsagkogeorgas, Georgios and Wagner, Robert and Williamson, Christina and Wimmer, Daniela and Winkler, Paul M. and Yan, Chao and Carslaw, Ken S.},
doi = {10.1002/2017JD026844},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {aug},
number = {16},
pages = {8739--8760},
title = {{Causes and importance of new particle formation in the present-day and preindustrial atmospheres}},
url = {http://doi.wiley.com/10.1002/2017JD026844},
volume = {122},
year = {2017}
}
@article{Gordon2016,
abstract = {The magnitude of aerosol radiative forcing caused by anthropogenic emissions depends on the baseline state of the atmosphere under pristine preindustrial conditions. Measurements show that particle formation in atmospheric conditions can occur solely from biogenic vapors. Here, we evaluate the potential effect of this source of particles on preindustrial cloud condensation nuclei (CCN) concentrations and aerosol-cloud radiative forcing over the industrial period. Model simulations show that the pure biogenic particle formation mechanism has a much larger relative effect on CCN concentrations in the preindustrial atmosphere than in the present atmosphere because of the lower aerosol concentrations. Consequently, preindustrial cloud albedo is increased more than under present day conditions, and therefore the cooling forcing of anthropogenic aerosols is reduced. The mechanism increases CCN concentrations by 20-100{\%} over a large fraction of the preindustrial lower atmosphere, and the magnitude of annual global mean radiative forcing caused by changes of cloud albedo since 1750 is reduced by 0.22 W m-2 (27{\%}) to -0.60 W m-2. Model uncertainties, relatively slow formation rates, and limited available ambient measurements make it difficult to establish the significance of a mechanism that has its dominant effect under preindustrial conditions. Our simulations predict more particle formation in the Amazon than is observed. However, the first observation of pure organic nucleation has now been reported for the free troposphere. Given the potentially significant effect on anthropogenic forcing, effort should be made to better understand such naturally driven aerosol processes.},
author = {Gordon, Hamish and Sengupta, Kamalika and Rap, Alexandru and Duplissy, Jonathan and Frege, Carla and Williamson, Christina and Heinritzi, Martin and Simon, Mario and Yan, Chao and Almeida, Jo{\~{a}}o and Tr{\"{o}}stl, Jasmin and Nieminen, Tuomo and Ortega, Ismael K. and Wagner, Robert and Dunne, Eimear M. and Adamov, Alexey and Amorim, Antonio and Bernhammer, Anne Kathrin and Bianchi, Federico and Breitenlechner, Martin and Brilke, Sophia and Chen, Xuemeng and Craven, Jill S. and Dias, Antonio and Ehrhart, Sebastian and Fischer, Lukas and Flagan, Richard C. and Franchin, Alessandro and Fuchs, Claudia and Guida, Roberto and Hakala, Jani and Hoyle, Christopher R. and Jokinen, Tuija and Junninen, Heikki and Kangasluoma, Juha and Kim, Jaeseok and Kirkby, Jasper and Krapf, Manuel and K{\"{u}}rten, Andreas and Laaksonen, Ari and Lehtipalo, Katrianne and Makhmutov, Vladimir and Mathot, Serge and Molteni, Ugo and Monks, Sarah A. and Onnela, Antti and Per{\"{a}}kyl{\"{a}}, Otso and Piel, Felix and Pet{\"{a}}j{\"{a}}, Tuukka and Praplan, Arnaud P. and Pringle, Kirsty J. and Richards, Nigel A.D. and Rissanen, Matti P. and Rondo, Linda and Sarnela, Nina and Schobesberger, Siegfried and Scott, Catherine E. and Seinfeld, John H. and Sharma, Sangeeta and Sipil{\"{a}}, Mikko and Steiner, Gerhard and Stozhkov, Yuri and Stratmann, Frank and Tom{\'{e}}, Antonio and Virtanen, Annele and Vogel, Alexander Lucas and Wagner, Andrea C. and Wagner, Paul E. and Weingartner, Ernest and Wimmer, Daniela and Winkler, Paul M. and Ye, Penglin and Zhang, Xuan and Hansel, Armin and Dommen, Josef and Donahue, Neil M. and Worsnop, Douglas R. and Baltensperger, Urs and Kulmala, Markku and Curtius, Joachim and Carslaw, Kenneth S.},
doi = {10.1073/pnas.1602360113},
issn = {10916490},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Aerosol,Biogenic,Climate,Forcing},
month = {oct},
number = {43},
pages = {12053--12058},
publisher = {National Academy of Sciences},
title = {{Reduced anthropogenic aerosol radiative forcing caused by biogenic new particle formation}},
volume = {113},
year = {2016}
}
@article{Gordon2014,
abstract = {AbstractThe relationship between low-level cloud optical depth and atmospheric and surface air temperature is examined in the control climate of 13 climate models to determine if cloud optical depth-temperature relationships found in observations are replicated in climate models and if climate model behavior found in control climate simulations provides information about the optical depth feedback in climate warming simulations forced by increasing carbon dioxide. A positive relationship between cloud optical depth and cloud temperature exists in all models for low clouds with relatively cold temperatures at middle and high latitudes, whereas a negative relationship exists for warmer low clouds in the tropics and subtropics. This relationship is qualitatively similar to that in an earlier analysis of satellite observations, although modeled regression slopes tend to be too positive and their intermodel spread is large. In the models, the cold cloud response comes from increases in cloud water content with increasing temperature, while the warm cloud response comes from decreases in physical thickness with increasing cloud temperature. The intermodel and interregional spread of low-cloud optical depth feedback in climate warming simulations is well predicted by the corresponding spread in the relationships between optical depth and temperature for the current climate, suggesting that this aspect of cloud feedback may be constrained by observations. Because models have a positive bias relative to observations in the optical depth-temperature relationship, shortwave cloud feedback for climate changes may be more positive than climate models currently simulate.},
author = {Gordon, Neil D and Klein, Stephen A},
doi = {10.1002/2013JD021052},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {Climate Model,Feedback,Low-cloud,Optical Depth},
month = {may},
number = {10},
pages = {6052--6065},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Low-cloud optical depth feedback in climate models}},
url = {https://doi.org/10.1002/2013JD021052},
volume = {119},
year = {2014}
}
@article{Goren2014,
abstract = {A method for separating the three components of the marine stratocumulus (MSC) aerosol cloud interactions radiative effects, i.e., the cloud cover, liquid water path (LWP) and cloud drop radius (Twomey), was developed and tested. It is based on the assumption that changes in MSC cloud regimes that occur at short distance in homogeneous meteorological conditions are related to respective changes in the concentration of cloud condensation nuclei (CCN). The method was applied to 50 cases of well defined transitions from closed to open cells. It was found that the negative cloud radiative effect (CRE) over the closed cells is on average higher by 109±18Wm−2 than that over the adjacent open cells. This large negative CRE is composed of the cloud cover (42±8{\%}), LWP (32±8{\%}) and Twomey (26±6{\%}) effects. This shows that the Twomey effect, which is caused by change in droplet concentration for a given LWP, contributes only a quarter of the difference in CRE, whereas the rest is contributed by added cloud water to the open cells both in the horizontal (cloud cover effect) and in the vertical (LWP effect) dimensions. The results suggest the possibility that anthropogenic aerosols that affect MSC-regime-changes might incur large negative radiative forcing on the global scale, mainly due to the cloud cover effect.},
author = {Goren, Tom and Rosenfeld, Daniel},
doi = {10.1016/J.ATMOSRES.2013.12.008},
issn = {0169-8095},
journal = {Atmospheric Research},
month = {mar},
pages = {378--393},
publisher = {Elsevier},
title = {{Decomposing aerosol cloud radiative effects into cloud cover, liquid water path and Twomey components in marine stratocumulus}},
volume = {138},
year = {2014}
}
@article{Grandey2018,
abstract = {Abstract. We quantify the effective radiative forcing (ERF) of anthropogenic aerosols modelled by the aerosol–climate model CAM5.3-MARC-ARG. CAM5.3-MARC-ARG is a new configuration of the Community Atmosphere Model version 5.3 (CAM5.3) in which the default aerosol module has been replaced by the two-Moment, Multi-Modal, Mixing-state-resolving Aerosol model for Research of Climate (MARC). CAM5.3-MARC-ARG uses the default ARG aerosol activation scheme, consistent with the default configuration of CAM5.3. We compute differences between simulations using year-1850 aerosol emissions and simulations using year-2000 aerosol emissions in order to assess the radiative effects of anthropogenic aerosols. We compare the aerosol column burdens, cloud properties, and radiative effects produced by CAM5.3-MARC-ARG with those produced by the default configuration of CAM5.3, which uses the modal aerosol module with three log-normal modes (MAM3). Compared with MAM3, we find that MARC produces stronger cooling via the direct radiative effect, stronger cooling via the surface albedo radiative effect, and stronger warming via the cloud longwave radiative effect. The global mean cloud shortwave radiative effect is similar between MARC and MAM3, although the regional distributions differ. Overall, MARC produces a global mean net ERF of {\&}minus;1.75±0.04Wm{\&}minus;2, which is stronger than the global mean net ERF of {\&}minus;1.57±0.04Wm{\&}minus;2 produced by MAM3. The regional distribution of ERF also differs between MARC and MAM3, largely due to differences in the regional distribution of the cloud shortwave radiative effect. We conclude that the specific representation of aerosols in global climate models, including aerosol mixing state, has important implications for climate modelling.},
author = {Grandey, Benjamin S. and Rothenberg, Daniel and Avramov, Alexander and Jin, Qinjian and Lee, Hsiang He and Liu, Xiaohong and Lu, Zheng and Albani, Samuel and Wang, Chien},
doi = {10.5194/acp-18-15783-2018},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
number = {21},
pages = {15783--15810},
title = {{Effective radiative forcing in the aerosol–climate model CAM5.3-MARC-ARG}},
volume = {18},
year = {2018}
}
@article{Grandey2013,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Strong positive relationships between cloud fraction ({\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater}) and aerosol optical depth ($\tau$) have been reported. Data retrieved from the MODerate resolution Imaging Spectroradiometer (MODIS) instrument show positive {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater}–$\tau$ relationships across most of the globe. A global mean {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater} increase of approximately 0.2 between low and high $\tau$ conditions is found for both ocean and land. However, these relationships are not necessarily due to cloud–aerosol interactions. Using state-of-the-art Monitoring Atmospheric Composition and Climate (MACC) reanalysis-forecast $\tau$ data, which should be less affected by retrieval artefacts, it is demonstrated that a large part of the observed {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater}–$\tau$ signal may be due to cloud contamination of satellite-retrieved $\tau$. For longer MACC forecast time steps of 24 h, which likely contain less cloud contamination, some negative {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater}–$\tau$ relationships are found. The global mean {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater} increase between low and high $\tau$ conditions is reduced to 0.1, suggesting that cloud contamination may account for approximately one half of the satellite-retrieved increase in {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater}. ECHAM5-HAM general circulation model (GCM) simulations further demonstrate that positive {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater}–$\tau$ relationships may arise due to covariation with relative humidity. Widespread negative simulated {\textless}i{\textgreater}f{\textless}/i{\textgreater}{\textless}sub{\textgreater}c{\textless}/sub{\textgreater}–$\tau$ relationships in the tropics are shown to arise due to scavenging of aerosol by convective precipitation. Wet scavenging events are likely poorly sampled in satellite-retrieved data, because the properties of aerosol below clouds cannot be retrieved. Quantifying the role of wet scavenging, and assessing GCM representations of this important process, remains a challenge for future observational studies of aerosol–cloud–precipitation interactions.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Grandey, B. S. and Stier, P. and Wagner, T. M.},
doi = {10.5194/acp-13-3177-2013},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {mar},
number = {6},
pages = {3177--3184},
title = {{Investigating relationships between aerosol optical depth and cloud fraction using satellite, aerosol reanalysis and general circulation model data}},
url = {https://www.atmos-chem-phys.net/13/3177/2013/},
volume = {13},
year = {2013}
}
@article{Graversen2016,
author = {Graversen, Rune G. and Burtu, Mattias},
doi = {10.1002/qj.2802},
isbn = {1477-870X},
issn = {1477870X},
journal = {Quarterly Journal of the Royal Meteorological Society},
keywords = {Arctic amplification,cyclones,energy transport,planetary waves},
number = {698},
pages = {2046--2054},
title = {{Arctic amplification enhanced by latent energy transport of atmospheric planetary waves}},
volume = {142},
year = {2016}
}
@article{Graversen2009,
abstract = {In recent years, a substantial reduction of the sea ice in the Arctic has been observed. At the same time, the near-surface air in this region is warming at a rate almost twice as large as the global average-this phenomenon is known as the Arctic amplification. The role of the ice-albedo feedback for the Arctic amplification is still a matter of debate. Here the effect of the surface-albedo feedback (SAF) was studied using a coupled climate model CCSM3 from the National Center for Atmospheric Research. Experiments, where the SAF was suppressed by locking the surface albedo in the entire coupled model system, were conducted. The results reveal polar temperature amplification when this model, with suppressed albedo, is forced by a doubling of the atmospheric CO2 content. Comparisons with variable albedo experiments show that SAF amplifies the surface-temperature response in the Arctic area by about 33{\%}, whereas the corresponding value for the global-mean surface temperature is about 15{\%}. Even though SAF is an important process underlying excessive warming at high latitudes, the Arctic amplification is only 15{\%} larger in the variable than in the locked-albedo experiments. It is found that an increase of water vapour and total cloud cover lead to a greenhouse effect, which is larger in the Arctic than at lower latitudes. This is expected to explain a part of the Arctic surface-air-temperature amplification.},
author = {Graversen, Rune Grand and Wang, Minghuai},
doi = {10.1007/s00382-009-0535-6},
isbn = {0930-7575},
issn = {09307575},
journal = {Climate Dynamics},
keywords = {Albedo feedback,Climate-model experiment,Greenhouse effect,Polar amplification},
title = {{Polar amplification in a coupled climate model with locked albedo}},
year = {2009}
}
@article{doi:10.1175/JCLI-D-13-00551.1,
abstract = { AbstractA vertically nonuniform warming of the troposphere yields a lapse rate feedback by altering the infrared irradiance to space relative to that of a vertically uniform tropospheric warming. The lapse rate feedback is negative at low latitudes, as a result of moist convective processes, and positive at high latitudes, due to stable stratification conditions that effectively trap warming near the surface. It is shown that this feedback pattern leads to polar amplification of the temperature response induced by a radiative forcing. The results are obtained by suppressing the lapse rate feedback in the Community Climate System Model, version 4 (CCSM4). The lapse rate feedback accounts for 15{\%} of the Arctic amplification and 20{\%} of the amplification in the Antarctic region. The fraction of the amplification that can be attributed to the surface albedo feedback, associated with melting of snow and ice, is 40{\%} in the Arctic and 65{\%} in Antarctica. It is further found that the surface albedo and lapse rate feedbacks interact considerably at high latitudes to the extent that they cannot be considered independent feedback mechanisms at the global scale. },
author = {Graversen, Rune G and Langen, Peter L and Mauritsen, Thorsten},
doi = {10.1175/JCLI-D-13-00551.1},
journal = {Journal of Climate},
number = {12},
pages = {4433--4450},
title = {{Polar Amplification in CCSM4: Contributions from the Lapse Rate and Surface Albedo Feedbacks}},
url = {https://doi.org/10.1175/JCLI-D-13-00551.1},
volume = {27},
year = {2014}
}
@article{Gray2009,
abstract = {The 11-yr solar cycle temperature response to spectrally resolved solar irradiance changes and associated ozone changes is calculated using a fixed dynamical heating (FDH) model. Imposed ozone changes are from satellite observations, in contrast to some earlier studies. A maximum of 1.6 K is found in the equatorial upper stratosphere and a secondary maximum of 0.4 K in the equatorial lower stratosphere, forming a double peak in the vertical. The upper maximum is primarily due to the irradiance changes while the lower maximum is due to the imposed ozone changes. The results compare well with analyses using the 40-yr ECMWF Re-Analysis (ERA-40) and NCEP/NCAR datasets. The equatorial lower stratospheric structure is reproduced even though, by definition, the FDH calculations exclude dynamically driven temperature changes, suggesting an important role for an indirect dynamical effect through ozone redistribution. The results also suggest that differences between the Stratospheric Sounding Unit (SSU)/Microwave Sounding Unit (MSU) and ERA-40 estimates of the solar cycle signal can be explained by the poor vertical resolution of the SSU/MSU measurements. The adjusted radiative forcing of climate change is also investigated. The forcing due to irradiance changes was 0.14 W m−2, which is only 78{\%} of the value obtained by employing the standard method of simple scaling of the total solar irradiance (TSI) change. The difference arises because much of the change in TSI is at wavelengths where ozone absorbs strongly. The forcing due to the ozone change was only 0.004 W m−2 owing to strong compensation between negative shortwave and positive longwave forcings.},
author = {Gray, L. J. and Rumbold, S. T. and Shine, K. P.},
doi = {10.1175/2009jas2866.1},
issn = {0022-4928},
journal = {Journal of the Atmospheric Sciences},
number = {8},
pages = {2402--2417},
title = {{Stratospheric Temperature and Radiative Forcing Response to 11-Year Solar Cycle Changes in Irradiance and Ozone}},
volume = {66},
year = {2009}
}
@article{Gregory2002,
abstract = {A probability distribution for values of the effective climate sensitivity, with a lower bound of 1.6 K (5th percentile), is obtained on the basis of the increase in ocean heat content in recent decades from analyses of observed interior-ocean temperature changes, surface temperature changes measured since 1860, and estimates of anthropogenic and natural radiative forcing of the climate system. Radiative forcing is the greatest source of uncertainty in the calculation; the result also depends somewhat on the rate of ocean heat uptake in the late nineteenth century, for which an assumption is needed as there is no observational estimate. Because the method does not use the climate sensitivity simulated by a general circulation model, it provides an independent observationally based constraint on this important parameter of the climate system.},
author = {Gregory, J. M. and Stouffer, R. J. and Raper, S. C.B. and Stott, P. A. and Rayner, N. A.},
doi = {10.1175/1520-0442(2002)015<3117:AOBEOT>2.0.CO;2},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
number = {22},
pages = {3117--3121},
title = {{An observationally based estimate of the climate sensitivity}},
volume = {15},
year = {2002}
}
@article{Gregory2016,
abstract = {In both the observational record and atmosphere-ocean general circulation model (AOGCM) simulations of the last {\$}\backslash{\$}{\{}$\backslash$backslash{\}}sim{\$}{\$} ∼ 150 years, short-lived negative radiative forcing due to volcanic aerosol, following explosive eruptions, causes sudden global-mean cooling of up to {\$}\backslash{\$}{\{}$\backslash$backslash{\}}sim{\$}{\$} ∼ 0.3 K. This is about five times smaller than expected from the transient climate response parameter (TCRP, K of global-mean surface air temperature change per W m−2 of radiative forcing increase) evaluated under atmospheric CO2 concentration increasing at 1 {\%} yr−1. Using the step model (Good et al. in Geophys Res Lett 38:L01703, 2011. doi: 10.1029/2010GL045208 ), we confirm the previous finding (Held et al. in J Clim 23:2418--2427, 2010. doi: 10.1175/2009JCLI3466.1 ) that the main reason for the discrepancy is the damping of the response to short-lived forcing by the thermal inertia of the upper ocean. Although the step model includes this effect, it still overestimates the volcanic cooling simulated by AOGCMs by about 60 {\%}. We show that this remaining discrepancy can be explained by the magnitude of the volcanic forcing, which may be smaller in AOGCMs (by 30 {\%} for the HadCM3 AOGCM) than in off-line calculations that do not account for rapid cloud adjustment, and the climate sensitivity parameter, which may be smaller than for increasing CO2 (40 {\%} smaller than for 4 {\{}$\backslash$texttimes{\}} CO2 in HadCM3).},
author = {Gregory, J. M. and Andrews, T. and Good, P. and Mauritsen, T. and Forster, P. M.},
doi = {10.1007/s00382-016-3055-1},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Aerosol,Climate sensitivity,Ocean heat uptake,Radiative forcing,Transient climate response,Volcano},
number = {12},
pages = {3979--3991},
publisher = {Springer Berlin Heidelberg},
title = {{Small global-mean cooling due to volcanic radiative forcing}},
volume = {47},
year = {2016}
}
@article{Gregory2000,
abstract = {In response to increasing atmospheric con- centrations of greenhouse gases, the rate of time- dependent climate change is determined jointly by the strength of climate feedbacks and the eciency of pro- cesses which remove heat from the surface into the deep ocean. This work examines the vertical heat transport processes in the ocean of the HADCM2 atmosphere± ocean general circulation model (AOGCM) in experi- ments with CO2 held constant (control) and increasing at 1{\%} per year (anomaly). The control experiment shows that global average heat exchanges between the upper and lower ocean are dominated by the Southern Ocean, where heat is pumped downwards by the wind- driven circulation and di€uses upwards along sloping isopycnals. This is the reverse of the low-latitude balance used in upwelling±di€usion ocean models, the global average upward di€usive transport being against the temperature gradient. In the anomaly experiment, weakened convection at high latitudes leads to reduced diffusive and convective heat loss from the deep ocean, and hence to net heat uptake, since the advective heat input is less a€ected. Reduction of deep water produc- tion at high latitudes results in reduced upwelling of cold water at low latitudes, giving a further contribution to net heat uptake. On the global average, high-latitude processes thus have a controlling in¯uence. The impor- tant role of di€usion highlights the need to ensure that the schemes employed in AOGCMs give an accurate representation of the relevant sub-grid-scale processes.},
author = {Gregory, J. M.},
doi = {10.1007/s003820000059},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {jul},
number = {7},
pages = {501--515},
title = {{Vertical heat transports in the ocean and their effect on time-dependent climate change}},
url = {http://link.springer.com/10.1007/s003820000059},
volume = {16},
year = {2000}
}
@article{Gregory2009,
abstract = {Abstract Perturbations to the carbon cycle could constitute large feedbacks on future changes in atmospheric CO2 concentration and climate. This paper demonstrates how carbon cycle feedback can be expressed in formally similar ways to climate feedback, and thus compares their magnitudes. The carbon cycle gives rise to two climate feedback terms: the concentration–carbon feedback, resulting from the uptake of carbon by land and ocean as a biogeochemical response to the atmospheric CO2 concentration, and the climate–carbon feedback, resulting from the effect of climate change on carbon fluxes. In the earth system models of the Coupled Climate–Carbon Cycle Model Intercomparison Project (C4MIP), climate–carbon feedback on warming is positive and of a similar size to the cloud feedback. The concentration–carbon feedback is negative; it has generally received less attention in the literature, but in magnitude it is 4 times larger than the climate–carbon feedback and more uncertain. The concentration–carbon feed...},
archivePrefix = {arXiv},
arxivId = {arXiv:1011.1669v3},
author = {Gregory, J. M. and Jones, C. D. and Cadule, P. and Friedlingstein, P.},
doi = {10.1175/2009JCLI2949.1},
eprint = {arXiv:1011.1669v3},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
number = {19},
pages = {5232--5250},
pmid = {11089968},
title = {{Quantifying carbon cycle feedbacks}},
volume = {22},
year = {2009}
}
@article{Gregory2016a,
abstract = {We investigate the climate feedback parameter $\alpha$ (Wm−2 K−1) during the historical period (since 1871) in experiments using the HadGEM2 and HadCM3 atmosphere general circulation models (AGCMs) with constant pre-industrial atmospheric composition and time-dependent observational sea-surface temperature (SST) and sea-ice boundary conditions. In both AGCMs, for the historical period as a whole, the effective climate sensitivity is ∼2 K ($\alpha$≃1.7 Wm−2 K−1), and $\alpha$ shows substantial decadal variation caused by the patterns of SST change. Both models agree with the AGCMs of the latest Coupled Model Intercomparison Project in showing a considerably smaller effective climate sensitivity of ∼1.5 K ($\alpha$ = 2.3 ± 0.7 Wm−2 K−1), given the time-dependent changes in sea-surface conditions observed during 1979–2008, than the corresponding coupled atmosphere–ocean general circulation models (AOGCMs) give under constant quadrupled CO2 concentration. These findings help to relieve the apparent contradiction between the larger values of effective climate sensitivity diagnosed from AOGCMs and the smaller values inferred from historical climate change.},
author = {Gregory, J. M. and Andrews, T.},
doi = {10.1002/2016GL068406},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {AGCM,AMIP,climate feedback,climate sensitivity,climate variability,radiative forcing},
month = {apr},
number = {8},
pages = {3911--3920},
title = {{Variation in climate sensitivity and feedback parameters during the historical period}},
url = {http://doi.wiley.com/10.1002/2016GL068406},
volume = {43},
year = {2016}
}
@article{Gregory2004,
abstract = {We describe a new method for evaluating the radiative forcing, the climate feedback parameter (W m−2 K−1) and hence the effective climate sensitivity from any GCM experiment in which the climate is responding to a constant forcing. The method is simply to regress the top of atmosphere radiative flux against the global average surface air temperature change. This method does not require special integrations or off-line estimates, such as for stratospheric adjustment, to obtain the forcing, and eliminates the need for double radiation calculations and tropopause radiative fluxes. We show that for CO2 and solar forcing in a slab model and an AOGCM the method gives results consistent with those obtained by conventional methods. For a single integration it is less precise but since it does not require a steady state to be reached its precision could be improved by running an ensemble of short integrations.},
author = {Gregory, J. M. and Ingram, W. J. and Palmer, M. A. and Jones, G. S. and Stott, P. A. and Thorpe, R. B. and Lowe, J. A. and Johns, T. C. and Williams, K. D.},
doi = {10.1029/2003GL018747},
isbn = {1944-8007},
issn = {00948276},
journal = {Geophysical Research Letters},
number = {3},
pages = {L03205},
title = {{A new method for diagnosing radiative forcing and climate sensitivity}},
volume = {31},
year = {2004}
}
@article{Gregory2015,
abstract = {Sixty years after industry executives first decided to fight the facts of tobacco, the exploitation of doubt and uncertainty as a defensive tactic has spread to a diverse set of industries and issues with an interest in challenging scientific evidence. However, one can find examples of doubt-mongering before tobacco. One involves the early history of electricity generation in the USA. In the 1920s, the American National Electric Light Association ran a major propaganda campaign against public sector electricity generation, focused on the insistence that privately generated electricity was cheaper and that public power generation was socialistic and therefore unAmerican. This campaign included advertisements, editorials (generally ghost-written), the rewriting of textbooks and the development of high school and college curricula designed to cast doubt on the costeffectiveness of public electricity generation and extol the virtues of laissez-faire capitalism. It worked in large part by finding, cultivating and paying experts to endorse the industry's claims in the mass media and the public debate, and to legitimatize the alterations to textbooks and curricula. The similarities between the electric industry strategy and the defence of tobacco, lead paint and fossil fuels suggests that these strategies work for reasons that are not specific to the particular technical claims under consideration. This paper argues that a reason for the cultural persistence of doubt is what we may label the ‘fact of uncertainty'. Uncertainty is intrinsic to science, and this creates vulnerabilities that interested parties may, and commonly do, exploit, both by attempting to challenge the specific conclusions of technical experts and by implying that those conclusions threaten other social values.},
author = {Gregory, J. M. and Andrews, T. and Good, P.},
doi = {10.1098/rsta.2014.0417},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
keywords = {Climate change,Climate modelling,Climate sensitivity,Ocean heat uptake,Radiative forcing},
month = {nov},
number = {2054},
pages = {20140417},
title = {{The inconstancy of the transient climate response parameter under increasing CO2}},
url = {http://rsta.royalsocietypublishing.org/content/373/2054/20140417.abstract},
volume = {373},
year = {2015}
}
@article{Gregory2020,
abstract = {The equilibrium climate sensitivity (ECS, in K) to CO 2 doubling is a large source of uncertainty in projections of future anthropogenic climate change. Estimates of ECS made from non-equilibrium states or in response to radiative forcings other than 2 × CO 2 are called “effective climate sensitivity” (EffCS, in K). Taking a “perfect-model” approach, using coupled atmosphere–ocean general circulation model (AOGCM) experiments, we evaluate the accuracy with which CO 2 EffCS can be estimated from climate change in the “historical” period (since about 1860). We find that (1) for statistical reasons, unforced variability makes the estimate of historical EffCS both uncertain and biased; it is overestimated by about 10{\%} if the energy balance is applied to the entire historical period, 20{\%} for 30-year periods, and larger factors for interannual variability, (2) systematic uncertainty in historical radiative forcing translates into an uncertainty of ±30to45{\%} (standard deviation) in historical EffCS, (3) the response to the changing relative importance of the forcing agents, principally CO 2 and volcanic aerosol, causes historical EffCS to vary over multidecadal timescales by a factor of two. In recent decades it reached its maximum in the AOGCM historical experiment (similar to the multimodel-mean CO 2 EffCS of 3.6 K from idealised experiments), but its minimum in the real world (1.6 K for an observational estimate for 1985–2011, similar to the multimodel-mean value for volcanic forcing). The real-world variations mean that historical EffCS underestimates CO 2 EffCS by 30{\%} when considering the entire historical period. The difference for recent decades implies that either unforced variability or the response to volcanic forcing causes a much stronger regional pattern of sea surface temperature change in the real world than in AOGCMs. We speculate that this could be explained by a deficiency in simulated coupled atmosphere–ocean feedbacks which reinforce the pattern (resembling the Interdecadal Pacific Oscillation in some respects) that causes the low EffCS. We conclude that energy-balance estimates of CO 2 EffCS are most accurate from periods unaffected by volcanic forcing. Atmosphere GCMs provided with observed sea surface temperature for the 1920s to the 1950s, which was such a period, give a range of about 2.0–4.5 K, agreeing with idealised CO 2 AOGCM experiments; the consistency is a reason for confidence in this range as an estimate of CO 2 EffCS. Unless a{\ldots}},
author = {Gregory, J. M. and Andrews, T. and Ceppi, P. and Mauritsen, T. and Webb, M. J.},
doi = {https://doi.org/10.1007/s00382-019-04991-y},
issn = {14320894},
journal = {Climate Dynamics},
pages = {129--157},
publisher = {Springer Verlag},
title = {{How accurately can the climate sensitivity to CO2 be estimated from historical climate change?}},
volume = {54},
year = {2020}
}
@article{Grise2013,
abstract = {This study quantifies the response of the clouds and the radiative budget of the Southern Hemisphere (SH) to the poleward shift in the tropospheric circulation induced by the development of the Antarctic ozone hole. Single forcing climate model integrations, in which only stratospheric ozone depletion is specified, indicate that (1) high-level and midlevel clouds closely follow the poleward shift in the SH midlatitude jet and that (2) low-level clouds decrease across most of the Southern Ocean. Similar cloud anomalies are found in satellite observations during periods when the jet is anomalously poleward. The hemispheric annual mean radiation response to the cloud anomalies is calculated to be approximately +0.25 W m(-2), arising largely from the reduction of the total cloud fraction at SH midlatitudes during austral summer. While these dynamically induced cloud and radiation anomalies are considerable and are supported by observational evidence, quantitative uncertainties remain from model biases in mean-state cloud-radiative processes.},
author = {Grise, Kevin M. and Polvani, Lorenzo M. and Tselioudis, George and Wu, Yutian and Zelinka, Mark D.},
doi = {10.1002/grl.50675},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {cloud-radiative processes,ozone hole},
month = {jul},
number = {14},
pages = {3688--3692},
title = {{The ozone hole indirect effect: Cloud-radiative anomalies accompanying the poleward shift of the eddy-driven jet in the Southern Hemisphere}},
url = {http://doi.wiley.com/10.1002/grl.50675},
volume = {40},
year = {2013}
}
@article{Grise2014,
abstract = {This study explores the impact of Antarctic stratospheric ozone depletion on extratropical cyclones. Output from the Community Atmosphere Model is combined with a Lagrangian cyclone-tracking algorithm to identify the response of Southern Hemisphere extratropical cyclones to ozone and greenhouse gas forcings over the period 1960–2000. Stratospheric ozone depletion induces a significant poleward shift in cyclone frequency over the Southern Ocean, but has minimal influence on cyclone intensity and lifetime. The response of the cyclones to late 20th century greenhouse gas increases has similar characteristics, but falls within the range of natural variability in the model.},
author = {Grise, Kevin M. and Son, Seok-Woo and Correa, Gustavo J P and Polvani, Lorenzo M.},
doi = {10.1002/asl2.458},
issn = {1530261X},
journal = {Atmospheric Science Letters},
keywords = {Extratropical cyclones,Southern Hemisphere,Stratospheric ozone},
month = {jan},
number = {1},
pages = {29--36},
title = {{The response of extratropical cyclones in the Southern Hemisphere to stratospheric ozone depletion in the 20th century}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/asl2.458},
volume = {15},
year = {2014}
}
@article{Grise2016,
abstract = {AbstractThis study examines the dynamical mechanisms responsible for changes in midlatitude clouds and cloud radiative effects (CRE) that occur in conjunction with meridional shifts in the jet streams over the North Atlantic, North Pacific, and Southern Oceans. When the midlatitude jet shifts poleward, extratropical cyclones and their associated upward vertical velocity anomalies closely follow. As a result, a poleward jet shift contributes to a poleward shift in high-topped storm-track clouds and their associated longwave CRE. However, when the jet shifts poleward, downward vertical velocity anomalies increase equatorward of the jet, contributing to an enhancement of the boundary layer estimated inversion strength (EIS) and an increase in low cloud amount there. Because shortwave CRE depends on the reflection of solar radiation by clouds in all layers, the shortwave cooling effects of midlatitude clouds increase with both upward vertical velocity anomalies and positive EIS anomalies. Over midlatitude oceans where a poleward jet shift contributes to positive EIS anomalies but downward vertical velocity anomalies, the two effects cancel, and net observed changes in shortwave CRE are small.Global climate models generally capture the observed anomalies associated with midlatitude jet shifts. However, there is large intermodel spread in the shortwave CRE anomalies, with a subset of models showing a large shortwave cloud radiative warming over midlatitude oceans with a poleward jet shift. In these models, midlatitude shortwave CRE is sensitive to vertical velocity perturbations, but the observed sensitivity to EIS perturbations is underestimated. Consequently, these models might incorrectly estimate future midlatitude cloud feedbacks in regions where appreciable changes in both vertical velocity and EIS are projected.},
author = {Grise, Kevin M and Medeiros, Brian},
doi = {10.1175/JCLI-D-16-0295.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {24},
pages = {9005--9025},
publisher = {American Meteorological Society},
title = {{Understanding the Varied Influence of Midlatitude Jet Position on Clouds and Cloud Radiative Effects in Observations and Global Climate Models}},
url = {https://doi.org/10.1175/JCLI-D-16-0295.1},
volume = {29},
year = {2016}
}
@article{Grose2018,
abstract = {Transient climate response (TCR), transient response at 140 years (T140), and equilibrium climate sensitivity (ECS) indices are intended as benchmarks for comparing the magnitude of climate response projected by climate models. It is generally assumed that TCR or T140 would explain more variability between models than ECS for temperature change over the 21st century, since this timescale is the realm of transient climate change. Here we find that TCR explains more variability across Coupled Model Intercomparison Project phase 5 than ECS for global temperature change since preindustrial, for 50 or 100 year global trends up to the present, and for projected change under representative concentration pathways in regions of delayed warming such as the Southern Ocean. However, unexpectedly, we find that ECS correlates higher than TCR for projected change from the present in the global mean and in most regions. This higher correlation does not relate to aerosol forcing, and the physical cause requires further investigation.},
author = {Grose, Michael R. and Gregory, Jonathan and Colman, Robert and Andrews, Timothy},
doi = {10.1002/2017GL075742},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {CMIP5,climate sensitivity,projections},
number = {3},
pages = {1559--1566},
title = {{What Climate Sensitivity Index Is Most Useful for Projections?}},
volume = {45},
year = {2018}
}
@article{Grosvenor2018,
author = {Grosvenor, Daniel P. and Sourdeval, Odran and Zuidema, Paquita and Ackerman, Andrew and Alexandrov, Mikhail D. and Bennartz, Ralf and Boers, Reinout and Cairns, Brian and Chiu, J. Christine and Christensen, Matthew and Deneke, Hartwig and Diamond, Michael and Feingold, Graham and Fridlind, Ann and H{\"{u}}nerbein, Anja and Knist, Christine and Kollias, Pavlos and Marshak, Alexander and McCoy, Daniel and Merk, Daniel and Painemal, David and Rausch, John and Rosenfeld, Daniel and Russchenberg, Herman and Seifert, Patric and Sinclair, Kenneth and Stier, Philip and van Diedenhoven, Bastiaan and Wendisch, Manfred and Werner, Frank and Wood, Robert and Zhang, Zhibo and Quaas, Johannes},
doi = {10.1029/2017RG000593},
issn = {87551209},
journal = {Reviews of Geophysics},
keywords = {cloud droplet concentrations,lidar,passive retrievals,radar,remote sensing,satellite},
month = {jun},
number = {2},
pages = {409--453},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Remote Sensing of Droplet Number Concentration in Warm Clouds: A Review of the Current State of Knowledge and Perspectives}},
url = {http://doi.wiley.com/10.1029/2017RG000593},
volume = {56},
year = {2018}
}
@article{Gryspeerdt2018,
abstract = {Abstract. The impact of aerosols on cloud properties is one of the largest uncertainties in the anthropogenic radiative forcing of the climate. In recent years, significant progress has been made in constraining this forcing using observations, but uncertainty still remains, particularly in the adjustments of cloud properties to aerosol perturbations. Cloud liquid water path (LWP) is the leading control on liquid-cloud albedo, making it important to observationally constrain the aerosol impact LWP. Previous modelling and observational studies have shown that multiple processes play a role in determining the LWP response to aerosol perturbations, but that the aerosol effect can be difficult to isolate. Following previous studies using mediating variables, this work investigates use of the relationship between cloud droplet number concentration (Nd) and LWP for constraining the role of aerosols. Using joint probability histograms to account for the non-linear relationship, this work finds a relationship that is broadly consistent with previous studies. There is significant geographical variation in the relationship, partly due to role of meteorological factors (particularly relative humidity) in the relationship. However, the Nd-LWP relationship is negative in the majority of regions, suggesting that aerosol induced LWP reductions could offset a significant fraction of the radiative forcing from aerosol-cloud interactions (RFaci). However, variations in the Nd-LWP relationship in response to volcanic and shipping aerosol perturbations indicate that the Nd-LWP relationship overestimates the Nd impact on LWP. As such, the estimate of LWP changes due to aerosol in this work provides an upper bound to the radiative forcing from aerosol-induced changes in the LWP.},
author = {Gryspeerdt, Edward and Goren, Tom and Sourdeval, Odran and Quaas, Johannes and M{\"{u}}lmenst{\"{a}}dt, Johannes and Dipu, Sudhakar and Unglaub, Claudia and Gettelman, Andrew and Christensen, Matthew},
doi = {https://doi.org/10.5194/acp-19-5331-2019},
issn = {1680-7375},
journal = {Atmospheric Chemistry and Physics},
month = {sep},
pages = {5331--5347},
title = {{Constraining the aerosol influence on cloud liquid water path}},
url = {https://www.atmos-chem-phys-discuss.net/acp-2018-885/},
volume = {19},
year = {2019}
}
@article{Gryspeerdt2017,
abstract = {Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol-cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration (Nd ), previous studies have used the sensitivity of the Nd to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties in the present-day climate may not be suitable for determining the sensitivity of the Nd to anthropogenic aerosol perturbations. Using an ensemble of global aerosol-climate models, this study demonstrates how joint histograms between Nd and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20{\%} of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol-cloud interactions in satellite data.},
author = {Gryspeerdt, Edward and Quaas, Johannes and Ferrachat, Sylvaine and Gettelman, Andrew and Ghan, Steven and Lohmann, Ulrike and Morrison, Hugh and Neubauer, David and Partridge, Daniel G and Stier, Philip and Takemura, Toshihiko and Wang, Hailong and Wang, Minghuai and Zhang, Kai},
doi = {10.1073/pnas.1617765114},
issn = {1091-6490},
journal = {Proceedings of the National Academy of Sciences},
keywords = {aerosols,clouds,radiative forcing},
month = {may},
number = {19},
pages = {4899--4904},
pmid = {28446614},
publisher = {National Academy of Sciences},
title = {{Constraining the instantaneous aerosol influence on cloud albedo.}},
url = {http://www.ncbi.nlm.nih.gov/pubmed/28446614 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC5441736},
volume = {114},
year = {2017}
}
@article{Gryspeerdt2016,
author = {Gryspeerdt, E. and Quaas, J. and Bellouin, N.},
doi = {10.1002/2015JD023744},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aerosols,aerosol‐cloud interactions,causality,clouds},
month = {apr},
number = {7},
pages = {3566--3583},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Constraining the aerosol influence on cloud fraction}},
url = {http://doi.wiley.com/10.1002/2015JD023744},
volume = {121},
year = {2016}
}
@article{Gryspeerdt2014,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Many different interactions between aerosols and clouds have been postulated, based on correlations between satellite retrieved aerosol and cloud properties. Previous studies highlighted the importance of meteorological covariations to the observed correlations. {\textless}br{\textgreater}{\textless}br{\textgreater} In this work, we make use of multiple temporally-spaced satellite retrievals to observe the development of cloud regimes. The observation of cloud regime development allows us to account for the influences of cloud fraction (CF) and meteorological factors on the aerosol retrieval. By accounting for the aerosol index (AI)-CF relationship, we reduce the influence of meteorological correlations compared to "snapshot" studies, finding that simple correlations overestimate any aerosol effect on CF by at least a factor of two. {\textless}br{\textgreater}{\textless}br{\textgreater} We find an increased occurrence of transitions into the stratocumulus regime over ocean with increases in MODIS AI, consistent with the hypothesis that aerosols increase stratocumulus persistence. We also observe an increase in transitions into the deep convective regime over land, consistent with the aerosol invigoration hypothesis. We find changes in the transitions from the shallow cumulus regime in different aerosol environments. The strength of these changes is strongly dependent on Low Troposphere Static Stability and 10 m windspeed, but less so on other meteorological factors. {\textless}br{\textgreater}{\textless}br{\textgreater} Whilst we have reduced the error due to meteorological and CF effects on the aerosol retrieval, meteorological covariation with the cloud and aerosol properties is harder to remove, so these results likely represent an upper bound on the effect of aerosols on cloud development and CF.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Gryspeerdt, E. and Stier, P. and Partridge, D. G.},
doi = {10.5194/acp-14-1141-2014},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {feb},
number = {3},
pages = {1141--1158},
title = {{Satellite observations of cloud regime development: the role of aerosol processes}},
url = {https://www.atmos-chem-phys.net/14/1141/2014/},
volume = {14},
year = {2014}
}
@article{Gryspeerdt2014a,
author = {Gryspeerdt, E. and Stier, P. and Grandey, B. S.},
doi = {10.1002/2014GL059524},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {aerosol,aerosol‐cloud interactions},
month = {may},
number = {10},
pages = {3622--3627},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Cloud fraction mediates the aerosol optical depth-cloud top height relationship}},
url = {http://doi.wiley.com/10.1002/2014GL059524},
volume = {41},
year = {2014}
}
@article{Gryspeerdt2018a,
abstract = {{\textless}p{\textgreater}{\textless}![CDATA[{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} The ice crystal number concentration ({\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater}) is a key property of ice clouds, both radiatively and microphysically. Due to sparse in situ measurements of ice cloud properties, the controls on the {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater} have remained difficult to determine. As more advanced treatments of ice clouds are included in global models, it is becoming increasingly necessary to develop strong observational constraints on the processes involved.{\textless}/p{\textgreater} {\textless}p{\textgreater}This work uses the DARDAR-Nice {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater} retrieval described in Part 1 to investigate the controls on the {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater} at a global scale. The retrieved clouds are separated by type. The effects of temperature, proxies for in-cloud updraft and aerosol concentrations are investigated. Variations in the cloud top {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater} ({\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i(top){\textless}/sub{\textgreater}{\textless}/span{\textgreater}) consistent with both homogeneous and heterogeneous nucleation are observed along with differing relationships between aerosol and {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i(top){\textless}/sub{\textgreater}{\textless}/span{\textgreater} depending on the prevailing meteorological situation and aerosol type. Away from the cloud top, the {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater} displays a different sensitivity to these controlling factors, providing a possible explanation for the low {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater} sensitivity to temperature and ice nucleating particles (INP) observed in previous in situ studies.{\textless}/p{\textgreater} {\textless}p{\textgreater}This satellite dataset provides a new way of investigating the response of cloud properties to meteorological and aerosol controls. The results presented in this work increase our confidence in the retrieved {\textless}span class="inline-formula"{\textgreater}{\textless}i{\textgreater}N{\textless}/i{\textgreater}{\textless}sub{\textgreater}i{\textless}/sub{\textgreater}{\textless}/span{\textgreater} and will form the basis for further study into the processes influencing ice and mixed phase clouds.{\textless}/p{\textgreater}]]{\textgreater}{\textless}/p{\textgreater}},
author = {Gryspeerdt, Edward and Sourdeval, Odran and Quaas, Johannes and Delano{\"{e}}, Julien and Kr{\"{a}}mer, Martina and K{\"{u}}hne, Philipp},
doi = {10.5194/acp-18-14351-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {oct},
number = {19},
pages = {14351--14370},
title = {{Ice crystal number concentration estimates from lidar–radar satellite remote sensing – Part 2: Controls on the ice crystal number concentration}},
url = {https://www.atmos-chem-phys.net/18/14351/2018/},
volume = {18},
year = {2018}
}
@article{Gryspeerdt2020,
abstract = {The radiative forcing from aerosols (particularly through their interaction with clouds) remains one of the most uncertain components of the human forcing of the climate. Observation-based studies have typically found a smaller aerosol effective radiative forcing than in model simulations and were given preferential weighting in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). With their own sources of uncertainty, it is not clear that observation-based estimates are more reliable. Understanding the source of the model and observational differences is thus vital to reduce uncertainty in the impact of aerosols on the climate. These reported discrepancies arise from the different methods of separating the components of aerosol forcing used in model and observational studies. Applying the observational decomposition to global climate model (GCM) output, the two different lines of evidence are surprisingly similar, with a much better agreement on the magnitude of aerosol impacts on cloud properties. Cloud adjustments remain a significant source of uncertainty, particularly for ice clouds. However, they are consistent with the uncertainty from observation-based methods, with the liquid water path adjustment usually enhancing the Twomey effect by less than 50{\%}. Depending on different sets of assumptions, this work suggests that model and observation-based estimates could be more equally weighted in future synthesis studies.},
author = {Gryspeerdt, Edward and M{\"{u}}lmenst{\"{a}}dt, Johannes and Gettelman, Andrew and Malavelle, Florent F. and Morrison, Hugh and Neubauer, David and Partridge, Daniel G. and Stier, Philip and Takemura, Toshihiko and Wang, Hailong and Wang, Minghuai and Zhang, Kai},
doi = {10.5194/acp-20-613-2020},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
number = {1},
pages = {613--623},
publisher = {Copernicus GmbH},
title = {{Surprising similarities in model and observational aerosol radiative forcing estimates}},
volume = {20},
year = {2020}
}
@article{ISI:000299130000012,
abstract = {To analyze the probability density distributions of surface turbulent heat fluxes, the authors apply the two-parametric modified Fisher-Tippett (MFT) distribution to the sensible and latent turbulent heat fluxes recomputed from 6-hourly NCEP-NCAR reanalysis state variables for the period from 1948 to 2008. They derived the mean climatology and seasonal cycle of the location and scale parameters of the MFT distribution. Analysis of the parameters of probability distributions identified the areas where similar surface turbulent fluxes are determined by the very different shape of probability density functions. Estimated extreme turbulent heat fluxes amount to 1500-2000 W m(-2) (for the 99th percentile) and can exceed 2000 W m(-2) for higher percentiles in the subpolar latitudes and western boundary current regions. Analysis of linear trends and interannual variability in the mean and extreme fluxes shows that the strongest trends in extreme fluxes (more than 15 W m(-2) decade(-1)) in the western boundary current regions are associated with the changes in the shape of distribution. In many regions changes in extreme fluxes may be different from those for the mean fluxes at interannual and decadal time scales. The correlation between interannual variability of the mean and extreme fluxes is relatively low in the tropics, the Southern Ocean, and the Kuroshio Extension region. Analysis of probability distributions in turbulent fluxes has also been used in assessing the impact of sampling errors in the Voluntary Observing Ship (VOS)-based surface flux climatologies, allowed for the estimation of the impact of sampling in extreme fluxes. Although sampling does not have a visible systematic effect on mean fluxes, sampling uncertainties result in the underestimation of extreme flux values exceeding 100 W m(-2) in poorly sampled regions.},
address = {45 BEACON ST, BOSTON, MA 02108-3693 USA},
author = {Gulev, Sergey K and Belyaev, Konstantin},
doi = {10.1175/2011JCLI4211.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jan},
number = {1},
pages = {184--206},
publisher = {AMER METEOROLOGICAL SOC},
title = {{Probability Distribution Characteristics for Surface Air–Sea Turbulent Heat Fluxes over the Global Ocean}},
type = {Article},
volume = {25},
year = {2012}
}
@article{Hahn2020,
abstract = {The lapse rate feedback is the dominant driver of stronger warming in the Arctic than the Antarctic in simulations with increased CO2. While Antarctic surface elevation has been implicated in promoting a weaker Antarctic lapse rate feedback, the mechanisms in which elevation impacts the lapse rate feedback are still unclear. Here we suggest that weaker Antarctic warming under CO2 forcing stems from shallower, less intense climatological inversions due to limited atmospheric heat transport above the ice sheet elevation and elevation-induced katabatic winds. In slab ocean model experiments with flattened Antarctic topography, stronger climatological inversions support a stronger lapse rate feedback and annual mean Antarctic warming comparable to the Arctic under CO2 doubling. Unlike the Arctic, seasonality in warming over flat Antarctica is mainly driven by a negative shortwave cloud feedback, which exclusively dampens summer warming, with a smaller contribution from the winter-enhanced lapse rate feedback.},
author = {Hahn, L. C. and Armour, K. C. and Battisti, D. S. and Donohoe, A. and Pauling, A. G. and Bitz, C. M.},
doi = {10.1029/2020GL088965},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {Antarctica,climate change,lapse rate feedback,polar amplification},
month = {aug},
number = {16},
pages = {e2020GL088965},
publisher = {Blackwell Publishing Ltd},
title = {{Antarctic Elevation Drives Hemispheric Asymmetry in Polar Lapse Rate Climatology and Feedback}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL088965},
volume = {47},
year = {2020}
}
@article{ISI:000345298100008,
abstract = {The spatial representativeness of a point measurement of surface solar radiation (SSR) of its larger-scale surrounding, e.g., collocated grid cell, is a potential source of uncertainty in the validation of climate models and satellite products. Here we expand our previous study over Europe to the entire Meteosat disk, covering additional climate zones in Africa, the Middle east, and South America between -70 degrees to 70 degrees East and -70 degrees to 70 degrees North. Using a high-resolution (0.03 degrees) satellite-based SSR data set (2001-2005), we quantify the spatial subgrid variability in grids of 1 degrees and 3 degrees resolution and the spatial representativeness of 887 surface sites with respect to site-centered surroundings of variable size. In the multiannual mean the subgrid variability is the largest in some mountainous and coastal regions but varies seasonally due to changes in the Intertropical Convergence Zone location. The absolute mean representation errors at the surface sites with respect to surroundings of 1 degrees and 3 degrees are on average 1-2{\%} (3Wm(-2)) and 2-3{\%} (4Wm(-2)), respectively. The majority of sites are found to be representative within the in situ measurement accuracy. We show that their site-specific representativeness can be reliably approximated by the subgrid variability in a fixed grid (1 degrees). The subgrid variability in turn is only moderately reduced when computed from coarser grid data, typically the only data available in areas not covered by the 0.03 degrees resolved Meteosat disk. Together, this paves the way to a fully global assessment of site-specific spatial representativeness.},
author = {Hakuba, M Z and Folini, D and Sanchez-Lorenzo, A and Wild, M},
doi = {10.1002/2014JD021946},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {oct},
number = {20},
pages = {11760--11771},
title = {{Spatial representativeness of ground-based solar radiation measurements – Extension to the full Meteosat disk}},
url = {http://doi.wiley.com/10.1002/2014JD021946},
volume = {119},
year = {2014}
}
@article{Hall2006a,
abstract = {{\%}Z {\%}+ {\%}{\^{}}},
author = {Hall, Alex and Qu, Xin},
doi = {10.1029/2005GL025127},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {doi:10.1029/2005GL025127,http://dx.doi.org/10.1029/2005GL025127},
number = {3},
pages = {1--4},
pmid = {235156800006},
title = {{Using the current seasonal cycle to constrain snow albedo feedback in future climate change}},
volume = {33},
year = {2006}
}
@article{Hall2004,
abstract = {A coarse resolution coupled oceanatmosphere simulation in which surface albedo feedback is suppressed by prescribing surface albedo, is compared to one where snow and sea ice anomalies are allowed to affect surface albedo. Canonical CO2 -doubling experiments were performed with both models to assess the impact of this feedback on equilibrium response to external forcing. It accounts for about half the high-latitude response to the forcing. Both models were also run for 1000 yr without forcing to assess the impact of surface albedo feedback on internal variability. Surprisingly little internal variability can be attributed to this feedback, except in the Northern Hemisphere continents during spring and in the sea ice zone of the Southern Hemisphere year- round. At these locations and during these seasons, it accounts for, at most, 20{\%} of the variability. The main reason for this relatively weak signal is that horizontal damping processes dilute the impact of surface albedo feedback. When snow albedo feedback in Northern Hemisphere continents is isolated from horizontal damping processes, it has a similar strength in the CO2 -doubling and internal variability contexts; a given temperature anomaly in these regions is associated with approximately the same change in snow depth and surface albedo whether it was externally forced or internally generated. This suggests that the presence of internal variability in the observed record is not a barrier to extracting information about snow albedo feedbacks contribution to equilibrium climate sensitivity. This is demonstrated in principle in a scenario run, where estimates of past, present, and future changes in greenhouse gases and sulfate aerosols are imposed on the model with surface albedo feedback. This simulation contains a mix of internal variations and externally forced anomalies similar to the observed record. The snow albedo feedback to the scenario runs climate anomalies agrees very well with the snow albedo feedback in the CO2 -doubling context. Moreover, the portion of the scenario run corresponding to the present- day satellite record is long enough to capture this feedback, suggesting this record could be used to estimate snow albedo feedbacks contribution to equilibrium climate sensitivity.},
author = {Hall, Alex},
doi = {10.1175/1520-0442(2004)017<1550:TROSAF>2.0.CO;2},
isbn = {0001250000},
issn = {08948755},
journal = {Journal of Climate},
number = {7},
pages = {1550--1568},
title = {{The role of surface albedo feedback in climate}},
volume = {17},
year = {2004}
}
@article{Hansen2013,
abstract = {Cenozoic temperature, sea level and CO2 covariations provide insights into climate sensitivity to external forcings and sea-level sensitivity to climate change. Climate sensitivity depends on the initial climate state, but potentially can be accurately inferred from precise palaeoclimate data. Pleistocene climate oscillations yield a fast-feedback climate sensitivity of 3 ± 1°C for a 4Wm-2 CO2 forcing if Holocene warming relative to the Last GlacialMaximum (LGM) is used as calibration, but the error (uncertainty) is substantial and partly subjective because of poorly defined LGM global temperature and possible human influences in the Holocene. Glacial-to-interglacial climate change leading to the prior (Eemian) interglacial is less ambiguous and implies a sensitivity in the upper part of the above range, i.e. 3-4°C for a 4Wm-2 CO2 forcing. Slow feedbacks, especially change of ice sheet size and atmospheric CO 2, amplify the total Earth system sensitivity by an amount that depends on the time scale considered. Ice sheet response time is poorly defined, but we show that the slow response and hysteresis in prevailing ice sheet models are exaggerated. We use a global model, simplified to essential processes, to investigate state dependence of climate sensitivity, finding an increased sensitivity towards warmer climates, as low cloud cover is diminished and increased water vapour elevates the tropopause. Burning all fossil fuels, we conclude, would make most of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.},
archivePrefix = {arXiv},
arxivId = {1211.4846},
author = {Hansen, James and Sato, Makiko and Russell, Gary and Kharecha, Pushker},
doi = {10.1098/rsta.2012.0294},
eprint = {1211.4846},
issn = {1364503X},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
keywords = {Climate,Climate sensitivity,Palaeoclimate,Sea level},
number = {2001},
pages = {20120294},
title = {{Climate sensitivity, sea level and atmospheric carbon dioxide}},
volume = {371},
year = {2013}
}
@article{HANSEN857,
abstract = {The factors that determine climate response times were investigated with simple models and scaling statements. The response times are particularly sensitive to (i) the amount that the climate response is amplified by feedbacks and (ii) the representation of ocean mixing. If equilibrium climate sensitivity is 3{\{}$\backslash$textdegree{\}}C or greater for a doubling of the carbon dioxide concentration, then most of the expected warming attributable to trace gases added to the atmosphere by man probably has not yet occurred. This yet to be realized warming calls into question a policy of "wait and see" regarding the issue of how to deal with increasing atmospheric carbon dioxide and other trace gases.},
author = {Hansen, J and Russell, G and Lacis, A and Fung, I and Rind, D and Stone, P},
doi = {10.1126/science.229.4716.857},
issn = {0036-8075},
journal = {Science},
number = {4716},
pages = {857--859},
publisher = {American Association for the Advancement of Science},
title = {{Climate Response Times: Dependence on Climate Sensitivity and Ocean Mixing}},
url = {http://science.sciencemag.org/content/229/4716/857},
volume = {229},
year = {1985}
}
@article{Hansen2005a,
abstract = {We use a global climate model to compare the effectiveness of many climate forcing agents for producing climate change. We find a substantial range in the "efficacy'' of different forcings, where the efficacy is the global temperature response per unit forcing relative to the response to CO2 forcing. Anthropogenic CH4 has efficacy similar to 110{\%}, which increases to similar to 145{\%} when its indirect effects on stratospheric H2O and tropospheric O-3 are included, yielding an effective climate forcing of similar to 0.8 W/m(2) for the period 1750 - 2000 and making CH4 the largest anthropogenic climate forcing other than CO2. Black carbon (BC) aerosols from biomass burning have a calculated efficacy similar to 58{\%}, while fossil fuel BC has an efficacy similar to 78{\%}. Accounting for forcing efficacies and for indirect effects via snow albedo and cloud changes, we find that fossil fuel soot, defined as BC + OC organic carbon), has a net positive forcing while biomass burning BC + OC has a negative forcing. We show that replacement of the traditional instantaneous and adjusted forcings, Fi and Fa, with an easily computed alternative, Fs, yields a better predictor of climate change, i.e., its efficacies are closer to unity. Fs is inferred from flux and temperature changes in a fixed-ocean model run. There is remarkable congruence in the spatial distribution of climate change, normalized to the same forcing Fs, for most climate forcing agents, suggesting that the global forcing has more relevance to regional climate change than may have been anticipated. Increasing greenhouse gases intensify the Hadley circulation in our model, increasing rainfall in the Intertropical Convergence Zone (ITCZ), Eastern United States, and East Asia, while intensifying dry conditions in the subtropics including the Southwest United States, the Mediterranean region, the Middle East, and an expanding Sahel. These features survive in model simulations that use all estimated forcings for the period 1880 - 2000. Responses to localized forcings, such as land use change and heavy regional concentrations of BC aerosols, include more specific regional characteristics. We suggest that anthropogenic tropospheric O-3 and the BC snow albedo effect contribute substantially to rapid warming and sea ice loss in the Arctic. As a complement to a priori forcings, such as Fi, Fa, and Fs, we tabulate the a posteriori effective forcing, Fe, which is the product of the forcing and its efficacy. Fe requires calculation of the climate response and introduces greater model dependence, but once it is calculated for a given amount of a forcing agent it provides a good prediction of the response to other forcing amounts.},
author = {Hansen, J. and Sato, M. and Ruedy, R. and Nazarenko, L. and Lacis, A. and Schmidt, G. a. and Russell, G. and Aleinov, I. and Bauer, M. and Bauer, S. and Bell, N. and Cairns, B. and Canuto, V. and Chandler, M. and Cheng, Y. and {Del Genio}, A. and Faluvegi, G. and Fleming, E. and Friend, A. and Hall, T. and Jackman, C. and Kelley, M. and Kiang, N. and Koch, D. and Lean, J. and Lerner, J. and Lo, K. and Menon, S. and Miller, R. and Minnis, P. and Novakov, T. and Oinas, V. and Perlwitz, Ju Ja and Perlwitz, Ju Ja and Rind, D. and Romanou, A. and Shindell, D. and Stone, P. and Sun, S. and Tausnev, N. and Thresher, D. and Wielicki, B. and Wong, T. and Yao, M. and Zhang, S.},
doi = {10.1029/2005JD005776},
isbn = {01480227 (ISSN)},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
number = {18},
pages = {1--45},
title = {{Efficacy of climate forcings}},
volume = {110},
year = {2005}
}
@incollection{Hansen.Lacis.ea-book-1984,
address = {Washington, DC, USA},
author = {Hansen, J. and Lacis, A. and Rind, D. and Russell, G. and Stone, P. and Fung, I. and Ruedy, R. and Lerner, J.},
booktitle = {Climate Processes and Climate Sensitivity, AGU Geophysical Monograph 29, Maurice Ewing Volume 5},
doi = {10.1029/GM029p0130},
editor = {Hansen, J. E. and Takahashi, T.},
pages = {130--163},
publisher = {American Geophysical Union (AGU)},
title = {{Climate sensitivity: Analysis of feedback mechanisms}},
volume = {29},
year = {1984}
}
@article{ISI:000229619300043,
abstract = {Our climate model, driven mainly by increasing human-made greenhouse gases and aerosols, among other forcings, calculates that Earth is now absorbing 0.85 +/- 0.15 watts per square meter more energy from the Sun than it is emitting to space. This imbalance is confirmed by precise measurements of increasing ocean heat content over the past 10 years. Implications include(i) the expectation of additional global warming of about 0.60 degrees C without further change of atmospheric composition; (ii) the confirmation of the climate system's tag in responding to forcings, implying the need for anticipatory actions to avoid any specified level of climate change; and (iii) the likelihood of acceleration of ice sheet disintegration and sea level rise.},
address = {1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA},
author = {Hansen, J and Nazarenko, L and Ruedy, R and Sato, M and Willis, J and {Del Genio}, A and Koch, D and Lacis, A and Lo, K and Menon, S and Novakov, T and Perlwitz, J and Russell, G and Schmidt, G A and Tausnev, N},
doi = {10.1126/science.1110252},
issn = {0036-8075},
journal = {Science},
month = {jun},
number = {5727},
pages = {1431--1435},
publisher = {AMER ASSOC ADVANCEMENT SCIENCE},
title = {{Earth's energy imbalance: Confirmation and implications}},
type = {Article},
volume = {308},
year = {2005}
}
@article{Hargreaves2016,
abstract = {The mid-PlioceneWarm Period (mPWP) is the most recent interval in which atmospheric carbon dioxide was substantially higher than in modern pre-industrial times. It is, therefore, a potentially valuable target for testing the ability of climate models to simulate climates warmer than the pre-industrial state. The recent Pliocene model inter-comparison Project (PlioMIP) presented boundary conditions for the mPWP, and a protocol for climate model experiments. Here we analyse results from the PlioMIP and, for the first time, discuss the potential for this interval to usefully constrain the equilibrium climate sensitivity. We present an estimate of 1.8–3.6 °C, but there are considerable uncertainties surrounding the analysis. We consider the extent to which these uncertainties may be lessened in the next few years.},
author = {Hargreaves, J. C. and Annan, J. D.},
doi = {10.5194/cp-12-1591-2016},
isbn = {1814-9359},
issn = {18149332},
journal = {Climate of the Past},
number = {8},
pages = {1591--1599},
title = {{Could the Pliocene constrain the equilibrium climate sensitivity?}},
volume = {12},
year = {2016}
}
@article{Hargreaves2012a,
abstract = {We investigate the relationship between the Last Glacial Maximum (LGM) and climate sensitivity across the PMIP2 multi-model ensemble of GCMs, and find a correlation between tropical temperature and climate sensitivity which is statistically significant and physically plausible. We use this relationship, together with the LGM temperature reconstruction of Annan and Hargreaves (2012), to generate estimates for the equilibrium climate sensitivity. We estimate the equilibrium climate sensitivity to be about 2.5�C with a high probability of being under 4�C, though these results are subject to several important caveats. The forthcoming PMIP3/CMIP5 models were not considered in this analysis, as very few LGM simulations are currently available from these models. We propose that these models will provide a useful validation of the correlation presented here.},
author = {Hargreaves, J. C. and Annan, J. D. and Yoshimori, M. and Abe-Ouchi, A.},
doi = {10.1029/2012GL053872},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
number = {24},
pages = {1--5},
title = {{Can the Last Glacial Maximum constrain climate sensitivity?}},
volume = {39},
year = {2012}
}
@article{Harper2018,
author = {Harper, A B and Wiltshire, A J and Cox, P M and Friedlingstein, P and Jones, C D and Mercado, L M and Sitch, S and Williams, K and Duran-Rojas, C},
doi = {10.5194/gmd-11-2857-2018},
journal = {Geoscientific Model Development},
number = {7},
pages = {2857--2873},
title = {{Vegetation distribution and terrestrial carbon cycle in a carbon cycle configuration of JULES4.6 with new plant functional types}},
volume = {11},
year = {2018}
}
@article{Hartmann2002a,
author = {Hartmann, D. L. and Larson, K.},
doi = {10.1029/2002GL015835},
journal = {Geophysical Research Letters},
pages = {1951},
title = {{An important constraint on tropical cloud - climate feedback}},
volume = {29},
year = {2002}
}
@article{Hartmann2001,
abstract = {Earth Radiation Budget Experiment (ERBE) and International Satellite Cloud Climatology Project (ISCCP) data are used in conjunction with a radiative transfer model to estimate the effect of various cloud types on the top-of-atmosphere radiation budget in convective regions of the Tropics. This analysis shows that individual convective cloud elements can have strongly positive or negative effects on the radiation balance. Nonetheless, the ensemble of cloud types that occurs in association with deep convection in the Tropics arranges itself so that the individual positive and negative contributions cancel each other when averaged over the convective cloud system. This behavior of the cloud ensemble is extremely interesting, and the authors speculate that it is indicative of feedbacks in the climate system that have not been explored adequately. A simple model is introduced that includes feedbacks that drive the net radiation in convective regions toward the net radiation in adjacent nonconvective areas. If the nonconvective regions have small cloud forcing, then this model predicts small net radiative forcing by the convective cloud ensemble. This feedback process requires that the circulations in the Tropics be sensitive to small SST gradients and that the convective cloud albedo be sensitive to the vertical motion.},
author = {Hartmann, Dennis L and Moy, Leslie A and Fu, Qiang},
doi = {10.1175/1520-0442(2001)014<4495:TCATEB>2.0.CO;2},
issn = {0894-8755},
journal = {Journal of Climate},
month = {dec},
number = {24},
pages = {4495--4511},
title = {{Tropical Convection and the Energy Balance at the Top of the Atmosphere}},
url = {https://doi.org/10.1175/1520-0442(2001)014{\%}3C4495:TCATEB{\%}3E2.0.CO http://0.0.0.2},
volume = {14},
year = {2001}
}
@incollection{Hartmann2013,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Hartmann, Dennis J and {Klein Tank}, Albert M G and Rusticucci, Matilde and Alexander, Lisa V and Br{\"{o}}nnimann, Stefan and Charabi, Yassine Abdul-Rahman and Dentener, Frank J and Dlugokencky, Edward J and Easterling, David R and Kaplan, Alexey and Soden, Brian J and Thorne, Peter W and Wild, Martin and Zhai, Panmao},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
doi = {10.1017/CBO9781107415324.008},
editor = {Stocker, T.F. and Qin, D. and Plattner, G.-K. and Tignor, M. and Allen, S.K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.},
isbn = {9781107661820},
pages = {159--254},
publisher = {Cambridge University Press},
title = {{Observations: Atmosphere and Surface}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Hasekamp2019,
abstract = {Anthropogenic aerosol emissions lead to an increase in the amount of cloud condensation nuclei and consequently an increase in cloud droplet number concentration and cloud albedo. The corresponding negative radiative forcing due to aerosol cloud interactions (RFaci) is one of the most uncertain radiative forcing terms as reported in the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Here we show that previous observation-based studies underestimate aerosol-cloud interactions because they used measurements of aerosol optical properties that are not directly related to cloud formation and are hampered by measurement uncertainties. We have overcome this problem by the use of new polarimetric satellite retrievals of the relevant aerosol properties (aerosol number, size, shape). The resulting estimate of RFaci = −1.14 Wm-2 (range between −0.84 and −1.72 Wm-2) is more than a factor 2 stronger than the IPCC estimate that includes also other aerosol induced changes in cloud properties.},
author = {Hasekamp, Otto P. and Gryspeerdt, Edward and Quaas, Johannes},
doi = {10.1038/s41467-019-13372-2},
isbn = {4146701913372},
issn = {20411723},
journal = {Nature Communications},
number = {1},
pages = {1--7},
pmid = {31776336},
publisher = {Springer US},
title = {{Analysis of polarimetric satellite measurements suggests stronger cooling due to aerosol–cloud interactions}},
url = {http://dx.doi.org/10.1038/s41467-019-13372-2},
volume = {10},
year = {2019}
}
@article{Hasselmann1976,
abstract = {A stochastic model of climate variability is considered in which slow changes of climate are explained as the integral response to continuous random excitation by short period ?weather? disturbances. The coupled ocean-atmosphere-cryosphere-land system is divided into a rapidly varying ?weather? system (essentially the atmosphere) and a slowly responding ?climate? system (the ocean, cryosphere, land vegetation, etc.). In the usual Statistical Dynamical Model (SDM) only the average transport effects of the rapidly varying weather components are parameterised in the climate system. The resultant prognostic equations are deterministic, and climate variability can normally arise only through variable external conditions. The essential feature of stochastic climate models is that the non-averaged ?weather? components are also retained. They appear formally as random forcing terms. The climate system, acting as an integrator of this short-period excitation, exhibits the same random-walk response characteristics as large particles interacting with an ensemble of much smaller particles in the analogous Brownian motion problem. The model predicts ?red? variance spectra, in qualitative agreement with observations. The evolution of the climate probability distribution is described by a Fokker-Planck equation, in which the effect of the random weather excitation is represented by diffusion terms. Without stabilising feedback, the model predicts a continuous increase in climate variability, in analogy with the continuous, unbounded dispersion of particles in Brownian motion (or in a homogeneous turbulent fluid). Stabilising feedback yields a statistically stationary climate probability distribution. Feedback also results in a finite degree of climate predictability, but for a stationary climate the predictability is limited to maximal skill parameters of order 0.5.},
annote = {doi: 10.1111/j.2153-3490.1976.tb00696.x},
author = {Hasselmann, K},
doi = {10.3402/tellusa.v28i6.11316},
issn = {0040-2826},
journal = {Tellus},
month = {jan},
number = {6},
pages = {473--485},
publisher = {John Wiley {\&} Sons, Ltd (10.1111)},
title = {{Stochastic climate models Part I. Theory}},
url = {https://www.tandfonline.com/doi/full/10.3402/tellusa.v28i6.11316},
volume = {28},
year = {1976}
}
@article{Haugstad2017,
author = {Haugstad, A. D. and Armour, K. C. and Battisti, D. S. and Rose, B. E. J.},
doi = {10.1002/2017GL074372},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {aquaplanet,climate,feedbacks,forcing,radiative,transient},
month = {jul},
number = {14},
pages = {7455--7463},
publisher = {Wiley-Blackwell},
title = {{Relative roles of surface temperature and climate forcing patterns in the inconstancy of radiative feedbacks}},
url = {http://doi.wiley.com/10.1002/2017GL074372},
volume = {44},
year = {2017}
}
@article{doi:10.1029/2011GL050087,
abstract = {The time at which the signal of climate change emerges from the noise of natural climate variability (Time of Emergence, ToE) is a key variable for climate predictions and risk assessments. Here we present a methodology for estimating ToE for individual climate models, and use it to make maps of ToE for surface air temperature (SAT) based on the CMIP3 global climate models. Consistent with previous studies we show that the median ToE occurs several decades sooner in low latitudes, particularly in boreal summer, than in mid-latitudes. We also show that the median ToE in the Arctic occurs sooner in boreal winter than in boreal summer. A key new aspect of our study is that we quantify the uncertainty in ToE that arises not only from inter-model differences in the magnitude of the climate change signal, but also from large differences in the simulation of natural climate variability. The uncertainty in ToE is at least 30 years in the regions examined, and as much as 60 years in some regions. Alternative emissions scenarios lead to changes in both the median ToE (by a decade or more) and its uncertainty. The SRES B1 scenario is associated with a very large uncertainty in ToE in some regions. Our findings have important implications for climate modelling and climate policy which we discuss.},
author = {Hawkins, E and Sutton, R},
doi = {10.1029/2011GL050087},
journal = {Geophysical Research Letters},
keywords = {climate variability,temperature change,time of emergence},
number = {1},
pages = {L01702},
title = {{Time of emergence of climate signals}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2011GL050087},
volume = {39},
year = {2012}
}
@article{cp-12-663-2016,
author = {Haywood, A M and Dowsett, H J and Dolan, A M and Rowley, D and Abe-Ouchi, A and Otto-Bliesner, B and Chandler, M A and Hunter, S J and Lunt, D J and Pound, M and Salzmann, U},
doi = {10.5194/cp-12-663-2016},
journal = {Climate of the Past},
number = {3},
pages = {663--675},
title = {{The Pliocene Model Intercomparison Project (PlioMIP) Phase 2: scientific objectives and experimental design}},
url = {https://www.clim-past.net/12/663/2016/},
volume = {12},
year = {2016}
}
@article{Haywood20120515,
abstract = {The characteristics of the mid-Pliocene warm period (mPWP: 3.264{\{}$\backslash$textendash{\}}3.025 Ma BP) have been examined using geological proxies and climate models. While there is agreement between models and data, details of regional climate differ. Uncertainties in prescribed forcings and in proxy data limit the utility of the interval to understand the dynamics of a warmer than present climate or evaluate models. This uncertainty comes, in part, from the reconstruction of a time slab rather than a time slice, where forcings required by climate models can be more adequately constrained. Here, we describe the rationale and approach for identifying a time slice(s) for Pliocene environmental reconstruction. A time slice centred on 3.205 Ma BP (3.204{\{}$\backslash$textendash{\}}3.207 Ma BP) has been identified as a priority for investigation. It is a warm interval characterized by a negative benthic oxygen isotope excursion (0.21{\{}$\backslash$textendash{\}}0.23{\{}$\backslash$textperthousand{\}}) centred on marine isotope stage KM5c (KM5.3). It occurred during a period of orbital forcing that was very similar to present day. Climate model simulations indicate that proxy temperature estimates are unlikely to be significantly affected by orbital forcing for at least a precession cycle centred on the time slice, with the North Atlantic potentially being an important exception.},
author = {Haywood, Alan M and Dolan, Aisling M and Pickering, Steven J and Dowsett, Harry J and McClymont, Erin L and Prescott, Caroline L and Salzmann, Ulrich and Hill, Daniel J and Hunter, Stephen J and Lunt, Daniel J and Pope, James O and Valdes, Paul J},
doi = {10.1098/rsta.2012.0515},
issn = {1364-503X},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
number = {2001},
pages = {20120515},
publisher = {The Royal Society},
title = {{On the identification of a Pliocene time slice for data–model comparison}},
url = {http://rsta.royalsocietypublishing.org/content/371/2001/20120515},
volume = {371},
year = {2013}
}
@article{Haywood2016,
abstract = {The mid-Pliocene Warm Period (mPWP), analogous to future climate conditions, is considered a test-bed for the predictive capability of climate models. Here, Dowsett et al. review our understanding of the mPWP and discuss recent and future advances in the context of proxy data/model integration.},
author = {Haywood, Alan M and Dowsett, Harry J and Dolan, Aisling M},
doi = {10.1038/ncomms10646},
issn = {2041-1723},
journal = {Nature Communications},
number = {1},
pages = {10646},
title = {{Integrating geological archives and climate models for the mid-Pliocene warm period}},
url = {https://doi.org/10.1038/ncomms10646},
volume = {7},
year = {2016}
}
@article{cp-16-2095-2020,
author = {Haywood, A M and Tindall, J C and Dowsett, H J and Dolan, A M and Foley, K M and Hunter, S J and Hill, D J and Chan, W.-L. and Abe-Ouchi, A and Stepanek, C and Lohmann, G and Chandan, D and Peltier, W R and Tan, N and Contoux, C and Ramstein, G and Li, X and Zhang, Z and Guo, C and Nisancioglu, K H and Zhang, Q and Li, Q and Kamae, Y and Chandler, M A and Sohl, L E and Otto-Bliesner, B L and Feng, R and Brady, E C and von der Heydt, A S and Baatsen, M L J and Lunt, D J},
doi = {10.5194/cp-16-2095-2020},
journal = {Climate of the Past},
number = {6},
pages = {2095--2123},
title = {{The Pliocene Model Intercomparison Project Phase 2: large-scale climate features and climate sensitivity}},
url = {https://cp.copernicus.org/articles/16/2095/2020/},
volume = {16},
year = {2020}
}
@article{ISI:000434111700059,
abstract = {Observations show that the surface incident solar radiation (R-s) decreased over land from the 1950s to the 1980s and increased thereafter, known as global dimming and brightening. This claim has been questioned due to the inhomogeneity and low spatial-temporal coverage of R-s observations. Based on direct comparisons of similar to 200 observed and sunshine duration (SunDu) derived R-s station pairs, meeting data record lengths exceeding 60months and spatial distances less than 110 km, we show that meteorological observations of SunDu can be used as a proxy for measured R-s. Our revised results from similar to 2,600 stations show global dimming from the 1950s to the 1980s over China (-1.90 W/m(2) per decade), Europe (-1.36 W/m(2) per decade), and the United States (-1.10 W/m(2) per decade), brightening from 1980 to 2009 in Europe (1.66 W/m(2) per decade) and a decline from 1994 to 2010 in China (-1.06 W/m(2) per decade). Even if 1994-2010 is well known as a period of global brightening, the observed and SunDu-derived R-s over China still exhibit declining trends. Trends in R-s from 1923 to 1950 are also found over Europe (1.91W/m(2) per decade) and the United States (-1.31W/m(2) per decade), but the results in Europe may not well represent the actual trend for the European continent due to poor spatial sampling. Plain Language Summary Ground-based observations of the surface incident solar radiation (R-s) reveal the phenomena known as global dimming and brightening, that is, a downtrend over land from the 1950s to the 1980s and an uptrend thereafter. However, R-s observations suffer from inhomogeneity issues and low spatial-temporal coverage. Sunshine duration-derived R-s is not present above problems and was utilized here to compare with observed R-s from China, Europe, and the United States over the 1950-2010 common period. Results show a good agreement between two data sets except for the dimming period in China, mainly due to instrument sensitivity drift of R-s observations. Therefore, using more extensive sunshine duration-derived R-s data set at approximately 2,600 stations over China, Europe, and the United States since 1901, a revisit of global dimming and brightening has been reasonably conducted, including the early period prior to the 1950s.},
address = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
author = {He, Yanyi and Wang, Kaicun and Zhou, Chunlue and Wild, Martin},
doi = {10.1029/2018GL077424},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {may},
number = {9},
pages = {4281--4289},
publisher = {AMER GEOPHYSICAL UNION},
title = {{A Revisit of Global Dimming and Brightening Based on the Sunshine Duration}},
type = {Article},
volume = {45},
year = {2018}
}
@article{He2018,
abstract = {We implement a set of new parameterizations into the widely used Snow, Ice, and Aerosol Radiative (SNICAR) model to account for effects of snow grain shape (spherical vs. nonspherical) and black carbon (BC)-snow mixing state (external vs. internal). We find that nonspherical snow grains lead to higher pure albedo but weaker BC-induced albedo reductions relative to spherical snow grains, while BC-snow internal mixing significantly enhances albedo reductions relative to external mixing. The combination of snow nonsphericity and internal mixing suggests an important interactive effect on BC-induced albedo reduction. Comparisons with observations of clean and BC-contaminated snow albedo show that model simulations accounting for both snow nonsphericity and BC-snow internal mixing perform better than those using the common assumption of spherical snow grains and external mixing. We further apply the updated SNICAR model with comprehensive in situ measurements of BC concentrations in the Tibetan Plateau snowpack to quantify the present-day (2000-2015) BC-induced snow albedo effects from a regional and seasonal perspective. The BC concentrations show distinct and substantial sub-regional and seasonal variations, with higher values in the non-monsoon season and low altitudes. As a result, the BC-induced regional mean snow albedo reductions and surface radiative effects vary by up to an order of magnitude across different sub-regions and seasons, with values of 0.7-30.7 and 1.4-58.4 W m'2 for BC externally mixed with fresh and aged snow spheres, respectively. The BC radiative effects are further complicated by uncertainty in snow grain shape and BC-snow mixing state. BC-snow internal mixing enhances the mean albedo effects over the plateau by 30-60 {\%} relative to external mixing, while nonspherical snow grains decrease the mean albedo effects by up to 31 {\%} relative to spherical grains. Based on this study, extensive measurements and improved model characterization of snow grain shape and aerosol-snow mixing state are urgently needed in order to precisely evaluate BC-snow albedo effects.},
author = {He, Cenlin and Flanner, Mark G. and Chen, Fei and Barlage, Michael and Liou, Kuo Nan and Kang, Shichang and Ming, Jing and Qian, Yun},
doi = {10.5194/acp-18-11507-2018},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
month = {aug},
number = {15},
pages = {11507--11527},
publisher = {Copernicus GmbH},
title = {{Black carbon-induced snow albedo reduction over the Tibetan Plateau: Uncertainties from snow grain shape and aerosol-snow mixing state based on an updated SNICAR model}},
volume = {18},
year = {2018}
}
@article{Hedemann2017,
abstract = {During the first decade of the twenty-first century, the Earth's surface warmed more slowly than climate models simulated. This surface-warming hiatus is attributed by some studies to model errors in external forcing, while others point to heat rearrangements in the ocean caused by internal variability, the timing of which cannot be predicted by the models. However, observational analyses disagree about which ocean region is responsible. Here we show that the hiatus could also have been caused by internal variability in the top-of-atmosphere energy imbalance. Energy budgeting for the ocean surface layer over a 100-member historical ensemble reveals that hiatuses are caused by energy-flux deviations as small as 0.08 W m−2, which can originate at the top of the atmosphere, in the ocean, or both. Budgeting with existing observations cannot constrain the origin of the recent hiatus, because the uncertainty in observations dwarfs the small flux deviations that could cause a hiatus. The sensitivity of these flux deviations to the observational dataset and to energy budget choices helps explain why previous studies conflict, and suggests that the origin of the recent hiatus may never be identified.},
author = {Hedemann, Christopher and Mauritsen, Thorsten and Jungclaus, Johann and Marotzke, Jochem},
doi = {10.1038/nclimate3274},
isbn = {1758-678X},
issn = {17586798},
journal = {Nature Climate Change},
number = {5},
pages = {336--339},
title = {{The subtle origins of surface-warming hiatuses}},
volume = {7},
year = {2017}
}
@article{Heede2020,
author = {Heede, Ulla K and Fedorov, Alexey V. and Burls, Natalie},
doi = {https://doi.org/10.1175/JCLI-D-19-0690.1},
journal = {Journal of Climate},
number = {14},
pages = {6101--6118},
title = {{Time Scales and Mechanisms for the Tropical Pacific Response to Global Warming: A Tug of War between the Ocean Thermostat and Weaker Walker}},
volume = {33},
year = {2020}
}
@article{Held.Shell-jclim-2012,
author = {Held, I M and Shell, K M},
doi = {10.1175/JCLI-D-11-00721.1},
number = {8},
pages = {2578--2582},
title = {{Using Relative Humidity as a State Variable in Climate Feedback Analysis}},
volume = {25},
year = {2012}
}
@article{doi:10.1175/JCLI3990.1,
abstract = { Abstract Using the climate change experiments generated for the Fourth Assessment of the Intergovernmental Panel on Climate Change, this study examines some aspects of the changes in the hydrological cycle that are robust across the models. These responses include the decrease in convective mass fluxes, the increase in horizontal moisture transport, the associated enhancement of the pattern of evaporation minus precipitation and its temporal variance, and the decrease in the horizontal sensible heat transport in the extratropics. A surprising finding is that a robust decrease in extratropical sensible heat transport is found only in the equilibrium climate response, as estimated in slab ocean responses to the doubling of CO2, and not in transient climate change scenarios. All of these robust responses are consequences of the increase in lower-tropospheric water vapor. },
author = {Held, Isaac M and Soden, Brian J},
doi = {10.1175/JCLI3990.1},
journal = {Journal of Climate},
number = {21},
pages = {5686--5699},
title = {{Robust Responses of the Hydrological Cycle to Global Warming}},
url = {https://doi.org/10.1175/JCLI3990.1},
volume = {19},
year = {2006}
}
@article{Held2010,
abstract = {Abstract The fast and slow components of global warming in a comprehensive climate model are isolated by examining the response to an instantaneous return to preindustrial forcing. The response is characterized by an initial fast exponential decay with an e-folding time smaller than 5 yr, leaving behind a remnant that evolves more slowly. The slow component is estimated to be small at present, as measured by the global mean near-surface air temperature, and, in the model examined, grows to 0.4°C by 2100 in the A1B scenario from the Special Report on Emissions Scenarios (SRES), and then to 1.4°C by 2300 if one holds radiative forcing fixed after 2100. The dominance of the fast component at present is supported by examining the response to an instantaneous doubling of CO2 and by the excellent fit to the model?s ensemble mean twentieth-century evolution with a simple one-box model with no long times scales.},
author = {Held, Isaac M. and Winton, Michael and Takahashi, Ken and Delworth, Thomas and Zeng, Fanrong and Vallis, Geoffrey K.},
doi = {10.1175/2009JCLI3466.1},
isbn = {0894-8755$\backslash$n1520-0442},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jan},
number = {9},
pages = {2418--2427},
publisher = {American Meteorological Society},
title = {{Probing the Fast and Slow Components of Global Warming by Returning Abruptly to Preindustrial Forcing}},
url = {https://doi.org/10.1175/2009JCLI3466.1},
volume = {23},
year = {2010}
}
@article{Hellweg1109,
abstract = {In the modern economy, international value chains{\{}$\backslash$textemdash{\}}production, use, and disposal of goods{\{}$\backslash$textemdash{\}}have global environmental impacts. Life Cycle Assessment (LCA) aims to track these impacts and assess them from a systems perspective, identifying strategies for improvement without burden shifting. We review recent developments in LCA, including existing and emerging applications aimed at supporting environmentally informed decisions in policy-making, product development and procurement, and consumer choices. LCA constitutes a viable screening tool that can pinpoint environmental hotspots in complex value chains, but we also caution that completeness in scope comes at the price of simplifications and uncertainties. Future advances of LCA in enhancing regional detail and accuracy as well as broadening the assessment to economic and social aspects will make it more relevant for producers and consumers alike.},
author = {Hellweg, Stefanie and {Mil{\`{a}} i Canals}, Lloren{\c{c}}},
doi = {10.1126/science.1248361},
issn = {0036-8075},
journal = {Science},
number = {6188},
pages = {1109--1113},
publisher = {American Association for the Advancement of Science},
title = {{Emerging approaches, challenges and opportunities in life cycle assessment}},
url = {https://science.sciencemag.org/content/344/6188/1109},
volume = {344},
year = {2014}
}
@article{Heyn2017,
abstract = {In its 5th assessment report (AR5), the IPCC provides a best estimate of the effective radiative forcing (ERF) due to anthropogenic aerosol at −0.9Wm−2. This value is considerably weaker than the estimate of −1.2Wm−2 in AR4. A part of the difference can be explained by an offset of +0.2Wm−2 which AR5 added to all published estimates that only considered the solar spectrum, in order to account for adjustments in the terrestrial spectrum. We find that, in the CMIP5 multi-model median, the ERF in the terrestrial spectrum is small, unless microphysical effects on ice- and mixed-phase clouds are parameterized. In the latter case it is large but accompanied by a very strong ERF in the solar spectrum. The total adjustments can be separated into microphysical adjustments (aerosol “effects”) and thermodynamic adjustments. Using a kernel technique, we quantify the latter and find that the rapid thermodynamic adjustments of water vapor and temperature profiles are small. Observations-based constraints on these model results are urgently needed.},
author = {Heyn, Irene and Block, Karoline and M{\"{u}}lmenst{\"{a}}dt, Johannes and Gryspeerdt, Edward and K{\"{u}}hne, Philipp and Salzmann, Marc and Quaas, Johannes},
doi = {10.1002/2016GL071975},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {jan},
number = {2},
pages = {1001--1007},
title = {{Assessment of simulated aerosol effective radiative forcings in the terrestrial spectrum}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2016GL071975},
volume = {44},
year = {2017}
}
@incollection{HockR.Rasul2019,
author = {Hock, R. and Rasul, G. and Adler, C. and C{\'{a}}ceres, B. and Gruber, S. and Hirabayashi, Y. and Jackson, M. and K{\"{a}}{\"{a}}b, A. and Kang, S. and Kutuzov, S. and Milner, Al. and Molau, U. and Morin, S. and Orlove, B. and Steltzer, H.},
booktitle = {IPCC Special Report on the Ocean and Cryosphere in a Changing Climate},
editor = {Pörtner, H.-O. and Roberts, D.C. and Masson-Delmotte, V. and Zhai, P. and Tignor, M. and Poloczanska, E. and Mintenbeck, K. and Alegría, A. and Nicolai, M. and Okem, A. and Petzold, J. and Rama, B. and Weyer, N.M.},
pages = {131--202},
publisher = {In Press},
title = {{High Mountain Areas}},
url = {https://www.ipcc.ch/srocc/chapter/chapter-2},
year = {2019}
}
@article{Hodnebrog2018,
abstract = {{\textcopyright} 2018 The Authors. Atmospheric Science Letters published by John Wiley {\&} Sons Ltd on behalf of the Royal Meteorological Society. The atmospheric abundance of the non-methane volatile organic compounds (NMVOCs) ethane, propane, and butane increased during the industrial era. In addition to weak absorption and emission of longwave radiation, these gases influence the atmospheric radiative balance indirectly, mainly as precursors for ozone (O 3 ), and through reaction with the hydroxyl radical (OH), which leads to less OH and thereby longer atmospheric lifetime of methane (CH 4 ). In this study, we have calculated lifetimes, direct and indirect radiative forcing (RF), and global warming potentials (GWPs) for the three compounds, using a self-consistent methodology. Results show net RF per unit emission of 1.0, 0.9, and 0.6 mW m −2 (Tg year −1 ) −1 for ethane, propane, and butane, respectively. For all compounds, the direct effect is considerably smaller than the indirect effects (6{\%} or less of the total). The indirect O 3 and CH 4 effects are approximately of the same magnitude. Net GWPs for a 100-year time horizon are 10 for ethane and propane, and 7 for butane, whereof the direct GWPs are {\textless} 1 for all compounds. The net GWPs are generally higher than previous estimates, mainly because our calculations include emissions for a full year rather than one season. For the compounds studied here, 100-year GWP values do not differ substantially between each compound, considering the large uncertainties involved, and this may indicate that using values representative for a lump of NMVOCs may be sufficient. However, the climate effects may differ more between NMVOC compounds other than alkanes, such as alkenes and aromatics.},
author = {Hodnebrog, {\O}ivind and Dals{\o}ren, Stig B. and Myhre, Gunnar},
doi = {10.1002/asl.804},
issn = {1530261X},
journal = {Atmospheric Science Letters},
keywords = {GWP,butane,ethane,propane,radiative forcing},
number = {2},
pages = {e804},
title = {{Lifetimes, direct and indirect radiative forcing, and global warming potentials of ethane (C2H6), propane (C3H8), and butane (C4H10)}},
volume = {19},
year = {2018}
}
@article{Hodnebrog2020,
author = {Hodnebrog, {\O}. and Aamaas, B. and Fuglestvedt, J. S. and Marston, G. and Myhre, G. and Nielsen, C. J. and Sandstad, M. and Shine, K. P. and Wallington, T. J.},
doi = {10.1029/2019RG000691},
issn = {8755-1209},
journal = {Reviews of Geophysics},
month = {sep},
number = {3},
pages = {e2019RG000691},
title = {{Updated Global Warming Potentials and Radiative Efficiencies of Halocarbons and Other Weak Atmospheric Absorbers}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2019RG000691},
volume = {58},
year = {2020}
}
@article{Hodnebrog2020a,
abstract = {Rapid adjustments occur after initial perturbation of an external climate driver (e.g., CO 2) and involve changes in, e.g. atmospheric temperature, water vapour and clouds, independent of sea surface temperature changes. Knowledge of such adjustments is necessary to estimate effective radiative forcing (ERF), a useful indicator of surface temperature change, and to understand global precipitation changes due to different drivers. Yet, rapid adjustments have not previously been analysed in any detail for certain compounds, including halocarbons and N 2 O. Here we use several global climate models combined with radiative kernel calculations to show that individual rapid adjustment terms due to CFC-11, CFC-12 and N 2 O are substantial, but that the resulting flux changes approximately cancel at the top-of-atmosphere due to compensating effects. Our results further indicate that radiative forcing (which includes stratospheric temperature adjustment) is a reasonable approximation for ERF. These CFCs lead to a larger increase in precipitation per kelvin surface temperature change (2.2 ± 0.3{\%} K −1) compared to other well-mixed greenhouse gases (1.4 ± 0.3{\%} K −1 for CO 2). This is largely due to rapid upper tropospheric warming and cloud adjustments, which lead to enhanced atmospheric radiative cooling (and hence a precipitation increase) and partly compensate increased atmospheric radiative heating (i.e. which is associated with a precipitation decrease) from the instantaneous perturbation. npj Climate and Atmospheric Science (2020) 3:43 ; https://doi.org/10.1038/s41612-020-00150-x Ozone-depleting halocarbons and nitrous oxide (N 2 O) are well-mixed greenhouse gases that have contributed substantially to radiative forcing (RF) since pre-industrial time, by 0.33 ± 0.03 W m −2 (0.18 ± 0.17 W m −2 when including stratospheric ozone depletion) and 0.17 ± 0.03 W m −2 , respectively 1. A substantial contribution to global warming and Arctic sea-ice loss in the latter half of the 20th century was recently attributed to ozone-depleting substances 2,3. Atmospheric lifetimes of chlorofluorocar-bons (CFCs), an important group of ozone-depleting halocarbons, are typically several decades or centuries 4. Their impact on climate will therefore remain strong for many years to come despite regulations of halocarbon emissions through the Montreal Protocol signed in 1987. Most halocarbons, such as CFC-12, have their main infrared absorption bands at different spectral wavelengths compared to the two main anthropogenic greenhouse gases CO 2 and methane (CH 4), in the so-called atmospheric window region around 800-1200 cm −1 where the RF efficiency is strong 5,6. The main infrared absorption bands of N 2 O partly overlap with CH 4 , but an important difference is that CH 4 has more significant shortwave (SW) absorption bands 7,8. Although these factors may imply that the climate effects of halocarbons and N 2 O differ from those of CO 2 and CH 4 , relatively little is known about the details of short and long-term responses of halocarbons and N 2 O on climate. While numerous studies exist on radiative transfer modelling of halocarbons, only a few studies have performed global climate model (GCM) experiments to investigate the climate effects of halocarbons separately. Hansen et al. 9,10 found that the surface temperature response to a large forcing of CFCs and N 2 O had very similar geographical patterns as the response to CO 2 and CH 4 forcing. The efficacies (i.e. the warming per unit RF) for CFCs were, however, around 30{\%} larger than for CO 2 , but close to unity for CFCs and N 2 O when rapid adjustments were accounted for, as also found in a recent multi-model study 11. Forster and Joshi 12 investigated halocarbon contributions to atmospheric temperature change and found a significant warming at the tropical tropopause; e.g. this led to a {\~{}}6{\%} weaker surface warming per unit forcing for CFC-12 compared to CO 2. In the 5th Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), RF was diagnosed as effective radiative forcing (ERF), which includes instantaneous radiative forcing (IRF) and rapid adjustments including stratospheric temperature adjustment 1,13,14. These fast responses occur on timescales of days to months, before most of the changes in the global-mean and annual-mean surface temperature occur. ERF is shown to be a better indicator for surface temperature change than the earlier RF definition (RF which includes stratospheric temperature adjustment), and rapid adjustments have recently been quantified for some of the most important climate drivers 15,16. However, for halocarbons and N 2 O, contributions of different rapid adjustment terms remain largely unknown, with},
author = {Hodnebrog, {\O}ivind and Myhre, Gunnar and Kramer, Ryan J and Shine, Keith P and Andrews, Timothy and Faluvegi, Gregory and Kasoar, Matthew and Kirkev{\aa}g, Alf and Lamarque, Jean-Fran{\c{c}}ois and M{\"{u}}lmenst{\"{a}}dt, Johannes and Olivi{\'{e}}, Dirk and Samset, Bj{\o}rn H and Shindell, Drew and Smith, Christopher J and Takemura, Toshihiko and Voulgarakis, Apostolos},
doi = {https://doi.org/10.1038/s41612-020-00150-x},
journal = {npj Climate and Atmospheric Science},
number = {1},
pages = {43},
title = {{The effect of rapid adjustments to halocarbons and N2O on radiative forcing}},
url = {https://doi.org/10.1038/s41612-020-00150-x},
volume = {3},
year = {2020}
}
@article{Hoesly2018,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} We present a new data set of annual historical (1750–2014) anthropogenic chemically reactive gases (CO, CH{\textless}sub{\textgreater}4{\textless}/sub{\textgreater}, NH{\textless}sub{\textgreater}3{\textless}/sub{\textgreater}, NO{\textless}sub{\textgreater}x{\textless}/sub{\textgreater}, SO{\textless}sub{\textgreater}2{\textless}/sub{\textgreater}, NMVOCs), carbonaceous aerosols (black carbon – BC, and organic carbon – OC), and CO{\textless}sub{\textgreater}2{\textless}/sub{\textgreater} developed with the Community Emissions Data System (CEDS). We improve upon existing inventories with a more consistent and reproducible methodology applied to all emission species, updated emission factors, and recent estimates through 2014. The data system relies on existing energy consumption data sets and regional and country-specific inventories to produce trends over recent decades. All emission species are consistently estimated using the same activity data over all time periods. Emissions are provided on an annual basis at the level of country and sector and gridded with monthly seasonality. These estimates are comparable to, but generally slightly higher than, existing global inventories. Emissions over the most recent years are more uncertain, particularly in low- and middle-income regions where country-specific emission inventories are less available. Future work will involve refining and updating these emission estimates, estimating emissions' uncertainty, and publication of the system as open-source software.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Hoesly, Rachel M. and Smith, Steven J. and Feng, Leyang and Klimont, Zbigniew and Janssens-Maenhout, Greet and Pitkanen, Tyler and Seibert, Jonathan J. and Vu, Linh and Andres, Robert J. and Bolt, Ryan M. and Bond, Tami C. and Dawidowski, Laura and Kholod, Nazar and Kurokawa, June-ichi and Li, Meng and Liu, Liang and Lu, Zifeng and Moura, Maria Cecilia P. and O{\&}apos;Rourke, Patrick R. and Zhang, Qiang},
doi = {10.5194/gmd-11-369-2018},
issn = {1991-9603},
journal = {Geoscientific Model Development},
month = {jan},
number = {1},
pages = {369--408},
title = {{Historical (1750–2014) anthropogenic emissions of reactive gases and aerosols from the Community Emissions Data System (CEDS)}},
url = {https://www.geosci-model-dev.net/11/369/2018/},
volume = {11},
year = {2018}
}
@article{Holland2003,
abstract = {The Northern Hemisphere polar amplification of climate change is documented$\backslash$nin models taking part in the Coupled Model Intercomparison Project$\backslash$nand in the new version of the Community Climate System Model. In$\backslash$nparticular, the magnitude, spatial distribution, and seasonality$\backslash$nof the surface warming in the Arctic is examined and compared among$\backslash$nthe models. The range of simulated polar warming in the Arctic is$\backslash$nfrom 1.5 to 4.5 times the global mean warming. While ice-albedo feedback$\backslash$nis likely to account for much of the polar amplification, the strength$\backslash$nof the feedback depends on numerous physical processes and parametrizations$\backslash$nwhich differ considerably among the models. Nonetheless, the mean$\backslash$nsea-ice state in the control (or present) climate is found to influence$\backslash$nboth the magnitude and spatial distribution of the high-latitude$\backslash$nwarming in the models. In particular, the latitude of the maximum$\backslash$nwarming is correlated inversely and significantly with sea-ice extent$\backslash$nin the control climate. Additionally, models with relatively thin$\backslash$nArctic ice cover in the control climate tend to have higher polar$\backslash$namplification. An intercomparison of model results also shows that$\backslash$nincreases in poleward ocean heat transport at high latitudes and$\backslash$nincreases in polar cloud cover are significantly correlated to amplified$\backslash$nArctic warming. This suggests that these changes in the climate state$\backslash$nmay modify polar amplification. No significant correlation is found$\backslash$nbetween polar amplification and the control climate continental ice$\backslash$nand snow cover.},
author = {Holland, M. M. and Bitz, C. M.},
doi = {10.1007/s00382-003-0332-6},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {sep},
number = {3-4},
pages = {221--232},
title = {{Polar amplification of climate change in coupled models}},
url = {http://link.springer.com/10.1007/s00382-003-0332-6},
volume = {21},
year = {2003}
}
@article{gmd-12-3149-2019,
abstract = {Abstract. The early Eocene (56 to 48 million years ago) is inferred to have been the most recent time that Earth's atmospheric CO2 concentrations exceeded 1000 ppm. Global mean temperatures were also substantially warmer than those of the present day. As such, the study of early Eocene climate provides insight into how a super-warm Earth system behaves and offers an opportunity to evaluate climate models under conditions of high greenhouse gas forcing. The Deep Time Model Intercomparison Project (DeepMIP) is a systematic model–model and model–data intercomparison of three early Paleogene time slices: latest Paleocene, Paleocene–Eocene thermal maximum (PETM) and early Eocene climatic optimum (EECO). A previous article outlined the model experimental design for climate model simulations. In this article, we outline the methodologies to be used for the compilation and analysis of climate proxy data, primarily proxies for temperature and CO2. This paper establishes the protocols for a concerted and coordinated effort to compile the climate proxy records across a wide geographic range. The resulting climate “atlas” will be used to constrain and evaluate climate models for the three selected time intervals and provide insights into the mechanisms that control these warm climate states. We provide version 0.1 of this database, in anticipation that this will be expanded in subsequent publications.},
author = {Hollis, C J and {Dunkley Jones}, Tom and Anagnostou, Eleni and Bijl, Peter K. and Cramwinckel, Margot J. and Cui, Ying and Dickens, Gerald R. and Edgar, Kirsty M. and Eley, Yvette and Evans, David and Foster, Gavin L. and Frieling, Joost and Inglis, Gordon N. and Kennedy, Elizabeth M. and Kozdon, Reinhard and Lauretano, Vittoria and Lear, Caroline H. and Littler, Kate and Lourens, Lucas and Meckler, A. Nele and Naafs, B. David A. and P{\"{a}}like, Heiko and Pancost, Richard D. and Pearson, Paul N. and R{\"{o}}hl, Ursula and Royer, Dana L. and Salzmann, Ulrich and Schubert, Brian A. and Seebeck, Hannu and Sluijs, Appy and Speijer, Robert P. and Stassen, Peter and Tierney, Jessica and Tripati, Aradhna and Wade, Bridget and Westerhold, Thomas and Witkowski, Caitlyn and Zachos, James C. and Zhang, Yi Ge and Huber, Matthew and Lunt, Daniel J.},
doi = {10.5194/gmd-12-3149-2019},
issn = {1991-9603},
journal = {Geoscientific Model Development},
month = {jul},
number = {7},
pages = {3149--3206},
title = {{The DeepMIP contribution to PMIP4: methodologies for selection, compilation and analysis of latest Paleocene and early Eocene climate proxy data, incorporating version 0.1 of the DeepMIP database}},
url = {https://www.geosci-model-dev.net/12/3149/2019/},
volume = {12},
year = {2019}
}
@article{Holloway2017,
abstract = {Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.},
author = {Holloway, Christopher E and Wing, Allison A and Bony, Sandrine and Muller, Caroline and Masunaga, Hirohiko and L'Ecuyer, Tristan S and Turner, David D and Zuidema, Paquita},
doi = {10.1007/s10712-017-9419-1},
issn = {1573-0956},
journal = {Surveys in Geophysics},
month = {nov},
number = {6},
pages = {1199--1236},
title = {{Observing Convective Aggregation}},
url = {https://doi.org/10.1007/s10712-017-9419-1},
volume = {38},
year = {2017}
}
@article{Hopcroft2015a,
abstract = {Previous work demonstrated a significant correlation between tropical surface air temperature and equilibrium climate sensitivity (ECS) in PMIP (Paleoclimate Modelling Intercomparison Project) phase 2 model simulations of the last glacial maximum (LGM). This implies that reconstructed LGM cooling in this region could provide information about the climate system ECS value. We analyze results from new simulations of the LGM performed as part of Coupled Model Intercomparison Project (CMIP5) and PMIP phase 3. These results show no consistent relationship between the LGM tropical cooling and ECS. A radiative forcing and feedback analysis shows that a number of factors are responsible for this decoupling, some of which are related to vegetation and aerosol feedbacks. While several of the processes identified are LGM specific and do not impact on elevated CO2 simulations, this analysis demonstrates one area where the newer CMIP5 models behave in a qualitatively different manner compared with the older ensemble. The results imply that so-called Earth System components such as vegetation and aerosols can have a significant impact on the climate response in LGM simulations, and this should be taken into account in future analyses.},
author = {Hopcroft, Peter O. and Valdes, Paul J.},
doi = {10.1002/2015GL064903},
isbn = {00948276},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {CMIP5,Earth System,LGM,cloud radiative effects,feedbacks},
number = {13},
pages = {5533--5539},
title = {{How well do simulated last glacial maximum tropical temperatures constrain equilibrium climate sensitivity?}},
volume = {42},
year = {2015}
}
@article{Hourdin2017a,
abstract = {AbstractThe process of parameter estimation targeting a chosen set of observations is an essential aspect of numerical modeling. This process is usually named tuning in the climate modeling community. In climate models, the variety and complexity of physical processes involved, and their interplay through a wide range of spatial and temporal scales, must be summarized in a series of approximate submodels. Most submodels depend on uncertain parameters. Tuning consists of adjusting the values of these parameters to bring the solution as a whole into line with aspects of the observed climate. Tuning is an essential aspect of climate modeling with its own scientific issues, which is probably not advertised enough outside the community of model developers. Optimization of climate models raises important questions about whether tuning methods a priori constrain the model results in unintended ways that would affect our confidence in climate projections. Here, we present the definition and rationale behind model tuning, review specific methodological aspects, and survey the diversity of tuning approaches used in current climate models. We also discuss the challenges and opportunities in applying so-called objective methods in climate model tuning. We discuss how tuning methodologies may affect fundamental results of climate models, such as climate sensitivity. The article concludes with a series of recommendations to make the process of climate model tuning more transparent.},
author = {Hourdin, Fr{\'{e}}d{\'{e}}ric and Mauritsen, Thorsten and Gettelman, Andrew and Golaz, Jean-Christophe and Balaji, Venkatramani and Duan, Qingyun and Folini, Doris and Ji, Duoying and Klocke, Daniel and Qian, Yun and Rauser, Florian and Rio, Catherine and Tomassini, Lorenzo and Watanabe, Masahiro and Williamson, Daniel},
doi = {10.1175/BAMS-D-15-00135.1},
isbn = {9780321733016},
issn = {0003-0007},
journal = {Bulletin of the American Meteorological Society},
month = {jul},
number = {3},
pages = {589--602},
publisher = {American Meteorological Society},
title = {{The Art and Science of Climate Model Tuning}},
url = {https://doi.org/10.1175/BAMS-D-15-00135.1 http://journals.ametsoc.org/doi/10.1175/BAMS-D-15-00135.1},
volume = {98},
year = {2017}
}
@article{Howard2018,
abstract = {We report on the carbon footprint of 22 scenario pathways for the transition of the Australian electricity sector to predominantly renewable energy (RE). The analysis employs a dynamic and discrete numerical model that takes into account what we have termed renewable energy ‘breeding', i.e. RE technologies are being made increasingly with renewable electricity as the transition progresses. Our results show that every scenario under investigation fails to achieve the sector's share of Australia's national carbon budget for a 1.5 °C global warming limit and around one-third fail the 2 °C target by 2050. In most of the scenarios considered, the reduction in annual life-cycle CO2e emissions in the year 2050, from taking into account the effect of RE breeding, was substantial, in some cases reducing annual emissions by more than 90{\%}. But, the reduction in cumulative CO2e emissions resulting from RE breeding only became significant post-2040. Unless a very rapid transition is made to more than 80{\%} renewable electricity in Australia well before mid-century, any positive ‘breeding' effect is simply dwarfed by fossil-fuel derived emissions prior to and during the actual transition. Therefore, early, decisive, wide-scale deployment of a suitable mix of RE technologies is needed to reduce cumulative emissions.},
author = {Howard, Bahareh Sara and Hamilton, Nicholas E. and Diesendorf, Mark and Wiedmann, Thomas},
doi = {10.1016/j.renene.2018.02.013},
issn = {18790682},
journal = {Renewable Energy},
keywords = {CO2 emissions,Carbon budget,Carbon footprint,Energy transition,Scenario modeling},
month = {sep},
pages = {712--728},
publisher = {Elsevier Ltd},
title = {{Modeling the carbon budget of the Australian electricity sector's transition to renewable energy}},
volume = {125},
year = {2018}
}
@article{Hua2018,
abstract = {Abstract There is substantial uncertainty in the relative contributions of internal variability and external forcing to the recent Pacific decadal variability, especially regarding their linkage with the Interdecadal Pacific Oscillation. By analyzing observations and large ensembles of coupled climate model simulations, here we show that observed Pacific decadal variations since 1920 resulted primarily from internal variability, although greenhouse gas (GHG) and other external forcing did modulate decadal variations in Pacific sea surface temperatures (SSTs) significantly, especially for the period since the early 1990s. Specifically, the GHG-induced warming and the recovery from the volcanic cooling caused by the 1991 Pinatubo eruption led to large warming in the tropical Pacific during 1993–2012, while recent anthropogenic aerosols contributed to Pacific regional SST variations on multiyear to decadal scales, causing a La Ni{\~{n}}a-like cooling pattern in the Pacific since 1998 in some of the models. Our results provide new evidence that both internal variability and external forcing have contributed to the recent decadal variations in Pacific SSTs since the early 1990s, although large uncertainties exist among the model-simulated effects of anthropogenic aerosols.},
author = {Hua, Wenjian and Dai, Aiguo and Qin, Minhua},
doi = {10.1029/2018GL079033},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {Interdecadal Pacific Oscillation,Pacific decadal variations,external forcing,internal variability},
month = {jul},
number = {14},
pages = {7084--7092},
publisher = {Blackwell Publishing Ltd},
title = {{Contributions of Internal Variability and External Forcing to the Recent Pacific Decadal Variations}},
volume = {45},
year = {2018}
}
@article{Huang2017f,
abstract = {A set of general circulation model experiments are conducted to analyze how the poleward energy transport (PET) is related to the spatial pattern of CO2 radiative forcing. The effects of forcing pattern are affirmed by comparing the conventional doubling CO2 experiment, in which the forcing pattern is inhomogeneous, to a set of forcing homogenization experiments, in which the top of atmosphere (TOA), surface, or atmospheric forcing distribution is homogenized respectively. In addition, we separate and compare the effects of CO2 forcing to various feedbacks on atmospheric and oceanic PETs, by using a set of radiative kernels that we have developed for both TOA and surface radiation fluxes. The results here show that both the enhancement of atmospheric PET and weakening of oceanic PET during global warming are directly driven by the meridional gradients of the CO2 forcing. Interestingly, the overall feedback effect is to reinforce the forcing effect, mainly through the cloud feedback in the case of atmospheric PET and the albedo feedback in the case of the oceanic PET. Contrary to previous studies, we find that the water vapor feedback only has a weak effect on atmospheric PET. The Arctic warming amplification, which strongly affects atmospheric PET, is sensitive to the CO2 forcing pattern.},
author = {Huang, Yi and Xia, Yan and Tan, Xiaoxiao},
doi = {10.1002/2017JD027221},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {CO2,Poleward Energy Transport,Radiative forcing,arctic amplification,climate feedback,water vapor},
number = {20},
pages = {10578--10593},
title = {{On the pattern of CO2 radiative forcing and poleward energy transport}},
volume = {122},
year = {2017}
}
@article{Huang2014a,
abstract = {The distributions of radiative forcing and feedback in the CMIP5 abrupt4xCO2 and Historical experiments are diagnosed, with a focus on their effects on the zonal mean structure of the top-of-the-atmosphere radiation anomalies and implications for the meridional energy transport. It is found that because the greenhouse gas longwave forcing peaks in the low latitudes it reinforces the equator-to-pole net radiation gradient and accounts for the increase in the poleward energy transport in both hemispheres under global warming. The shortwave forcing by aerosol, ozone, etc. peaks in the northern hemisphere and instead implies an inter-hemispheric energy transport. Although the water vapor feedback also reinforces the equator-to-pole gradient of the net radiation, the temperature and albedo feedbacks act against it. The feedbacks tend to offset the zonal mean radiation anomaly caused by the forcing, although the overall feedback effect on the energy transport is rather uncertain, mainly due to the uncertainty in the cloud feedback.},
author = {Huang, Yi and Zhang, Minghong},
doi = {10.1002/2013GL059079},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate feedback,poleward energy transport,radiative forcing},
month = {mar},
number = {5},
pages = {1665--1672},
pmid = {20944749},
title = {{The implication of radiative forcing and feedback for meridional energy transport}},
url = {http://doi.wiley.com/10.1002/2013GL059079},
volume = {41},
year = {2014}
}
@article{Huang2019a,
abstract = {Surface Solar Irradiance (SSI) is a key parameter dictating surface-atmosphere interactions, driving radiative, hydrological, and land surface processes, and can thus impinge greatly upon weather and climate. It is thereby a prerequisite of many studies and applications. Estimating SSI from satellites began in the 1960s, and is currently the principal way to map SSI spatiotemporal distributions from regional to global scales. Starting from an overview of historical studies carried out in the past several decades, this paper reviews the progresses made in methodology, validation, and products over these years. First, the requirements of SSI in various studies or applications are presented along with the theoretical background of SSI satellite estimation. Methods to estimate SSI from satellites are then summarized as well as their advantages and limitations. Validations of satellite-based SSI on two typical spatial scales are discussed followed by a brief description of existing products and their accuracies. Finally, the challenges faced by current SSI satellite estimation are analyzed, and possible improvements to implement in the future are suggested. This review not only updates the review paper by Pinker et al. (1995) on satellite methods to derive SSI but also offers a more comprehensive summary of the related studies and applications.},
author = {Huang, Guanghui and Li, Zhanqing and Li, Xin and Liang, Shunlin and Yang, Kun and Wang, Dongdong and Zhang, Yi},
doi = {10.1016/J.RSE.2019.111371},
issn = {0034-4257},
journal = {Remote Sensing of Environment},
month = {nov},
pages = {111371},
publisher = {Elsevier},
title = {{Estimating surface solar irradiance from satellites: Past, present, and future perspectives}},
url = {https://www.sciencedirect.com/science/article/pii/S0034425719303906},
volume = {233},
year = {2019}
}
@article{Huang2016,
abstract = {The radiative impacts of the stratosphere in global warming simulations are investigated using abrupt CO2 quadrupling experiments of the Coupled Model Inter-comparison Project phase 5 (CMIP5), with a focus on stratospheric temperature and water vapor. It is found that the stratospheric temperature change has a robust bullhorn-like zonal-mean pattern due to a strengthening of the stratospheric overturning circulation. This temperature change modifies the zonal mean top-of-the-atmosphere energy balance, but the compensation of the regional effects leads to an insignificant global-mean radiative feedback (−0.02 {\{}$\backslash$textpm{\}} 0.04 W m−2 K−1). The stratospheric water vapor concentration generally increases, which leads to a weak positive global-mean radiative feedback (0.02 {\{}$\backslash$textpm{\}} 0.01 W m−2 K−1). The stratospheric moistening is related to mixing of elevated upper-tropospheric humidity, and, to a lesser extent, to change in tropical tropopause temperature. Our results indicate that the strength of the stratospheric water vapor feedback is noticeably larger in high-top models than in low-top ones. The results here indicate that although its radiative impact as a forcing adjustment is significant, the stratosphere makes a minor contribution to the overall climate feedback in CMIP5 models.},
author = {Huang, Yi and Zhang, Minghong and Xia, Yan and Hu, Yongyun and Son, Seok-Woo},
doi = {10.1007/s00382-015-2577-2},
issn = {1432-0894},
journal = {Climate Dynamics},
month = {jan},
number = {1},
pages = {177--186},
title = {{Is there a stratospheric radiative feedback in global warming simulations?}},
url = {https://doi.org/10.1007/s00382-015-2577-2},
volume = {46},
year = {2016}
}
@article{doi:10.1029/2020GL087987,
abstract = {Abstract Most global climate models project a considerable stratospheric moistening during global warming. It is important to quantify how significantly the increase of stratospheric humidity affects the radiation budget and contributes to the surface warming. Here, we conduct a mechanism denial experiment to investigate the warming effect of the stratospheric water vapor (SWV) using a global climate model. By locking the SWV in a quadrupling CO2 experiment, we find that the surface warming effect of SWV is not as significant as previously thought, increasing the global mean surface warming by about 2{\%}. This is due to compensating changes in other feedback, especially those of tropospheric temperature and cloud, affected by SWV.},
annote = {e2020GL087987 2020GL087987},
author = {Huang, Yi and Wang, Yuwei and Huang, Han},
doi = {10.1029/2020GL087987},
journal = {Geophysical Research Letters},
keywords = {carbon dioxide,climate model,global warming,radiative feedback,radiative forcing,stratospheric water vapor},
number = {12},
pages = {e2020GL087987},
title = {{Stratospheric Water Vapor Feedback Disclosed by a Locking Experiment}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL087987},
volume = {47},
year = {2020}
}
@article{cp-7-603-2011,
author = {Huber, M and Caballero, R},
doi = {10.5194/cp-7-603-2011},
journal = {Climate of the Past},
number = {2},
pages = {603--633},
title = {{The early Eocene equable climate problem revisited}},
url = {https://www.clim-past.net/7/603/2011/},
volume = {7},
year = {2011}
}
@article{Huber2010,
abstract = {Abstract The estimated range of climate sensitivity, the equilibrium warming resulting from a doubling of the atmospheric carbon dioxide concentration, has not decreased substantially in past decades. New statistical methods for estimating the climate sensitivity have been proposed and provide a better quantification of relative probabilities of climate sensitivity within the almost canonical range of 2?4.5 K; however, large uncertainties remain, in particular for the upper bound. Simple indices of spatial radiation patterns are used here to establish a relationship between an observable radiative quantity and the equilibrium climate sensitivity. The indices are computed for the Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset and offer a possibility to constrain climate sensitivity by considering radiation patterns in the climate system. High correlations between the indices and climate sensitivity are found, for example, in the cloud radiative forcing of the incoming longwave surface radiation and in the clear-sky component of the incoming surface shortwave flux, the net shortwave surface budget, and the atmospheric shortwave attenuation variable ?. The climate sensitivity was estimated from the mean of the indices during the years 1990?99 for the CMIP3 models. The surface radiative flux dataset from the Clouds and the Earth?s Radiant Energy System (CERES) together with its top-of-atmosphere Energy Balanced and Filled equivalent (CERES EBAF) are used as a reference observational dataset, resulting in a best estimate for climate sensitivity of 3.3 K with a likely range of 2.7?4.0 K. A comparison with other satellite and reanalysis datasets show similar likely ranges and best estimates of 1.7?3.8 (3.3 K) [Earth Radiation Budget Experiment (ERBE)], 2.9?3.7 (3.3 K) [International Satellite Cloud Climatology Project radiative surface flux data (ISCCP-FD)], 2.8?4.1 (3.5 K) [NASA?s Modern Era Retrospective-Analysis for Research and Application (MERRA)], 3.0?4.2 (3.6 K) [Japanese 25-yr Reanalysis (JRA-25)], 2.7?3.9 (3.4 K) [European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-Interim)], 3.0?4.0 (3.5 K) [ERA-40], and 3.1?4.7 (3.6 K) for the NCEP reanalysis. For each individual reference dataset, the results suggest that values for the sensitivity below 1.7 K are not likely to be consistent with observed radiation patterns given the structure of current climate models. For the aggregation of the reference datasets, the climate sensitivity is not likely to be below 2.9 K within the framework of this study, whereas values exceeding 4.5 K cannot be excluded from this analysis. While these ranges cannot be interpreted properly in terms of probability, they are consistent with other estimates of climate sensitivity and reaffirm that the current climatology provides a strong constraint on the lower bound of climate sensitivity even in a set of structurally different models.},
annote = {doi: 10.1175/2010JCLI3403.1},
author = {Huber, Markus and Mahlstein, Irina and Wild, Martin and Fasullo, John and Knutti, Reto},
doi = {10.1175/2010JCLI3403.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {4},
pages = {1034--1052},
publisher = {American Meteorological Society},
title = {{Constraints on Climate Sensitivity from Radiation Patterns in Climate Models}},
url = {https://doi.org/10.1175/2010JCLI3403.1},
volume = {24},
year = {2010}
}
@article{Hurtt2011a,
abstract = {In preparation for the fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), the international community is developing new advanced Earth System Models (ESMs) to assess the combined effects of human activities (e.g. land use and fossil fuel emissions) on the carbon-climate system. In addition, four Representative Concentration Pathway (RCP) scenarios of the future (2005–2100) are being provided by four Integrated Assessment Model (IAM) teams to be used as input to the ESMs for future carbon-climate projections (Moss et al. 2010). The diversity of approaches and requirements among IAMs and ESMs for tracking land-use change, along with the dependence of model projections on land-use history, presents a challenge for effectively passing data between these communities and for smoothly transitioning from the historical estimates to future projections. Here, a harmonized set of land-use scenarios are presented that smoothly connects historical reconstructions of land use with future projections, in the format required by ESMs. The land-use harmonization strategy estimates fractional land-use patterns and underlying land-use transitions annually for the time period 1500–2100 at 0.5° × 0.5° resolution. Inputs include new gridded historical maps of crop and pasture data from HYDE 3.1 for 1500–2005, updated estimates of historical national wood harvest and of shifting cultivation, and future information on crop, pasture, and wood harvest from the IAM implementations of the RCPs for the period 2005–2100. The computational method integrates these multiple data sources, while minimizing differences at the transition between the historical reconstruction ending conditions and IAM initial conditions, and working to preserve the future changes depicted by the IAMs at the grid cell level. This study for the first time harmonizes land-use history data together with future scenario information from multiple IAMs into a single consistent, spatially gridded, set of land-use change scenarios for studies of human impacts on the past, present, and future Earth system.},
author = {Hurtt, G. C. and Chini, L. P. and Frolking, S. and Betts, R. A. and Feddema, J. and Fischer, G. and Fisk, J. P. and Hibbard, K. and Houghton, R. A. and Janetos, A. and Jones, C. D. and Kindermann, G. and Kinoshita, T. and {Klein Goldewijk}, Kees and Riahi, K. and Shevliakova, E. and Smith, S. and Stehfest, E. and Thomson, A. and Thornton, P. and van Vuuren, D. P. and Wang, Y. P.},
doi = {10.1007/s10584-011-0153-2},
issn = {0165-0009},
journal = {Climatic Change},
month = {nov},
number = {1-2},
pages = {117--161},
title = {{Harmonization of land-use scenarios for the period 1500–2100: 600 years of global gridded annual land-use transitions, wood harvest, and resulting secondary lands}},
url = {http://link.springer.com/10.1007/s10584-011-0153-2},
volume = {109},
year = {2011}
}
@article{ISI:000272441700002,
abstract = {A 94-year time series of annual glacier melt at four high elevation sites in the European Alps is used to investigate the effect of global dimming and brightening of solar radiation on glacier mass balance. Snow and ice melt was stronger in the 1940s than in recent years, in spite of significantly higher air temperatures in the present decade. An inner Alpine radiation record shows that in the 1940s global shortwave radiation over the summer months was 8{\%} above the long-term average and significantly higher than today, favoring rapid glacier mass loss. Dimming of solar radiation from the 1950s until the 1980s is in line with reduced melt rates and advancing glaciers. Citation: Huss, M., M. Funk, and A. Ohmura (2009), Strong Alpine glacier melt in the 1940s due to enhanced solar radiation, Geophys. Res. Lett., 36, L23501, doi:10.1029/2009GL040789.},
author = {Huss, M and Funk, M and Ohmura, A},
doi = {10.1029/2009GL040789},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {dec},
number = {23},
pages = {L23501},
title = {{Strong Alpine glacier melt in the 1940s due to enhanced solar radiation}},
url = {http://doi.wiley.com/10.1029/2009GL040789},
volume = {36},
year = {2009}
}
@article{Huybers2010,
abstract = {Abstract The spread in climate sensitivity obtained from 12 general circulation model runs used in the Fourth Assessment of the Intergovernmental Panel on Climate Change indicates a 95{\%} confidence interval of 2.1°?5.5°C, but this reflects compensation between model feedbacks. In particular, cloud feedback strength negatively covaries with the albedo feedback as well as with the combined water vapor plus lapse rate feedback. If the compensation between feedbacks is removed, the 95{\%} confidence interval for climate sensitivity expands to 1.9°?8.0°C. Neither of the quoted 95{\%} intervals adequately reflects the understanding of climate sensitivity, but their differences illustrate that model interdependencies must be understood before model spread can be correctly interpreted. The degree of negative covariance between feedbacks is unlikely to result from chance alone. It may, however, result from the method by which the feedbacks were estimated, physical relationships represented in the models, or from conditioning the models upon some combination of observations and expectations. This compensation between model feedbacks?when taken together with indications that variations in radiative forcing and the rate of ocean heat uptake play a similar compensatory role in models?suggests that conditioning of the models acts to curtail the intermodel spread in climate sensitivity. Observations used to condition the models ought to be explicitly stated, or there is the risk of doubly calling on data for purposes of both calibration and evaluation. Conditioning the models upon individual expectation (e.g., anchoring to the Charney range of 3° ± 1.5°C), to the extent that it exists, greatly complicates statistical interpretation of the intermodel spread.},
annote = {doi: 10.1175/2010JCLI3380.1},
author = {Huybers, Peter},
doi = {10.1175/2010JCLI3380.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {feb},
number = {11},
pages = {3009--3018},
publisher = {American Meteorological Society},
title = {{Compensation between Model Feedbacks and Curtailment of Climate Sensitivity}},
url = {https://doi.org/10.1175/2010JCLI3380.1},
volume = {23},
year = {2010}
}
@article{Hwang2011,
abstract = {The relationship between poleward energy transport and Arctic amplification is examined using climate models and an energy balance model. In 21st century projections, models with large Arctic amplification have strong surface albedo and longwave cloud feedbacks, but only weak increases (or even decreases) in total energy transport into the Arctic. Enhanced Arctic warming weakens the equator-to-pole temperature gradient and decreases atmospheric dry static energy transport, a decrease that often outweighs increases from atmospheric moisture transport and ocean heat transport. Model spread in atmospheric energy transport cannot explain model spread in polar amplification; models with greater polar amplification must instead have stronger local feedbacks. Because local feedbacks affect temperature gradients, coupling between energy transports and Arctic feedbacks cannot be neglected when studying Arctic amplification. Citation: Hwang, Y.-T., D. M. W. Frierson, and J. E. Kay (2011), Coupling between Arctic feedbacks and changes in poleward energy transport, Geophys. Res. Lett., 38, L17704, doi:10.1029/2011GL048546.},
author = {Hwang, Yen-Ting and Frierson, Dargan M. W. and Kay, Jennifer E.},
doi = {10.1029/2011GL048546},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {sep},
number = {17},
pages = {L17704},
title = {{Coupling between Arctic feedbacks and changes in poleward energy transport}},
url = {http://doi.wiley.com/10.1029/2011GL048546},
volume = {38},
year = {2011}
}
@article{Hwang2010,
abstract = {Most state‐of‐the‐art global climate models (GCMs) project an increase in atmospheric poleward energy transport with global warming; however, the amount of increase varies significantly from model to model. Using an energy balance model that diffuses moist static energy, it is shown that: (1) the increase in atmospheric moisture content causes most of the increase in transport, and (2) changes in the radiation budget due to clouds explain most of the spread among GCMs. This work also shows that biases in clouds, surface albedo, ocean heat uptake, and aerosols will not only affect climate locally but will also influence other latitudes through energy transport.},
author = {Hwang, Yen-Ting and Frierson, Dargan M. W.},
doi = {10.1029/2010GL045440},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {dec},
number = {24},
pages = {L24807},
title = {{Increasing atmospheric poleward energy transport with global warming}},
url = {http://doi.wiley.com/10.1029/2010GL045440},
volume = {37},
year = {2010}
}
@article{Hwang2013c,
abstract = {The double-Intertropical Convergence Zone (ITCZ) problem, in which excessive precipitation is produced in the Southern Hemisphere tropics, which resembles a Southern Hemisphere counterpart to the strong Northern Hemisphere ITCZ, is perhaps the most significant and most persistent bias of global climate models. In this study, we look to the extratropics for possible causes of the double-ITCZ problem by performing a global energetic analysis with historical simulations from a suite of global climate models and comparing with satellite observations of the Earth's energy budget. Our results show that models with more energy flux into the Southern Hemisphere atmosphere (at the top of the atmosphere and at the surface) tend to have a stronger double-ITCZ bias, consistent with recent theoretical studies that suggest that the ITCZ is drawn toward heating even outside the tropics. In particular, we find that cloud biases over the Southern Ocean explain most of the model-to-model differences in the amount of excessive precipitation in Southern Hemisphere tropics, and are suggested to be responsible for this aspect of the double-ITCZ problem in most global climate models.},
author = {Hwang, Y.-T. and Frierson, D. M. W.},
doi = {10.1073/pnas.1213302110},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
month = {mar},
number = {13},
pages = {4935--4940},
title = {{Link between the double-Intertropical Convergence Zone problem and cloud biases over the Southern Ocean}},
url = {http://www.pnas.org/cgi/doi/10.1073/pnas.1213302110},
volume = {110},
year = {2013}
}
@article{Hwang2017,
abstract = {Under increasing greenhouse gas forcing, climate models project tropical warming that is greater in the Northern than the Southern Hemisphere, accompanied by a reduction in the northeast trade winds and a strengthening of the southeast trades. While the ocean-atmosphere coupling indicates a positive feedback, what triggers the coupled asymmetry and favors greater warming in the northern tropics remains unclear. Far away from the tropics, the Southern Ocean (SO) has been identified as the major region of ocean heat uptake. Beyond its local effect on the magnitude of sea surface warming, we show by idealized modeling experiments in a coupled slab ocean configuration that enhanced SO heat uptake has a profound global impact. This SO-to-tropics connection is consistent with southward atmospheric energy transport across the equator. Enhanced SO heat uptake results in a zonally asymmetric La-Nina-like pattern of sea surface temperature change that not only affects tropical precipitation but also has influences on the Asian and North American monsoons.},
author = {Hwang, Yen-Ting and Xie, Shang Ping and Deser, Clara and Kang, Sarah M.},
doi = {10.1002/2017GL074972},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {global warming,heat uptake,teleconnection},
month = {sep},
number = {18},
pages = {9449--9457},
publisher = {Blackwell Publishing Ltd},
title = {{Connecting tropical climate change with Southern Ocean heat uptake}},
volume = {44},
year = {2017}
}
@article{Hyder2018,
abstract = {The Southern Ocean is a pivotal component of the global climate system yet it is poorly represented in climate models, with significant biases in upper-ocean temperatures, clouds and winds. Combining Atmospheric and Coupled Model Inter-comparison Project (AMIP5/CMIP5) simulations, with observations and equilibrium heat budget theory, we show that across the CMIP5 ensemble variations in sea surface temperature biases in the 40–60°S Southern Ocean are primarily caused by AMIP5 atmospheric model net surface flux bias variations, linked to cloud-related short-wave errors. Equilibration of the biases involves local coupled sea surface temperature bias feedbacks onto the surface heat flux components. In combination with wind feedbacks, these biases adversely modify upper-ocean thermal structure. Most AMIP5 atmospheric models that exhibit small net heat flux biases appear to achieve this through compensating errors. We demonstrate that targeted developments to cloud-related parameterisations provide a route to better represent the Southern Ocean in climate models and projections.},
author = {Hyder, Patrick and Edwards, John M. and Allan, Richard P. and Hewitt, Helene T. and Bracegirdle, Thomas J. and Gregory, Jonathan M. and Wood, Richard A. and Meijers, Andrew J.S. and Mulcahy, Jane and Field, Paul and Furtado, Kalli and Bodas-Salcedo, Alejandro and Williams, Keith D. and Copsey, Dan and Josey, Simon A. and Liu, Chunlei and Roberts, Chris D. and Sanchez, Claudio and Ridley, Jeff and Thorpe, Livia and Hardiman, Steven C. and Mayer, Michael and Berry, David I. and Belcher, Stephen E.},
doi = {10.1038/s41467-018-05634-2},
issn = {20411723},
journal = {Nature Communications},
keywords = {Atmospheric dynamics,Physical oceanography,Projection and prediction},
month = {dec},
number = {1},
pages = {1--17},
pmid = {30206222},
publisher = {Nature Publishing Group},
title = {{Critical Southern Ocean climate model biases traced to atmospheric model cloud errors}},
url = {www.nature.com/naturecommunications},
volume = {9},
year = {2018}
}
@article{Imamovic2016a,
abstract = {Global dimming refers to the decrease in surface solar radiation (SSR) observed from the 1960s to the 1980s at different measurement sites all around the world. It is under debate whether anthropogenic aerosols emitted from urban areas close to the measurement sites are mainly responsible for the dimming. In order to assess this urbanization impact on SSR, we use spatially explicit population density data of 0.08A degrees resolution to construct population indices (PI) at 157 high data quality sites. Our study extends previous population-based studies by incorporating distance-weighting as a simple aerosol diffusion model. We measured urbanization in the surrounding of a site as the PI change from 1960 to 1990 and found no negative correlation with the corresponding SSR trends from 1964 to 1989 for the 92 sites in Europe and Japan. For the 39 sites in China the correlation coefficients are significant at the 5 {\%} level and reach around -0.35, while for the 26 remaining Asian, mostly Russian sites the correlation coefficients reach around -0.55 at the 1 {\%} significance level. Results are similar, when the absolute levels of PIs are taken as an indicator for urbanization. Our findings call into question the existence of an urbanization effect for the sites in Europe and Japan, while such an effect cannot be ruled out for the sites in Asia, especially in Russia.},
address = {Swiss Fed Inst Technol, Inst Atmospher {\&} Climate Sci, Zurich, Switzerland Natl Inst Environm Studies, Tsukuba, Ibaraki, Japan},
annote = {Dk1vd
Times Cited:1
Cited References Count:17},
author = {Imamovic, A and Tanaka, K and Folini, D and Wild, M},
doi = {10.5194/acp-16-2719-2016},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
keywords = {energy-balance archive solar-radiation surface},
language = {English},
number = {5},
pages = {2719--2725},
title = {{Global dimming and urbanization: did stronger negative SSR trends collocate with regions of population growth?}},
volume = {16},
year = {2016}
}
@article{cp-16-1953-2020,
author = {Inglis, G N and Bragg, F and Burls, N J and Cramwinckel, M J and Evans, D and Foster, G L and Huber, M and Lunt, D J and Siler, N and Steinig, S and Tierney, J E and Wilkinson, R and Anagnostou, E and de Boer, A M and {Dunkley Jones}, T and Edgar, K M and Hollis, C J and Hutchinson, D K and Pancost, R D},
doi = {10.5194/cp-16-1953-2020},
journal = {Climate of the Past},
number = {5},
pages = {1953--1968},
title = {{Global mean surface temperature and climate sensitivity of the early Eocene Climatic Optimum (EECO), Paleocene–Eocene Thermal Maximum (PETM), and latest Paleocene}},
url = {https://cp.copernicus.org/articles/16/1953/2020/},
volume = {16},
year = {2020}
}
@article{Ingram2013,
abstract = {The water vapour feedback probably makes the largest contribution to climate sensitivity, and the second-largest contribution to its uncertainty, in the sense of disagreement between General Circulation Models (GCMs, the most physically detailed models of climate we have). Yet there has been no quantification of it which allows these differences to be attributed physically with the aim of constraining the true value. This paper develops a new breakdown of the non-cloud LW (longwave) response to climate change, which avoids the problems of the conventional breakdown, and applies it to a set of 4 GCMs. The basic physical differences are that temperature is used as the vertical coordinate, and relative humidity as the humidity variable. In this framework the different GCMs' feedbacks look more alike, consistent with our understanding that their water vapour responses are physically very similar. Also, in the global mean all the feedback components have the same sign, allowing us to conveniently attribute the overall response fractionally (e.g. about 60{\%} from the ``partly-Simpsonian'' component). The systematic cancellation between different feedback components in the conventional breakdown is lost, so now a difference in a feedback component actually contributes to a difference in climate sensitivity, and the differences between these GCMs in the non-cloud LW part of this can be traced to differences in formulation, mean climate and climate change response. Physical effects such as those due to variations in the formulation of LW radiative transfer become visible. Differences in the distribution of warming no longer dominate comparison of GCMs. The largest component depends locally only on the GCM's mean climate, so it can in principle be calculated for the real world and validated. However, components dependent on the climate change response probably account for most of the variation between GCMs. The effect of simply changing the humidity variable in the conventional breakdown is also examined. It gives some of this improvement---the loss of the cancellations that leave the conventional breakdown of no use to understand differences between GCMs' climate sensitivities---but not the link to mean climate.},
author = {Ingram, William},
doi = {10.1007/s00382-012-1294-3},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {3},
pages = {913--924},
title = {{A new way of quantifying GCM water vapour feedback}},
url = {https://doi.org/10.1007/s00382-012-1294-3},
volume = {40},
year = {2013}
}
@article{doi:10.1002/qj.546,
author = {Ingram, William},
doi = {10.1002/qj.546},
journal = {Quarterly Journal of the Royal Meteorological Society},
keywords = {Simpson model,climate sensitivity,relative humidity},
number = {646},
pages = {30--40},
title = {{A very simple model for the water vapour feedback on climate change}},
volume = {136},
year = {2010}
}
@techreport{IPCC2019,
author = {IPCC},
editor = {P{\"{o}}rtner, H.-O. and Roberts, D.C. and Masson-Delmotte, V. and Zhai, P. and Tignor, M. and Poloczanska, E. and Mintenbeck, K. and Alegr{\'{i}}a, A. and Nicolai, M. and Okem, A. and Petzold, J. and Rama, B. and Weyer, N.M.},
pages = {755},
publisher = {In Press},
title = {{IPCC Special Report on the Ocean and Cryosphere in a Changing Climate}},
url = {https://www.ipcc.ch/srocc},
year = {2019}
}
@incollection{IPCC2019a,
author = {IPCC},
booktitle = {Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems},
editor = {Shukla, P.R. and Skea, J. and Buendia, E. Calvo and Masson-Delmotte, V. and P{\"{o}}rtner, H.- O. and Roberts, D. C. and Zhai, P. and Slade, R. and Connors, S. and van Diemen, R. and Ferrat, M. and Haughey, E. and Luz, S. and Neogi, S. and Pathak, M. and Petzold, J. and Pereira, J. Portugal and Vyas, P. and Huntley, E. and Kissick, K. and Belkacemi, M. and Malley, J.},
isbn = {9789291691548},
pages = {3--36},
publisher = {In Press},
title = {{Summary for Policymakers}},
url = {https://www.ipcc.ch/srccl/chapter/summary-for-policymakers},
year = {2019}
}
@incollection{IPCC2018,
author = {IPCC},
booktitle = {Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change,},
editor = {Masson-Delmotte, V. and Zhai, P. and P{\"{o}}rtner, H.-O. and Roberts, D. and Skea, J. and Shukla, P.R. and Pirani, A. and Moufouma-Okia, W. and P{\'{e}}an, C. and Pidcock, R. and Connors, S. and Matthews, J.B.R. and Chen, Y. and Zhou, X. and Gomis, M.I. and Lonnoy, E. and Maycock, T. and Tignor, M. and Waterfield, T.},
pages = {3--24},
publisher = {In Press},
title = {{Summary for Policymakers}},
url = {https://www.ipcc.ch/sr15/chapter/spm},
year = {2018}
}
@techreport{IPCC2014,
address = {Geneva, Switzerland},
author = {IPCC},
editor = {{Core Writing Team} and Pachauri, R.K. and Meyer, L.A.},
pages = {151},
publisher = {IPCC},
title = {{Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change}},
url = {https://www.ipcc.ch/report/ar5/syr},
year = {2014}
}
@article{Ishii2017,
author = {Ishii, Masayoshi and Fukuda, Yoshikazu and Hirahara, Shoji and Yasui, Soichiro and Suzuki, Toru and Sato, Kanako},
doi = {10.2151/sola.2017-030},
journal = {SOLA},
pages = {163--167},
title = {{Accuracy of Global Upper Ocean Heat Content Estimation Expected from Present Observational Data Sets}},
volume = {13},
year = {2017}
}
@article{ISI:000426729300032,
abstract = {This study investigates the spatio-temporal variations of global solar radiation and its relationships with cloud cover (CC) during 1998-2015 in Iran, where no previous information about the variations of solar radiation based on direct measurements exists. The variations in the mentioned variables were detected using a modified Mann-Kendall trend test and the magnitudes of trends were estimated by using the Theil-Sen's slope estimator method. A widespread dimming with a magnitude of about -4.3 and -1.7{\%} per decade is found under all- and clear-sky conditions in Iran since the 2000s (median over nine observation sites). A significant increase in CC was observed at most of the stations studied, at 20.0{\%} per decade (median over nine sites). The decrease in the amount of all-sky global solar radiation seems to have occurred as a combined effect of aerosol and CC increase over Iran. However, in the south of Iran and at the station Tehran dimming appears to be mostly due to an increase in the amount of aerosol loadings.},
address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA},
author = {Jahani, Babak and Dinpashoh, Yagob and Wild, Martin},
doi = {10.1002/joc.5265},
issn = {08998418},
journal = {International Journal of Climatology},
keywords = {Iran,Mann-Ke,cloud cover,global solar radiation},
month = {mar},
number = {3},
pages = {1543--1559},
publisher = {WILEY},
title = {{Dimming in Iran since the 2000s and the potential underlying causes}},
type = {Article},
url = {https://onlinelibrary.wiley.com/doi/10.1002/joc.5265},
volume = {38},
year = {2018}
}
@article{Jenkins2018b,
abstract = {The relationship between cumulative CO2 emissions and CO2-induced warming is determined by the Transient Climate Response to Emissions (TCRE), but total anthropogenic warming also depends on non-CO2 forcing, complicating the interpretation of emissions budgets based on CO2 alone. An alternative is to frame emissions budgets in terms of CO2-forcing-equivalent (CO2-fe) emissions—the CO2 emissions that would yield a given total anthropogenic radiative forcing pathway. Unlike conventional “CO2-equivalent” emissions, these are directly related to warming by the TCRE and need to fall to zero to stabilize warming: hence, CO2-fe emissions generalize the concept of a cumulative carbon budget to multigas scenarios. Cumulative CO2-fe emissions from 1870 to 2015 inclusive are found to be 2,900 ± 600 GtCO2-fe, increasing at a rate of 67 ± 9.5 GtCO2-fe/yr. A TCRE range of 0.8–2.5°C per 1,000 GtC implies a total budget for 0.6°C of additional warming above the present decade of 880–2,750 GtCO2-fe, with 1,290 GtCO2-fe implied by the Coupled Model Intercomparison Project Phase 5 median response, corresponding to 19 years' CO2-fe emissions at the current rate.},
author = {Jenkins, S. and Millar, R. J. and Leach, N. and Allen, M. R.},
doi = {10.1002/2017GL076173},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate stabilization,cumulative carbon budget,forcing equivalent index,greenhouse gas metric},
month = {mar},
number = {6},
pages = {2795--2804},
title = {{Framing Climate Goals in Terms of Cumulative CO2-Forcing-Equivalent Emissions}},
url = {http://doi.wiley.com/10.1002/2017GL076173},
volume = {45},
year = {2018}
}
@incollection{Jia2019,
author = {Jia, Gensuo and Shevliakova, Elena and Artaxo, Paulo and {De Noblt-Ducoudre}, Nathalie and Houghton, Richard},
booktitle = {Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems},
editor = {Shukla, P. R. and Skea, J. and {Calvo Buendia}, E. and Masson-Delmotte, V. and P{\"{o}}rtner, H.-O. and Roberts, D. C. and Zhai, P. and Slade, R. and Connors, S. and van Diemen, R. and Ferrat, M. and Haughey, E. and Luz, S. and Neogi, S. and Pathak, M. and Petzold, J. and {J. Portugal Pereira, P. Vyas, E. Huntley, K. Kissick, M, Belkacemi}, J. Malley},
pages = {131--247},
publisher = {In Press},
title = {{Land–climate interactions}},
url = {https://www.ipcc.ch/srccl/chapter/chapter-2},
year = {2019}
}
@article{Jimenez-de-la-Cuesta2019,
abstract = {Future global warming is determined by both greenhouse gas emission pathways and Earth's transient and equilibrium climate response to doubled atmospheric CO2. Energy-balance inference from the instrumental record typically yields central estimates for the transient response of around 1.3 K and the equilibrium response of 1.5–2.0 K, which is at the lower end of those from contemporary climate models. Uncertainty arises primarily from poorly known aerosol-induced cooling since the early industrialization era and a temporary cooling induced by evolving sea surface temperature patterns. Here we present an emergent constraint on post-1970s warming, taking advantage of the weakly varying aerosol cooling during this period. We derive a relationship between the transient response and the post-1970s warming in Coupled Model Intercomparison Project Phase 5 (CMIP5) models. We thereby constrain, with the observations, the transient response to 1.67 K (1.17–2.16 K, 5–95th percentiles). This is a 20{\%} increase relative to energy-balance inference stemming from previously neglected upper-ocean energy storage. For the equilibrium climate sensitivity we obtain a best estimate of 2.83 K (1.72–4.12 K) contingent on the temporary pattern effects exhibited by climate models. If the real world's surface temperature pattern effects are substantially stronger, then the upper-bound equilibrium sensitivity may be higher than found here. Warming in climate simulations since about 1970, when aerosol cooling showed little variation, constrains the transient climate response to doubled atmospheric CO2 levels to about 1.67 K, according to an analysis of this emergent constraint.},
author = {Jim{\'{e}}nez-de-la-Cuesta, Diego and Mauritsen, Thorsten},
doi = {10.1038/s41561-019-0463-y},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {nov},
number = {11},
pages = {902--905},
title = {{Emergent constraints on Earth's transient and equilibrium response to doubled CO2 from post-1970s global warming}},
url = {http://www.nature.com/articles/s41561-019-0463-y},
volume = {12},
year = {2019}
}
@article{Johansson2015,
author = {Johansson, Daniel J A and O'Neill, Brian C and Tebaldi, Claudia and H{\"{a}}ggstr{\"{o}}m, Olle},
doi = {10.1038/nclimate2573},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {may},
number = {5},
pages = {449--453},
publisher = {Nature Publishing Group},
title = {{Equilibrium climate sensitivity in light of observations over the warming hiatus}},
url = {http://www.nature.com/articles/nclimate2573},
volume = {5},
year = {2015}
}
@article{Johnson2016a,
abstract = {Improving estimates of Earth's energy imbalance},
author = {Johnson, Gregory C. and Lyman, John M. and Loeb, Norman G.},
doi = {10.1038/nclimate3043},
issn = {17586798},
journal = {Nature Climate Change},
number = {7},
pages = {639--640},
publisher = {Nature Publishing Group},
title = {{Improving estimates of Earth's energy imbalance}},
url = {http://dx.doi.org/10.1038/nclimate3043},
volume = {6},
year = {2016}
}
@article{Jonko2013,
abstract = {Are equilibrium climate sensitivity and the associated radiative feedbacks a constant property of the climate system, or do they change with forcing magnitude and base climate? Using the radiative kernel technique, feedbacks and climate sensitivity are evaluated in a fully coupled general circulation model (GCM) for three successive doublings of carbon dioxide starting from present-day concentrations. Climate sensitivity increases by 23{\%} between the first and third CO2 doublings. Increases in the positive water vapor and cloud feedbacks are partially balanced by a decrease in the positive surface albedo feedback and an increase in the negative lapse rate feedback. Feedbacks can be decomposed into a radiative flux change and a climate variable response to temperature change. The changes in water vapor and Planck feedbacks are due largely to changes in the radiative response with climate state. Higher concentrations of greenhouse gases and higher temperatures lead to more absorption and emission of ...},
author = {Jonko, Alexandra K. and Shell, Karen M. and Sanderson, Benjamin M. and Danabasoglu, Gokhan},
doi = {10.1175/JCLI-D-12-00479.1},
issn = {08948755},
journal = {Journal of Climate},
number = {9},
pages = {2784--2795},
title = {{Climate Feedbacks in CCSM3 under Changing CO2 Forcing. Part II: Variation of Climate Feedbacks and Sensitivity with Forcing}},
volume = {26},
year = {2013}
}
@article{Joos2013,
abstract = {The responses of carbon dioxide (CO2) and other climate variables to an emission pulse of CO2into the atmosphere are often used to compute the Global Warming Potential (GWP) and Global Temperature change Potential (GTP), to characterize the response timescales of Earth System models, and to build reduced-form models. In this carbon cycle-climate model intercomparison project, which spans the full model hierarchy, we quantify responses to emission pulses of different magnitudes injected under different conditions. The CO2response shows the known rapid decline in the first few decades followed by a millennium-scale tail. For a 100 Gt-C emission pulse added to a constant CO2concentration of 389 ppm, 25 ± 9 {\%} is still found in the atmosphere after 1000 yr; the ocean has absorbed 59 ± 12 {\%} and the land the remainder (16 ± 14 {\%}). The response in global mean surface air temperature is an increase by 0.20 ± 0.12°C within the first twenty years; thereafter and until year 1000, temperature decreases only slightly, whereas ocean heat content and sea level continue to rise. Our best estimate for the Absolute Global Warming Potential, given by the time-integrated response in CO2at year 100 multiplied by its radiative efficiency, is 92.5 × 10-15yr W m-2per kg-CO2. This value very likely (5 to 95 {\%} confidence) lies within the range of (68 to 117) × 10-15yr W m-2per kg-CO2. Estimates for time-integrated response in CO2published in the IPCC First, Second, and Fourth Assessment and our multi-model best estimate all agree within 15{\%} during the first 100 yr. The integrated CO2response, normalized by the pulse size, is lower for pre-industrial conditions, compared to present day, and lower for smaller pulses than larger pulses. In contrast, the response in temperature, sea level and ocean heat content is less sensitive to these choices. Although, choices in pulse size, background concentration, and model lead to uncertainties, the most important and subjective choice to determine AGWP of CO2and GWP is the time horizon. {\textcopyright} Author(s) 2013.},
author = {Joos, F. and Roth, R. and Fuglestvedt, J.S. and Peters, G.P. and Enting, I.G. and {Von Bloh}, W. and Brovkin, V. and Burke, E.J. and Eby, M. and Edwards, N.R. and Friedrich, T. and Fr{\"{o}}licher, T.L. and Halloran, P.R. and Holden, P.B. and Jones, C. and Kleinen, T. and Mackenzie, F.T. and Matsumoto, K. and Meinshausen, M. and Plattner, G.-K. and Reisinger, A. and Segschneider, J. and Shaffer, G. and Steinacher, M. and Strassmann, K. and Tanaka, K. and Timmermann, A. and Weaver, A.J.},
doi = {10.5194/acp-13-2793-2013},
journal = {Atmospheric Chemistry and Physics},
number = {5},
pages = {2793--2825},
title = {{Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: A multi-model analysis}},
volume = {13},
year = {2013}
}
@article{Joshi2010,
abstract = {It has been shown previously that one member of the Met Office Hadley Centre single-parameter perturbed physics ensemble-the so-called "low entrainment parameter" member-has a much higher climate sensitivity than other individual parameter perturbations. Here we show that the concentration of stratospheric water vapour in this member is over three times higher than observations, and, more importantly for climate sensitivity, increases significantly when climate warms. The large surface temperature response of this ensemble member is more consistent with stratospheric humidity change, rather than upper tropospheric clouds as has been previously suggested. The direct relationship between the bias in the control state (elevated stratospheric humidity) and the cause of the high climate sensitivity (a further increase in stratospheric humidity) lends further doubt as to the realism of this particular integration. This, together with other evidence, lowers the likelihood that the climate system's physical sensitivity is significantly higher than the likely upper range quoted in the Intergovernmental Panel on Climate Change's Fourth Assessment Report. {\textcopyright} 2010 Author(s).},
author = {Joshi, M. M. and Webb, M. J. and Maycock, A. C. and Collins, M.},
doi = {10.5194/acp-10-7161-2010},
issn = {16807316},
journal = {Atmospheric Chemistry and Physics},
number = {15},
pages = {7161--7167},
title = {{Stratospheric water vapour and high climate sensitivity in a version of the HadSM3 climate model}},
volume = {10},
year = {2010}
}
@article{Jungclaus2014,
abstract = {Oceanic heat transport variations, carried by the northward flowing Atlantic Water, strongly influence Arctic sea-ice distribution, ocean–atmosphere exchanges, and pan-Arctic temperatures. Paleoceanographic reconstructions from marine sediments near Fram Strait have documented a dramatic increase in Atlantic Water temperatures over the 20th century, unprecedented in the last millennium. Here we present results from Earth system model simulations over the last millennium that reproduce and explain reconstructed integrated quantities such as pan-Arctic temperature evolution during the pre-industrial millennium as well as the exceptional Atlantic Water warming in Fram Strait in the 20th century. The associated increase in ocean heat transfer to the Arctic can be traced back to changes in the ocean circulation in the sub-polar North Atlantic. An interplay between a weakening overturning circulation and a strengthening sub-polar gyre as a consequence of 20th century global warming is identified as driving mechanism for the pronounced warming along the Atlantic Water path toward the Arctic. Simulations covering the late Holocene provide a reference frame that allows us to conclude that the changes during the last century are unprecedented in the last 1150 years and that they cannot be explained by internal variability or natural forcing alone.},
author = {Jungclaus, J. H. and Lohmann, K. and Zanchettin, D.},
doi = {https://doi.org/10.5194/cp-10-2201-2014},
issn = {1814-9359},
journal = {Climate of the Past},
pages = {2201--2213},
title = {{Enhanced 20th century heat transfer to the Arctic simulated in the context of climate variations over the last millennium}},
volume = {10},
year = {2014}
}
@article{gmd-10-4005-2017,
author = {Jungclaus, J H and Bard, E and Baroni, M and Braconnot, P and Cao, J and Chini, L P and Egorova, T and Evans, M and Gonz{\'{a}}lez-Rouco, J F and Goosse, H and Hurtt, G C and Joos, F and Kaplan, J O and Khodri, M and {Klein Goldewijk}, K and Krivova, N and LeGrande, A N and Lorenz, S J and Luterbacher, J and Man, W and Maycock, A C and Meinshausen, M and Moberg, A and Muscheler, R and Nehrbass-Ahles, C and Otto-Bliesner, B I and Phipps, S J and Pongratz, J and Rozanov, E and Schmidt, G A and Schmidt, H and Schmutz, W and Schurer, A and Shapiro, A I and Sigl, M and Smerdon, J E and Solanki, S K and Timmreck, C and Toohey, M and Usoskin, I G and Wagner, S and Wu, C.-J. and Yeo, K L and Zanchettin, D and Zhang, Q and Zorita, E},
doi = {10.5194/gmd-10-4005-2017},
journal = {Geoscientific Model Development},
number = {11},
pages = {4005--4033},
title = {{The PMIP4 contribution to CMIP6 Part 3: The last millennium, scientific objective, and experimental design for PMIP4 simulations}},
url = {https://www.geosci-model-dev.net/10/4005/2017/},
volume = {10},
year = {2017}
}
@article{Kohler2015a,
abstract = {It is still an open question how equilibrium warming in response to increasing radiative forcing – the specific equilibrium climate sensitivity S – depends on background climate. We here present palaeodata-based evidence on the state dependency of S, by using CO2 proxy data together with a 3-D ice-sheet-model-based reconstruction of land ice albedo over the last 5 million years (Myr). We find that the land ice albedo forcing depends non-linearly on the background climate, while any non-linearity of CO2 radiative forcing depends on the CO2 data set used. This non-linearity has not, so far, been accounted for in similar approaches due to previously more simplistic approximations, in which land ice albedo radiative forcing was a linear function of sea level change. The latitudinal dependency of ice-sheet area changes is important for the non-linearity between land ice albedo and sea level. In our set-up, in which the radiative forcing of CO2 and of the land ice albedo (LI) is combined, we find a state dependence in the calculated specific equilibrium climate sensitivity, S[CO2,LI], for most of the Pleistocene (last 2.1 Myr). During Pleistocene intermediate glaciated climates and interglacial periods, S[CO2,LI] is on average {\~{}} 45 {\%} larger than during Pleistocene full glacial conditions. In the Pliocene part of our analysis (2.6–5 Myr BP) the CO2 data uncertainties prevent a well-supported calculation for S[CO2,LI], but our analysis suggests that during times without a large land ice area in the Northern Hemisphere (e.g. before 2.82 Myr BP), the specific equilibrium climate sensitivity, S[CO2,LI], was smaller than during interglacials of the Pleistocene. We thus find support for a previously proposed state change in the climate system with the widespread appearance of northern hemispheric ice sheets. This study points for the first time to a so far overlooked non-linearity in the land ice albedo radiative forcing, which is important for similar palaeodata-based approaches to calculate climate sensitivity. However, the implications of this study for a suggested warming under CO2 doubling are not yet entirely clear since the details of necessary corrections for other slow feedbacks are not fully known and the uncertainties that exist in the ice-sheet simulations and global temperature reconstructions are large.},
author = {K{\"{o}}hler, P. and {De Boer}, B. and {Von Der Heydt}, A. S. and Stap, L. B. and {Van De Wal}, R. S.W.},
doi = {10.5194/cp-11-1801-2015},
isbn = {1814-9332},
issn = {18149332},
journal = {Climate of the Past},
number = {12},
pages = {1801--1823},
title = {{On the state dependency of the equilibrium climate sensitivity during the last 5 million years}},
volume = {11},
year = {2015}
}
@article{Kohler2017a,
author = {K{\"{o}}hler, Peter and Stap, Lennert B and von der Heydt, Anna S. and de Boer, Bas and van de Wal, Roderik S. W. and Bloch-Johnson, J},
doi = {10.1002/2017PA003190},
issn = {08838305},
journal = {Paleoceanography},
month = {nov},
number = {11},
pages = {1102--1114},
title = {{A State-Dependent Quantification of Climate Sensitivity Based on Paleodata of the Last 2.1 Million Years}},
url = {http://doi.wiley.com/10.1002/2017PA003190},
volume = {32},
year = {2017}
}
@article{Kohler2018,
abstract = {We reanalyze existing paleodata of global mean surface temperature $\Delta$T g and radiative forcing $\Delta$R of CO 2 and land ice albedo for the last 800,000 years to show that a state-dependency in paleoclimate sensitivity S, as previously suggested, is only found if $\Delta$T g is based on reconstructions, and not when $\Delta$T g is based on model simulations. Furthermore, during times of decreasing obliquity (periods of land ice sheet growth and sea level fall) the multimillennial component of reconstructed $\Delta$T g diverges from CO 2 , while in simulations both variables vary more synchronously, suggesting that the differences during these times are due to relatively low rates of simulated land ice growth and associated cooling. To produce a reconstruction-based extrapolation of S for the future, we exclude intervals with strong $\Delta$T g-CO 2 divergence and find that S is less state-dependent, or even constant state-independent), yielding a mean equilibrium warming of 2-4 K for a doubling of CO 2. Plain Language Summary Anthropogenic carbon dioxide (CO 2) emissions will lead to rising global mean temperature through the greenhouse effect. The amplitude of this warming, as estimated with computer simulations for the equilibrium climate response to a doubling of atmospheric CO 2 concentration, is called climate sensitivity. It is necessary to verify these simulation-based quantifications of climate sensitivity with independent alternative approaches. One such approach is the analysis of past (paleo) climates, which has indicated a state-dependent paleoclimate sensitivity. Here we compare different data-based reconstructions and computer-based simulations of paleoclimate sensitivity of the last 800,000 years and find that they disagree. In data-based reconstructions global mean temperature and CO 2 diverge during intervals when land ice growth is particularly pronounced. This temperature-CO 2 divergence is not observed in simulations, probably due to an underestimation of the rate of land ice growth and the associated cooling. However, these periods of pronounced land ice growth are not of relevance for a warming future and can therefore be neglected when estimating climate sensitivity from reconstructions of the past. Consequently, we find that paleoclimate sensitivity derived from reconstructions is less state-dependent than previously thought and agrees with warming estimates of 2-4 ∘ C as derived from simulated equilibrium climate response for CO 2 doubling.},
author = {K{\"{o}}hler, Peter and Knorr, Gregor and Stap, Lennert B and Ganopolski, Andrey and de Boer, Bas and van de Wal, Roderik S. W. and Barker, Stephen and R{\"{u}}pke, Lars H},
doi = {10.1029/2018GL077717},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {jul},
number = {13},
pages = {6661--6671},
title = {{The Effect of Obliquity-Driven Changes on Paleoclimate Sensitivity During the Late Pleistocene}},
url = {https://doi.org/10.1029/2018GL077717 http://doi.wiley.com/10.1029/2018GL077717},
volume = {45},
year = {2018}
}
@article{Kageyama9999a,
author = {Kageyama, Masa and Harrison, Sandy P and Kapsch, Marie-L. and Lofverstrom, Marcus and Lora, Juan M and Mikolajewicz, Uwe and Sherriff-Tadano, Sam and Vadsaria, Tristan and Abe-Ouchi, Ayako and Bouttes, Nathaelle and Chandan, Deepak and Gregoire, Lauren J. and Ivanovic, Ruza F. and Izumi, Kenji and LeGrande, Allegra N and Lhardy, Fanny and Lohmann, Gerrit and Morozova, Polina A and Ohgaito, Rumi and Paul, Andr{\'{e}} and Peltier, W. Richard and Poulsen, Christopher J. and Quiquet, Aur{\'{e}}lien and Roche, Didier M and Shi, Xiaoxu and Tierney, Jessica E and Valdes, Paul J. and Volodin, Evgeny and Zhu, Jiang},
doi = {10.5194/cp-17-1065-2021},
issn = {1814-9332},
journal = {Climate of the Past},
keywords = {Climate change,Climate model,Climatology,Coupled model intercomparison project,Geology,Jet stream,Ocean current,Paleoclimatology,Polar amplification,Precipitation},
month = {may},
number = {3},
pages = {1065--1089},
title = {{The PMIP4 Last Glacial Maximum experiments: preliminary results and comparison with the PMIP3 simulations}},
url = {https://cp.copernicus.org/articles/17/1065/2021/},
volume = {17},
year = {2021}
}
@article{Kajtar2017,
abstract = {Complex interactions manifest between modes of tropical climate variability across the Pacific, Indian, and Atlantic Oceans. For example, the El Ni{\~{n}}o–Southern Oscillation (ENSO) extends its influence on modes of variability in the tropical Indian and Atlantic Oceans, which in turn feed back onto ENSO. Interactions between pairs of modes can alter their strength, periodicity, seasonality, and ultimately their predictability, yet little is known about the role that a third mode plays. Here we examine the interactions and relative influences between pairs of climate modes using ensembles of 100-year partially coupled experiments in an otherwise fully coupled general circulation model. In these experiments, the air–sea interaction over each tropical ocean basin, as well as pairs of ocean basins, is suppressed in turn. We find that Indian Ocean variability has a net damping effect on ENSO and Atlantic Ocean variability, and conversely they each promote Indian Ocean variability. The connection between the Pacific and the Atlantic is most clearly revealed in the absence of Indian Ocean variability. Our model runs suggest a weak damping influence by Atlantic variability on ENSO, and an enhancing influence by ENSO on Atlantic variability.},
author = {Kajtar, Jules B. and Santoso, Agus and England, Matthew H. and Cai, Wenju},
doi = {10.1007/s00382-016-3199-z},
isbn = {0038201631},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Atlantic Ni{\~{n}}o,Climate modes,ENSO,Indian Ocean Basinwide Mode,Indian Ocean Dipole,Tropical variability},
month = {apr},
number = {7-8},
pages = {2173--2190},
pmid = {2012292365},
publisher = {Springer Verlag},
title = {{Tropical climate variability: interactions across the Pacific, Indian, and Atlantic Oceans}},
volume = {48},
year = {2017}
}
@article{Kajtar2018,
author = {Kajtar, Jules B. and Santoso, Agus and McGregor, Shayne and England, Matthew H. and Baillie, Zak},
doi = {10.1007/s00382-017-3699-5},
journal = {Climate Dynamics},
month = {jun},
number = {3-4},
pages = {1471--1484},
publisher = {Springer Nature},
title = {{Model under-representation of decadal Pacific trade wind trends and its link to tropical Atlantic bias}},
volume = {50},
year = {2018}
}
@article{Kamae2016a,
author = {Kamae, Youichi and Ogura, Tomoo and Watanabe, Masahiro and Xie, Shang-Ping and Ueda, Hiroaki},
doi = {10.1002/2015JD024525},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {mar},
number = {6},
pages = {2593--2609},
title = {{Robust cloud feedback over tropical land in a warming climate}},
url = {http://doi.wiley.com/10.1002/2015JD024525},
volume = {121},
year = {2016}
}
@article{LowerTroposphericMixingasaConstraintonCloudFeedbackinaMultiparameterMultiphysicsEnsemble,
address = {Boston MA, USA},
author = {Kamae, Youichi and Shiogama, Hideo and Watanabe, Masahiro and Ogura, Tomoo and Yokohata, Tokuta and Kimoto, Masahide},
doi = {10.1175/JCLI-D-16-0042.1},
journal = {Journal of Climate},
number = {17},
pages = {6259--6275},
publisher = {American Meteorological Society},
title = {{Lower-Tropospheric Mixing as a Constraint on Cloud Feedback in a Multiparameter Multiphysics Ensemble}},
url = {https://journals.ametsoc.org/view/journals/clim/29/17/jcli-d-16-0042.1.xml},
volume = {29},
year = {2016}
}
@article{Kang2014a,
abstract = {This study shows that the magnitude of global surface warming greatly depends on the meridional distribution of surface thermal forcing. An atmospheric model coupled to an aquaplanet slab mixed layer ocean is perturbed by prescribing heating to the ocean mixed layer. The heating is distributed uniformly globally or confined to narrow tropical or polar bands, and the amplitude is adjusted to ensure that the globalmean remains the same for all cases. Since the tropical temperature is close to a moist adiabat, the prescribed heating leads to a maximized warming near the tropopause, whereas the polar warming is trapped near the surface because of strong atmospheric stability. Hence, the surface warming is more effectively damped by radiation in the tropics than in the polar region. As a result, the global surface temperature increase is weak (strong) when the given amount of heating is confined to the tropical (polar) band. The degree of this contrast is shown to depend on water vapor– and cloud–radiative feedbacks that alter the effective strength of prescribed thermal forcing.},
author = {Kang, Sarah M. and Xie, Shang Ping},
doi = {10.1175/JCLI-D-13-00622.1},
isbn = {10.1175/JCLI-D-13-00622.1},
issn = {08948755},
journal = {Journal of Climate},
number = {14},
pages = {5593--5600},
title = {{Dependence of climate response on meridional structure of external thermal forcing}},
volume = {27},
year = {2014}
}
@article{Kanji2017,
abstract = {Ice particle formation in tropospheric clouds significantly changes cloud radiative and microphysical properties. Ice nucleation in the troposphere via homogeneous freezing occurs at temperatures lower than 2388C and relative humidity with respect to ice above 140{\%}. In the absence of these conditions, ice formation can proceed via heterogeneous nucleation aided by aerosol particles known as ice nucleating particles (INPs). In this chapter, new developments in identifying the heterogeneous freezing mechanisms, atmospheric relevance, uncertainties, and unknowns about INPs are described. The change in conventional wisdom regarding the requirements of INPs as new studies discover physical and chemical properties of these particles is explained. INP sources and known reasons for their ice nucleating properties are presented. The need for more studies to systematically identify particle properties that facilitate ice nucleation is highlighted. The atmospheric relevance of long-range transport, aerosol aging, and coating studies (in the laboratory) of INPs are also presented. Possible mechanisms for processes that change the ice nucleating potential of INPs and the corresponding challenges in understanding and applying these in models are discussed. How primary ice nucleation affects total ice crystal number concentrations in clouds and the discrepancy between INP concentrations and ice crystal number concentrations are presented. Finally, limitations of parameterizing INPs and of models in representing known and unknown processes related to heterogeneous ice nucleation processes are discussed.},
author = {Kanji, Zamin A. and Ladino, Luis A. and Wex, Heike and Boose, Yvonne and Burkert-Kohn, Monika and Cziczo, Daniel James and Kr{\"{a}}mer, Martina},
doi = {10.1175/AMSMONOGRAPHS-D-16-0006.1},
isbn = {0065-9401},
issn = {0065-9401},
journal = {Meteorological Monographs},
pages = {1.1--1.33},
title = {{Overview of Ice Nucleating Particles}},
volume = {58},
year = {2017}
}
@article{Karset2018,
abstract = {{\textless}p{\textgreater}{\textless}![CDATA[{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Uncertainties in effective radiative forcings through aerosol–cloud interactions (ERF{\textless}span class="inline-formula"{\textgreater}{\textless}sub{\textgreater}aci{\textless}/sub{\textgreater}{\textless}/span{\textgreater}, also called aerosol indirect effects) contribute strongly to the uncertainty in the total preindustrial-to-present-day anthropogenic forcing. Some forcing estimates of the total aerosol indirect effect are so negative that they even offset the greenhouse gas forcing. This study highlights the role of oxidants in modeling of preindustrial-to-present-day aerosol indirect effects. We argue that the aerosol precursor gases should be exposed to oxidants of its era to get a more correct representation of secondary aerosol formation. Our model simulations show that the total aerosol indirect effect changes from {\textless}span class="inline-formula"{\textgreater}−{\textless}/span{\textgreater}1.32 to {\textless}span class="inline-formula"{\textgreater}−{\textless}/span{\textgreater}1.07 W m{\textless}span class="inline-formula"{\textgreater}{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}{\textless}/span{\textgreater} when the precursor gases in the preindustrial simulation are exposed to preindustrial instead of present-day oxidants. This happens because of a brightening of the clouds in the preindustrial simulation, mainly due to large changes in the nitrate radical ({\textless}span class="inline-formula"{\textgreater}NO{\textless}sub{\textgreater}3{\textless}/sub{\textgreater}{\textless}/span{\textgreater}). The weaker oxidative power of the preindustrial atmosphere extends the lifetime of the precursor gases, enabling them to be transported higher up in the atmosphere and towards more remote areas where the susceptibility of the cloud albedo to aerosol changes is high. The oxidation changes also shift the importance of different chemical reactions and produce more condensate, thus increasing the size of the aerosols and making it easier for them to activate as cloud condensation nuclei.{\textless}/p{\textgreater}]]{\textgreater}{\textless}/p{\textgreater}},
author = {Karset, Inger Helene Hafsahl and Berntsen, Terje Koren and Storelvmo, Trude and Alterskj{\ae}r, Kari and Grini, Alf and Olivi{\'{e}}, Dirk and Kirkev{\aa}g, Alf and Seland, {\O}yvind and Iversen, Trond and Schulz, Michael},
doi = {10.5194/acp-18-7669-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jun},
number = {10},
pages = {7669--7690},
title = {{Strong impacts on aerosol indirect effects from historical oxidant changes}},
url = {https://www.atmos-chem-phys.net/18/7669/2018/},
volume = {18},
year = {2018}
}
@article{Kato2018a,
abstract = {The algorithm to produce the Clouds and the Earth's Radiant Energy System (CERES) Edition 4.0 (Ed4) Energy Balanced and Filled (EBAF)-surface data product is explained. The algorithm forces computed top-of-atmosphere (TOA) irradiances to match with Ed4 EBAF-TOA irradiances by adjusting surface, cloud, and atmospheric properties. Surface irradiances are subsequently adjusted using radiative kernels. The adjustment process is composed of two parts: bias correction and Lagrange multiplier. The bias in temperature and specific humidity between 200 and 500 hPa used for the irradiance computation is corrected based on observations by Atmospheric Infrared Sounder (AIRS). Similarly, the bias in the cloud fraction is corrected based on observations by Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations ( CALIPSO) and CloudSat. Remaining errors in surface, cloud, and atmospheric properties are corrected in the Lagrange multiplier process. Ed4 global annual mean (January 2005 through December 2014) surface net shortwave (SW) and longwave (LW) irradiances increase by 1.3 W m −2 and decrease by 0.2 W m −2 , respectively, compared to EBAF Edition 2.8 (Ed2.8) counterparts (the previous version), resulting in an increase in net SW + LW surface irradiance of 1.1 W m −2 . The uncertainty in surface irradiances over ocean, land, and polar regions at various spatial scales are estimated. The uncertainties in all-sky global annual mean upward and downward shortwave irradiance are 3 and 4 W m −2 , respectively, and the uncertainties in upward and downward longwave irradiance are 3 and 6 W m −2 , respectively. With an assumption of all errors being independent, the uncertainty in the global annual mean surface LW + SW net irradiance is 8 W m −2 .},
author = {Kato, Seiji and Rose, Fred G and Rutan, David A and Thorsen, Tyler J and Loeb, Norman G and Doelling, David R and Huang, Xianglei and Smith, William L and Su, Wenying and Ham, Seung-Hee},
doi = {10.1175/JCLI-D-17-0523.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jun},
number = {11},
pages = {4501--4527},
title = {{Surface Irradiances of Edition 4.0 Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Data Product}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0523.1},
volume = {31},
year = {2018}
}
@article{ISI:000384149700017,
abstract = {Observationally based atmospheric energy balance is analyzed using Clouds and the Earth's Radiant Energy System (CERES)-derived TOA and surface irradiance, Global Precipitation Climatology Project (GPCP)-derived precipitation, dry static and kinetic energy tendency and divergence estimated from ERA-Interim, and surface sensible heat flux from SeaFlux. The residual tends to be negative over the tropics and positive over midlatitudes. A negative residual implies that the precipitation rate is too small, divergence is too large, or radiative cooling is too large. The residual of atmospheric energy is spatially and temporally correlated with cloud objects to identify cloud types associated with the residual. Spatially, shallow cumulus, cirrostratus, and deep convective cloud-object occurrence are positively correlated with the absolute value of the residual. The temporal correlation coefficient between the number of deep convective cloud objects and individual energy components, net atmospheric irradiance, precipitation rate, and the sum of dry static and kinetic energy divergence and their tendency over the western Pacific are 0.84, 0.95, and 0.93, respectively. However, when all energy components are added, the atmospheric energy residual over the tropical Pacific is temporally correlated well with the number of shallow cumulus cloud objects over tropical Pacific. Because shallow cumulus alters not enough atmospheric energy compared to the residual, this suggests the following: 1) if retrieval errors associated with deep convective clouds are causing the column-integrated atmospheric energy residual, the errors vary among individual deep convective clouds, and 2) it is possible that the residual is associated with processes in which shallow cumulus clouds affect deep convective clouds and hence atmospheric energy budget over the tropical western Pacific.},
address = {45 BEACON ST, BOSTON, MA 02108-3693 USA},
author = {Kato, Seiji and Xu, Kuan-Man and Wong, Takmeng and Loeb, Norman G and Rose, Fred G and Trenberth, Kevin E and Thorsen, Tyler J},
doi = {10.1175/JCLI-D-15-0782.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {20},
pages = {7435--7452},
publisher = {AMER METEOROLOGICAL SOC},
title = {{Investigation of the Residual in Column-Integrated Atmospheric Energy Balance Using Cloud Objects}},
type = {Article},
volume = {29},
year = {2016}
}
@article{Kaufman2006,
abstract = {Pollution and smoke aerosols can increase or decrease the cloud cover. This duality in the effects of aerosols forms one of the largest uncertainties in climate research. Using solar measurements from Aerosol Robotic Network sites around the globe, we show an increase in cloud cover with an increase in the aerosol column concentration and an inverse dependence on the aerosol absorption of sunlight. The emerging rule appears to be independent of geographical location or aerosol type, thus increasing our confidence in the understanding of these aerosol effects on the clouds and climate. Preliminary estimates suggest an increase of 5{\%} in cloud cover.},
author = {Kaufman, Yoram J and Koren, Ilan},
doi = {10.1126/science.1126232},
issn = {0036-8075},
journal = {Science},
month = {aug},
number = {5787},
pages = {655--658},
pmid = {16840661},
publisher = {American Association for the Advancement of Science},
title = {{Smoke and Pollution Aerosol Effect on Cloud Cover}},
url = {https://www.sciencemag.org/lookup/doi/10.1126/science.1126232},
volume = {313},
year = {2006}
}
@article{Kawai2017,
abstract = {This paper reports on a new index for low cloud cover (LCC), the estimated cloud-top entrainment index (ECTEI), which is a modification of estimated inversion strength (EIS) and takes into account a cloud-top entrainment (CTE) criterion. Shipboard cloud observation data confirm that the index is strongly correlated with LCC. It is argued here that changes in LCC cannot be fully determined from changes in EIS only, but can be better determined from changes in both EIS and sea surface temperature (SST) based on the ECTEI. Furthermore, it is argued that various proposed predictors of LCC change, including the moist static energy vertical gradient, SST, and midlevel clouds, can be better understood from the perspective of the ECTEI.},
author = {Kawai, Hideaki and Koshiro, Tsuyoshi and Webb, Mark J},
doi = {10.1175/JCLI-D-16-0825.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {22},
pages = {9119--9131},
title = {{Interpretation of Factors Controlling Low Cloud Cover and Low Cloud Feedback Using a Unified Predictive Index}},
url = {https://doi.org/10.1175/JCLI-D-16-0825.1},
volume = {30},
year = {2017}
}
@article{doi:10.1175/JCLI-D-11-00622.1,
abstract = { AbstractThis study uses coupled climate model experiments to identify the influence of atmospheric physics [Community Atmosphere Model, versions 4 and 5 (CAM4; CAM5)] and ocean model complexity (slab ocean, full-depth ocean) on the equilibrium Arctic climate response to an instantaneous CO2 doubling. In slab ocean model (SOM) experiments using CAM4 and CAM5, local radiative feedbacks, not atmospheric heat flux convergence, are the dominant control on the Arctic surface response to increased greenhouse gas forcing. Equilibrium Arctic surface air temperature warming and amplification are greater in the CAM5 SOM experiment than in the equivalent CAM4 SOM experiment. Larger 2 × CO2 radiative forcing, more positive Arctic surface albedo feedbacks, and less negative Arctic shortwave cloud feedbacks all contribute to greater Arctic surface warming and sea ice loss in CAM5 as compared to CAM4. When CAM4 is coupled to an active full-depth ocean model, Arctic Ocean horizontal heat flux convergence increases in response to the instantaneous CO2 doubling. Though this increased ocean northward heat transport slightly enhances Arctic sea ice extent loss, the representation of atmospheric processes (CAM4 versus CAM5) has a larger influence on the equilibrium Arctic surface climate response than the degree of ocean coupling (slab ocean versus full-depth ocean). These findings underscore that local feedbacks can be more important than northward heat transport for explaining the equilibrium Arctic surface climate response and response differences in coupled climate models. That said, the processes explaining the equilibrium climate response differences here may be different than the processes explaining intermodel spread in transient climate projections. },
author = {Kay, Jennifer E and Holland, Marika M and Bitz, Cecilia M and Blanchard-Wrigglesworth, Edward and Gettelman, Andrew and Conley, Andrew and Bailey, David},
doi = {10.1175/JCLI-D-11-00622.1},
journal = {Journal of Climate},
number = {16},
pages = {5433--5450},
title = {{The Influence of Local Feedbacks and Northward Heat Transport on the Equilibrium Arctic Climate Response to Increased Greenhouse Gas Forcing}},
url = {https://doi.org/10.1175/JCLI-D-11-00622.1},
volume = {25},
year = {2012}
}
@article{Kay2009,
abstract = {Recent declines in Arctic sea ice extent provide new opportunities to assess cloud influence on and response to seasonal sea ice loss. This study combines unique satellite observations with complementary data sets to document Arctic cloud and atmospheric structure during summer and early fall. The analysis focuses on 2006?2008, a period over which ice extent plummeted to record levels, substantial variability in atmospheric circulation patterns occurred, and spaceborne radar and lidar observations of vertical cloud structure became available. The observations show that large-scale atmospheric circulation patterns, near-surface static stability, and surface conditions control Arctic cloud cover during the melt season. While no summer cloud response to sea ice loss was found, low clouds did form over newly open water during early fall. This seasonal variation in the cloud response to sea ice loss can be explained by near-surface static stability and air-sea temperature gradients. During summer, temperature inversions and weak air-sea temperature gradients limit atmosphere-ocean coupling. In contrast, relatively low static stability and strong air-sea gradients during early fall permit upward turbulent fluxes of moisture and heat and increased low cloud formation over newly open water. Because of their seasonal timing, cloud changes resulting from sea ice loss play a minor role in regulating ice-albedo feedbacks during summer, but may contribute to a cloud-ice feedback during early fall.},
author = {Kay, Jennifer E and Gettelman, Andrew},
doi = {10.1029/2009JD011773},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {Arctic,clouds,sea ice},
month = {sep},
number = {D18},
pages = {D18204},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Cloud influence on and response to seasonal Arctic sea ice loss}},
url = {https://doi.org/10.1029/2009JD011773},
volume = {114},
year = {2009}
}
@article{Kay2016,
abstract = {While the representation of clouds in climate models has become more sophisticated over the last 30+ years, the vertical and seasonal fingerprints of Arctic greenhouse warming have not changed. Are the models right? Observations in recent decades show the same fingerprints: surface amplified warming especially in late fall and winter. Recent observations show no summer cloud response to Arctic sea ice loss but increased cloud cover and a deepening atmospheric boundary layer in fall. Taken together, clouds appear to not affect the fingerprints of Arctic warming. Yet, the magnitude of warming depends strongly on the representation of clouds. Can we check the models? Having observations alone does not enable robust model evaluation and model improvement. Comparing models and observations is hard enough, but to improve models, one must both understand why models and observations differ and fix the parameterizations. It is all a tall order, but recent progress is summarized here.},
author = {Kay, Jennifer E and L'Ecuyer, Tristan and Chepfer, Helene and Loeb, Norman and Morrison, Ariel and Cesana, Gregory},
doi = {10.1007/s40641-016-0051-9},
issn = {2198-6061},
journal = {Current Climate Change Reports},
number = {4},
pages = {159--169},
title = {{Recent Advances in Arctic Cloud and Climate Research}},
url = {https://doi.org/10.1007/s40641-016-0051-9},
volume = {2},
year = {2016}
}
@article{Kay2016a,
abstract = {Abstract Spaceborne lidar observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite are used to evaluate cloud amount and cloud phase in the Community Atmosphere Model version 5 (CAM5), the atmospheric component of a widely used state-of-the-art global coupled climate model (Community Earth System Model). By embedding a lidar simulator within CAM5, the idiosyncrasies of spaceborne lidar cloud detection and phase assignment are replicated. As a result, this study makes scale-aware and definition-aware comparisons between model-simulated and observed cloud amount and cloud phase. In the global mean, CAM5 has insufficient liquid cloud and excessive ice cloud when compared to CALIPSO observations. Over the ice-covered Arctic Ocean, CAM5 has insufficient liquid cloud in all seasons. Having important implications for projections of future sea level rise, a liquid cloud deficit contributes to a cold bias of 2?3°C for summer daily maximum near-surface air temperatures at Summit, Greenland. Over the midlatitude storm tracks, CAM5 has excessive ice cloud and insufficient liquid cloud. Storm track cloud phase biases in CAM5 maximize over the Southern Ocean, which also has larger-than-observed seasonal variations in cloud phase. Physical parameter modifications reduce the Southern Ocean cloud phase and shortwave radiation biases in CAM5 and illustrate the power of the CALIPSO observations as an observational constraint. The results also highlight the importance of using a regime-based, as opposed to a geographic-based, model evaluation approach. More generally, the results demonstrate the importance and value of simulator-enabled comparisons of cloud phase in models used for future climate projection.},
annote = {doi: 10.1002/2015JD024699},
author = {Kay, Jennifer E and Bourdages, Line and Miller, Nathaniel B and Morrison, Ariel and Yettella, Vineel and Chepfer, Helene and Eaton, Brian},
doi = {10.1002/2015JD024699},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {Greenland,Southern Ocean,climate model,cloud phase,supercooled liquid clouds},
month = {apr},
number = {8},
pages = {4162--4176},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Evaluating and improving cloud phase in the Community Atmosphere Model version 5 using spaceborne lidar observations}},
url = {https://doi.org/10.1002/2015JD024699},
volume = {121},
year = {2016}
}
@article{ISI:000425505500003,
abstract = {We present a long-term series of surface solar radiation (SSR) from the city of Athens, Greece. SSR measurements were performed from 1954 to 2012, and before that (1900-1953) sunshine duration (SD) records were used in order to reconstruct monthly SSR. Analysis of the whole data set (1900-2012) mainly showed very small (0.02 {\%}) changes in SSR from 1900 to 1953, including a maximum decrease of -2.9 {\%} decade(-1) in SSR during the 1910 to 1940 period, assuming a linear change. For the dimming period 1955-1980, -2 {\%} decade(-1) was observed that matches various European long-term SSR-measurement-related studies. This percentage in Athens is in the lower limit, compared to other studies in the Mediterranean area. For the brightening period 1980-2012 we calculated +1.5 {\%} decade(-1), which is also in the lower limit of the reported positive changes in SSR around Europe. Comparing the 30-year periods 1954-1983 and 1983-2012, we found a difference of 4.5 {\%}. However, measurements of the first 30-year period are associated with higher uncertainties than those of the second period, especially when looking at year-to-year changes. The difference between the two periods was observed for all seasons except winter. Analyzing SSR calculations of all-sky and clear-sky (cloudless) conditions/days, we report that most of the observed changes in SSR after 1954 can be attributed partly to cloudiness and mostly to aerosol load changes.},
author = {Kazadzis, Stelios and Founda, Dimitra and Psiloglou, Basil E and Kambezidis, Harry and Mihalopoulos, Nickolaos and Sanchez-Lorenzo, Arturo and Meleti, Charikleia and Raptis, Panagiotis I and Pierros, Fragiskos and Nabat, Pierre},
doi = {10.5194/acp-18-2395-2018},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
month = {feb},
number = {4},
pages = {2395--2411},
title = {{Long-term series and trends in surface solar radiation in Athens, Greece}},
volume = {18},
year = {2018}
}
@article{Kennedy-Asser2019,
author = {Kennedy-Asser, A. T. and Lunt, D. J. and Farnsworth, A. and Valdes, P. J.},
doi = {10.1029/2018PA003380},
issn = {25724517},
journal = {Paleoceanography and Paleoclimatology},
month = {jan},
number = {1},
pages = {16--34},
title = {{Assessing Mechanisms and Uncertainty in Modeled Climatic Change at the Eocene–Oligocene Transition}},
url = {http://doi.wiley.com/10.1029/2018PA003380},
volume = {34},
year = {2019}
}
@article{Khairoutdinov2013,
abstract = {The results of a series of cloud-resolving radiative-convective equilibrium (RCE) simulations are presented. The RCE simulations, used as an idealization for the mean tropical climate, are run for a wide range of prescribed sea-surface temperatures (SSTs), from 21 degrees C to 36 degrees C, representing the range of past, present, and, possibly, future mean tropical SSTs. The RCE with constant Coriolis parameter f is contrasted with nonrotating RCE. The Coriolis parameter is artificially increased from typical values in the Tropics by about one order of magnitude to allow multiple tropical cyclones (TCs) to coexist in a relatively small 2300 x 2300 km(2) domain with a 3 km horizontal grid spacing. Nonrotating RCE is also simulated, but using a substantially smaller, 384 x 384 km(2) domain. Rotating RCE, which we nickname "TC World," contains from 8 to 26 TCs with the average number of TCs monotonically decreasing with increasing SST. At the same time, the TCs' size, intensity, and per-TC precipitation rate tend to increase in response to increasing SST. For example, the average per-TC kinetic energy and precipitation rate tend to double for every 6 degrees C SST increase. These results are consistent with scaling laws in which TC velocities and inner core diameters scale with the potential intensity and its ratio to the Coriolis parameter, respectively, while the separation between cyclone centers appears to scale with the deformation radius. It is also found that the outflow temperature of TC's, as defined as the height of the local maximum of the upper-troposphere cloud fraction, remains relatively invariant with SST. The cold-point tropopause height in TC World is found to be about 2 km higher than the corresponding height in nonrotating RCE.},
author = {Khairoutdinov, Marat and Emanuel, Kerry},
doi = {10.1002/2013ms000253},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
number = {4},
pages = {816--825},
title = {{Rotating radiative-convective equilibrium simulated by a cloud-resolving model}},
volume = {5},
year = {2013}
}
@article{Kiehl2007,
abstract = {Climate forcing and climate sensitivity are two key factors in understanding Earth's climate. There is considerable interest in decreasing our uncertainty in climate sensitivity. This study explores the role of these two factors in climate simulations of the 20th century. It is found that the total anthropogenic forcing for a wide range of climate models differs by a factor of two and that the total forcing is inversely correlated to climate sensitivity. Much of the uncertainty in total anthropogenic forcing derives from a threefold range of uncertainty in the aerosol forcing used in the simulations.},
author = {Kiehl, Jeffrey T.},
doi = {10.1029/2007GL031383},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
number = {22},
pages = {1--4},
title = {{Twentieth century climate model response and climate sensitivity}},
volume = {34},
year = {2007}
}
@article{Kiehl20130093,
abstract = {The Palaeocene{\{}$\backslash$textendash{\}}Eocene Thermal Maximum (PETM) was a significant global warming event in the Earth{\{}$\backslash$textquoteright{\}}s history (approx. 55 Ma). The cause for this warming event has been linked to increases in greenhouse gases, specifically carbon dioxide and methane. This rapid warming took place in the presence of the existing Early Eocene warm climate. Given that projected business-as-usual levels of atmospheric carbon dioxide reach concentrations of 800{\{}$\backslash$textendash{\}}1100 ppmv by 2100, it is of interest to study past climates where atmospheric carbon dioxide was higher than present. This is especially the case given the difficulty of climate models in simulating past warm climates. This study explores the sensitivity of the simulated pre-PETM and PETM periods to change in cloud condensation nuclei (CCN) and microphysical properties of liquid water clouds. Assuming lower levels of CCN for both of these periods leads to significant warming, especially at high latitudes. The study indicates that past differences in cloud properties may be an important factor in accurately simulating past warm climates. Importantly, additional shortwave warming from such a mechanism would imply lower required atmospheric CO2 concentrations for simulated surface temperatures to be in reasonable agreement with proxy data for the Eocene.},
author = {Kiehl, Jeffrey T and Shields, Christine A},
doi = {10.1098/rsta.2013.0093},
issn = {1364-503X},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
number = {2001},
pages = {20130093},
publisher = {The Royal Society},
title = {{Sensitivity of the Palaeocene–Eocene Thermal Maximum climate to cloud properties}},
url = {http://rsta.royalsocietypublishing.org/content/371/2001/20130093},
volume = {371},
year = {2013}
}
@article{Kim2019,
abstract = {Sea ice reduction is accelerating in the Barents and Kara Seas. Several mechanisms are proposed to explain the accelerated loss of Arctic sea ice, which remains to be controversial. In the present study, detailed physical mechanism of sea ice reduction in winter (December–February) is identified from the daily ERA interim reanalysis data. Downward longwave radiation is an essential element for sea ice reduction, but can primarily be sustained by excessive upward heat flux from the sea surface exposed to air in the region of sea ice loss. The increased turbulent heat flux is used to increase air temperature and specific humidity in the lower troposphere, which in turn increases downward longwave radiation. This feedback process is clearly observed in the Barents and Kara Seas in the reanalysis data. A quantitative assessment reveals that this feedback process is being amplified at the rate of {\~{}}8.9{\%} every year during 1979–2016. Availability of excessive heat flux is necessary for the maintenance of this feedback process; a similar mechanism of sea ice loss is expected to take place over the sea-ice covered polar region, when sea ice is not fully recovered in winter.},
author = {Kim, Kwang Yul and Kim, Ji Young and Kim, Jinju and Yeo, Saerim and Na, Hanna and Hamlington, Benjamin D. and Leben, Robert R.},
doi = {10.1038/s41598-018-38109-x},
issn = {20452322},
journal = {Scientific Reports},
month = {dec},
number = {1},
pages = {1184},
publisher = {Nature Publishing Group},
title = {{Vertical Feedback Mechanism of Winter Arctic Amplification and Sea Ice Loss}},
volume = {9},
year = {2019}
}
@article{Kinne2019,
author = {Kinne, Stefan},
doi = {https://doi.org/10.5194/acp-19-10919-2019},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
pages = {10919--10959},
title = {{Aerosol radiative effects with MACv2}},
url = {https://www.atmos-chem-phys-discuss.net/acp-2018-949/},
volume = {19},
year = {2019}
}
@article{Kirkby2016,
abstract = {Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of $\alpha$-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.},
author = {Kirkby, Jasper and Duplissy, Jonathan and Sengupta, Kamalika and Frege, Carla and Gordon, Hamish and Williamson, Christina and Heinritzi, Martin and Simon, Mario and Yan, Chao and Almeida, Joa{\~{o}} and Trostl, Jasmin and Nieminen, Tuomo and Ortega, Ismael K. and Wagner, Robert and Adamov, Alexey and Amorim, Antonio and Bernhammer, Anne Kathrin and Bianchi, Federico and Breitenlechner, Martin and Brilke, Sophia and Chen, Xuemeng and Craven, Jill and Dias, Antonio and Ehrhart, Sebastian and Flagan, Richard C. and Franchin, Alessandro and Fuchs, Claudia and Guida, Roberto and Hakala, Jani and Hoyle, Christopher R. and Jokinen, Tuija and Junninen, Heikki and Kangasluoma, Juha and Kim, Jaeseok and Krapf, Manuel and Kurten, Andreas and Laaksonen, Ari and Lehtipalo, Katrianne and Makhmutov, Vladimir and Mathot, Serge and Molteni, Ugo and Onnela, Antti and Perakyla, Otso and Piel, Felix and Petaja, Tuukka and Praplan, Arnaud P. and Pringle, Kirsty and Rap, Alexandru and Richards, Nigel A.D. and Riipinen, Ilona and Rissanen, Matti P. and Rondo, Linda and Sarnela, Nina and Schobesberger, Siegfried and Scott, Catherine E. and Seinfeld, John H. and Sipila, Mikko and Steiner, Gerhard and Stozhkov, Yuri and Stratmann, Frank and Tom{\'{e}}, Antonio and Virtanen, Annele and Vogel, Alexander L. and Wagner, Andrea C. and Wagner, Paul E. and Weingartner, Ernest and Wimmer, Daniela and Winkler, Paul M. and Ye, Penglin and Zhang, Xuan and Hansel, Armin and Dommen, Josef and Donahue, Neil M. and Worsnop, Douglas R. and Baltensperger, Urs and Kulmala, Markku and Carslaw, Kenneth S. and Curtius, Joachim},
doi = {10.1038/nature17953},
issn = {14764687},
journal = {Nature},
month = {may},
number = {7604},
pages = {521--526},
publisher = {Nature Publishing Group},
title = {{Ion-induced nucleation of pure biogenic particles}},
volume = {533},
year = {2016}
}
@misc{Kirkby2007,
abstract = {Among the most puzzling questions in climate change is that of solar-climate variability, which has attracted the attention of scientists for more than two centuries. Until recently, even the existence of solar-climate variability has been controversial-perhaps because the observations had largely involved correlations between climate and the sunspot cycle that had persisted for only a few decades. Over the last few years, however, diverse reconstructions of past climate change have revealed clear associations with cosmic ray variations recorded in cosmogenic isotope archives, providing persuasive evidence for solar or cosmic ray forcing of the climate. However, despite the increasing evidence of its importance, solar-climate variability is likely to remain controversial until a physical mechanism is established. Although this remains a mystery, observations suggest that cloud cover may be influenced by cosmic rays, which are modulated by the solar wind and, on longer time scales, by the geomagnetic field and by the galactic environment of Earth. Two different classes of microphysical mechanisms have been proposed to connect cosmic rays with clouds: firstly, an influence of cosmic rays on the production of cloud condensation nuclei and, secondly, an influence of cosmic rays on the global electrical circuit in the atmosphere and, in turn, on ice nucleation and other cloud microphysical processes. Considerable progress on understanding ion-aerosol-cloud processes has been made in recent years, and the results are suggestive of a physically-plausible link between cosmic rays, clouds and climate. However, a concerted effort is now required to carry out definitive laboratory measurements of the fundamental physical and chemical processes involved, and to evaluate their climatic significance with dedicated field observations and modelling studies. {\textcopyright} Springer Science+Business Media B.V. 2008.},
author = {Kirkby, Jasper},
booktitle = {Surveys in Geophysics},
doi = {10.1007/s10712-008-9030-6},
issn = {01693298},
keywords = {Aerosols,CERN CLOUD facility,Climate,Clouds,Cosmic rays,Global electrical circuit,Ions,Solar-climate variability},
month = {nov},
number = {5-6},
pages = {333--375},
title = {{Cosmic rays and climate}},
volume = {28},
year = {2007}
}
@article{Klein2015,
abstract = {Emergent constraints are physically explainable empirical relationships between characteristics of the current climate and long-term climate prediction that emerge in collections of climate model simulations. With the prospect of constraining long-term climate prediction, scientists have recently uncovered several emergent constraints related to long-term cloud feedbacks. We review these proposed emergent constraints, many of which involve the behavior of low-level clouds, and discuss criteria to assess their credibility. With further research, some of the cases we review may eventually become confirmed emergent constraints, provided they are accompanied by credible physical explanations. Because confirmed emergent constraints identify a source of model error that projects onto climate predictions, they deserve extra attention from those developing climate models and climate observations. While a systematic bias cannot be ruled out, it is noteworthy that the promising emergent constraints suggest larger cloud feedback and hence climate sensitivity.},
author = {Klein, Stephen A. and Hall, Alex},
doi = {10.1007/s40641-015-0027-1},
issn = {2198-6061},
journal = {Current Climate Change Reports},
keywords = {climate,climate sensitivity,cloud feedbacks,constraint,emergent constraints,models,power of human mind,to assess the,what is an emergent,when combined with the},
number = {4},
pages = {276--287},
title = {{Emergent Constraints for Cloud Feedbacks}},
url = {http://link.springer.com/10.1007/s40641-015-0027-1},
volume = {1},
year = {2015}
}
@article{KleinStephenA.;HallAlex;NorrisJoelR.;Pincus2017,
abstract = {The response to warming of tropical low-level clouds including both marine stratocumulus and trade cumulus is a major source of uncertainty in projections of future climate. Climate model simulations of the response vary widely, reflecting the difficulty the models have in simulating these clouds. These inadequacies have led to alternative approaches to predict low-cloud feedbacks. Here, we review an observational approach that relies on the assumption that observed relationships between low clouds and the “cloud-controlling factors” of the large-scale environment are invariant across time-scales. With this assumption, and given predictions of how the cloud-controlling factors change with climate warming, one can predict low-cloud feedbacks without using any model simulation of low clouds. We discuss both fundamental and implementation issues with this approach and suggest steps that could reduce uncertainty in the predicted low-cloud feedback. Recent studies using this approach predict that the tropical low-cloud feedback is positive mainly due to the observation that reflection of solar radiation by low clouds decreases as temperature increases, holding all other cloud-controlling factors fixed. The positive feedback from temperature is partially offset by a negative feedback from the tendency for the inversion strength to increase in a warming world, with other cloud-controlling factors playing a smaller role. A consensus estimate from these studies for the contribution of tropical low clouds to the global mean cloud feedback is 0.25 ± 0.18 W m−2 K−1 (90{\%} confidence interval), suggesting it is very unlikely that tropical low clouds reduce total global cloud feedback. Because the prediction of positive tropical low-cloud feedback with this approach is consistent with independent evidence from low-cloud feedback studies using high-resolution cloud models, progress is being made in reducing this key climate uncertainty.},
author = {Klein, Stephen A. and Hall, Alex and Norris, Joel R. and Pincus, Robert},
doi = {https://doi.org/10.1007/s10712-017-9433-3},
isbn = {1071201794},
issn = {15730956},
journal = {Surveys in Geophysics},
keywords = {Climate change,Cloud feedbacks,Low clouds},
number = {6},
pages = {1307--1329},
title = {{Low-cloud feedbacks from cloud-controlling factors: A review}},
url = {https://doi.org/10.1007/s10712-017-9433-3},
volume = {38},
year = {2017}
}
@article{Knutti2005,
abstract = {Probabilistic projections of future climate change for a range of$\backslash$nCO2 stabilization profiles intended for the Fourth Assessment Report$\backslash$nof the Intergovernmental Panel on Climate Change are presented. A$\backslash$nvery large ensemble of simulations with the reduced complexity, Bern2.5D$\backslash$nclimate model is used to explore the uncertainties in projected long-term$\backslash$nchanges in surface air temperature and sea level due to uncertainties$\backslash$nin climate sensitivity and ocean heat uptake. Previously published$\backslash$nprobability density functions of climate sensitivity are used to$\backslash$ncalculate probabilistic projections for different CO2 stabilization$\backslash$nlevels and to calculate the probability of not exceeding a certain$\backslash$nglobal mean surface temperature for a given stabilization level.$\backslash$nThis provides a new way of communicating long-term uncertainty which$\backslash$ncan serve as a basis for selecting a CO2 stabilization level given$\backslash$na temperature limit and help to estimate the overshoot risk society$\backslash$nis willing to accept.},
author = {Knutti, Reto and Joos, Fortunat and M{\"{u}}ller, Simon A. and Plattner, Gian Kasper and Stocker, Thomas F.},
doi = {10.1029/2005GL023294},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
number = {20},
pages = {1--4},
title = {{Probabilistic climate change projections for CO2 stabilization profiles}},
volume = {32},
year = {2005}
}
@article{Knutti2002,
author = {Knutti, Reto and Stocker, Thomas F. and Joos, Fortunat and Plattner, Gian-Kasper},
doi = {10.1038/416719a},
issn = {0028-0836},
journal = {Nature},
month = {apr},
number = {6882},
pages = {719--723},
title = {{Constraints on radiative forcing and future climate change from observations and climate model ensembles}},
url = {http://www.nature.com/articles/416719a},
volume = {416},
year = {2002}
}
@article{Knutti2006,
abstract = {Abstract The estimated range of climate sensitivity has remained unchanged for decades, resulting in large uncertainties in long-term projections of future climate under increased greenhouse gas concentrations. Here the multi-thousand-member ensemble of climate model simulations from the climateprediction.net project and a neural network are used to establish a relation between climate sensitivity and the amplitude of the seasonal cycle in regional temperature. Most models with high sensitivities are found to overestimate the seasonal cycle compared to observations. A probability density function for climate sensitivity is then calculated from the present-day seasonal cycle in reanalysis and instrumental datasets. Subject to a number of assumptions on the models and datasets used, it is found that climate sensitivity is very unlikely (5{\%} probability) to be either below 1.5?2 K or above about 5?6.5 K, with the best agreement found for sensitivities between 3 and 3.5 K. This range is narrower than most probabilistic estimates derived from the observed twentieth-century warming. The current generation of general circulation models are within that range but do not sample the highest values.},
annote = {doi: 10.1175/JCLI3865.1},
author = {Knutti, Reto and Meehl, Gerald A and Allen, Myles R and Stainforth, David A},
doi = {10.1175/JCLI3865.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {17},
pages = {4224--4233},
publisher = {American Meteorological Society},
title = {{Constraining Climate Sensitivity from the Seasonal Cycle in Surface Temperature}},
url = {https://doi.org/10.1175/JCLI3865.1},
volume = {19},
year = {2006}
}
@article{Knutti2013b,
abstract = {AbstractA new ensemble of climate models is becoming available and provides the basis for climate change projections. Here, we show a first analysis indicating that the models in the new ensemble agree better with observations than those in older ones and that the poorest models have been eliminated. Most models are strongly tied to their predecessors, and some also exchange ideas and code with other models, thus supporting an earlier hypothesis that the models in the new ensemble are neither independent of each other nor independent of the earlier generation. On the basis of one atmosphere model, we show how statistical methods can identify similarities between model versions and complement process understanding in characterizing how and why a model has changed. We argue that the interdependence of models complicates the interpretation of multimodel ensembles but largely goes unnoticed.},
annote = {doi: 10.1002/grl.50256},
author = {Knutti, Reto and Masson, David and Gettelman, Andrew},
doi = {10.1002/grl.50256},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {GCM,independence,model genealogy,multimodel},
month = {mar},
number = {6},
pages = {1194--1199},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Climate model genealogy: Generation CMIP5 and how we got there}},
url = {https://doi.org/10.1002/grl.50256},
volume = {40},
year = {2013}
}
@article{Knutti2017a,
abstract = {Equilibrium climate sensitivity characterizes the Earth's long-term global temperature response to increased atmospheric CO2 concentration. It has reached almost iconic status as the single number that describes how severe climate change will be. The consensus on the 'likely' range for climate sensitivity of 1.5 °C to 4.5 °C today is the same as given by Jule Charney in 1979, but now it is based on quantitative evidence from across the climate system and throughout climate history. The quest to constrain climate sensitivity has revealed important insights into the timescales of the climate system response, natural variability and limitations in observations and climate models, but also concerns about the simple concepts underlying climate sensitivity and radiative forcing, which opens avenues to better understand and constrain the climate response to forcing. Estimates of the transient climate response are better constrained by observed warming and are more relevant for predicting warming over the next decades. Newer metrics relating global warming directly to the total emitted CO2 show that in order to keep warming to within 2 °C, future CO2 emissions have to remain strongly limited, irrespective of climate sensitivity being at the high or low end.},
author = {Knutti, Reto and Rugenstein, Maria A.A. and Hegerl, Gabriele C.},
doi = {10.1038/NGEO3017},
issn = {17520908},
journal = {Nature Geoscience},
number = {10},
pages = {727--736},
publisher = {Nature Publishing Group},
title = {{Beyond equilibrium climate sensitivity}},
url = {https://www.nature.com/articles/ngeo3017},
volume = {10},
year = {2017}
}
@article{Knutti2008,
abstract = {The Earth's climate is changing rapidly as a result of anthropogenic carbon emissions, and damaging impacts are expected to increase with warming. To prevent these and limit long-term global surface warming to, for example, 2 °C, a level of stabilization or of peak atmospheric CO2 concentrations needs to be set. Climate sensitivity, the global equilibrium surface warming after a doubling of atmospheric CO2 concentration, can help with the translation of atmospheric CO2 levels to warming. Various observations favour a climate sensitivity value of about 3 °C, with a likely range of about 2–4.5 °C. However, the physics of the response and uncertainties in forcing lead to fundamental difficulties in ruling out higher values. The quest to determine climate sensitivity has now been going on for decades, with disturbingly little progress in narrowing the large uncertainty range. However, in the process, fascinating new insights into the climate system and into policy aspects regarding mitigation have been gained. The well-constrained lower limit of climate sensitivity and the transient rate of warming already provide useful information for policy makers. But the upper limit of climate sensitivity will be more difficult to quantify.},
author = {Knutti, Reto and Hegerl, Gabriele C.},
doi = {10.1038/ngeo337},
isbn = {1752-0894},
issn = {17520894},
journal = {Nature Geoscience},
month = {oct},
pages = {735},
publisher = {Nature Publishing Group},
title = {{The equilibrium sensitivity of the Earth's temperature to radiation changes}},
volume = {1},
year = {2008}
}
@article{Knutti2010b,
abstract = {1 The trillion dollar garden party—an analogy Imagine you are hosting a garden party tomorrow and you are trying to decide whether or not to put up a tent against the rain. You read the weather forecast in the newspaper and you ask the farmer next door, and you look at the sky (knowing that persistence is often not a bad weather forecast). So you get three predictions, but how would you aggregate them? Would you average them with equal weight? You might trust the forecast model more (or less) than the farmer, not because you understand how either of them generates their prediction, but because of your past experience in similar situations. But why seek advice from more than one source in the first place? We intuitively assume that the combined information from multiple sources improves our understanding and therefore our ability to decide. Now having read one newspaper forecast already, would a second and a third one increase your confidence? That seems unlikely, because you know that all newspaper forecasts are based on one of only a few numerical weather prediction models. Now once you have decided on a set of forecasts, and irrespective of whether they agree or not, you will have to synthesize the different pieces of information and decide about the tent for the party. The optimal decision probably involves more than just the most likely prediction. If the damage without the tent is likely to be large, and if putting up the tent is easy, then you might go for the tent in a case of large prediction uncertainty even if the most likely outcome is no rain. Although it may seem far-fetched at first, the problem of climate projection is in fact similar in many respects to the garden party situation discussed above. So far, projections from multiple climate models were often aggregated into simple averages, standard deviations and ranges. One example is the recent Fourth Assess-ment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC), 396 Climatic Change (2010) 102:395–404 which was based largely on multi-model averages of the models participating in the World Climate Research Project (WCRP) Coupled Model Intercomparison Project Phase 3 (CMIP3) (Meehl et al. 2007). But is this the best use of the information? Or are we finally ready to move beyond the 'one-model-one-vote' approach? Some recent publications suggest that 'the end of model democracy' (a quote first used by Vladimir Kattsov at an IPCC meeting in 2006) may be near, but the problem is far from trivial. In this issue, Smith and Chandler (2010) propose that for rainfall over the Murray Darling basin in south east Australia, present-day precipitation mean and variability are useful indicators for the evaluation of models, and they find that models performing well today show a more similar trend in the future. At least in their case, eliminating poor models therefore decreases the spread of the ensemble. Although this is not always the case, similar findings for Alaska and Greenland are reported by Walsh et al. (2008). Ideas of down-weighting or eliminating models have been around for a while (Giorgi and Mearns 2002, 2003) but the widespread availability of perturbed physics and multi-model ensembles has sparked more interest in the community for methods to evaluate, combine and possibly weight models, and constrain projections using observations (Annan et al. 2005; Eyring et al. 2007; Forest et al. 2002; Furrer et al. 2007a, b; Greene et al. 2006; Hall and Qu 2006; Hargreaves et al. 2004; Jun et al. 2008a, b; Knutti 2008a; Knutti et al. 2009; Lopez et al. 2006; Murphy et al. 2004; Piani et al. 2005; R{\"{a}}is{\"{a}}nen 2005, 2007; Sanderson et al. 2008; Schmittner et al. 2005; Shukla et al. 2006; Tebaldi and Knutti 2007; Tebaldi et al. 2004, 2005; Tebaldi and Sanso 2009; van Oldenborgh et al. 2005; Weigel et al. 2008). In the following section, I try to summarize some of the pertinent questions that in my view remain unresolved in combining multiple models. There are of course several aspects where the analogy with the garden party above will fail. First, we are working with a forecast system that strictly speaking has never been proven to have skill, nor to be wrong, at least on the time scales of centuries. Second, we are dealing with a rather expensive garden party that involves billions of people and trillions of dollars. The decisions based on our forecasts might shape the world of the future, so a prediction that is overconfident might be an expensive failure. And finally, it is not just about deciding yes or no as in the case of the tent, but about deciding on one of many possible strategies based on an admittedly incomplete understanding of an extremely complex system. Accordingly, providing a clear recommendation for a way forward is far from trivial. 2 Making sense of multiple models},
author = {Knutti, Reto},
doi = {10.1007/s10584-010-9800-2},
isbn = {1058401098002},
issn = {01650009},
journal = {Climatic Change},
number = {3},
pages = {395--404},
title = {{The end of model democracy?}},
volume = {102},
year = {2010}
}
@article{Knutti2008a,
author = {Knutti, Reto and Kr{\"{a}}henmann, Stefan and Frame, David J. and Allen, Myles R.},
doi = {10.1029/2007JD009473},
issn = {01480227},
journal = {Journal of Geophysical Research: Atmospheres},
number = {15},
pages = {1--6},
title = {{Comment on “Heat capacity, time constant, and sensitivity of Earth's climate system” by S. E. Schwartz}},
volume = {113},
year = {2008}
}
@article{Koenigk2014,
abstract = {The ocean heat transport into the Arctic and the heat budget of the Barents Sea are analyzed in an ensemble of historical and future climate simulations performed with the global coupled climate model EC-Earth. The zonally integrated northward heat flux in the ocean at 70°N is strongly enhanced and compensates for a reduction of its atmospheric counterpart in the twenty first century. Although an increase in the northward heat transport occurs through all of Fram Strait, Canadian Archipelago, Bering Strait and Barents Sea Opening, it is the latter which dominates the increase in ocean heat transport into the Arctic. Increased temperature of the northward transported Atlantic water masses are the main reason for the enhancement of the ocean heat transport. The natural variability in the heat transport into the Barents Sea is caused to the same extent by variations in temperature and volume transport. Large ocean heat transports lead to reduced ice and higher atmospheric temperature in the Barents Sea area and are related to the positive phase of the North Atlantic Oscillation. The net ocean heat transport into the Barents Sea grows until about year 2050. Thereafter, both heat and volume fluxes out of the Barents Sea through the section between Franz Josef Land and Novaya Zemlya are strongly enhanced and compensate for all further increase in the inflow through the Barents Sea Opening. Most of the heat transported by the ocean into the Barents Sea is passed to the atmosphere and contributes to warming of the atmosphere and Arctic temperature amplification. Latent and sensible heat fluxes are enhanced. Net surface long-wave and solar radiation are enhanced upward and downward, respectively and are almost compensating each other. We find that the changes in the surface heat fluxes are mainly caused by the vanishing sea ice in the twenty first century. The increasing ocean heat transport leads to enhanced bottom ice melt and to an extension of the area with bottom ice melt further northward. However, no indication for a substantial impact of the increased heat transport on ice melt in the Central Arctic is found. Most of the heat that is not passed to the atmosphere in the Barents Sea is stored in the Arctic intermediate layer of Atlantic water, which is increasingly pronounced in the twenty first century.},
author = {Koenigk, Torben and Brodeau, Laurent},
doi = {10.1007/s00382-013-1821-x},
isbn = {0930-7575},
journal = {Climate Dynamics},
keywords = {Arctic,Climate change,Climate variability,Global coupled modelling,Ocean heat transport,Ocean volume transport},
month = {jun},
number = {11-12},
pages = {3101--3120},
title = {{Ocean heat transport into the Arctic in the twentieth and twenty-first century in EC-Earth}},
url = {http://link.springer.com/10.1007/s00382-013-1821-x},
volume = {42},
year = {2014}
}
@article{Kohyama2017,
abstract = {AbstractThe majority of the models that participated in the Coupled Model Intercomparison Project Phase 5 global warming experiments warm faster in the eastern equatorial Pacific Ocean than in the west. GFDL-ESM2M is an exception among the state-of-the-art global climate models in that the equatorial Pacific sea surface temperature (SST) in the west warms faster than in the east, and the Walker circulation strengthens in response to warming. This study shows that this “La Ni{\~{n}}a-like” trend simulated by GFDL-ESM2M could be a physically consistent response to warming, and that the forced response could have been detectable since the late 20th Century. Two additional models are examined: GFDL-ESM2G, which differs from GFDL-ESM2M only in the oceanic components, warms without a clear zonal SST gradient; HadGEM2-CC exhibits a warming pattern that resembles the multi-model mean. A fundamental observed constraint between the amplitude of the El Ni{\~{n}}o Southern Oscillation (ENSO) and the mean-state zonal SST gradient...},
author = {Kohyama, Tsubasa and Hartmann, Dennis L. and Battisti, David S.},
doi = {10.1175/JCLI-D-16-0441.1},
isbn = {0025-729X (Print)$\backslash$r0025-729X (Linking)},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Atmosphere-ocean interaction,Climate change,Climate models,Climate variability,ENSO,Trends},
month = {jun},
number = {11},
pages = {4207--4225},
pmid = {4456148},
publisher = {American Meteorological Society},
title = {{La Ni{\~{n}}a-like mean-state response to global warming and potential oceanic roles}},
volume = {30},
year = {2017}
}
@article{Kooperman2012,
abstract = {Natural modes of variability on many timescales influence aerosol particle distributions and cloud properties such that isolating statistically significant differences in cloud radiative forcing due to anthropogenic aerosol perturbations (indirect effects) typically requires integrating over long simulations. For state-of-the-art global climate models (GCM), especially those in which embedded cloud-resolving models replace conventional statistical parameterizations (i.e., multiscale modeling framework, MMF), the required long integrations can be prohibitively expensive. Here an alternative approach is explored, which implements Newtonian relaxation (nudging) to constrain simulations with both pre-industrial and present-day aerosol emissions toward identical meteorological conditions, thus reducing differences in natural variability and dampening feedback responses in order to isolate radiative forcing. Ten-year GCM simulations with nudging provide a more stable estimate of the global-annual mean net aerosol indirect radiative forcing than do conventional free-running simulations. The estimates have mean values and 95{\%} confidence intervals of -1.19 0.02 W/m2 and -1.37 0.13 W/m 2 for nudged and free-running simulations, respectively. Nudging also substantially increases the fraction of the world's area in which a statistically significant aerosol indirect effect can be detected (66{\%} and 28{\%} of the Earth's surface for nudged and free-running simulations, respectively). One-year MMF simulations with and without nudging provide global-annual mean net aerosol indirect radiative forcing estimates of -0.81 W/m2 and -0.82 W/m2, respectively. These results compare well with previous estimates from three-year free-running MMF simulations (-0.83 W/m2), which showed the aerosol-cloud relationship to be in better agreement with observations and high-resolution models than in the results obtained with conventional cloud parameterizations. {\textcopyright} 2012. American Geophysical Union. All Rights Reserved.},
author = {Kooperman, Gabriel J. and Pritchard, Michael S. and Ghan, Steven J. and Wang, Minghuai and Somerville, Richard C. J. and Russell, Lynn M.},
doi = {10.1029/2012JD018588},
issn = {01480227},
journal = {Journal of Geophysical Research: Atmospheres},
month = {dec},
number = {D23},
pages = {D23204},
title = {{Constraining the influence of natural variability to improve estimates of global aerosol indirect effects in a nudged version of the Community Atmosphere Model 5}},
url = {http://doi.wiley.com/10.1029/2012JD018588},
volume = {117},
year = {2012}
}
@article{Koren2005a,
author = {Koren, Ilan and Kaufman, Yoram J. and Rosenfeld, Daniel and Remer, Lorraine A. and Rudich, Yinon},
doi = {10.1029/2005GL023187},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {jul},
number = {14},
pages = {L14828},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Aerosol invigoration and restructuring of Atlantic convective clouds}},
url = {http://doi.wiley.com/10.1029/2005GL023187},
volume = {32},
year = {2005}
}
@article{Koren2010,
author = {Koren, I. and Feingold, G. and Remer, L. A.},
doi = {10.5194/acp-10-8855-2010},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {sep},
number = {18},
pages = {8855--8872},
title = {{The invigoration of deep convective clouds over the Atlantic: aerosol effect, meteorology or retrieval artifact?}},
url = {http://www.atmos-chem-phys.net/10/8855/2010/},
volume = {10},
year = {2010}
}
@article{Kostov2014,
abstract = {We propose here that the Atlantic meridional overturning circulation (AMOC) plays an important role in setting the effective heat capacity of the World Ocean and thus impacts the pace of transient climate change. The depth and strength of AMOC are shown to be strongly correlated with the depth of heat storage across a suite of state-of-the-art general circulation models (GCMs). In those models with a deeper and stronger AMOC, a smaller portion of the heat anomaly remains in the ocean mixed layer, and consequently, the surface temperature response is delayed. Representations of AMOC differ vastly across the GCMs, providing a major source of intermodel spread in the sea surface temperature (SST) response. A two-layer model fit to the GCMs is used to demonstrate that the intermodel spread in SSTs due to variations in the ocean's effective heat capacity is significant but smaller than the spread due to climate feedbacks.},
author = {Kostov, Yavor and Armour, Kyle C. and Marshall, John},
doi = {10.1002/2013GL058998},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {AMOC,CMIP5,climate change,climate sensitivity,inter-model spread,ocean heat uptake},
month = {mar},
number = {6},
pages = {2108--2116},
title = {{Impact of the Atlantic meridional overturning circulation on ocean heat storage and transient climate change}},
url = {http://doi.wiley.com/10.1002/2013GL058998},
volume = {41},
year = {2014}
}
@article{Kostov2018,
author = {Kostov, Yavor and Ferreira, David and Armour, Kyle C. and Marshall, John},
doi = {10.1002/2017GL074964},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {CMIP5,Southern Annular Mode,Southern Ocean,climate variability,greenhouse gas forcing,ozone forcing},
month = {jan},
number = {2},
pages = {1086--1097},
title = {{Contributions of Greenhouse Gas Forcing and the Southern Annular Mode to Historical Southern Ocean Surface Temperature Trends}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2017GL074964},
volume = {45},
year = {2018}
}
@article{Kostov2017,
abstract = {We investigate how sea surface temperatures (SSTs) around Antarctica respond to the Southern Annular Mode (SAM) on multiple timescales. To that end we examine the relationship between SAM and SST within unperturbed preindustrial control simulations of coupled general circulation models (GCMs) included in the Climate Modeling Intercomparison Project phase 5 (CMIP5). We develop a technique to extract the response of the Southern Ocean SST (55{\{}$\backslash$textdegree{\}}S--70{\{}$\backslash$textdegree{\}}S) to a hypothetical step increase in the SAM index. We demonstrate that in many GCMs, the expected SST step response function is nonmonotonic in time. Following a shift to a positive SAM anomaly, an initial cooling regime can transition into surface warming around Antarctica. However, there are large differences across the CMIP5 ensemble. In some models the step response function never changes sign and cooling persists, while in other GCMs the SST anomaly crosses over from negative to positive values only 3 years after a step increase in the SAM. This intermodel diversity can be related to differences in the models' climatological thermal ocean stratification in the region of seasonal sea ice around Antarctica. Exploiting this relationship, we use observational data for the time-mean meridional and vertical temperature gradients to constrain the real Southern Ocean response to SAM on fast and slow timescales.},
author = {Kostov, Yavor and Marshall, John and Hausmann, Ute and Armour, Kyle C. and Ferreira, David and Holland, Marika M.},
doi = {10.1007/s00382-016-3162-z},
isbn = {0038201631},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {Atmosphere–ocean interaction,CMIP5,Southern Annular Mode,Southern Ocean,Surface westerlies},
month = {mar},
number = {5-6},
pages = {1595--1609},
title = {{Fast and slow responses of Southern Ocean sea surface temperature to SAM in coupled climate models}},
url = {http://link.springer.com/10.1007/s00382-016-3162-z},
volume = {48},
year = {2017}
}
@article{doi:10.1029/2018JD029021,
abstract = {Abstract Radiative kernels describe the differential response of radiative fluxes to small perturbations in state variables and are widely used to quantify radiative feedbacks on the climate system. Radiative kernels have traditionally been generated using simulated data from a global climate model, typically sourced from the model's base climate. Consequently, these radiative kernels are subject to model bias from the climatological fields used to produce them. Here, we introduce the first observation-based temperature, water vapor, and surface albedo radiative kernels, developed from CloudSat's fluxes and heating rates data set, 2B-FLXHR-LIDAR, which is supplemented with cloud information from the Cloud�Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). We compare the radiative kernels to a previously published set generated from the Geophysical Fluid Dynamics Laboratory (GFDL) model and find general agreement in magnitude and structure. However, several key differences illustrate the sensitivity of radiative kernels to the distribution of clouds. The radiative kernels are used to quantify top-of-atmosphere and surface cloud feedbacks in an ensemble of global climate models from the Climate Model Intercomparison Project Phase 5, showing that biases in the GFDL low clouds likely cause the GFDL kernel to underestimate longwave surface cloud feedback. Since the CloudSat kernels are free of model bias in the base state, they will be ideal for future analysis of radiative feedbacks and forcing in both models and observations and for evaluating biases in model-derived radiative kernels.},
author = {Kramer, Ryan J and Matus, Alexander V and Soden, Brian J and L'Ecuyer, Tristan S},
doi = {10.1029/2018JD029021},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {cloud distribution,cloud feedback,cloud masking,radiative kernel,remote sensing},
number = {10},
pages = {5431--5444},
title = {{Observation-Based Radiative Kernels From CloudSat/CALIPSO}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD029021},
volume = {124},
year = {2019}
}
@article{Krasting2018,
abstract = {Oceanic heat uptake (OHU) is a significant source of uncertainty in both the transient and equilibrium responses to increasing the planetary radiative forcing. OHU differs among climate models and is related in part to their representation of vertical and lateral mixing. This study examines the role of ocean model formulation—specifically the choice of the vertical coordinate and the strength of the background diapycnal diffusivity Kd—in the millennial-scale near-equilibrium climate response to a quadrupling of atmospheric CO2. Using two fully coupled Earth system models (ESMs) with nearly identical atmosphere, land, sea ice, and biogeochemical components, it is possible to independently configure their ocean model components with different formulations and produce similar near-equilibrium climate responses. The SST responses are similar between the two models (r2 = 0.75, global average {\~{}}4.3°C) despite their initial preindustrial climate mean states differing by 0.4°C globally. The surface and interior responses of temperature and salinity are also similar between the two models. However, the Atlantic meridional overturning circulation (AMOC) responses are different between the two models, and the associated differences in ventilation and deep-water formation have an impact on the accumulation of dissolved inorganic carbon in the ocean interior. A parameter sensitivity analysis demonstrates that increasing the amount of Kd produces very different near-equilibrium climate responses within a given model. These results suggest that the impact of the ocean vertical coordinate on the climate response is small relative to the representation of subgrid-scale mixing.},
author = {Krasting, John P. and Stouffer, Ronald J. and Griffies, Stephen M. and Hallberg, Robert W. and Malyshev, Sergey L. and Samuels, Bonita L. and Sentman, Lori T.},
doi = {10.1175/JCLI-D-18-0035.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {nov},
number = {22},
pages = {9313--9333},
title = {{Role of Ocean Model Formulation in Climate Response Uncertainty}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-18-0035.1},
volume = {31},
year = {2018}
}
@article{Kretzschmar2017,
author = {Kretzschmar, Jan and Salzmann, Marc and M{\"{u}}lmenst{\"{a}}dt, Johannes and Boucher, Olivier and Quaas, Johannes},
doi = {10.1175/JCLI-D-16-0668.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Aerosols,Anthropogenic effects,Climate change,Climate models,Cloud forcing,Radiative forcing},
number = {16},
pages = {6579--6584},
publisher = {American Meteorological Society},
title = {{Comment on “Rethinking the Lower Bound on Aerosol Radiative Forcing”}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-16-0668.1},
volume = {30},
year = {2017}
}
@article{Krishna-PillaiSukumara-Pillai2019,
abstract = {Abstract. Reduction of surface temperatures of the planet by injecting sulfate aerosols in the stratosphere has been suggested as an option to reduce the amount of human-induced climate warming. Several previous studies have shown that for a specified amount of injection, aerosols injected at a higher altitude in the stratosphere would produce more cooling because aerosol sedimentation would take longer time. In this study, we isolate and assess the sensitivity to the altitude of the aerosol layer of stratospheric aerosol radiative forcing and the resulting climate change. We study this by prescribing a specified amount of sulfate aerosols, of a size typical of what is produced by volcanoes, distributed uniformly at different levels in the stratosphere. We find that stratospheric sulfate aerosols are more effective in cooling climate when they reside higher in the stratosphere. We explain this sensitivity in terms of effective radiative forcing: volcanic aerosols heat the stratospheric layers where they reside, altering stratospheric water vapor content, tropospheric stability and clouds, and consequently the effective radiative forcing. We show that the magnitude of the effective radiative forcing is larger when aerosols are prescribed at higher altitudes and the differences in radiative forcing due to fast adjustment processes can account for a substantial part of the dependence of amount of cooling on aerosol altitude. These altitude effects would be additional to dependences on aerosol microphysics, transport, and sedimentation, which are outside the scope of this study. The cooling effectiveness of stratospheric sulfate aerosols likely increases with altitude of the aerosol layer both because aerosols higher in the stratosphere have larger effective radiative forcing and because they have a longer stratospheric residence time; these two effects are likely to be of comparable importance.},
author = {Krishnamohan, K. S. and Bala, Govindasamy and Cao, Long and Duan, Lei and Caldeira, Ken},
doi = {https://doi.org/10.5194/esd-10-885-2019},
journal = {Earth System Dynamics},
number = {4},
pages = {885--900},
title = {{Climate System Response to Stratospheric Sulfate Aerosols: Sensitivity to Altitude of Aerosol Layer}},
volume = {10},
year = {2019}
}
@article{Kristjansson2008,
abstract = {{\textless}p{\textgreater}Abstract. The response of clouds to sudden decreases in the flux of galactic cosmic rays (GCR) – Forbush decrease events – has been investigated using cloud products from the space-borne MODIS instrument, which has been in operation since 2000. By focusing on pristine Southern Hemisphere ocean regions we examine areas where we believe that a cosmic ray signal should be easier to detect than elsewhere. While previous studies have mainly considered cloud cover, the high spatial and spectral resolution of MODIS allows for a more thorough study of microphysical parameters such as cloud droplet size, cloud water content and cloud optical depth, in addition to cloud cover. Averaging the results from the 22 Forbush decrease events that were considered, no statistically significant correlations were found between any of the four cloud parameters and GCR, when autocorrelations were taken into account. Splitting the area of study into six domains, all of them have a negative correlation between GCR and cloud droplet size, in agreement with a cosmic ray – cloud coupling, but in only one of the domains (eastern Atlantic Ocean) was the correlation statistically significant. Conversely, cloud optical depth is mostly negatively correlated with GCR, and in the eastern Atlantic Ocean domain that correlation is statistically significant. For cloud cover and liquid water path, the correlations with GCR are weaker, with large variations between the different domains. When only the six Forbush decrease events with the largest amplitude (more than 10{\%} decrease) were studied, the correlations fit the hypothesis slightly better, with 16 out of 24 correlations having the expected sign, although many of the correlations are quite weak. Introducing a time lag of a few days for clouds to respond to the cosmic ray signal the correlations tend to become weaker and even to change sign.{\textless}/p{\textgreater}},
author = {Kristj{\'{a}}nsson, J. E. and Stjern, C. W. and Stordal, F. and Fj{\ae}raa, A. M. and Myhre, G. and J{\'{o}}nasson, K.},
doi = {10.5194/acp-8-7373-2008},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {dec},
number = {24},
pages = {7373--7387},
title = {{Cosmic rays, cloud condensation nuclei and clouds – a reassessment using MODIS data}},
url = {https://www.atmos-chem-phys.net/8/7373/2008/},
volume = {8},
year = {2008}
}
@article{Krivova2006,
abstract = {Solar irradiance variations show a strong wavelength dependence. Whereas the total solar irradiance varies by about 0.1{\%} during the course of the solar cycle, variations at the wavelengths around the Ly-a emission line near 121.6 nm range up to 50-100{\%}. These variations may have a significant impact on the Earth's climate system. Being almost completely absorbed in the upper atmosphere, solar UV radiation below 300 nm affects stratospheric chemistry and controls production and destruction of ozone. Models of the solar UV irradiance remain far from perfect, even though considerable progress has been made in modelling the irradiance variations longwards of about 200-300 nm. We show that after correcting for the exposure dependent degradation of the SUSIM channels sampling irradiance at A {\textgreater} 240 nm (making use of the Mg II core-to-wing ratio) the agreement between model and measurement is significantly improved. At shorter wavelengths the LTE approximation usually made in such models fails, which makes a reconstruction of the solar UV irradiance a rather intricate problem. We choose an alternative approach and use the observed SUSIM UV spectra to extrapolate available models to shorter wavelengths. The model reproduces observed solar cycle variations of the irradiance at wavelengths down to 115 nm and indicates an important role of UV irradiance variability: up to 60{\%} of the total irradiance variations over the solar cycle might be produced at wavelengths below 400 nm. {\textcopyright} ESO 2006.},
author = {Krivova, N. A. and Solanki, S. K. and Floyd, L.},
doi = {10.1051/0004-6361:20064809},
issn = {0004-6361},
journal = {Astronomy {\&} Astrophysics},
keywords = {Solar-terrestrial relations,Sun: UV radiation,Sun: activity,Sun: faculae, plages,Sun: magnetic fields,Sunspots},
month = {jun},
number = {2},
pages = {631--639},
publisher = {EDP Sciences},
title = {{Reconstruction of solar UV irradiance in cycle 23}},
url = {http://www.aanda.org/10.1051/0004-6361:20064809},
volume = {452},
year = {2006}
}
@article{Kucharski2014,
author = {Kucharski, F. and Syed, F. S. and Burhan, A. and Farah, I. and Gohar, A.},
doi = {10.1007/s00382-014-2228-z},
journal = {Climate Dynamics},
month = {jun},
number = {3-4},
pages = {881--896},
publisher = {Springer Nature},
title = {{Tropical Atlantic influence on Pacific variability and mean state in the twentieth century in observations and CMIP5}},
volume = {44},
year = {2014}
}
@article{Kucharski2015,
author = {Kucharski, Fred and No, Hyun-Ho and King, Martin P. and Ikram, Farah and Mogensen, Kristian and Molteni, Franco and Kang, In-Sik and Giuliani, Graziano and Farneti, Riccardo},
doi = {10.1007/s00382-015-2705-z},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {jun},
number = {7-8},
pages = {2337--2351},
publisher = {Springer Nature},
title = {{Atlantic forcing of Pacific decadal variability}},
volume = {46},
year = {2015}
}
@article{Kucharski2011,
abstract = {The analysis of a series of regionally coupled ocean-atmospheric simulations suggests that the Atlantic warming that has occurred in the 20th century may have reduced the concomitant warming in the eastern tropical Pacific. The Pacific response to the Atlantic warming shows La Nina-like features even in the presence of greenhouse gas (GHG) forcing. The physical mechanism for the Atlantic warming influence on the tropical Pacific is a change in the Walker circulation that results in easterly surface wind anomalies in the central-west Pacific. Coupled ocean-atmosphere processes then amplify the signal. The possibility of an Atlantic Ocean induced cooling of the eastern tropical Pacific is complementary to the hypothesis that the GHG forcing itself may have caused the observed relative eastern Pacific cooling. It is argued that the uncertainties in the projected future mean state in the Pacific may be partly due to the competition of the GHG induced warming and the Atlantic induced cooling.},
author = {Kucharski, F. and Kang, I.-S. S. and Farneti, R. and Feudale, L.},
doi = {10.1029/2010GL046248},
journal = {Geophysical Research Letters},
month = {feb},
number = {3},
pages = {L03702},
publisher = {Blackwell Publishing Ltd},
title = {{Tropical Pacific response to 20th century Atlantic warming}},
volume = {38},
year = {2011}
}
@article{Kuhlbrodt2015a,
abstract = {About 90 {\%} of the anthropogenic increase in heat stored in the climate system is found in the oceans. Therefore it is relevant to understand the details of ocean heat uptake. Here we present a detailed, process-based analysis of ocean heat uptake (OHU) processes in HiGEM1.2, an atmosphere–ocean general circulation model with an eddy-permitting ocean component of 1/3° resolution. Similarly to various other models, HiGEM1.2 shows that the global heat budget is dominated by a downward advection of heat compensated by upward isopycnal diffusion. Only in the upper tropical ocean do we find the classical balance between downward diapycnal diffusion and upward advection of heat. The upward isopycnal diffusion of heat is located mostly in the Southern Ocean, which thus dominates the global heat budget. We compare the responses to a 4xCO2 forcing and an enhancement of the windstress forcing in the Southern Ocean. This highlights the importance of regional processes for the global ocean heat uptake. These are mainly surface fluxes and convection in the high latitudes, and advection in the Southern Ocean mid-latitudes. Changes in diffusion are less important. In line with the CMIP5 models, HiGEM1.2 shows a band of strong OHU in the mid-latitude Southern Ocean in the 4xCO2 run, which is mostly advective. By contrast, in the high-latitude Southern Ocean regions it is the suppression of convection that leads to OHU. In the enhanced windstress run, convection is strengthened at high Southern latitudes, leading to heat loss, while the magnitude of the OHU in the Southern mid-latitudes is very similar to the 4xCO2 results. Remarkably, there is only very small global OHU in the enhanced windstress run. The wind stress forcing just leads to a redistribution of heat. We relate the ocean changes at high Southern latitudes to the effect of climate change on the Antarctic Circumpolar Current (ACC). It weakens in the 4xCO2 run and strengthens in the wind stress run. The weakening is due to a narrowing of the ACC, caused by an expansion of the Weddell Gyre, and a flattening of the isopycnals, which are explained by a combination of the wind stress forcing and increased precipitation.},
author = {Kuhlbrodt, T and Gregory, J M and Shaffrey, L C},
doi = {10.1007/s00382-015-2534-0},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {11},
pages = {3205--3226},
title = {{A process-based analysis of ocean heat uptake in an AOGCM with an eddy-permitting ocean component}},
url = {https://doi.org/10.1007/s00382-015-2534-0},
volume = {45},
year = {2015}
}
@article{Kummer2014,
abstract = {Estimates of the Earth's equilibrium climate sensitivity (ECS) from twentieth century observations predict a lower ECS than estimates from climate models, paleoclimate data, and interannual variability. Here we show that estimates of ECS from the twentieth century observations are sensitive to the assumed efficacy of aerosol and ozone forcing (efficacy for a forcer is the amount of warming per unit global average forcing divided by the warming per unit forcing from CO2). Previous estimates of ECS based on the twentieth century observations have assumed that the efficacy is unity, which in our study yields an ECS of 2.3 K (5{\%}–95{\%} confidence range of 1.6–4.1 K), near the bottom of the Intergovernmental Panel on Climate Change's likely range of 1.5–4.5 K. Increasing the aerosol and ozone efficacy to 1.33 increases the ECS to 3.0 K (1.9–6.8 K), a value in excellent agreement with other estimates. Forcing efficacy therefore provides a way to bridge the gap between the different estimates of ECS.},
author = {Kummer, J. R. and Dessler, A. E.},
doi = {10.1002/2014GL060046},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {equilibrium climate sensitivity,forcing,forcing efficacy},
number = {10},
pages = {3565--3568},
title = {{The impact of forcing efficacy on the equilibrium climate sensitivity}},
volume = {41},
year = {2014}
}
@article{Kutzbach2013a,
abstract = {We investigate the sensitivity of climate to a broad range of greenhouse gas forcing with coupled atmosphere-ocean general circulation models using atmospheric CO2 concentrations ranging from similar to 1400 to similar to 200ppm. We show that climate sensitivity is greater when the base state climate is colder, a result noted previously but with models of much lower resolution and different parameterizations. The enhanced cold state sensitivity is more apparent in models coupled to dynamical versus slab oceans. The disproportionately large sensitivity for cold climates has applications to studies of climates colder than present.},
author = {Kutzbach, John E. and He, Feng and Vavrus, Steve J. and Ruddiman, William F.},
doi = {10.1002/grl.50724},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate change,climate models,climate sensitivity,greenhouse gases},
number = {14},
pages = {3721--3726},
title = {{The dependence of equilibrium climate sensitivity on climate state: Applications to studies of climates colder than present}},
volume = {40},
year = {2013}
}
@article{LEcuyer2015a,
abstract = {New objectively balanced observation-based reconstructions of global and continental energy budgets and their seasonal variability are presented that span the golden decade of Earth-observing satellites at the start of the twenty-first century. In the absence of balance constraints, various combinations of modern flux datasets reveal that current estimates of net radiation into Earth's surface exceed corresponding turbulent heat fluxes by 13-24 W m(-2). The largest imbalances occur over oceanic regions where the component algorithms operate independent of closure constraints. Recent uncertainty assessments suggest that these imbalances fall within anticipated error bounds for each dataset, but the systematic nature of required adjustments across different regions confirm the existence of biases in the component fluxes. To reintroduce energy and water cycle closure information lost in the development of independent flux datasets, a variational method is introduced that explicitly accounts for the relative accuracies in all component fluxes. Applying the technique to a 10-yr record of satellite observations yields new energy budget estimates that simultaneously satisfy all energy and water cycle balance constraints. Globally, 180 W m(-2) of atmospheric longwave cooling is balanced by 74 W m(-2) of shortwave absorption and 106 W m(-2) of latent and sensible heat release. At the surface, 106 W m(-2) of downwelling radiation is balanced by turbulent heat transfer to within a residual heat flux into the oceans of 0.45 W m(-2), consistent with recent observations of changes in ocean heat content. Annual mean energy budgets and their seasonal cycles for each of seven continents and nine ocean basins are also presented.},
address = {Univ Wisconsin, Madison, WI 53574 USA NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA },
annote = {Cu8bn
Times Cited:2
Cited References Count:142},
author = {L'Ecuyer, T S and Beaudoing, H K and Rodell, M and Olson, W and Lin, B and Kato, S and Clayson, C A and Wood, E and Sheffield, J and Adler, R and Huffman, G and Bosilovich, M and Gu, G and Robertson, F and Houser, P R and Chambers, D and Famiglietti, J S and Fetzer, E and Liu, W T and Gao, X and Schlosser, C A and Clark, E and Lettenmaier, D P and Hilburn, K},
doi = {10.1175/Jcli-D-14-00556.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {climatology energy budget balance heat budgets flu},
language = {English},
number = {21},
pages = {8319--8346},
title = {{The Observed State of the Energy Budget in the Early Twenty-First Century}},
volume = {28},
year = {2015}
}
@article{Laine2016,
abstract = {AbstractArctic amplification (AA) is a major characteristic of observed global warming, yet the different mechanisms responsible for it and their quantification are still under investigation. In this study, the roles of different factors contributing to local surface warming are quantified using the radiative kernel method applied at the surface after 100 years of global warming under a representative concentration pathway 4.5 (RCP4.5) scenario simulated by 32 climate models from phase 5 of the Coupled Model Intercomparison Project. The warming factors and their seasonality for land and oceanic surfaces were investigated separately and for different domains within each surface type where mechanisms differ. Common factors contribute to both land and oceanic surface warming: tropospheric-mean atmospheric warming and greenhouse gas increases (mostly through water vapor feedback) for both tropical and Arctic regions, nonbarotropic warming and surface warming sensitivity effects (negative in the tropics, positive in the Arctic), and warming cloud feedback in the Arctic in winter. Some mechanisms differ between land and oceanic surfaces: sensible and latent heat flux in the tropics, albedo feedback peaking at different times of the year in the Arctic due to different mean latitudes, a very large summer energy uptake and winter release by the Arctic Ocean, and a large evaporation enhancement in winter over the Arctic Ocean, whereas the peak occurs in summer over the ice-free Arctic land. The oceanic anomalous energy uptake and release is further studied, suggesting the primary role of seasonal variation of oceanic mixed layer temperature changes.},
author = {La{\^{i}}n{\'{e}}, Alexandre and Yoshimori, Masakazu and Abe-Ouchi, Ayako},
doi = {10.1175/JCLI-D-15-0497.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {feb},
number = {9},
pages = {3297--3316},
publisher = {American Meteorological Society},
title = {{Surface Arctic Amplification Factors in CMIP5 Models: Land and Oceanic Surfaces and Seasonality}},
url = {https://doi.org/10.1175/JCLI-D-15-0497.1},
volume = {29},
year = {2016}
}
@article{Lade2018,
abstract = {Changes to climate–carbon cycle feedbacks may significantly affect the Earth system's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth system models. Here, we construct a stylised global climate–carbon cycle model, test its output against comprehensive Earth system models, and investigate the strengths of its climate–carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon cycle feedbacks and the operation of the carbon cycle. Specific results include that different feedback formalisms measure fundamentally the same climate–carbon cycle processes; temperature dependence of the solubility pump, biological pump, and CO2 solubility all contribute approximately equally to the ocean climate–carbon feedback; and concentration–carbon feedbacks may be more sensitive to future climate change than climate–carbon feedbacks. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the planetary boundaries, that are currently too uncertain to be included in comprehensive Earth system models.},
author = {Lade, Steven J. and Donges, Jonathan F. and Fetzer, Ingo and Anderies, John M. and Beer, Christian and Cornell, Sarah E. and Gasser, Thomas and Norberg, Jon and Richardson, Katherine and Rockstr{\"{o}}m, Johan and Steffen, Will},
doi = {10.5194/esd-9-507-2018},
issn = {2190-4987},
journal = {Earth System Dynamics},
month = {may},
number = {2},
pages = {507--523},
title = {{Analytically tractable climate–carbon cycle feedbacks under 21st century anthropogenic forcing}},
url = {https://esd.copernicus.org/articles/9/507/2018/},
volume = {9},
year = {2018}
}
@article{Laepple2014,
abstract = {The variability of sea surface temperatures (SSTs) at multidecadal and longer timescales is poorly constrained, primarily because instrumental records are short and proxy records are noisy. Through applying a new noise filtering technique to a global network of late Holocene SST proxies, we estimate SST variability between annual and millennial timescales. Filtered estimates of SST variability obtained from coral, foraminifer, and alkenone records are shown to be consistent with one another and with instrumental records in the frequency bands at which they overlap. General circulation models, however, simulate SST variability that is systematically smaller than instrumental and proxy-based estimates. Discrepancies in variability are largest at low latitudes and increase with timescale, reaching two orders of magnitude for tropical variability at millennial timescales. This result implies major deficiencies in observational estimates or model simulations, or both, and has implications for the attribution of past variations and prediction of future change.},
author = {Laepple, Thomas and Huybers, Peter},
doi = {10.1073/pnas.1412077111},
issn = {10916490},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Climate variability,Multiproxy synthesis,Proxy data reconstruction,Sea surface temperature},
month = {nov},
number = {47},
pages = {16682--16687},
publisher = {National Academy of Sciences},
title = {{Ocean surface temperature variability: Large model–data differences at decadal and longer periods}},
volume = {111},
year = {2014}
}
@article{Lago2019,
abstract = {The sinking and recirculation of Antarctic Bottom Water (AABW) are a major regulator of the storage of heat, carbon, and nutrients in the ocean. This sinking is sensitive to changes in surface buoyancy, in particular because of freshening since salinity plays a greater role in determining density at cold temperatures. Acceleration in Antarctic ice-shelf and land-ice melt could thus significantly impact the ventilation of the world's oceans, yet future projections do not usually include this effect in models. Here we use an ocean-sea ice model to investigate the potential long-term impact of Antarctic meltwater on ocean circulation and heat storage. The freshwater forcing is derived from present-day estimates of meltwater input from drifting icebergs and basal melt, combined with RCP2.6, RCP4.5, and RCP8.5 scenarios of projected amplification of Antarctic meltwater. We find that the additional freshwater induces a substantial slowdown in the formation rate of AABW, reducing ventilation of the abyssal ocean. Under both the RCP4.5 and RCP8.5 meltwater scenarios, there is a near-complete shutdown ofAABWformation within just 50 years, something that is not captured by climate model projections. The abyssal overturning at ∼308S also weakens, with an ∼20-yr delay relative to the onset of AABW slowdown. After 200 years, up to ∼50{\%} of the original volume of AABW has disappeared as a result of abyssal warming, induced by vertical mixing in the absence ofAABWventilation. This result suggests that climate change could induce the disappearance of present-day abyssal water masses, with implications for the global distribution of heat, carbon, and nutrients.},
author = {Lago, V{\'{e}}ronique and England, Matthew H.},
doi = {10.1175/JCLI-D-18-0622.1},
issn = {08948755},
journal = {Journal of Climate},
month = {oct},
number = {19},
pages = {6319--6335},
publisher = {American Meteorological Society},
title = {{Projected Slowdown of Antarctic Bottom Water Formation in Response to Amplified Meltwater Contributions}},
volume = {32},
year = {2019}
}
@article{Laken2016,
author = {Laken, Benjamin A.},
doi = {10.1051/swsc/2016005},
issn = {2115-7251},
journal = {Journal of Space Weather and Space Climate},
month = {feb},
pages = {A11},
title = {{Can Open Science save us from a solar-driven monsoon?}},
url = {http://www.swsc-journal.org/10.1051/swsc/2016005},
volume = {6},
year = {2016}
}
@article{Larson2016,
abstract = {Effective radiative forcing (ERF) is calculated as the flux change at the top of the atmosphere after allowing rapid adjustments resulting from a forcing agent, such as greenhouse gases. Rapid adjustments include changes to atmospheric temperature, water vapor, and clouds. Accurate estimates of ERF are necessary in order to understand the drivers of climate change. This work presents a new method of calculating ERF using a kernel derived from the time series of a model variable (e.g., global mean surface temperature) in a model-step change experiment. The top-of-atmosphere (TOA) radiative imbalance has the best noise tolerance for retrieving the ERF of the model variables tested. This temporal kernel method is compared with an energy balance method, which equates ERF to the TOA radiative imbalance plus the scaled surface temperature change. Sensitivities and biases of these methods are quantified using output from phase 5 of the the Coupled Model Intercomparison Project (CMIP5). The temporal kernel method is likely more accurate for models in which a linear fit is a poor approximation for the relationship between temperature change and TOA imbalance. The difference between these methods is most apparent in forcing estimates for the representative concentration pathway 8.5 (RCP8.5) scenario. The CMIP5 multimodel mean ERF calculated for large volcanic eruptions is 80{\%} of the adjusted forcing reported by the IPCC Fifth Assessment Report (AR5). This suggests that about 5{\%} more energy has come into the earth system since 1870 than suggested by the IPCC AR5.},
author = {Larson, Erik J. L. and Portmann, Robert W.},
doi = {10.1175/JCLI-D-15-0577.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {feb},
number = {4},
pages = {1497--1509},
title = {{A Temporal Kernel Method to Compute Effective Radiative Forcing in CMIP5 Transient Simulations}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0577.1},
volume = {29},
year = {2016}
}
@article{Lauder2013,
abstract = {It is widely recognised that defining trade-offs between greenhouse gas emissions using 'emission equivalence' based on global warming potentials (GWPs) referenced to carbon dioxide produces anomalous results when applied to methane. The short atmospheric lifetime of methane, compared to the timescales of CO2 uptake, leads to the greenhouse warming depending strongly on the temporal pattern of emission substitution.We argue that a more appropriate way to consider the relationship between the warming effects of methane and carbon dioxide is to define a 'mixed metric' that compares ongoing methane emissions (or reductions) to one-off emissions (or reductions) of carbon dioxide. Quantifying this approach, we propose that a one-off sequestration of 1t of carbon would offset an ongoing methane emission in the range 0.90-1.05kg CH4 per year. We present an example of how our approach would apply to rangeland cattle production, and consider the broader context of mitigation of climate change, noting the reverse trade-off would raise significant challenges in managing the risk of non-compliance.Our analysis is consistent with other approaches to addressing the criticisms of GWP-based emission equivalence, but provides a simpler and more robust approach while still achieving close equivalence of climate mitigation outcomes ranging over decadal to multi-century timescales. {\textcopyright} 2012 Elsevier.},
author = {Lauder, A. R. and Enting, I. G. and Carter, J. O. and Clisby, N. and Cowie, A. L. and Henry, B. K. and Raupach, M. R.},
doi = {10.1016/j.ijggc.2012.11.028},
issn = {17505836},
journal = {International Journal of Greenhouse Gas Control},
keywords = {Agricultural emissions,CO2-equivalence,Methane,Offsets,Rangeland grazing},
month = {jan},
pages = {419--429},
publisher = {Elsevier},
title = {{Offsetting methane emissions – An alternative to emission equivalence metrics}},
volume = {12},
year = {2013}
}
@article{doi:10.1002/2017EA000357,
abstract = {Abstract Solar total and spectral irradiance are estimated from 850 to 1610 by regressing cosmogenic irradiance indices against the National Oceanic and Atmospheric Administration Solar Irradiance Climate Data Record after 1610. The new estimates differ from those recommended for use in the Paleoclimate Model Intercomparison Project (PMIP4) in the magnitude of multidecadal irradiance changes, spectral distribution of the changes, and amplitude and phasing of the 11-year activity cycle. The new estimates suggest that total solar irradiance increased 0.036 ± 0.009{\%} from the Maunder Minimum (1645–1715) to the Medieval Maximum (1100 to 1250), compared with 0.068{\%} from the Maunder Minimum to the Modern Maximum (1950–2009). PMIP4's corresponding increases are 0.026{\%} and 0.055{\%}, respectively. Multidecadal irradiance changes in the new estimates are comparable in magnitude to the PMIP4 recommendations in the ultraviolet spectrum (100–400 nm) but somewhat larger at visible (400–700 nm) and near-infrared (700–1,000 nm) wavelengths; the new estimates suggest increases from the Maunder Minimum to the Medieval Maximum of 0.17 ± 0.04{\%}, 0.030 ± 0.008{\%}, and 0.036 ± 0.009{\%} in the ultraviolet, visible, and near-infrared spectral regions, respectively, compared with PMIP4 increases of 0.17{\%}, 0.021{\%}, and 0.016{\%}. The uncertainties are 1$\sigma$ estimates accruing from the statistical procedures that reconstruct irradiance in the Medieval Maximum relative to the Modern Maximum, not from the specification of Modern Maximum irradiances per se. In the new estimates, solar irradiance cycle amplitudes in the Medieval Maximum are comparable to those in the Modern Maximum, whereas in the PMIP4 reconstruction they are at times almost a factor of 2 larger at some wavelengths and differ also in phase.},
author = {Lean, J L},
doi = {10.1002/2017EA000357},
journal = {Earth and Space Science},
keywords = {natural climate forcing,preindustrial millennium,solar irradiance},
number = {4},
pages = {133--149},
title = {{Estimating Solar Irradiance Since 850 CE}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017EA000357},
volume = {5},
year = {2018}
}
@article{Lebsock2008,
author = {Lebsock, Matthew D. and Stephens, Graeme L. and Kummerow, Christian},
doi = {10.1029/2008JD009876},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
month = {aug},
number = {D15},
pages = {D15205},
publisher = {Wiley-Blackwell},
title = {{Multisensor satellite observations of aerosol effects on warm clouds}},
volume = {113},
year = {2008}
}
@article{Lee2017,
abstract = {The Arctic has been warming faster than elsewhere, especially during the cold season. According to the leading theory, ice?albedo feedback warms the Arctic Ocean during the summer, and the heat gained by the ocean is released during the winter, causing the cold?season warming. Screen and Simmonds (2010; SS10) concluded that the theory is correct by comparing trend patterns in surface air temperature (SAT), surface turbulence heat flux (HF), and net surface infrared radiation (IR). However, in this comparison, downward IR is more appropriate to use. By analyzing the same data used in SS10 using the surface energy budget, it is shown here that over most of the Arctic the skin temperature trend, which closely resembles the SAT trend, is largely accounted for by the downward IR, not the HF, trend.},
author = {Lee, Sukyoung and Gong, Tingting and Feldstein, Steven B. and Screen, James A. and Simmonds, Ian},
doi = {10.1002/2017GL075375},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {Arctic surface warming,downward infrared radiation,surface energy balance},
month = {oct},
number = {20},
pages = {10654--10661},
title = {{Revisiting the Cause of the 1989–2009 Arctic Surface Warming Using the Surface Energy Budget: Downward Infrared Radiation Dominates the Surface Fluxes}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2017GL075375},
volume = {44},
year = {2017}
}
@misc{Lee2019d,
abstract = {New particle formation (NPF) represents the first step in the complex processes leading to formation of cloud condensation nuclei. Newly formed nanoparticles affect human health, air quality, weather, and climate. This review provides a brief history, synthesizes recent significant progresses, and outlines the challenges and future directions for research relevant to NPF. New developments include the emergence of state-of-the-art instruments that measure prenucleation clusters and newly nucleated nanoparticles down to about 1 nm; systematic laboratory studies of multicomponent nucleation systems, including collaborative experiments conducted in the Cosmics Leaving Outdoor Droplets chamber at CERN; observations of NPF in different types of forests, extremely polluted urban locations, coastal sites, polar regions, and high-elevation sites; and improved nucleation theories and parameterizations to account for NPF in atmospheric models. The challenges include the lack of understanding of the fundamental chemical mechanisms responsible for aerosol nucleation and growth under diverse environments, the effects of SO2 and NOx on NPF, and the contribution of anthropogenic organic compounds to NPF. It is also critical to develop instruments that can detect chemical composition of particles from 3 to 20 nm and improve parameterizations to represent NPF over a wide range of atmospheric conditions of chemical precursor, temperature, and humidity.},
author = {Lee, Shan Hu and Gordon, Hamish and Yu, Huan and Lehtipalo, Katrianne and Haley, Ryan and Li, Yixin and Zhang, Renyi},
booktitle = {Journal of Geophysical Research: Atmospheres},
doi = {10.1029/2018JD029356},
issn = {21698996},
keywords = {CCN,HOMs,ammonia,new particle formation,nucleation and growth,sulfuric acid},
month = {jul},
number = {13},
pages = {7098--7146},
publisher = {Blackwell Publishing Ltd},
title = {{New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate}},
volume = {124},
year = {2019}
}
@article{Lee9999,
abstract = {Global aviation operations contribute to anthropogenic climate change via a complex set of processes that lead to a net surface warming. Of importance are aviation emissions of carbon dioxide (CO2), nitrogen oxides (NOx), water vapor, soot and sulfate aerosols, and increased cloudiness due to contrail formation. Aviation grew strongly over the past decades (1960–2018) in terms of activity, with revenue passenger kilometers increasing from 109 to 8269 billion km yr−1, and in terms of climate change impacts, with CO2 emissions increasing by a factor of 6.8 to 1034 Tg CO2 yr−1. Over the period 2013–2018, the growth rates in both terms show a marked increase. Here, we present a new comprehensive and quantitative approach for evaluating aviation climate forcing terms. Both radiative forcing (RF) and effective radiative forcing (ERF) terms and their sums are calculated for the years 2000–2018. Contrail cirrus, consisting of linear contrails and the cirrus cloudiness arising from them, yields the largest positive net (warming) ERF term followed by CO2 and NOx emissions. The formation and emission of sulfate aerosol yields a negative (cooling) term. The mean contrail cirrus ERF/RF ratio of 0.42 indicates that contrail cirrus is less effective in surface warming than other terms. For 2018 the net aviation ERF is +100.9 milliwatts (mW) m−2 (5–95{\%} likelihood range of (55, 145)) with major contributions from contrail cirrus (57.4 mW m−2), CO2 (34.3 mW m−2), and NOx (17.5 mW m−2). Non-CO2 terms sum to yield a net positive (warming) ERF that accounts for more than half (66{\%}) of the aviation net ERF in 2018. Using normalization to aviation fuel use, the contribution of global aviation in 2011 was calculated to be 3.5 (4.0, 3.4) {\%} of the net anthropogenic ERF of 2290 (1130, 3330) mW m−2. Uncertainty distributions (5{\%}, 95{\%}) show that non-CO2 forcing terms contribute about 8 times more than CO2 to the uncertainty in the aviation net ERF in 2018. The best estimates of the ERFs from aviation aerosol-cloud interactions for soot and sulfate remain undetermined. CO2-warming-equivalent emissions based on global warming potentials (GWP* method) indicate that aviation emissions are currently warming the climate at approximately three times the rate of that associated with aviation CO2 emissions alone. CO2 and NOx aviation emissions and cloud effects remain a continued focus of anthropogenic climate change research and policy discussions.},
author = {Lee, D.S. and Fahey, D.W. and Skowron, A. and Allen, M.R. and Burkhardt, U. and Chen, Q. and Doherty, S.J. and Freeman, S. and Forster, P.M. and Fuglestvedt, J. and Gettelman, A. and {De Le{\'{o}}n}, R.R. and Lim, L.L. and Lund, M.T. and Millar, R.J. and Owen, B. and Penner, J.E. and Pitari, G. and Prather, M.J. and Sausen, R. and Wilcox, L.J.},
doi = {10.1016/j.atmosenv.2020.117834},
issn = {13522310},
journal = {Atmospheric Environment},
keywords = {Aviation,CO2,Climate,Contrail cirrus,NOx,Radiative forcing},
month = {jan},
pages = {117834},
title = {{The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018}},
url = {https://linkinghub.elsevier.com/retrieve/pii/S1352231020305689},
volume = {244},
year = {2021}
}
@article{Lejeune2020,
author = {Lejeune, Quentin and Davin, Edouard and Duveiller, Gr{\'{e}}gory and Crezee, Bas and Meier, Ronny and Cescatti, Alessandro and Seneviratne, Sonia},
doi = {https://doi.org/10.5194/esd-11-1209-2020},
issn = {2190-4979},
journal = {Earth System Dynamics},
pages = {1209--1232},
title = {{Biases in the albedo sensitivity to deforestation in CMIP5 models and their impacts on the associated historical Radiative Forcing}},
volume = {11},
year = {2020}
}
@article{Levasseur2016,
abstract = {Since the Global Warming Potential (GWP) was first presented in the Intergovernmental Panel on Climate Change (IPCC) First Assessment Report, the metric has been scrutinized and alternative metrics have been suggested. The IPCC Fifth Assessment Report gives a scientific assessment of the main recent findings from climate metrics research and provides the most up-to-date values for a subset of metrics and time horizons. The objectives of this paper are to perform a systematic review of available midpoint metrics (i.e. using an indicator situated in the middle of the cause-effect chain from emissions to climate change) for well-mixed greenhouse gases and near-term climate forcers based on the current literature, to provide recommendations for the development and use of characterization factors for climate change in life cycle assessment (LCA), and to identify research needs. This work is part of the ‘Global Guidance on Environmental Life Cycle Impact Assessment' project held by the UNEP/SETAC Life Cycle Initiative and is intended to support a consensus finding workshop. In an LCA context, it can make sense to use several complementary metrics that serve different purposes, and from there get an understanding about the robustness of the LCA study to different perspectives and metrics. We propose a step-by-step approach to test the sensitivity of LCA results to different modelling choices and provide recommendations for specific issues such as the consideration of climate-carbon feedbacks and the inclusion of pollutants with cooling effects (negative metric values).},
author = {Levasseur, Annie and Cavalett, Ot{\'{a}}vio and Fuglestvedt, Jan S. and Gasser, Thomas and Johansson, Daniel J.A. and J{\o}rgensen, Susanne V. and Raugei, Marco and Reisinger, Andy and Schivley, Greg and Str{\o}mman, Anders and Tanaka, Katsumasa and Cherubini, Francesco},
doi = {10.1016/j.ecolind.2016.06.049},
issn = {1470160X},
journal = {Ecological Indicators},
keywords = {Climate change,Climate metric,Life cycle assessment (LCA),Near-term climate forcer,Well-mixed greenhouse gas},
month = {dec},
pages = {163--174},
title = {{Enhancing life cycle impact assessment from climate science: Review of recent findings and recommendations for application to LCA}},
url = {https://linkinghub.elsevier.com/retrieve/pii/S1470160X16303776},
volume = {71},
year = {2016}
}
@article{Lewis2015,
abstract = {Abstract Energy budget estimates of equilibrium climate sensitivity (ECS) and transient climate response (TCR) are derived using the comprehensive 1750–2011 time series and the uncertainty ranges for forcing components provided in the Intergovernmental Panel on Climate Change Fifth Assessment Working Group I Report, along with its estimates of heat accumulation in the climate system. The resulting estimates are less dependent on global climate models and allow more realistically for forcing uncertainties than similar estimates based on forcings diagnosed from simulations by such models. Base and final periods are selected that have well matched volcanic activity and influence from internal variability. Using 1859–1882 for the base period and 1995–2011 for the final period, thus avoiding major volcanic activity, median estimates are derived for ECS of 1.64 K and for TCR of 1.33 K. ECS 17–83 and 5–95 {\%} uncertainty ranges are 1.25–2.45 and 1.05–4.05 K; the corresponding TCR ranges are 1.05–1.80 and 0.90–2.50 K. Results using alternative well-matched base and final periods provide similar best estimates but give wider uncertainty ranges, principally reflecting smaller changes in average forcing. Uncertainty in aerosol forcing is the dominant contribution to the ECS and TCR uncertainty ranges.},
author = {Lewis, Nicholas and Curry, Judith A.},
doi = {10.1007/s00382-014-2342-y},
isbn = {0930-7575},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {AR5,Climate sensitivity,Energy budget,Transient climate response},
number = {3-4},
pages = {1009--1023},
title = {{The implications for climate sensitivity of AR5 forcing and heat uptake estimates}},
volume = {45},
year = {2015}
}
@article{Lewis2018,
abstract = {Energy budget estimates of equilibrium climate sensitivity (ECS) and transient climate response (TCR) are derived based on the best estimates and uncertainty ranges for forcing provided in the IPCC Fifth Assessment Report (AR5). Recent revisions to greenhouse gas forcing and post-1990 ozone and aerosol forcing estimates are incorporated and the forcing data extended from 2011 to 2016. Reflecting recent evidence against strong aerosol forcing, its AR5 uncertainty lower bound is increased slightly. Using an 1869–82 base period and a 2007–16 final period, which are well matched for volcanic activity and influence from internal variability, medians are derived for ECS of 1.50 K (5{\%}–95{\%} range: 1.05–2.45 K) and for TCR of 1.20 K (5{\%}–95{\%} range: 0.9–1.7 K). These estimates both have much lower upper bounds than those from a predecessor study using AR5 data ending in 2011. Using infilled, globally complete temperature data give slightly higher estimates: a median of 1.66 K for ECS (5{\%}–95{\%} range: 1.15–2.7 K) and 1.33 K for TCR (5{\%}–95{\%} range: 1.0–1.9 K). These ECS estimates reflect climate feedbacks over the historical period, assumed to be time invariant. Allowing for possible time-varying climate feedbacks increases the median ECS estimate to 1.76 K (5{\%}–95{\%} range: 1.2–3.1 K), using infilled temperature data. Possible biases from non–unit forcing efficacy, temperature estimation issues, and variability in sea surface temperature change patterns are examined and found to be minor when using globally complete temperature data. These results imply that high ECS and TCR values derived from a majority of CMIP5 climate models are inconsistent with observed warming during the historical period.},
author = {Lewis, Nicholas and Curry, Judith},
doi = {10.1175/JCLI-D-17-0667.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Climate sensitivity,Feedback,Forcing},
month = {aug},
number = {15},
pages = {6051--6071},
title = {{The Impact of Recent Forcing and Ocean Heat Uptake Data on Estimates of Climate Sensitivity}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0667.1},
volume = {31},
year = {2018}
}
@article{Lewis2013,
abstract = {Adetailed reanalysis is presented of a ''Bayesian'' climate parameter study (as exemplified by Forest et al.) that estimates climate sensitivity (ECS) jointly with effective ocean diffusivity and aerosol forcing, using optimal fingerprints to compare multidecadal observations with simulations by the Massachusetts Institute of Technology 2D climate model at varying settings of the three climate parameters. Use of improved methodology primarily accounts for the 90{\%} confidence bounds for ECS reducing from 2.1-8.9K to 2.0-3.6 K. The revised methodology uses Bayes's theorem to derive a probability density function (PDF) for the whitened (made independent using an optimal fingerprint transformation) observations, for which a uniform prior is known to be noninformative.Adimensionally reducing change of variables onto the parameter surface is then made, deriving an objective joint PDF for the climate parameters. The PDF conversion factor from the whitened variables space to the parameter surface represents a noninformative joint parameter prior, which is far from uniform. The noninformative prior prevents more probability than data uncertainty distributions warrant being assigned to regions where data respond little to parameter changes, producing better-constrained PDFs. Incorporating 6 years of unused model simulation data and revising the experimental design to improve diagnostic power reduces the best-fit climate sensitivity. Employing the improvedmethodology, preferred 90{\%} bounds of 1.2-2.2K for ECS are then derived (mode and median 1.6K). The mode is identical to those from Aldrin et al. and [using the same Met Office Hadley Centre Climate Research Unit temperature, version 4 (HadCRUT4), observational dataset] from Ring et al. Incorporating nonaerosol forcing and observational surface temperature uncertainties, unlike in the original study, widens the 90{\%} range to 1.0-3.0 K. {\textcopyright} 2013 American Meteorological Society.},
author = {Lewis, Nicholas},
doi = {10.1175/JCLI-D-12-00473.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Bayesian methods,Climate sensitivity,Inverse methods,Statistical techniques},
number = {19},
pages = {7414--7429},
title = {{An Objective Bayesian Improved Approach for Applying Optimal Fingerprint Techniques to Estimate Climate Sensitivity}},
url = {http://dx.doi.org/10.1175/JCLI-D-12-},
volume = {26},
year = {2013}
}
@article{Lewis2020,
abstract = {Recently it has been suggested that natural variability in sea surface temperature (SST) patterns over the historical period causes a low bias in estimates of climate sensitivity based on instrumental records, in addition to that suggested by time variation of the climate feedback parameter in atmospheric general circulation models (GCMs) coupled to dynamic oceans. This excess, unforced, historical “pattern effect” (the effect of evolving surface temperature patterns on climate feedback strength) has been found in simulations performed using GCMs driven by AMIPII SST and sea ice changes (amipPiForcing). Here we show, in both amipPiForcing experiments with one GCM and by using Green's functions derived from another GCM, that whether such an unforced historical pattern effect is found depends on the underlying SST dataset used. When replacing the usual AMIPII SSTs with those from the HadISST1 dataset in amipPiForcing experiments, with sea ice changes unaltered, the first GCM indicates pattern effects that are indistinguishable from the forced pattern effect of the corresponding coupled GCM. Diagnosis of pattern effects using Green's functions derived from the second GCM supports this result for five out of six non-AMIPII SST reconstruction datasets. Moreover, internal variability in coupled GCMs is rarely sufficient to account for an unforced historical pattern effect of even one-quarter the strength previously reported. The presented evidence indicates that, if unforced pattern effects have been as small over the historical record as our findings suggest, they are unlikely to significantly bias climate sensitivity estimates that are based on long-term instrumental observations and account for forced pattern effects obtained from GCMs.},
author = {Lewis, Nicholas and Mauritsen, Thorsten},
doi = {10.1175/JCLI-D-19-0941.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jan},
number = {1},
pages = {39--55},
title = {{Negligible Unforced Historical Pattern Effect on Climate Feedback Strength Found in HadISST-Based AMIP Simulations}},
url = {https://journals.ametsoc.org/view/journals/clim/34/1/jcliD190941.xml},
volume = {34},
year = {2021}
}
@article{ISI:000324032900004,
abstract = {We evaluate the annual mean radiative shortwave flux downward at the surface (RSDS) and reflected shortwave (RSUT) and radiative longwave flux upward at top of atmosphere (RLUT) from the twentieth century Coupled Model Intercomparison Project Phase 5 (CMIP5) and Phase 3 (CMIP3) simulations as well as from the NASA GEOS5 model and Modern-Era Retrospective Analysis for Research and Applications analysis. The results show that a majority of the models have significant regional biases in the annual means of RSDS, RLUT, and RSUT, with biases from -30 to 30Wm(-2). While the global average CMIP5 ensemble mean biases of RSDS, RLUT, and RSUT are reduced compared to CMIP3 by about 32{\%} (e.g., -6.9 to 2.5Wm(-2)), 43{\%}, and 56{\%}, respectively. This reduction arises from a more complete cancellation of the pervasive negative biases over ocean and newly larger positive biases over land. In fact, based on these biases in the annual mean, Taylor diagram metrics, and RMSE, there is virtually no progress in the simulation fidelity of RSDS, RLUT, and RSUT fluxes from CMIP3 to CMIP5. A persistent systematic bias in CMIP3 and CMIP5 is the underestimation of RSUT and overestimation of RSDS and RLUT in the convectively active regions of the tropics. The amount of total ice and liquid atmospheric water content in these areas is also underestimated. We hypothesize that at least a part of these persistent biases stem from the common global climate model practice of ignoring the effects of precipitating and/or convective core ice and liquid in their radiation calculations.},
address = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
author = {Li, J -L. F and Waliser, D E and Stephens, G and Lee, Seungwon and L'Ecuyer, T and Kato, Seiji and Loeb, Norman and Ma, Hsi-Yen},
doi = {10.1002/jgrd.50378},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {CMIP3,CMIP5,Radiation},
month = {aug},
number = {15},
pages = {8166--8184},
publisher = {AMER GEOPHYSICAL UNION},
title = {{Characterizing and understanding radiation budget biases in CMIP3/CMIP5 GCMs, contemporary GCM, and reanalysis}},
type = {Article},
volume = {118},
year = {2013}
}
@article{Li2018b,
author = {Li, Jing and Jiang, Yiwei and Xia, Xiangao and Hu, Yongyun},
doi = {10.1088/1748-9326/aaa35a},
issn = {1748-9326},
journal = {Environmental Research Letters},
month = {mar},
number = {3},
pages = {034006},
publisher = {IOP Publishing},
title = {{Increase of surface solar irradiance across East China related to changes in aerosol properties during the past decade}},
volume = {13},
year = {2018}
}
@article{Li2017,
abstract = {The rapid Indian Ocean warming during the early-21th century was a major heat sink for the recent global surface warming slowdown. Analysis of observational data and ocean model experiments reveals that during 2003–2012 more than half of the increased upper Indian Ocean heat content was concentrated in the southeast Indian Ocean (SEIO), causing a warming “hot spot” of 0.8–1.2 K decade−1 near the west coast of Australia. This SEIO warming was primarily induced by the enhancements of the Pacific trade winds and Indonesian throughflow associated with the Interdecadal Pacific Oscillation's (IPO) transition to its negative phase, and to a lesser degree by local atmospheric forcing within the Indian Ocean. Large-ensemble climate model simulations suggest that this warming event was likely also exacerbated by anthropogenic forcing and thus unprecedentedly strong as compared to previous IPO transition periods. Climate model projections suggest an increasing possibility of such strong decadal warming in future.},
author = {Li, Yuanlong and Han, Weiqing and Zhang, Lei},
doi = {10.1002/2017GL075050},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {Indonesian throughflow,anthropogenic warming,decadal warming,global surface warming slowdown,southeast Indian Ocean},
month = {oct},
number = {19},
pages = {9876--9884},
publisher = {Blackwell Publishing Ltd},
title = {{Enhanced Decadal Warming of the Southeast Indian Ocean During the Recent Global Surface Warming Slowdown}},
volume = {44},
year = {2017}
}
@article{Li2016i,
abstract = {During the past three decades, tropical sea surface temperature (SST) has shown dipole-like trends, with warming over the tropical Atlantic and Indo-western Pacific but cooling over the eastern Pacific. Competing hypotheses relate this cooling, identified as a driver of the global warming hiatus 1,2 , to the warming trends in either the Atlantic 3,4 or Indian Ocean 5 . However, the mechanisms, the relative importance and the interactions between these teleconnections remain unclear. Using a state-of-the-art climate model, we show that the Atlantic plays a key role in initiating the tropical-wide teleconnection, and the Atlantic-induced anomalies contribute ∼55–75{\%} of the tropical SST and circulation changes during the satellite era. The Atlantic warming drives easterly wind anomalies over the Indo-western Pacific as Kelvin waves and westerly anomalies over the eastern Pacific as Rossby waves. The wind changes induce an Indo-western Pacific warming through the wind–evaporation–SST eeect 6,7 , and this warming intensifies the La Ni{\~{n}}a-type response in the tropical Pacific by enhancing the easterly trade winds and through the Bjerknes ocean dynamical processes 8 . The teleconnection develops into a tropical-wide SST dipole pattern. This mechanism, supported by observations and a hierarchy of climate models, reveals that the tropical ocean basins are more tightly connected than previously thought. The tropics have experienced marked climate change since 1979 when the era of global satellite observations began. SST trends exhibit a pan-tropical dipole-like pattern (Fig. 1a), with extensive warming from the tropical Atlantic to the Indo-western Pacific, and a triangular cooling pattern in the central–eastern Pacific. This tropical-wide gradient in the SST trend interacts with the atmo-spheric and oceanic circulation throughout the tropics (Fig. 1c,e), with an enhanced Walker circulation 9–11 and a La Ni{\~{n}}a-like Pacific subsurface response. These changes further contribute to global cli-mate change 1,12,13 through multiple atmospheric teleconnections 8,14 . The tropical ocean basins are connected through an atmospheric bridge 15 into an interactive system. On interannual timescales, El Ni{\~{n}}o/Southern Oscillation (ENSO) dominates the tropical inter-basin teleconnections 15,16 , although the Indian 17,18 and Atlantic 19–21},
author = {Li, Xichen and Xie, Shang-Ping Ping and Gille, Sarah T. and Yoo, Changhyun},
doi = {10.1038/nclimate2840},
isbn = {1758-678X},
journal = {Nature Climate Change},
month = {mar},
number = {3},
pages = {275--279},
pmid = {20104911},
publisher = {Nature Publishing Group},
title = {{Atlantic-induced pan-tropical climate change over the past three decades}},
volume = {6},
year = {2016}
}
@article{Li2013a,
abstract = {We integrate the coupled climate model ECHAM5/MPIOM to equilibrium under atmospheric CO2 quadrupling. The equilibrium global-mean surface-temperature change is 10.8 K. The surface equilibrates within about 1,200 years, the deep ocean within 5,000 years. The impact of the deep ocean on the equilibrium surface-temperature response is illustrated by the difference between ECHAM5/MPIOM and ECHAM5 coupled with slab ocean model (ECHAM5/SOM). The equilibrium global-mean surface temperature response is 11.1 K in ECHAM5/SOM and is thus 0.3 K higher than in ECHAM5/MPIOM. ECHAM5/MPIOM shows less warming over the northern-hemisphere mid and high latitudes, but larger warming over the tropical ocean and especially over the southern-hemisphere high latitudes. ECHAM5/MPIOM shows similar polar amplification in both the Arctic and the Antarctic, in contrast to ECHAM5/SOM, which shows stronger polar amplification in the northern hemisphere. The southern polar warming in ECHAM5/MPIOM is greatly delayed by Antarctic deep-ocean warming due to convective and isopycnal mixing. The equilibrium ocean temperature warming under CO2 quadrupling is around 8.0 K and is near-uniform with depth. The global-mean steric sea-level rise is 5.8 m in equilibrium; of this, 2.3 m are due to the deep-ocean warming after the surface temperature has almost equilibrated. This result suggests that the surface temperature change is a poor predictor for steric sea-level change in the long term. The effective climate response method described in Gregory et al. (2004) is evaluated with our simulation, which shows that their method to estimate the equilibrium climate response is accurate to within 10 {\%}.},
author = {Li, Chao and von Storch, Jin Song and Marotzke, Jochem},
doi = {10.1007/s00382-012-1350-z},
isbn = {0930-7575},
issn = {09307575},
journal = {Climate Dynamics},
keywords = {Climate sensitivity,Deep-ocean heat uptake,Equilibrium climate response},
number = {5-6},
pages = {1071--1086},
title = {{Deep-ocean heat uptake and equilibrium climate response}},
volume = {40},
year = {2013}
}
@article{ISI:000393217800004,
abstract = {The increasing severity of droughts/floods and worsening air quality from increasing aerosols in Asia monsoon regions are the two gravest threats facing over 60{\%} of the world population living in Asian monsoon regions. These dual threats have fueled a large body of research in the last decade on the roles of aerosols in impacting Asian monsoon weather and climate. This paper provides a comprehensive review of studies on Asian aerosols, monsoons, and their interactions. The Asian monsoon region is a primary source of emissions of diverse species of aerosols from both anthropogenic and natural origins. The distributions of aerosol loading are strongly influenced by distinct weather and climatic regimes, which are, in turn, modulated by aerosol effects. On a continental scale, aerosols reduce surface insolation and weaken the land-ocean thermal contrast, thus inhibiting the development of monsoons. Locally, aerosol radiative effects alter the thermodynamic stability and convective potential of the lower atmosphere leading to reduced temperatures, increased atmospheric stability, and weakened wind and atmospheric circulations. The atmospheric thermodynamic state, which determines the formation of clouds, convection, and precipitation, may also be altered by aerosols serving as cloud condensation nuclei or ice nuclei. Absorbing aerosols such as black carbon and desert dust in Asian monsoon regions may also induce dynamical feedback processes, leading to a strengthening of the early monsoon and affecting the subsequent evolution of the monsoon. Many mechanisms have been put forth regarding how aerosols modulate the amplitude, frequency, intensity, and phase of different monsoon climate variables. A wide range of theoretical, observational, and modeling findings on the Asian monsoon, aerosols, and their interactions are synthesized. A new paradigm is proposed on investigating aerosol-monsoon interactions, in which natural aerosols such as desert dust, black carbon from biomass burning, and biogenic aerosols from vegetation are considered integral components of an intrinsic aerosol-monsoon climate system, subject to external forcing of global warming, anthropogenic aerosols, and land use and change. Future research on aerosol-monsoon interactions calls for an integrated approach and international collaborations based on long-term sustained observations, process measurements, and improved models, as well as using observations to constrain model simulations and projections.},
author = {Li, Zhanqing and Lau, W K -M. and Ramanathan, V and Wu, G and Ding, Y and Manoj, M G and Liu, J and Qian, Y and Li, J and Zhou, T and Fan, J and Rosenfeld, D and Ming, Y and Wang, Y and Huang, J and Wang, B and Xu, X and Lee, S -S. and Cribb, M and Zhang, F and Yang, X and Zhao, C and Takemura, T and Wang, K and Xia, X and Yin, Y and Zhang, H and Guo, J and Zhai, P M and Sugimoto, N and Babu, S S and Brasseur, G P},
doi = {10.1002/2015RG000500},
issn = {8755-1209},
journal = {Reviews of Geophysics},
month = {dec},
number = {4},
pages = {866--929},
title = {{Aerosol and monsoon climate interactions over Asia}},
volume = {54},
year = {2016}
}
@article{Li2018o,
abstract = {AbstractExtratropical eddy-driven jets are predicted to shift poleward in a warmer climate. Recent studies have suggested that cloud radiative effects (CRE) may enhance the amplitude of such shifts. But there is still considerable uncertainty about the underlying mechanisms, whereby CRE govern the jet response to climate change. This study provides new insights into the role of CRE in the jet response to climate change by exploiting the output from six global warming simulations run with and without atmospheric CRE (ACRE). Consistent with previous studies, it is found that the magnitude of the jet shift under climate change is substantially increased in simulations run with ACRE. It is hypothesized that ACRE enhance the jet response to climate change by increasing the upper-tropospheric baroclinicity due to the radiative effects of rising high clouds. The lifting of the tropopause and high clouds in response to surface warming arises from the thermodynamic constraints placed on water vapor concentrations. Hence, the influence of ACRE on the jet shift in climate change simulations may be viewed as an additional ?robust? thermodynamic constraint placed on climate change by the Clausius?Clapeyron relation. The hypothesis is tested in simulations run with an idealized dry GCM, in which the model is perturbed with a thermal forcing that resembles the ACRE response to surface warming. It is demonstrated that 1) the enhanced jet shifts found in climate change simulations run with ACRE are consistent with the atmospheric response to the radiative warming associated with rising high clouds, and 2) the amplitude of the jet shift scales linearly with the amplitude of the ACRE forcing.},
author = {Li, Ying and Thompson, David W J and Bony, Sandrine and Merlis, Timothy M},
doi = {10.1175/JCLI-D-18-0417.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {dec},
number = {3},
pages = {917--934},
publisher = {American Meteorological Society},
title = {{Thermodynamic Control on the Poleward Shift of the Extratropical Jet in Climate Change Simulations: The Role of Rising High Clouds and Their Radiative Effects}},
url = {https://doi.org/10.1175/JCLI-D-18-0417.1},
volume = {32},
year = {2018}
}
@article{Li2019a,
abstract = {AbstractEstimates for equilibrium climate sensitivity from current climate models continue to exhibit a large spread, from 2.1 to 4.7 K per carbon dioxide doubling. Recent studies have found that the treatment of precipitation efficiency in deep convective clouds?specifically the conversion rate from cloud condensate to rain Cp?may contribute to the large intermodel spread. It is common for convective parameterization in climate models to carry a constant Cp, although its values are model and resolution dependent. In this study, we investigate how introducing a potential iris feedback, the cloud?climate feedback introduced by parameterizing Cp to increase with surface temperature, affects future climate simulations within a slab ocean configuration of the Community Earth System Model. Progressively stronger dependencies of Cp on temperature unexpectedly increase the equilibrium climate sensitivity monotonically from 3.8 to up to 4.6 K. This positive iris feedback puzzle, in which a reduction in cirrus clouds increases surface temperature, is attributed to changes in the opacity of convectively detrained cirrus. Cirrus clouds reduced largely in ice content and marginally in horizontal coverage, and thus the positive shortwave cloud radiative feedback dominates. The sign of the iris feedback is robust across different cloud macrophysics schemes, which control horizontal cloud cover associated with detrained ice. These results suggest a potentially strong but highly uncertain connection among convective precipitation, detrained anvil cirrus, and the high cloud feedback in a climate forced by increased atmospheric carbon dioxide concentrations.},
author = {Li, R L and Storelvmo, T and Fedorov, A V and Choi, Y.-S.},
doi = {10.1175/JCLI-D-18-0845.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jun},
number = {16},
pages = {5305--5324},
publisher = {American Meteorological Society},
title = {{A Positive Iris Feedback: Insights from Climate Simulations with Temperature-Sensitive Cloud–Rain Conversion}},
url = {https://doi.org/10.1175/JCLI-D-18-0845.1},
volume = {32},
year = {2019}
}
@article{2020ClDy...55.1585L,
author = {Li, Feng and Newman, Paul},
doi = {10.1007/s00382-020-05348-6},
journal = {Climate Dynamics},
keywords = {Arctic amplification,Brewer-Dobson circulation,Climate feedback,Climate impact,Stratospheric water vapor},
number = {5-6},
pages = {1585--1595},
title = {{Stratospheric water vapor feedback and its climate impacts in the coupled atmosphere–ocean Goddard Earth Observing System Chemistry–Climate Model}},
volume = {55},
year = {2020}
}
@article{doi:10.1002/2013JD021186,
abstract = {Abstract Organic aerosols (OA) play an important role in climate change. However, very few calculations of global OA radiative forcing include secondary organic aerosol (SOA) or the light-absorbing part of OA (brown carbon). Here we use a global model to assess the radiative forcing associated with the change in primary organic aerosol (POA) and SOA between present-day and preindustrial conditions in both the atmosphere and the land snow/sea ice. Anthropogenic emissions are shown to substantially influence the SOA formation rate, causing it to increase by 29 Tg/yr (93{\%}) since preindustrial times. We examine the effects of varying the refractive indices, size distributions for POA and SOA, and brown carbon fraction in SOA. The increase of SOA exerts a direct forcing ranging from −0.12 to −0.31 W m−2 and a first indirect forcing in warm-phase clouds ranging from −0.22 to −0.29 W m−2, with the range due to different assumed SOA size distributions and refractive indices. The increase of POA since preindustrial times causes a direct forcing varying from −0.06 to −0.11 W m−2, when strongly and weakly absorbing refractive indices for brown carbon are used. The change in the total OA exerts a direct forcing ranging from −0.14 to −0.40 W m−2. The atmospheric absorption from brown carbon ranges from +0.22 to +0.57 W m−2, which corresponds to 27{\%}{\~{}}70{\%} of the black carbon (BC) absorption predicted in the model. The radiative forcing of OA deposited in land snow and sea ice ranges from +0.0011 to +0.0031 W m−2 or as large as 24{\%} of the forcing caused by BC in snow and ice simulated by the model.},
author = {Lin, Guangxing and Penner, Joyce E and Flanner, Mark G and Sillman, Sanford and Xu, Li and Zhou, Cheng},
doi = {10.1002/2013JD021186},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {SOA,atmospheric chemistry,brown carbon,climate change,organic aerosol,radiative forcing},
number = {12},
pages = {7453--7476},
title = {{Radiative forcing of organic aerosol in the atmosphere and on snow: Effects of SOA and brown carbon}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2013JD021186},
volume = {119},
year = {2014}
}
@article{Lindzen2001,
abstract = {Harrison's (2001) Comment on the Methodology in Lindzen et al (2001) has prompted re-examination of several aspects of study. Probably the most significant disagreement in our conclusions is due to our different approaches to minimizing the influence of long-time-scale variations in the variables A and T on the results. Given the strength of the annual cycle and the 20-month period covered by the data, we believe that removing monthly means is a better approach to minimizing the long-time-scale behavior of the data than removal of the linear trend, which might actually add spurious long- time- scale variability into the modified data. We have also indicated how our statistical methods of establishing statistical significance differ. More definitive conclusions may only possible after more data have been analyzed, but we feel that our results are robust enough to encourage further study of this phenomenon.},
author = {Lindzen, Richard S. and Chou, Ming Dah and Hou, Arthur Y.},
doi = {10.1175/1520-0477(2001)082<0417:DTEHAA>2.3.CO;2},
isbn = {0003-0007},
issn = {00030007},
journal = {Bulletin of the American Meteorological Society},
number = {3},
pages = {417--432},
title = {{Does the Earth Have an Adaptive Infrared Iris?}},
volume = {82},
year = {2001}
}
@article{Lipat2017,
abstract = {This study analyzes CMIP5 model output to examine the covariability of interannual Southern Hemisphere Hadley cell (HC) edge latitude shifts and shortwave cloud radiative effect (SWCRE). In control climate runs, during years when the HC edge is anomalously poleward, most models substantially reduce the shortwave radiation reflected by clouds in the lower mid-latitude region (LML; ∼28∘S-∼48∘S), although no such reduction is seen in observations. These biases in HC-SWCRE covariability are linked to biases in the climatological HC extent. Notably, models with excessively equatorward climatological HC extents have weaker climatological LML subsidence and exhibit larger increases in LML subsidence with poleward HC edge expansion. This behavior, based on control climate interannual variability, has important implications for the CO2-forced model response. In 4×CO2-forced runs, models with excessively equatorward climatological HC extents produce stronger SW cloud radiative warming in the LML region and tend to have larger climate sensitivity values than models with more realistic climatological HC extents.},
author = {Lipat, Bernard R. and Tselioudis, George and Grise, Kevin M. and Polvani, Lorenzo M.},
doi = {10.1002/2017GL073151},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {ECS,Hadley cell,SW cloud radiative effect,climate sensitivity,cloud feedback,dynamics},
number = {11},
pages = {5739--5748},
title = {{CMIP5 models' shortwave cloud radiative response and climate sensitivity linked to the climatological Hadley cell extent}},
volume = {44},
year = {2017}
}
@article{doi:10.1029/2004PA001071,
abstract = {We present a 5.3-Myr stack (the “LR04” stack) of benthic $\delta$18O records from 57 globally distributed sites aligned by an automated graphic correlation algorithm. This is the first benthic $\delta$18O stack composed of more than three records to extend beyond 850 ka, and we use its improved signal quality to identify 24 new marine isotope stages in the early Pliocene. We also present a new LR04 age model for the Pliocene-Pleistocene derived from tuning the $\delta$18O stack to a simple ice model based on 21 June insolation at 65°N. Stacked sedimentation rates provide additional age model constraints to prevent overtuning. Despite a conservative tuning strategy, the LR04 benthic stack exhibits significant coherency with insolation in the obliquity band throughout the entire 5.3 Myr and in the precession band for more than half of the record. The LR04 stack contains significantly more variance in benthic $\delta$18O than previously published stacks of the late Pleistocene as the result of higher-resolution records, a better alignment technique, and a greater percentage of records from the Atlantic. Finally, the relative phases of the stack's 41- and 23-kyr components suggest that the precession component of $\delta$18O from 2.7–1.6 Ma is primarily a deep-water temperature signal and that the phase of $\delta$18O precession response changed suddenly at 1.6 Ma.},
author = {Lisiecki, Lorraine E and Raymo, Maureen E},
doi = {10.1029/2004PA001071},
journal = {Paleoceanography},
keywords = {Pliocene-Pleistocene,age model,benthic $\delta$18O},
number = {1},
pages = {PA1003},
title = {{A Pliocene-Pleistocene stack of 57 globally distributed benthic $\delta$18O records}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2004PA001071},
volume = {20},
year = {2005}
}
@article{Liu2005,
author = {Liu, Zhengyu and Vavrus, Steve and He, Feng and Wen, Na and Zhong, Yafang},
doi = {10.1175/jcli3579.1},
journal = {Journal of Climate},
month = {dec},
number = {22},
pages = {4684--4700},
publisher = {American Meteorological Society},
title = {{Rethinking Tropical Ocean Response to Global Warming: The Enhanced Equatorial Warming}},
volume = {18},
year = {2005}
}
@article{Liu1997,
abstract = {Based on results from analytic and general circulation models, the authors propose a theory for the coupled warm pool, cold tongue, and Walker circulation system. The intensity of the coupled system is determined by the coupling strength, the local equilibrium time, and latitudinal differential heating. Most importantly, this intensity is strongly regulated in the coupled system, with a saturation level that can be reached at a modest coupling strength. The saturation west-east sea surface temperature difference (and the associated Walker circulation) corresponds to about one-quarter of the latitudinal differential equilibrium temperature. This regulation is caused primarily by the decoupling of the SST gradient from a strong ocean current. The author's estimate suggests that the present Pacific is near the saturation state. Furthermore, the much weaker Walker circulation system in the Atlantic Ocean is interpreted as being the result of the influence of the adjacent land, which is able to extend into the entire Atlantic to change the zonal distribution of the trade wind. The theory is also applied to understand the tropical climatology in coupled GCM simulations, in the Last Glacial Maximum climate, and in the global warming climate, as well as in the regulation of the tropical sea surface temperature.},
author = {Liu, Zhengyu and Huang, Boyin},
doi = {10.1175/1520-0442(1997)010<1662:ACTOTC>2.0.CO;2},
issn = {08948755},
journal = {Journal of Climate},
number = {7},
pages = {1662--1679},
publisher = {American Meteorological Society},
title = {{A coupled theory of tropical climatology: Warm pool, cold tongue, and walker circulation}},
volume = {10},
year = {1997}
}
@article{Liu2017a,
author = {Liu, Yonggang and Hallberg, Robert and Sergienko, Olga and Samuels, Bonnie L. and Harrison, Matthew and Oppenheimer, Michael},
doi = {10.1007/s00382-017-3980-7},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {sep},
number = {5-6},
pages = {1733--1751},
title = {{Climate response to the meltwater runoff from Greenland ice sheet: evolving sensitivity to discharging locations}},
url = {http://link.springer.com/10.1007/s00382-017-3980-7},
volume = {51},
year = {2018}
}
@article{Liu2017,
abstract = {Changes in the Atlantic Meridional Overturning Circulation (AMOC) are moderate in most climate model projections under increasing greenhouse gas forcing. This intermodel consensus may be an artifact of common model biases that favor a stable AMOC. Observationally based freshwater budget analyses suggest that the AMOC is in an unstable regime susceptible for large changes in response to perturbations. By correcting the model biases, we show that the AMOC collapses 300 years after the atmospheric CO2 concentration is abruptly doubled from the 1990 level. Compared to an uncorrected model, the AMOC collapse brings about large, markedly different climate responses: a prominent cooling over the northern North Atlantic and neighboring areas, sea ice increases over the Greenland-Iceland-Norwegian seas and to the south of Greenland, and a significant southward rain-belt migration over the tropical Atlantic. Our results highlight the need to develop dynamical metrics to constrain models and the importance of reducing model biases in long-term climate projection.},
author = {Liu, Wei and Xie, Shang-Ping and Liu, Zhengyu and Zhu, Jiang},
doi = {10.1126/sciadv.1601666},
isbn = {1468-2044},
issn = {2375-2548},
journal = {Science Advances},
month = {jan},
number = {1},
pages = {e1601666},
pmid = {17475693},
title = {{Overlooked possibility of a collapsed Atlantic Meridional Overturning Circulation in warming climate}},
url = {https://www.science.org/doi/10.1126/sciadv.1601666},
volume = {3},
year = {2017}
}
@article{LiuE3501,
abstract = {Marine and terrestrial proxy records suggest global cooling during the Late Holocene, following the peak warming of the Holocene Thermal Maximum ({\~{}}10 to 6 ka) until the rapid warming induced by increasing anthropogenic greenhouses gases. However, the physical mechanism responsible for this global cooling has remained elusive. Here, we show that climate models simulate a robust global annual mean warming in the Holocene, mainly in response to rising CO2 and the retreat of ice sheets. This model-data inconsistency demands a critical reexamination of both proxy data and models.A recent temperature reconstruction of global annual temperature shows Early Holocene warmth followed by a cooling trend through the Middle to Late Holocene [Marcott SA, et al., 2013, Science 339(6124):1198{\{}$\backslash$textendash{\}}1201]. This global cooling is puzzling because it is opposite from the expected and simulated global warming trend due to the retreating ice sheets and rising atmospheric greenhouse gases. Our critical reexamination of this contradiction between the reconstructed cooling and the simulated warming points to potentially significant biases in both the seasonality of the proxy reconstruction and the climate sensitivity of current climate models.},
author = {Liu, Zhengyu and Zhu, Jiang and Rosenthal, Yair and Zhang, Xu and Otto-Bliesner, Bette L and Timmermann, Axel and Smith, Robin S and Lohmann, Gerrit and Zheng, Weipeng and {Elison Timm}, Oliver},
doi = {10.1073/pnas.1407229111},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {34},
pages = {E3501--E3505},
publisher = {National Academy of Sciences},
title = {{The Holocene temperature conundrum}},
url = {https://www.pnas.org/content/111/34/E3501},
volume = {111},
year = {2014}
}
@article{doi:10.1002/2017JD027512,
abstract = {Abstract Water vapor feedbacks on different time scales are investigated using radiative kernels applied to the Atmospheric Infrared Sounder and Microwave Limb Sounder satellite observations, as well as the Coupled Model Intercomparison Project Phase 5 model simulation results. We show that the magnitude of short-term global water vapor feedback based on observed interannual variations from 2004 to 2016 is 1.55 ± 0.23 W m−2 K−1, while model-simulated results derived from the Coupled Model Intercomparison Project Phase 5 runs driven by observed sea surface temperature range from 0.99 to 1.75 W m−2 K−1, with a multimodel mean of 1.40 W m−2 K−1. The long-term water vapor feedbacks derived from the quadrupling of CO2 runs range from 1.47 to 2.03 W m−2 K−1, higher than the short-term counterparts. The systematic difference between short-term and long-term water vapor feedbacks illustrates that care should be taken when inferring long-term feedbacks from interannual variabilities. Also, the magnitudes of the short-term and long-term feedbacks are closely correlated (R = 0.66) across the models, implying that the observed short-term water vapor feedback could be used to constrain the simulated long-term water vapor feedback. Based on satellite observations, the inferred long-term water vapor feedback is about 1.85 ± 0.32 W m−2 K−1.},
author = {Liu, Run and Su, Hui and Liou, Kuo-Nan and Jiang, Jonathan H and Gu, Yu and Liu, Shaw Chen and Shiu, Chein-Jung},
doi = {10.1002/2017JD027512},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {AIRS,CMIP5,MLS,climate models,radiative kernels,water vapor feedback},
number = {3},
pages = {1499--1509},
title = {{An Assessment of Tropospheric Water Vapor Feedback Using Radiative Kernels}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JD027512},
volume = {123},
year = {2018}
}
@article{Liueaau6060,
abstract = {The timing and mechanisms of the eastern equatorial Pacific (EEP) cold tongue development, a salient feature of the tropical ocean, are intensely debated on geological time scales. Here, we reconstruct cold tongue evolution over the past 8 million years by computing changes in temperature gradient between the cold tongue and eastern Pacific warm pool. Results indicate that the cold tongue remained very weak between 8 and 4.3 million years ago, implying much weaker zonal temperature gradients prevailing during the late Miocene{\{}$\backslash$textendash{\}}Pliocene, but then underwent gradual intensification with apparently increasing sensitivity of the cold tongue to extratropical temperature changes. Our results reveal that the EEP cold tongue intensification was mainly controlled by extratropical climate.},
author = {Liu, Jingjing and Tian, Jun and Liu, Zhonghui and Herbert, Timothy D and Fedorov, Alexey V and Lyle, Mitch},
doi = {10.1126/sciadv.aau6060},
journal = {Science Advances},
number = {4},
pages = {eaau6060},
publisher = {American Association for the Advancement of Science},
title = {{Eastern equatorial Pacific cold tongue evolution since the late Miocene linked to extratropical climate}},
url = {https://advances.sciencemag.org/content/5/4/eaau6060},
volume = {5},
year = {2019}
}
@article{ISI:000570476400003,
abstract = {The study of energy flows in the Earth system is essential for understanding current climate change. To understand how energy is accumulating and being distributed within the climate system, an updated reconstruction of energy fluxes at the top of atmosphere, surface and within the atmosphere derived from observations is presented. New satellite and ocean data are combined with an improved methodology to quantify recent variability in meridional and ocean to land heat transports since 1985. A global top of atmosphere net imbalance is found to increase from 0.10 +/- 0.61 W m(-2)over 1985-1999 to 0.62 +/- 0.1 W m(-2)over 2000-2016, and the uncertainty of +/- 0.61 W m(-2)is related to the Argo ocean heat content changes (+/- 0.1 W m(-2)) and an additional uncertainty applying prior to 2000 relating to homogeneity adjustments. The net top of atmosphere radiative flux imbalance is dominated by the southern hemisphere (0.36 +/- 0.04 PW, about 1.41 +/- 0.16 W m(-2)) with an even larger surface net flux into the southern hemisphere ocean (0.79 +/- 0.16 PW, about 3.1 +/- 0.6 W m(-2)) over 2006-2013. In the northern hemisphere the surface net flux is of opposite sign and directed from the ocean toward the atmosphere (0.44 +/- 0.16 PW, about 1.7 +/- 0.6 W m(-2)). The sea ice melting and freezing are accounted for in the estimation of surface heat flux into the ocean. The northward oceanic heat transports are inferred from the derived surface fluxes and estimates of ocean heat accumulation. The derived cross-equatorial oceanic heat transport of 0.50 PW is higher than most previous studies, and the derived mean meridional transport of 1.23 PW at 26 degrees N is very close to 1.22 PW from RAPID observation. The surface flux contribution dominates the magnitude of the oceanic transport, but the integrated ocean heat storage controls the interannual variability. Poleward heat transport by the atmosphere at 30 degrees N is found to increase after 2000 (0.17 PW decade(-1)). The multiannual mean (2006-2013) transport of energy by the atmosphere from ocean to land is estimated as 2.65 PW, and is closely related to the ENSO variability.},
author = {Liu, Chunlei and Allan, Richard P and Mayer, Michael and Hyder, Patrick and Desbruyeres, Damien and Cheng, Lijing and Xu, Jianjun and Xu, Feng and Zhang, Yu},
doi = {10.1007/s00382-020-05451-8},
journal = {Climate Dynamics},
month = {dec},
number = {11-12},
pages = {3381--3396},
title = {{Variability in the global energy budget and transports 1985-2017}},
volume = {55},
year = {2020}
}
@article{Lockwood2020,
abstract = {{\textless}p{\textgreater} Recent reconstructions of total solar irradiance (TSI) postulate that quiet-Sun variations could give significant changes to the solar power input to Earth's climate (radiative climate forcings of 0.7–1.1 W m {\textless}sup{\textgreater}−2{\textless}/sup{\textgreater} over 1700–2019) arising from changes in quiet-Sun magnetic fields that have not, as yet, been observed. Reconstructions without such changes yield solar forcings that are smaller by a factor of more than 10. We study the quiet-Sun TSI since 1995 for three reasons: (i) this interval shows rapid decay in average solar activity following the grand solar maximum in 1985 (such that activity in 2019 was broadly equivalent to that in 1900); (ii) there is improved consensus between TSI observations; and (iii) it contains the first modelling of TSI that is independent of the observations. Our analysis shows that the most likely upward drift in quiet-Sun radiative forcing since 1700 is between +0.07 and −0.13 W m {\textless}sup{\textgreater}−2{\textless}/sup{\textgreater} . Hence, we cannot yet discriminate between the quiet-Sun TSI being enhanced or reduced during the Maunder and Dalton sunspot minima, although there is a growing consensus from the combinations of models and observations that it was slightly enhanced. We present reconstructions that add quiet-Sun TSI and its uncertainty to models that reconstruct the effects of sunspots and faculae. {\textless}/p{\textgreater}},
author = {Lockwood, Mike and Ball, William T.},
doi = {10.1098/rspa.2020.0077},
issn = {1364-5021},
journal = {Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences},
keywords = {quiet-Sun magnetic fields,radiative forcing of climate,total solar irradiance},
month = {jun},
number = {2238},
pages = {20200077},
publisher = {The Royal Society},
title = {{Placing limits on long-term variations in quiet-Sun irradiance and their contribution to total solar irradiance and solar radiative forcing of climate}},
url = {https://royalsocietypublishing.org/doi/10.1098/rspa.2020.0077},
volume = {476},
year = {2020}
}
@article{Loeb2018a,
abstract = {The Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) top-of-atmosphere (TOA), Edition 4.0 (Ed4.0), data product is described. EBAF Ed4.0 is an update to EBAF Ed2.8, incorporating all of the Ed4.0 suite of CERES data product algorithm improvements and consistent input datasets throughout the record. A one-time adjustment to shortwave (SW) and longwave (LW) TOA fluxes is made to ensure that global mean net TOA flux for July 2005-June 2015 is consistent with the in situ value of 0.71 W m(-2). While global mean all-sky TOA flux differences between Ed4.0 and Ed2.8 are within 0.5 W m(-2), appreciable SW regional differences occur over marine stratocumulus and snow/sea ice regions. Marked regional differences in SW clear-sky TOA flux occur in polar regions and dust areas over ocean. Clear-sky LW TOA fluxes in EBAF Ed4.0 exceed Ed2.8 in regions of persistent high cloud cover. Owing to substantial differences in global mean clear-sky TOA fluxes, the net cloud radiative effect in EBAF Ed4.0 is -18 W m(-2) compared to -21 W m(-2) in EBAF Ed2.8. The overall uncertainty in 18 3 18 latitude-longitude regional monthly all-sky TOA flux is estimated to be 3 W m(-2) [one standard deviation (1 sigma)] for the Terra-only period and 2.5 W m(-2) for the Terra-Aqua period both for SW and LW fluxes. The SW clear-sky regional monthly flux uncertainty is estimated to be 6 W m(-2) for the Terra-only period and 5 W m(-2) for the Terra-Aqua period. The LW clear-sky regional monthly flux uncertainty is 5 W m(-2) for Terra only and 4.5 W m(-2) for Terra-Aqua.},
address = {NASA, Langley Res Ctr, Hampton, VA 23665 USA Sci Syst {\&} Applicat Inc, Hampton, VA USA},
annote = {Fw2wf
Times Cited:1
Cited References Count:47},
author = {Loeb, N G and Doelling, D R and Wang, H L and Su, W Y and Nguyen, C and Corbett, J G and Liang, L S and Mitrescu, C and Rose, F G and Kato, S},
doi = {10.1175/Jcli-D-17-0208.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {angular-distribution models temporal interpolation},
language = {English},
number = {2},
pages = {895--918},
title = {{Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Top-of-Atmosphere (TOA) Edition-4.0 Data Product}},
volume = {31},
year = {2018}
}
@article{Loeb2018c,
abstract = {This study examines changes in Earth's energy budget during and after the global warming "pause" (or "hiatus") using observations from the Clouds and the Earth's Radiant Energy System. We find a marked 0.83 ± 0.41 Wm −2 reduction in global mean reflected shortwave (SW) top-of-atmosphere (TOA) flux during the three years following the hiatus that results in an increase in net energy into the climate system. A partial radiative perturbation analysis reveals that decreases in low cloud cover are the primary driver of the decrease in SW TOA flux. The regional distribution of the SW TOA flux changes associated with the decreases in low cloud cover closely matches that of sea-surface temperature warming, which shows a pattern typical of the positive phase of the Pacific Decadal Oscillation. Large reductions in clear-sky SW TOA flux are also found over much of the Pacific and Atlantic Oceans in the northern hemisphere. These are associated with a reduction in aerosol optical depth consistent with stricter pollution controls in China and North America. A simple energy budget framework is used to show that TOA radiation (particularly in the SW) likely played a dominant role in driving the marked increase in temperature tendency during the post-hiatus period.},
author = {Loeb, Norman G and Thorsen, Tyler J and Norris, Joel R and Wang, Hailan and Su, Wenying},
doi = {10.3390/cli6030062},
journal = {Climate},
keywords = {clouds,energy budget,global warming hiatus},
number = {3},
pages = {62},
title = {{Changes in Earth's Energy Budget during and after the “Pause” in Global Warming: An Observational Perspective}},
url = {www.mdpi.com/journal/climate},
volume = {6},
year = {2018}
}
@article{Loeb2012a,
abstract = {Global climate change results from a small yet persistent imbalance between the amount of sunlight absorbed by Earth and the thermal radiation emitted back to space. An apparent inconsistency has been diagnosed between interannual variations in the net radiation imbalance inferred from satellite measurements and upper-ocean heating rate from in situ measurements, and this inconsistency has been interpreted as ‘missing energy' in the system. Here we present a revised analysis of net radiation at the top of the atmosphere from satellite data, and we estimate ocean heat content, based on three independent sources. We find that the difference between the heat balance at the top of the atmosphere and upper-ocean heat content change is not statistically significant when accounting for observational uncertainties in ocean measurements, given transitions in instrumentation and sampling. Furthermore, variability in Earth's energy imbalance relating to El Ni{\~{n}}o-Southern Oscillation is found to be consistent within observational uncertainties among the satellite measurements, a reanalysis model simulation and one of the ocean heat content records. We combine satellite data with ocean measurements to depths of 1,800 m, and show that between January 2001 and December 2010, Earth has been steadily accumulating energy at a rate of 0.50±0.43 Wm−2 (uncertainties at the 90{\%} confidence level). We conclude that energy storage is continuing to increase in the sub-surface ocean.},
author = {Loeb, Norman G. and Lyman, John M. and Johnson, Gregory C. and Allan, Richard P. and Doelling, David R. and Wong, Takmeng and Soden, Brian J. and Stephens, Graeme L.},
doi = {10.1038/ngeo1375},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {feb},
number = {2},
pages = {110--113},
title = {{Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty}},
url = {http://www.nature.com/articles/ngeo1375},
volume = {5},
year = {2012}
}
@article{ISI:000374970200035,
abstract = {Satellite based top-of-atmosphere (TOA) and surface radiation budget observations are combined with mass corrected vertically integrated atmospheric energy divergence and tendency from reanalysis to infer the regional distribution of the TOA, atmospheric and surface energy budget terms over the globe. Hemispheric contrasts in the energy budget terms are used to determine the radiative and combined sensible and latent heat contributions to the cross-equatorial heat transports in the atmosphere (AHT(EQ)) and ocean (OHTEQ). The contrast in net atmospheric radiation implies an AHT(EQ) from the northern hemisphere (NH) to the southern hemisphere (SH) (0.75 PW), while the hemispheric difference in sensible and latent heat implies an AHT(EQ) in the opposite direction (0.51 PW), resulting in a net NH to SH AHT(EQ) (0.24 PW). At the surface, the hemispheric contrast in the radiative component (0.95 PW) dominates, implying a 0.44 PW SH to NH OHTEQ. Coupled model intercomparison project phase 5 (CMIP5) models with excessive net downward surface radiation and surface-to-atmosphere sensible and latent heat transport in the SH relative to the NH exhibit anomalous northward AHT(EQ) and overestimate SH tropical precipitation. The hemispheric bias in net surface radiative flux is due to too much longwave surface radiative cooling in the NH tropics in both clear and all-sky conditions and excessive shortwave surface radiation in the SH subtropics and extratropics due to an underestimation in reflection by clouds.},
address = {233 SPRING ST, NEW YORK, NY 10013 USA},
author = {Loeb, Norman G and Wang, Hailan and Cheng, Anning and Kato, Seiji and Fasullo, John T and Xu, Kuan-Man and Allan, Richard P},
doi = {10.1007/s00382-015-2766-z},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {Energy budget,Heat transport,Precipit,Radiation},
month = {may},
number = {9-10},
pages = {3239--3257},
publisher = {SPRINGER},
title = {{Observational constraints on atmospheric and oceanic cross-equatorial heat transports: revisiting the precipitation asymmetry problem in climate models}},
type = {Article},
volume = {46},
year = {2016}
}
@article{ISI:000336889300017,
abstract = {Satellite and reanalysis data are used to observe interannual variations in atmospheric diabatic heating and circulation within the ascending and descending branches of the Hadley circulation (HC) during the past 12 yr. The column-integrated divergence of dry static energy (DSE) and kinetic energy is inferred from satellite-based observations of atmospheric radiation, precipitation latent heating, and reanalysis-based surface sensible heat flux for monthly positions of the HC branches, determined from a mass weighted zonal mean meridional streamfunction analysis. Mean surface radiative fluxes inferred from satellite and surface measurements are consistent to 1W m(-2) ({\textless}1{\%}) over land and 4W m(-2) (2{\%}) over ocean. In the ascending branch, where precipitation latent heating dominates over radiative cooling, discrepancies in latent heating among different precipitation datasets reach 22W m(-2) (17{\%}), compared to 3-6 W m(-2) in the descending branches. Whereas direct calculations of DSE divergence from two reanalyses show opposite trends, the implied DSE divergence from the satellite observations of atmospheric diabatic heating exhibits no trend in all three HC branches and is strongly correlated (reaching 0.90) with midtropospheric vertical velocity. The implied DSE divergence from satellite observations thus provides a useful independent measure of HC circulation strength variability. The sensitivity to circulation change is 4-5 times larger for precipitation latent heating compared to atmospheric radiative cooling in the descending branches and 20 times larger in the ascending branch. The difference in sensitivity is due to cloud radiative effects, which enhance atmospheric radiative cooling in the descending branches in response to an increase in HC strength but decrease it in the ascending branch.},
address = {45 BEACON ST, BOSTON, MA 02108-3693 USA},
author = {Loeb, Norman G and Rutan, David A and Kato, Seiji and Wang, Weijie},
doi = {10.1175/JCLI-D-13-00656.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jun},
number = {11},
pages = {4139--4158},
publisher = {AMER METEOROLOGICAL SOC},
title = {{Observing Interannual Variations in Hadley Circulation Atmospheric Diabatic Heating and Circulation Strength}},
type = {Article},
volume = {27},
year = {2014}
}
@article{Loeb9999,
abstract = {Key Points 29  There is good agreement between radiation budget variations observed by CERES and 30 simulated by seven state-of-the-art climate models 31  The relationship between global mean net TOA radiation and surface temperature is 32 sensitive to changes in regions dominated by low clouds 33  Most models underestimate shortwave flux changes in response to SST changes over 34 the east Pacific, suggesting too weak a "pattern effect" 35 36 37},
author = {Loeb, Norman G. and Wang, Hailan and Allan, Richard and Andrews, Timothy and Armour, Kyle and Cole, Jason N.S. and Dufresne, Jean-Louis and Forster, Piers and Gettelman, Andrew and Guo, Huan and Mauritsen, Thorsten and Ming, Yi and Paynter, David and Proistosescu, Cristian and Will{\'{e}}n, Ulrika and Wyser, Klaus and Stuecker, Malte F. and Will{\'{e}}n, Ulrika and Wyser, Klaus},
doi = {10.1029/2019GL086705},
journal = {Geophysical Research Letters},
number = {5},
pages = {e2019GL086705},
title = {{New Generation of Climate Models Track Recent Unprecedented Changes in Earth's Radiation Budget Observed by CERES}},
volume = {47},
year = {2020}
}
@article{Lohmann2018a,
author = {Lohmann, U and Neubauer, D},
doi = {10.5194/acp-18-8807-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jun},
number = {12},
pages = {8807--8828},
publisher = {Copernicus Publications},
title = {{The importance of mixed-phase and ice clouds for climate sensitivity in the global aerosol–climate model ECHAM6-HAM2}},
url = {https://www.atmos-chem-phys.net/18/8807/2018/ https://www.atmos-chem-phys.net/18/8807/2018/acp-18-8807-2018.pdf},
volume = {18},
year = {2018}
}
@article{Longman2014a,
abstract = {Trends in downwelling global solar irradiance were evaluated at high-elevation sites on the island of Maui, Hawai'i. Departures from monthly means were assessed for the 6 month Hawaiian wet and dry seasons over the period 1988 to 2012. Linear regression analysis was used to characterize trends in each season. For the dry season (May-October), statistically significant (p {\textless}= 0.05) positive trends of 9-18 W m(-2) (3-6{\%}) per decade were found at all four high-elevation stations tested. Wet season trends were not significant, except at the highest-elevation station, which had a significant negative trend. No consistent trends in aerosol concentrations have been observed at high elevations in Hawai'i; therefore, the observed dry season brightening is most likely the result of decreasing cloud cover. Supporting this hypothesis, analysis of 15 years (1997-2012) of high temporal resolution Geostationary Operational Environmental Satellite (GOES) imagery over the Hawaiian Islands showed a statistically significant decrease in leeward cloud cover amounting to 5-11{\%} per decade over the stations. In addition, analysis of Moderate Resolution Imaging Spectroradiometer data were in general agreement with the GOES trends, although statistically significant dry season trends were found at only one of the four stations.},
address = {Longman, RJ Univ Hawaii Manoa, Dept Geog, Honolulu, HI 96822 USA Univ Hawaii Manoa, Dept Geog, Honolulu, HI 96822 USA Univ Hawaii Manoa, Dept Geog, Honolulu, HI 96822 USA Northrop Grumman Corp, Mclean, VA USA Univ Hawaii Manoa, Dept Nat Resource {\&} Environ},
annote = {Aj5yq
Times Cited:0
Cited References Count:46},
author = {Longman, R J and Giambelluca, T W and Alliss, R J and Barnes, M L},
doi = {10.1002/2013jd021322},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {hadley-cell climate surface variability circulatio},
language = {English},
number = {10},
pages = {6022--6033},
title = {{Temporal solar radiation change at high elevations in Hawai'i}},
volume = {119},
year = {2014}
}
@article{Lund2018a,
abstract = {Black Carbon (BC) aerosols substantially affect the global climate. However, accurate simulation of BC atmospheric transport remains elusive, due to shortcomings in modeling and a shortage of constraining measurements. Recently, several studies have compared simulations with observed vertical concentration profiles, and diagnosed a global-mean BC atmospheric residence time of {\textless}5 days. These studies have, however, been focused on limited geographical regions, and used temporally and spatially coarse model information. Here we expand on previous results by comparing a wide range of recent aircraft measurements from multiple regions, including the Arctic and the Atlantic and Pacific oceans, to simulated distributions obtained at varying spatial and temporal resolution. By perturbing BC removal processes and using current best-estimate emissions, we confirm a constraint on the global-mean BC lifetime of {\textless}5.5 days, shorter than in many current global models, over a broader geographical range than has so far been possible. Sampling resolution influences the results, although generally without introducing major bias. However, we uncover large regional differences in the diagnosed lifetime, in particular in the Arctic. We also find that only a weak constraint can be placed in the African outflow region over the South Atlantic, indicating inaccurate emission sources or model representation of transport and microphysical processes. While our results confirm that BC lifetime is shorter than predicted by most recent climate models, they also cast doubt on the usability of the concept of a “global-mean BC lifetime” for climate impact studies, or as an indicator of model skill.},
author = {Lund, Marianne T. and Samset, Bj{\o}rn H. and Skeie, Ragnhild B. and Watson-Parris, Duncan and Katich, Joseph M. and Schwarz, Joshua P. and Weinzierl, Bernadett},
doi = {10.1038/s41612-018-0040-x},
issn = {2397-3722},
journal = {npj Climate and Atmospheric Science},
keywords = {Atmospheric chemistry,Atmospheric dynamics},
month = {dec},
number = {1},
pages = {31},
publisher = {Nature Publishing Group},
title = {{Short Black Carbon lifetime inferred from a global set of aircraft observations}},
url = {http://www.nature.com/articles/s41612-018-0040-x},
volume = {1},
year = {2018}
}
@article{Lund2018,
abstract = {{\textless}p{\textgreater}{\textless}![CDATA[{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} We document the ability of the new-generation Oslo chemistry-transport model, Oslo CTM3, to accurately simulate present-day aerosol distributions. The model is then used with the new Community Emission Data System (CEDS) historical emission inventory to provide updated time series of anthropogenic aerosol concentrations and consequent direct radiative forcing (RFari) from 1750 to 2014.{\textless}/p{\textgreater} {\textless}p{\textgreater}Overall, Oslo CTM3 performs well compared with measurements of surface concentrations and remotely sensed aerosol optical depth. Concentrations are underestimated in Asia, but the higher emissions in CEDS than previous inventories result in improvements compared to observations. The treatment of black carbon (BC) scavenging in Oslo CTM3 gives better agreement with observed vertical BC profiles relative to the predecessor Oslo CTM2. However, Arctic wintertime BC concentrations remain underestimated, and a range of sensitivity tests indicate that better physical understanding of processes associated with atmospheric BC processing is required to simultaneously reproduce both the observed features. Uncertainties in model input data, resolution, and scavenging affect the distribution of all aerosols species, especially at high latitudes and altitudes. However, we find no evidence of consistently better model performance across all observables and regions in the sensitivity tests than in the baseline configuration.{\textless}/p{\textgreater} {\textless}p{\textgreater}Using CEDS, we estimate a net RFari in 2014 relative to 1750 of {\textless}span class="inline-formula"{\textgreater}−0.17{\textless}/span{\textgreater}{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}W{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}m{\textless}span class="inline-formula"{\textgreater}{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}{\textless}/span{\textgreater}, significantly weaker than the IPCC AR5 2011–1750 estimate. Differences are attributable to several factors, including stronger absorption by organic aerosol, updated parameterization of BC absorption, and reduced sulfate cooling. The trend towards a weaker RFari over recent years is more pronounced than in the IPCC AR5, illustrating the importance of capturing recent regional emission changes.{\textless}/p{\textgreater}]]{\textgreater}{\textless}/p{\textgreater}},
author = {Lund, Marianne Tronstad and Myhre, Gunnar and Haslerud, Amund S{\o}vde and Skeie, Ragnhild Bieltvedt and Griesfeller, Jan and Platt, Stephen Matthew and Kumar, Rajesh and Myhre, Cathrine Lund and Schulz, Michael},
doi = {10.5194/gmd-11-4909-2018},
issn = {1991-9603},
journal = {Geoscientific Model Development},
month = {dec},
number = {12},
pages = {4909--4931},
title = {{Concentrations and radiative forcing of anthropogenic aerosols from 1750 to 2014 simulated with the Oslo CTM3 and CEDS emission inventory}},
url = {https://www.geosci-model-dev.net/11/4909/2018/},
volume = {11},
year = {2018}
}
@article{Lund2017,
abstract = {Abstract. This study examines the impacts of emissions from aviation in six source regions on global and regional temperatures. We consider the NOx-induced impacts on ozone and methane, aerosols and contrail-cirrus formation and calculate the global and regional emission metrics global warming potential (GWP), global temperature change potential (GTP) and absolute regional temperature change potential (ARTP). The GWPs and GTPs vary by a factor of 2–4 between source regions. We find the highest aviation aerosol metric values for South Asian emissions, while contrail-cirrus metrics are higher for Europe and North America, where contrail formation is prevalent, and South America plus Africa, where the optical depth is large once contrails form. The ARTP illustrate important differences in the latitudinal patterns of radiative forcing (RF) and temperature response: the temperature response in a given latitude band can be considerably stronger than suggested by the RF in that band, also emphasizing the importance of large-scale circulation impacts. To place our metrics in context, we quantify temperature change in four broad latitude bands following 1 year of emissions from present-day aviation, including CO2. Aviation over North America and Europe causes the largest net warming impact in all latitude bands, reflecting the higher air traffic activity in these regions. Contrail cirrus gives the largest warming contribution in the short term, but remain important at about 15 {\%} of the CO2 impact in several regions even after 100 years. Our results also illustrate both the short- and long-term impacts of CO2: while CO2 becomes dominant on longer timescales, it also gives a notable warming contribution already 20 years after the emission. Our emission metrics can be further used to estimate regional temperature change under alternative aviation emission scenarios. A first evaluation of the ARTP in the context of aviation suggests that further work to account for vertical sensitivities in the relationship between RF and temperature response would be valuable for further use of the concept.},
author = {Lund, Marianne T. and Aamaas, Borgar and Berntsen, Terje and Bock, Lisa and Burkhardt, Ulrike and Fuglestvedt, Jan S. and Shine, Keith P.},
doi = {10.5194/esd-8-547-2017},
issn = {2190-4987},
journal = {Earth System Dynamics},
month = {jul},
number = {3},
pages = {547--563},
title = {{Emission metrics for quantifying regional climate impacts of aviation}},
url = {https://esd.copernicus.org/articles/8/547/2017/},
volume = {8},
year = {2017}
}
@article{Lunt2009,
author = {Lunt, Daniel J and Haywood, Alan M and Schmidt, Gavin A and Salzmann, Ulrich and Valdes, Paul J and Dowsett, Harry J},
doi = {10.1038/ngeo706},
journal = {Nature Geoscience},
month = {dec},
number = {1},
pages = {60--64},
publisher = {Nature Publishing Group},
title = {{Earth system sensitivity inferred from Pliocene modelling and data}},
volume = {3},
year = {2010}
}
@article{cp-8-1717-2012,
author = {Lunt, D J and {Dunkley Jones}, T and Heinemann, M and Huber, M and LeGrande, A and Winguth, A and Loptson, C and Marotzke, J and Roberts, C D and Tindall, J and Valdes, P and Winguth, C},
doi = {10.5194/cp-8-1717-2012},
journal = {Climate of the Past},
number = {5},
pages = {1717--1736},
title = {{A model–data comparison for a multi-model ensemble of early Eocene atmosphere–ocean simulations: EoMIP}},
url = {https://www.clim-past.net/8/1717/2012/},
volume = {8},
year = {2012}
}
@article{LUNT2012128,
abstract = {The mid-Pliocene ({\~{}}3 to 3.3Ma ago), is a period of sustained global warmth in comparison to the late Quaternary (0 to {\~{}}1Ma ago), and has potential to inform predictions of long-term future climate change. However, given that several processes potentially contributed, relatively little is understood about the reasons for the observed warmth, or the associated polar amplification. Here, using a modelling approach and a novel factorisation method, we assess the relative contributions to mid-Pliocene warmth from: elevated CO2, lowered orography, and vegetation and ice sheet changes. The results show that on a global scale, the largest contributor to mid-Pliocene warmth is elevated CO2. However, in terms of polar amplification, changes to ice sheets contribute significantly in the Southern Hemisphere, and orographic changes contribute significantly in the Northern Hemisphere. We also carry out an energy balance analysis which indicates that that on a global scale, surface albedo and atmospheric emmissivity changes dominate over cloud changes. We investigate the sensitivity of our results to uncertainties in the prescribed CO2 and orographic changes, to derive uncertainty ranges for the various contributing processes.},
author = {Lunt, Daniel J and Haywood, Alan M and Schmidt, Gavin A and Salzmann, Ulrich and Valdes, Paul J and Dowsett, Harry J and Loptson, Claire A},
doi = {https://doi.org/10.1016/j.epsl.2011.12.042},
issn = {0012-821X},
journal = {Earth and Planetary Science Letters},
keywords = {mid-Pliocene,paleoclimate modelling,polar amplification},
pages = {128--138},
title = {{On the causes of mid-Pliocene warmth and polar amplification}},
url = {http://www.sciencedirect.com/science/article/pii/S0012821X12000027},
volume = {321-322},
year = {2012}
}
@article{Lunt9999,
abstract = {We present results from an ensemble of eight climate models, each of which has carried out simulations of the early Eocene climate optimum (EECO, g1/4 50 million years ago). These simulations have been carried out in the framework of the Deep-Time Model Intercomparison Project (DeepMIP; http://www.deepmip.org, last access: 10 January 2021); thus, all models have been configured with the same paleogeographic and vegetation boundary conditions. The results indicate that these non-CO2 boundary conditions contribute between 3 and 5 g C to Eocene warmth. Compared with results from previous studies, the DeepMIP simulations generally show a reduced spread of the global mean surface temperature response across the ensemble for a given atmospheric CO2 concentration as well as an increased climate sensitivity on average. An energy balance analysis of the model ensemble indicates that global mean warming in the Eocene compared with the preindustrial period mostly arises from decreases in emissivity due to the elevated CO2 concentration (and associated water vapour and long-wave cloud feedbacks), whereas the reduction in the Eocene in terms of the meridional temperature gradient is primarily due to emissivity and albedo changes owing to the non-CO2 boundary conditions (i.e. the removal of the Antarctic ice sheet and changes in vegetation). Three of the models (the Community Earth System Model, CESM; the Geophysical Fluid Dynamics Laboratory, GFDL, model; and the Norwegian Earth System Model, NorESM) show results that are consistent with the proxies in terms of the global mean temperature, meridional SST gradient, and CO2, without prescribing changes to model parameters. In addition, many of the models agree well with the first-order spatial patterns in the SST proxies. However, at a more regional scale, the models lack skill. In particular, the modelled anomalies are substantially lower than those indicated by the proxies in the southwest Pacific; here, modelled continental surface air temperature anomalies are more consistent with surface air temperature proxies, implying a possible inconsistency between marine and terrestrial temperatures in either the proxies or models in this region. Our aim is that the documentation of the large-scale features and model-data comparison presented herein will pave the way to further studies that explore aspects of the model simulations in more detail, for example the ocean circulation, hydrological cycle, and modes of variability, and encourage sensitivity studies to aspects such as paleogeography, orbital configuration, and aerosols.},
author = {Lunt, Daniel J. and Bragg, Fran and Chan, Wing-le Le W.-L. and Hutchinson, David K. and Ladant, Jean-baptiste J.-B. Baptiste J.-B. and Niezgodzki, Igor and Steinig, Sebastian and Zhang, Zhongshi and Zhu, Jiang and Abe-Ouchi, Ayako and {De Boer}, Agatha M. and Coxall, Helen K. and Donnadieu, Yannick and Knorr, Gregor and Langebroek, Petra M. and Lohmann, Gerrit and Poulsen, Christopher J. and Sepulchre, Pierre and Tierney, Jessica E. and Valdes, Paul J. and {Dunkley Jones}, Tom and Hollis, Christopher J. and Huber, Matthew and Otto-Bliesner, Bette L. and Boer, M De and Coxall, Helen K. and Donnadieu, Yannick and Knorr, Gregor and Langebroek, Petra M. and Lohmann, Gerrit and Poulsen, Christopher J. and Sepulchre, Pierre and Tierney, Jessica E. and Valdes, Paul J. and Jones, Tom Dunkley and Hollis, Christopher J. and Huber, Matthew and Otto-Bliesner, Bette L. and Morozova, Polina and Niezgodzki, Igor and Steinig, Sebastian and Zhang, Zhongshi and Zhu, Jiang and Abe-Ouchi, Ayako and Anagnostou, Eleni and {De Boer}, Agatha M. and Coxall, Helen K. and Donnadieu, Yannick and Foster, Gavin and Inglis, Gordon N. and Knorr, Gregor and Langebroek, Petra M. and Lear, Caroline H. and Lohmann, Gerrit and Poulsen, Christopher J. and Sepulchre, Pierre and Tierney, Jessica E. and Valdes, Paul J. and Volodin, Evgeny M. and {Dunkley Jones}, Tom and Hollis, Christopher J. and Huber, Matthew and Otto-Bliesner, Bette L.},
doi = {10.5194/cp-17-203-2021},
issn = {18149332},
journal = {Climate of the Past},
month = {jan},
number = {1},
pages = {203--227},
publisher = {Copernicus GmbH},
title = {{DeepMIP: Model intercomparison of early Eocene climatic optimum (EECO) large-scale climate features and comparison with proxy data}},
volume = {17},
year = {2021}
}
@article{Luo2015,
abstract = {The enhanced central and eastern Pacific SST warming and the associated ocean processes under global warming are investigated using the ocean component of the Community Earth System Model (CESM), Parallel Ocean Program version 2 (POP2). The tropical SST warming pattern in the coupled CESM can be faithfully reproduced by the POP2 forced with surface fluxes computed using the aerodynamic bulk formula. By prescribing the wind stress and/or wind speed through the bulk formula, the effects of wind stress change and/or the wind-evaporation-SST (WES) feedback are isolated and their linearity is evaluated in this ocean-alone setting. Result shows that, although the weakening of the equatorial easterlies contributes positively to the El Ni{\~{n}}o-like SST warming, 80 {\%} of which can be simulated by the POP2 without considering the effects of wind change in both mechanical and thermodynamic fluxes. This result points to the importance of the air–sea thermal interaction and the relative feebleness of the ocean dynamical process in the El Ni{\~{n}}o-like equatorial Pacific SST response to global warming. On the other hand, the wind stress change is found to play a dominant role in the oceanic response in the tropical Pacific, accounting for most of the changes in the equatorial ocean current system and thermal structures, including the weakening of the surface westward currents, the enhancement of the near-surface stratification and the shoaling of the equatorial thermocline. Interestingly, greenhouse gas warming in the absence of wind stress change and WES feedback also contributes substantially to the changes at the subsurface equatorial Pacific. Further, this warming impact can be largely replicated by an idealized ocean experiment forced by a uniform surface heat flux, whereby, arguably, a purest form of oceanic dynamical thermostat is revealed.},
author = {Luo, Yiyong and Lu, Jian and Liu, Fukai and Liu, Wei},
doi = {10.1007/s00382-014-2448-2},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {oct},
number = {7-8},
pages = {1945--1964},
title = {{Understanding the El Ni{\~{n}}o-like oceanic response in the tropical Pacific to global warming}},
url = {http://link.springer.com/10.1007/s00382-014-2448-2},
volume = {45},
year = {2015}
}
@article{Luo2018,
abstract = {Over the recent three decades sea surface temperate (SST) in the eastern equatorial Pacific has decreased, which helps reduce the rate of global warming. However, most CMIP5 model simulations with historical radiative forcing do not reproduce this Pacific La Ni�a-like cooling. Previous studies suggest that internal climate variations and errors in external radiative forcing may cause the discrepancy between the multi-model ensemble mean and the observation. We illustrate that common biases of current state-of-the-art climate models also contribute to this models-observation discrepancy. Our results reveal that underestimated inter-basin warming contrast across the tropical oceans, overestimated surface net heat flux and underestimated local SST-cloud negative feedback in the equatorial Pacific may favor an unrealistic El Ni�o-like warming in the models in response to external forcing},
author = {Luo, Jing Jia and Wang, Gang and Dommenget, Dietmar},
doi = {10.1007/s00382-017-3688-8},
isbn = {0123456789},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Air–sea interactions,CMIP5 simulations,Common model biases,Inter-basin influence,Pacific cooling trend},
month = {feb},
number = {3-4},
pages = {1335--1351},
publisher = {Springer Verlag},
title = {{May common model biases reduce CMIP5's ability to simulate the recent Pacific La Ni{\~{n}}a-like cooling?}},
volume = {50},
year = {2018}
}
@article{Luo2017a,
abstract = {The role of ocean dynamics in the response of the equatorial Pacific Ocean to climate warming is in-vestigated using both an atmosphere–ocean coupled climate system and its ocean component. Results show that the initial response (fast pattern) to an uniform heating imposed on the ocean is a warming centered to the west of the date line owing to the conventional ocean dynamical thermostat (ODT) mechanism in the eastern equatorial Pacific—a cooling effect arising from the up-gradient upwelling. In time, the warming pattern gradually propagates eastward, becoming more El Ni{\~{n}}o–like (slow pattern). The transition from the fast to the slow pattern likely results from 1) the gradual warming of the equatorial thermocline temperature, which is associated with the arrival of the relatively warmer extratropical waters advected along the sub-surface branch of the subtropical cells (STCs), and 2) the reduction of the STC strength itself. A mixed layer heat budget analysis finds that it is the total ocean dynamical effect rather than the conventional ODT that holds the key for understanding the pattern of the SST in the equatorial Pacific and that the surface heat flux works mainly to compensate the ocean dynamics. Further passive tracer experiments with the ocean com-ponent of the coupled system verify the role of the ocean dynamical processes in initiating a La Ni{\~{n}}a–like SST warming and in setting the pace of the transition to an El Ni{\~{n}}o–like warming and identify an oceanic origin for the slow eastern Pacific warming independent of the weakening trade wind.},
author = {Luo, Yiyong and Lu, Jian and Liu, Fukai and Garuba, Oluwayemi},
doi = {10.1175/JCLI-D-16-0454.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Air-sea interaction,Climate change,ENSO,Heat budgets/fluxes,Ocean dynamics},
month = {apr},
number = {8},
pages = {2811--2827},
publisher = {American Meteorological Society},
title = {{The role of ocean dynamical thermostat in delaying the El Ni{\~{n}}o-Like response over the equatorial Pacific to climate warming}},
volume = {30},
year = {2017}
}
@article{Luo2017,
abstract = {The impact of winter atmospheric blocking over the Ural Mountains region (UB) coincident with different phases of the North Atlantic Oscillation (NAO) on the sea ice variability over the Barents and Kara Seas (BKS) in winter is investigated. It is found that the UB in conjunction with the positive phase of the NAO (NAO+) leads to the strongest sea ice decline. During this phase composites and trajectory analyses reveal an efficient moisture pathway to the BKS from the mid-latitude North Atlantic near the Gulf Stream Extension region where water vapor is abundant due to high sea surface temperatures. The NAO+-UB combination is an optimal circulation pattern that significantly increases the BKS water vapor that plays a major role in the BKS warming and sea ice reduction, while the increased sensible and latent heat fluxes play secondary roles. By contrast, much fewer dramatic impacts on the BKS are observed when the UB coincides with the neutral or negative phases of the NAO. Our results present new insights into the complex processes involved with Arctic sea ice reduction and warming. The mechanisms highlighted here potentially offer a perspective into the mechanisms behind Arctic multi-decadal climate variability.},
author = {Luo, Binhe and Luo, Dehai and Wu, Lixin and Zhong, Linhao and Simmonds, Ian},
doi = {10.1088/1748-9326/aa69d0},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {Arctic sea ice decline,North Atlantic Oscillation,Ural blocking,moisture intrusion},
month = {may},
number = {5},
pages = {054017},
publisher = {Institute of Physics Publishing},
title = {{Atmospheric circulation patterns which promote winter Arctic sea ice decline}},
volume = {12},
year = {2017}
}
@article{Luo2012,
abstract = {It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Ni{\~{n}}a-like state (with enhanced east-west Walker circulation) through the Pacific ocean-atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific's could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries.},
author = {Luo, Jing Jia and Sasaki, Wataru and Masumoto, Yukio},
doi = {10.1073/pnas.1210239109},
issn = {00278424},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Centennial trends,El Ni{\~{n}}o change,Interbasin influence,Multidecadal fluctuations},
month = {nov},
number = {46},
pages = {18701--18706},
title = {{Indian Ocean warming modulates Pacific climate change}},
volume = {109},
year = {2012}
}
@article{Lurton2020,
abstract = {The implementation of boundary conditions is a key aspect of climate simulations. We describe here how the Climate Model Intercomparison Project Phase 6 (CMIP6) forcing data sets have been processed and implemented in Version 6 of the Institut Pierre-Simon Laplace (IPSL) climate model (IPSL-CM6A-LR) as used for CMIP6. Details peculiar to some of the Model Intercomparison Projects are also described. IPSL-CM6A-LR is run without interactive chemistry; thus, tropospheric and stratospheric aerosols as well as ozone have to be prescribed. We improved the aerosol interpolation procedure and highlight a new methodology to adjust the ozone vertical profile in a way that is consistent with the model dynamical state at the time step level. The corresponding instantaneous and effective radiative forcings have been estimated and are being presented where possible.},
author = {Lurton, Thibaut and Balkanski, Yves and Bastrikov, Vladislav and Bekki, Slimane and Bopp, Laurent and Braconnot, Pascale and Brockmann, Patrick and Cadule, Patricia and Contoux, Camille and Cozic, Anne and Cugnet, David and Dufresne, Jean Louis and {\'{E}}th{\'{e}}, Christian and Foujols, Marie Alice and Ghattas, Josefine and Hauglustaine, Didier and Hu, Rong Ming and Kageyama, Masa and Khodri, Myriam and Lebas, Nicolas and Levavasseur, Guillaume and Marchand, Marion and Ottl{\'{e}}, Catherine and Peylin, Philippe and Sima, Adriana and Szopa, Sophie and Thi{\'{e}}blemont, R{\'{e}}mi and Vuichard, Nicolas and Boucher, Olivier},
doi = {10.1029/2019MS001940},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
number = {4},
pages = {1--22},
title = {{Implementation of the CMIP6 Forcing Data in the IPSL-CM6A-LR Model}},
volume = {12},
year = {2020}
}
@article{Lutsko2018,
abstract = {AbstractThe relationship between climate models? internal variability and their response to external forcings is investigated. Frequency-dependent regressions are performed between the outgoing top-of-atmosphere (TOA) energy fluxes and the global-mean surface temperature in the preindustrial control simulations of the CMIP5 archive. Two distinct regimes are found. At subdecadal frequencies the surface temperature and the outgoing shortwave flux are in quadrature, while the outgoing longwave flux is linearly related to temperature and acts as a negative feedback on temperature perturbations. On longer time scales the outgoing shortwave and longwave fluxes are both linearly related to temperature, with the longwave continuing to act as a negative feedback and the shortwave acting as a positive feedback on temperature variability. In addition to the different phase relationships, the two regimes can also be seen in estimates of the coherence and of the frequency-dependent regression coefficients. The frequency-dependent regression coefficients for the total cloudy-sky flux on time scales of 2.5 to 3 years are found to be strongly (r2 {\textgreater} 0.6) related to the models? equilibrium climate sensitivities (ECSs), suggesting a potential ?emergent constraint? for Earth?s ECS. However, O(100) years of data are required for this relationship to become robust. A simple model for Earth?s surface temperature variability and its relationship to the TOA fluxes is used to provide a physical interpretation of these results.},
annote = {doi: 10.1175/JCLI-D-17-0736.1},
author = {Lutsko, Nicholas J and Takahashi, Ken},
doi = {10.1175/JCLI-D-17-0736.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {apr},
number = {13},
pages = {5051--5069},
publisher = {American Meteorological Society},
title = {{What Can the Internal Variability of CMIP5 Models Tell Us about Their Climate Sensitivity?}},
url = {https://doi.org/10.1175/JCLI-D-17-0736.1},
volume = {31},
year = {2018}
}
@article{Lutsko2019,
abstract = {Abstract The rate of transient warming is determined by a number of factors, notably the radiative forcing from increasing CO2 concentrations and the net radiative feedback. Uncertainty in transient warming comes from both the uncertainty in each factor and from the warming's sensitivity to uncertainty in each factor. An energy balance model is used to untangle these two components of uncertainty in transient warming, which is shown to be most sensitive to uncertainty in the forcing and not to uncertainty in radiative feedbacks. Additionally, uncertainty in the efficacy of ocean heat uptake is more important than uncertainty in the rate of ocean heat uptake. Three further implications are as follows: (1) transient warming is highly sensitive to uncertainty in emissions, (2) caution is warranted when extrapolating future warming trends from short-lived climate perturbations, and (3) climate models tuned using the historical record are highly sensitive to assumptions made about the historical forcing.},
annote = {https://doi.org/10.1029/2019GL084018},
author = {Lutsko, Nicholas J and Popp, Max},
doi = {10.1029/2019GL084018},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {climate change,climate sensitivity,radiative feedback,radiative forcing,uncertainty},
month = {oct},
number = {20},
pages = {11367--11377},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Probing the Sources of Uncertainty in Transient Warming on Different Timescales}},
url = {https://doi.org/10.1029/2019GL084018},
volume = {46},
year = {2019}
}
@article{Luyssaert2014,
abstract = {The direct effects of land-cover change on surface climate are increasingly well understood, but fewer studies have investigated the consequences of the trend towards more intensive land management practices. Now, research investigating the biophysical effects of temperate land-management changes reveals a net warming effect of similar magnitude to that driven by changing land cover.},
author = {Luyssaert, Sebastiaan and Jammet, Mathilde and Stoy, Paul C. and Estel, Stephan and Pongratz, Julia and Ceschia, Eric and Churkina, Galina and Don, Axel and Erb, Karlheinz and Ferlicoq, Morgan and Gielen, Bert and Gr{\"{u}}nwald, Thomas and Houghton, Richard A. and Klumpp, Katja and Knohl, Alexander and Kolb, Thomas and Kuemmerle, Tobias and Laurila, Tuomas and Lohila, Annalea and Loustau, Denis and McGrath, Matthew J. and Meyfroidt, Patrick and Moors, Eddy J. and Naudts, Kim and Novick, Kim and Otto, Juliane and Pilegaard, Kim and Pio, Casimiro A. and Rambal, Serge and Rebmann, Corinna and Ryder, James and Suyker, Andrew E. and Varlagin, Andrej and Wattenbach, Martin and Dolman, A. Johannes},
doi = {10.1038/nclimate2196},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {may},
number = {5},
pages = {389--393},
title = {{Land management and land-cover change have impacts of similar magnitude on surface temperature}},
url = {http://www.nature.com/articles/nclimate2196},
volume = {4},
year = {2014}
}
@article{doi:10.1175/2008JCLI2259.1,
abstract = { Abstract The effects of irregular in situ ocean sampling on estimates of annual globally integrated upper ocean heat content anomalies (OHCA) are investigated for sampling patterns from 1955 to 2006. An analytical method is presented for computing the effective area covered by an objective map for any given in situ sampling distribution. To evaluate the method, appropriately scaled sea surface height (SSH) anomaly maps from Archiving, Validation, and Interpretation of Satellite Oceanographic data (AVISO) are used as a proxy for OHCA from 1993 to 2006. Use of these proxy data demonstrates that the simple area integral (SI) of such an objective map for sparse datasets does not agree as well with the actual integral as the weighted integral (WI), defined as the simple integral weighted by the ratio of the total area over the “observed” area. From 1955 to 1966, in situ ocean sampling is inadequate to estimate accurately annual global integrals of the proxy upper OHCA. During this period, the SI for the sampling pattern of any given year underestimates the 13-yr trend in proxy OHCA from 1993 to 2006 by around 70{\%}, and confidence limits for the WI are often very large. From 1967 to 2003 there appear to be sufficient data to estimate annual global integrals. Limited by the constraints of this analysis, the SI for any given year's sampling pattern still underestimates the 1993–2006 13-yr trend in the proxy by around 30{\%}, but the WI matches the trend well with small confidence limits. For 2004 through 2006 in situ sampling, with near-global in situ Argo data coverage, the 1993–2006 13-yr trend in the proxy is equally well represented by the SI or WI. },
author = {Lyman, John M and Johnson, Gregory C},
doi = {10.1175/2008JCLI2259.1},
journal = {Journal of Climate},
number = {21},
pages = {5629--5641},
title = {{Estimating Annual Global Upper-Ocean Heat Content Anomalies despite Irregular In Situ Ocean Sampling}},
url = {https://doi.org/10.1175/2008JCLI2259.1},
volume = {21},
year = {2008}
}
@article{Lynch2021,
abstract = {Agriculture is a significant contributor to anthropogenic global warming, and reducing agricultural emissions—largely methane and nitrous oxide—could play a significant role in climate change mitigation. However, there are important differences between carbon dioxide (CO 2 ), which is a stock pollutant, and methane (CH 4 ), which is predominantly a flow pollutant. These dynamics mean that conventional reporting of aggregated CO 2 -equivalent emission rates is highly ambiguous and does not straightforwardly reflect historical or anticipated contributions to global temperature change. As a result, the roles and responsibilities of different sectors emitting different gases are similarly obscured by the common means of communicating emission reduction scenarios using CO 2 -equivalence. We argue for a shift in how we report agricultural greenhouse gas emissions and think about their mitigation to better reflect the distinct roles of different greenhouse gases. Policy-makers, stakeholders, and society at large should also be reminded that the role of agriculture in climate mitigation is a much broader topic than climate science alone can inform, including considerations of economic and technical feasibility, preferences for food supply and land-use, and notions of fairness and justice. A more nuanced perspective on the impacts of different emissions could aid these conversations.},
author = {Lynch, John and Cain, Michelle and Frame, David and Pierrehumbert, Raymond},
doi = {10.3389/fsufs.2020.518039},
issn = {2571-581X},
journal = {Frontiers in Sustainable Food Systems},
keywords = {CO2,agriculture,climate change,climate policy,methane,nitrous oxide},
month = {feb},
pages = {518039},
publisher = {Frontiers Media SA},
title = {{Agriculture's Contribution to Climate Change and Role in Mitigation Is Distinct From Predominantly Fossil CO2-Emitting Sectors}},
url = {https://www.frontiersin.org/articles/10.3389/fsufs.2020.518039/full},
volume = {4},
year = {2021}
}
@article{Lynch2020,
abstract = {The atmospheric lifetime and radiative impacts of different climate pollutants can both differ markedly, so metrics that equate emissions using a single scaling factor, such as the 100-year Global Warming Potential (GWP100), can be misleading. An alternative approach is to report emissions as 'warming-equivalents' that result in similar warming impacts without requiring a like-for-like weighting per emission. GWP, an alternative application of GWPs where the CO2-equivalence of short-lived climate pollutant emissions is predominantly determined by changes in their emission rate, provides a straightforward means of generating warming-equivalent emissions. In this letter we illustrate the contrasting climate impacts resulting from emissions of methane, a short-lived greenhouse gas, and CO2, and compare GWP100 and GWP CO2-equivalents for a number of simple emissions scenarios. We demonstrate that GWP provides a useful indication of warming, while conventional application of GWP100 falls short in many scenarios and particularly when methane emissions are stable or declining, with important implications for how we consider 'zero emission' or 'climate neutral' targets for sectors emitting different compositions of gases. We then illustrate how GWP can provide an improved means of assessing alternative mitigation strategies. GWP allows warming-equivalent emissions to be calculated directly from CO2-equivalent emissions reported using GWP100, consistent with the Paris Rulebook agreed by the UNFCCC, on condition that short-lived and cumulative climate pollutants are aggregated separately, which is essential for transparency. It provides a direct link between emissions and anticipated warming impacts, supporting stocktakes of progress towards a long-term temperature goal and compatible with cumulative emissions budgets.},
author = {Lynch, John and Cain, Michelle and Pierrehumbert, Raymond and Allen, Myles},
doi = {10.1088/1748-9326/ab6d7e},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {Carbon dioxide equivalent,Carbon dioxide warming equivalent,Climate change,Global warming potential,Gwp,Methane},
month = {apr},
number = {4},
pages = {044023},
publisher = {Institute of Physics Publishing},
title = {{Demonstrating GWP*: A means of reporting warming-equivalent emissions that captures the contrasting impacts of short- and long-lived climate pollutants}},
url = {https://doi.org/10.1088/1748-9326/ab6d7e},
volume = {15},
year = {2020}
}
@article{Mulmenstadt2019,
abstract = {Abstract. Using the method of offline radiative transfer modelling within the partial radiative perturbations (PRP) approach, the effective radiative forcing (ERF) by aerosol{\&}ndash;cloud interactions (ACI) in the ECHAM-HAMMOZ aerosol climate model is decomposed into a radiative forcing by anthropogenic cloud droplet number change and adjustments of the liquid water path and cloud fraction. The simulated radiative forcing and liquid water path adjustment are of approximately equal magnitude at {\&}minus;0.52{\&}thinsp;W{\&}thinsp;m{\&}minus;2 and {\&}minus;0.53{\&}thinsp;W{\&}thinsp;m{\&}minus;2, respectively, while the cloud fraction adjustment is somewhat weaker at {\&}minus;0.31{\&}thinsp;W{\&}thinsp;m{\&}minus;2 (constituting 38{\&}thinsp;{\%}, 39{\&}thinsp;{\%}, and 23{\&}thinsp;{\%} of the total ERFaci, respectively); geographically, all three ERF components in the simulation peak over China, the subtropical eastern ocean boundaries, the northern Atlantic and Pacific Ocean, Europe, and eastern North America (in order of prominence). Spatial correlations indicate that the temporal-mean liquid water path adjustment is proportional to the temporal-mean radiative forcing, while the relationship between cloud fraction adjustment and radiative forcing is less direct. While the estimate of warm-cloud ACI is relatively insensitive to the treatment of ice and mixed-phase cloud overlying warm cloud, there are indications that more restrictive treatments of ice in the column result in a low bias in the estimated magnitude of the liquid water path adjustment and a high bias in the estimated magnitude of the droplet number forcing. Since the present work is the first PRP decomposition of the aerosol ERF into RFaci and fast cloud adjustments, idealized experiments are conducted to provide evidence that the PRP results are accurate. The experiments show that using low-frequency (daily or monthly) time-averaged model output of the cloud property fields underestimates the ERF, but 3-hourly mean output is sufficiently frequent.},
author = {M{\"{u}}lmenst{\"{a}}dt, Johannes and Gryspeerdt, Edward and Salzmann, Marc and Ma, Po-Lun and Dipu, Sudhakar and Quaas, Johannes},
doi = {10.5194/acp-19-15415-2019},
journal = {Atmospheric Chemistry and Physics},
pages = {15415--15429},
title = {{Separating radiative forcing by aerosol–cloud interactions and fast cloud adjustments in the ECHAM-HAMMOZ aerosol–climate model using the method of partial radiative perturbations}},
volume = {19},
year = {2019}
}
@article{doi:10.1002/2014JD021670,
abstract = {Abstract Large uncertainties exist in estimations of aerosol direct radiative forcing and indirect radiative forcing, and the values derived from global modeling differ substantially with satellite-based calculations. Following the approach of Quaas et al. (2008; hereafter named Quaas2008), we reassess satellite-based clear- and cloudy-sky radiative forcings and their seasonal variations by employing updated satellite products from 2004 to 2011 in combination with the anthropogenic aerosol optical depth (AOD) fraction obtained from model simulations using the Goddard Earth Observing System-Chemistry-Advanced Particle Microphysics (GEOS-Chem-APM). Our derived annual mean aerosol clear-sky forcing (−0.59 W m−2) is lower, while the cloudy-sky forcing (−0.34 W m−2) is higher than the corresponding results (−0.9 W m−2 and −0.2 W m−2, respectively) reported in Quaas2008. Our study indicates that the derived forcings are sensitive to the anthropogenic AOD fraction and its spatial distribution but insensitive to the temporal resolution used to obtain the regression coefficients, i.e., monthly or seasonal based. The forcing efficiency (i.e., the magnitude per anthropogenic AOD) for the clear-sky forcing based on this study is 19.9 W m−2, which is about 5{\%} smaller than Quaas2008's value of 21.1 W m−2. In contrast, the efficiency for the cloudy-sky forcing of this study (11 W m−2) is more than a factor of 2 larger than Quaas2008's value of 4.7 W m−2. Uncertainties tests indicate that anthropogenic fraction of AOD strongly affects the computed forcings while using aerosol index instead of AOD from satellite data as aerosol proxy does not appear to cause any significant differences in regression slopes and derived forcings.},
author = {Ma, Xiaoyan and Yu, Fangqun and Quaas, Johannes},
doi = {10.1002/2014JD021670},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aerosol,direct forcing,indirect forcing,satellite-based estimate},
number = {17},
pages = {10394--10409},
title = {{Reassessment of satellite-based estimate of aerosol climate forcing}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014JD021670},
volume = {119},
year = {2014}
}
@article{MacDougall2015,
abstract = {The near proportionality between cumulative CO 2 emissions and change in near surface temperature can be used to define a carbon budget: a finite quantity of carbon that can be burned associated with a chosen 'safe' temperature change threshold. Here we evaluate the sensitivity of this carbon budget to permafrost carbon dynamics and changes in non-CO 2 forcings. The carbon budget for 2.0 of warming is reduced from 1320 Pg C when considering only forcing from CO 2 to 810 Pg C when considering permafrost carbon feedbacks as well as other anthropogenic contributions to climate change. We also examined net carbon budgets following an overshoot of and return to a warming target. That is, the net cumulative CO 2 emissions at the point in time a warming target is restored following artificial removal of CO 2 from the atmosphere to cool the climate back to a chosen temperature target. These overshoot net carbon budgets are consistently smaller than the conventional carbon budgets. Overall carbon budgets persist as a robust and simple conceptual framework to relate the principle cause of climate change to the impacts of climate change.},
author = {MacDougall, Andrew H. and Zickfeld, Kirsten and Knutti, Reto and Matthews, H. Damon},
doi = {10.1088/1748-9326/10/12/125003},
issn = {1748-9326},
journal = {Environmental Research Letters},
keywords = {TCRE,carbon budget,climate change},
month = {dec},
number = {12},
pages = {125003},
title = {{Sensitivity of carbon budgets to permafrost carbon feedbacks and non-CO2 forcings}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/10/12/125003},
volume = {10},
year = {2015}
}
@article{MacIntosh2016a,
abstract = {The precipitation response to radiative forcing (RF) can be decomposed into a fast precipitation response (FPR), which depends on the atmospheric component of RF, and a slow response, which depends on surface temperature change. We present the first detailed climate model study of the FPR due to tropospheric and stratospheric ozone changes. The FPR depends strongly on the altitude of ozone change. Increases below about 3 km cause a positive FPR; increases above cause a negative FPR. The FPR due to stratospheric ozone change is, per unit RF, about 3 times larger than that due to tropospheric ozone. As historical ozone trends in the troposphere and stratosphere are opposite in sign, so too are the FPRs. Simple climate model calculations of the time-dependent total (fast and slow) precipitation change, indicate that ozone's contribution to precipitation change in 2011, compared to 1765, could exceed 50{\%} of that due to CO2change.},
author = {MacIntosh, C.R. and Allan, R.P. and Baker, L.H. and Bellouin, N. and Collins, W. and Mousavi, Z. and Shine, K.P.},
doi = {10.1002/2015GL067231},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {feb},
number = {3},
pages = {1263--1271},
title = {{Contrasting fast precipitation responses to tropospheric and stratospheric ozone forcing}},
url = {http://doi.wiley.com/10.1002/2015GL067231 https://onlinelibrary.wiley.com/doi/abs/10.1002/2015GL067231},
volume = {43},
year = {2016}
}
@article{Maher2018,
abstract = {Interannual to decadal variability in the Pacific Ocean is a prominent feature of Earth's climate system, with global telecon-nections. Recent studies have identified Pacific decadal variability as a major driver of periods of rapid and slower global mean surface air temperature change. Here, we use an eddy-permitting global ocean model to investigate the role of the observed 1992-2011 trade wind intensification and concurrent trends in surface atmospheric variables over the Pacific associated with the negative phase of the Interdecadal Pacific Oscillation (IPO) in driving ocean circulation and heat content changes. We find a strengthening of the Equatorial Undercurrent (EUC) in response to strengthened winds, which brings cooler water to the surface of the eastern Pacific and an increase in the Pacific shallow overturning cells (PSOC), which in turn drives additional heat into the subsurface western Pacific. The wind acceleration also results in an increase in the strength and subsequent heat transport of the Indonesian throughflow (ITF), which transports some of the additional heat from the western Pacific into the Indian Ocean. The circulation changes result in warming of the subsurface western Pacific, cooling of the upper eastern Pacific Ocean and warming of the subsurface Indian Ocean, with an overall increase in Indo-Pacific heat content. Further experiments impose a symmetric reversal of the atmospheric state to examine how the ocean would behave if the winds (and other atmospheric variables) were to revert to their initial state. This mimics a return to the neutral phase of the IPO, characterised by a weakening of the Pacific trade winds. In response we find a slowdown of the EUC and the PSOC, which results in a return to climatological SST conditions in the western and eastern Pacific. The ITF also slows towards its original strength. However, the subsurface temperature, heat content and ITF responses are not symmetric due to an overall increase in the surface heat flux into the ocean associated with the cooler surface of the Pacific. There may also be irreversible heat transport across the thermocline via diapycnal mixing, further contributing to this asymmetry. The net result of the experiment is that the Indo-Pacific subsurface ocean is warmer than it was in its initial state.},
author = {Maher, Nicola and England, Matthew H. and Gupta, Alex Sen and Spence, Paul},
doi = {10.1007/s00382-017-3923-3},
isbn = {0038201739},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {Decadal climate variability,Global temperature trends,Pacific Ocean,Trade winds,Warming slowdown},
month = {jul},
number = {1-2},
pages = {321--336},
publisher = {Springer Verlag},
title = {{Role of Pacific trade winds in driving ocean temperatures during the recent slowdown and projections under a wind trend reversal}},
volume = {51},
year = {2018}
}
@article{Mahlstein2011,
abstract = {The Arctic climate is governed by complex interactions and feedback mechanisms between the atmosphere, ocean, and solar radiation. One of its characteristic features, the Arctic sea ice, is very vulnerable to anthropogenically caused warming. Production and melting of sea ice is influenced by several physical processes. The authors show that the northward ocean heat transport is an important factor in the simulation of the sea ice extent in the current general circulation models. Those models that transport more energy to the Arctic show a stronger future warming, in the Arctic as well as globally. Larger heat transport to the Arctic, in particular in the Barents Sea, reduces the sea ice cover in this area. More radiation is then absorbed during summer months and is radiated back to the atmosphere in winter months. This process leads to an increase in the surface temperature and therefore to a stronger polar amplification. The models that show a larger global warming agree better with the observed sea ice extent in the Arctic. In general, these models also have a higher spatial resolution.},
author = {Mahlstein, Irina and Knutti, Reto},
doi = {10.1175/2010JCLI3713.1},
issn = {1520-0442},
journal = {Journal of Climate},
keywords = {Arctic,General circulation models,Heat budgets,Radiative forcing,Sea ice,Transport},
month = {mar},
number = {5},
pages = {1451--1460},
title = {{Ocean Heat Transport as a Cause for Model Uncertainty in Projected Arctic Warming}},
url = {http://journals.ametsoc.org/doi/10.1175/2010JCLI3713.1},
volume = {24},
year = {2011}
}
@article{Mahowald2017a,
abstract = {Purpose of Review: Atmospheric aerosol deposition is an important source of nutrients and pollution to many continental and marine ecosystems. Humans have heavily perturbed the cycles of several important aerosol species, potentially affecting terrestrial and marine carbon budgets and consequently climate. The most ecologically important aerosol elements impacted by humans are nitrogen, sulfur, iron, phosphorus, and base cations. Here, we review the latest research on the modification of the atmospheric cycles of these aerosols and their resulting effects on continental and marine ecosystems. Recent Findings: Recent studies have improved our understanding of how humans have perturbed atmospheric aerosol cycles and how they may continue to evolve in the future. Research in both aquatic and terrestrial environments has highlighted the role of atmospheric deposition as a nutrient subsidy, with effects on ecosystem productivity. These studies further emphasize the importance of local biogeochemical conditions and biota species composition to the regional responses to aerosol deposition. Summary: The size of the impact of anthropogenic aerosol deposition on the carbon cycle and the resulting climate forcing is at present not well understood. It is estimated that increases in nutrient subsidies from atmospheric deposition across all ecosystems are causing an increase in carbon dioxide uptake between 0.2 and 1.5 PgC/year. As aerosol emissions from industrial sources are reduced to improve air quality, these enhancements in carbon uptake may be reduced in the future leading to reduced carbon dioxide emission offsets. However, large uncertainties remain, not only because of limited information on how humans have modified and will modify aerosol emissions, but also because of a lack of quantitative understanding of how aerosol deposition impacts carbon cycling in many ecosystems.},
author = {Mahowald, Natalie M. and Scanza, Rachel and Brahney, Janice and Goodale, Christine L. and Hess, Peter G. and Moore, J. Keith and Neff, Jason},
doi = {10.1007/s40641-017-0056-z},
issn = {2198-6061},
journal = {Current Climate Change Reports},
keywords = {Aerosols,Biogeochemistry,Carbon cycle,Nutrients},
month = {mar},
number = {1},
pages = {16--31},
title = {{Aerosol Deposition Impacts on Land and Ocean Carbon Cycles}},
url = {http://link.springer.com/10.1007/s40641-017-0056-z},
volume = {3},
year = {2017}
}
@article{Mahrt2018,
abstract = {235 K). In the cirrus regime (T≤235 K), soot types show different freezing behavior depending on particle size and soot type, but the freezing is closely linked to the soot particle properties. Specifically, our results suggest that if soot aggregates contain mesopores (pore diameters of 2–50 nm) and have sufficiently low water–soot contact angles, they show ice nucleation activity and can contribute to ice formation in the cirrus regime at RH well below homogeneous freezing of solution droplets. We attribute the observed ice nucleation to a pore condensation and freezing (PCF) mechanism. Nevertheless, soot particles without cavities of the right size and/or too-high contact angles nucleate ice only at or well above the RH required for homogeneous freezing conditions of solution droplets. Thus, our results imply that soot particles able to nucleate ice via PCF could impact the microphysical properties of ice clouds.]]{\textgreater}},
author = {Mahrt, Fabian and Marcolli, Claudia and David, Robert O. and Gr{\"{o}}nquist, Philippe and {Barthazy Meier}, Eszter J. and Lohmann, Ulrike and Kanji, Zamin A.},
doi = {10.5194/acp-18-13363-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {sep},
number = {18},
pages = {13363--13392},
title = {{Ice nucleation abilities of soot particles determined with the Horizontal Ice Nucleation Chamber}},
url = {https://www.atmos-chem-phys.net/18/13363/2018/},
volume = {18},
year = {2018}
}
@article{Malavelle2017b,
abstract = {Aerosols cast a wide shadow across many aspects of the Earth system. They reflect solar radiation, increase snow and ice melt, and contribute to local air pollution. Aerosols also interact with clouds, but the net effect of these interactions is difficult to disentangle from coinciding meteorological variations. Sulfate aerosols tend to increase reflection, and theoretical principles state that aerosols should lead to more but smaller cloud particles and should increase cloud lifetime and liquid water path. However, firm confirmation of these indirect effects has been hard to come by. Now, Florent Malavelle et al. use observations and modelling to help to understand the effects of a recent volcanic eruption in Iceland. The sulfate aerosols associated with the eruption caused a discernible yet transient brightening effect, but the effects on liquid water path were negligible. This result will help to reduce uncertainties in future climate projections, because results from climate models with excessive liquid-water-path responses can now be rejected.},
archivePrefix = {arXiv},
arxivId = {NIHMS150003},
author = {Malavelle, Florent F. and Haywood, Jim M. and Jones, Andy and Gettelman, Andrew and Clarisse, Lieven and Bauduin, Sophie and Allan, Richard P. and Karset, Inger Helene H. and Kristj{\'{a}}nsson, J{\'{o}}n Egill and Oreopoulos, Lazaros and Cho, Nayeong and Lee, Dongmin and Bellouin, Nicolas and Boucher, Olivier and Grosvenor, Daniel P. and Carslaw, Ken S. and Dhomse, Sandip and Mann, Graham W. and Schmidt, Anja and Coe, Hugh and Hartley, Margaret E. and Dalvi, Mohit and Hill, Adrian A. and Johnson, Ben T. and Johnson, Colin E. and Knight, Jeff R. and O'Connor, Fiona M. and Stier, Philip and Myhre, Gunnar and Platnick, Steven and Stephens, Graeme L. and Takahashi, Hanii and Thordarson, Thorvaldur},
doi = {10.1038/nature22974},
eprint = {NIHMS150003},
isbn = {0028-0836},
issn = {14764687},
journal = {Nature},
number = {7659},
pages = {485--491},
pmid = {28640263},
publisher = {Nature Publishing Group},
title = {{Strong constraints on aerosol-cloud interactions from volcanic eruptions}},
url = {http://dx.doi.org/10.1038/nature22974},
volume = {546},
year = {2017}
}
@article{Mallapragada2017,
abstract = {Comparing the potential climate impacts of different technologies is challenging for several reasons, including the fact that any given technology may be associated with emissions of multiple greenhouse gases when evaluated on a life cycle basis. In general, analysts must decide how to aggregate the climatic effects of different technologies, taking into account differences in the properties of the gases (differences in atmospheric lifetimes and instantaneous radiative efficiencies) as well as different technology characteristics (differences in emission factors and technology lifetimes). Available metrics proposed in the literature have incorporated these features in different ways and have arrived at different conclusions. In this paper, we develop a general framework for classifying metrics based on whether they measure: (a) cumulative or end point impacts, (b) impacts over a fixed time horizon or up to a fixed end year, and (c) impacts from a single emissions pulse or from a stream of pulses over multiple years. We then use the comparison between compressed natural gas and gasoline-fueled vehicles to illustrate how the choice of metric can affect conclusions about technologies. Finally, we consider tradeoffs involved in selecting a metric, show how the choice of metric depends on the framework that is assumed for climate change mitigation, and suggest which subset of metrics are likely to be most analytically self-consistent.},
author = {Mallapragada, Dharik and Mignone, Bryan K.},
doi = {10.1088/1748-9326/aa7397},
issn = {1748-9326},
journal = {Environmental Research Letters},
keywords = {climate change metrics,greenhouse gas abatement,methane,natural gas,technology assessment},
month = {jul},
number = {7},
pages = {074022},
title = {{A consistent conceptual framework for applying climate metrics in technology life cycle assessment}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/aa7397},
volume = {12},
year = {2017}
}
@article{ISI:000386592900001,
abstract = {Canopy and aerodynamic conductances (g(C) and g(A)) are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (lambda E-T) and evaporation (lambda E-E) flux components of the terrestrial latent heat flux (lambda E), which has important implications for global climate change and water resource management. By physical integration of radiometric surface temperature (T-R) into an integrated framework of the Penman-Monteith and Shuttleworth-Wallace models, we present a novel approach to directly quantify the canopy-scale biophysical controls on lambda E-T and lambda E-E over multiple plant functional types (PFTs) in the Amazon Basin. Combining data from six LBA (Large-scale Biosphere-Atmosphere Experiment in Amazonia) eddy covariance tower sites and a T-R-driven physically based modeling approach, we identified the canopy-scale feedback-response mechanism between g(C), lambda E-T, and atmospheric vapor pressure deficit (D-A), without using any leaf-scale empirical parameterizations for the modeling. The T-R-based model shows minor biophysical control on lambda E-T during the wet (rainy) seasons where lambda E-T becomes predominantly radiation driven and net radiation (RN) determines 75 to 80{\%} of the variances of lambda E-T. However, biophysical control on lambda E-T is dramatically increased during the dry seasons, and particularly the 2005 drought year, explaining 50 to 65{\%} of the variances of lambda E-T, and indicates lambda E-T to be substantially soil moisture driven during the rainfall deficit phase. Despite substantial differences in g(A) between forests and pastures, very similar canopy-atmosphere ``coupling{\{}''{\}} was found in these two biomes due to soil moistureinduced decrease in g(C) in the pasture. This revealed the pragmatic aspect of the T-R-driven model behavior that exhibits a high sensitivity of g(C) to per unit change in wetness as opposed to g(A) that is marginally sensitive to surface wetness variability. Our results reveal the occurrence of a significant hysteresis between lambda E-T and g(C) during the dry season for the pasture sites, which is attributed to relatively low soil water availability as compared to the rainforests, likely due to differences in rooting depth between the two systems. Evaporation was significantly influenced by g(A) for all the PFTs and across all wetness conditions. Our analytical framework logically captures the responses of g(C) and g(A) to changes in atmospheric radiation, D-A, and surface radiometric temperature, and thus appears to be promising for the improvement of existing land-surface-atmosphere exchange parameterizations across a range of spatial scales.},
address = {BAHNHOFSALLEE 1E, GOTTINGEN, 37081, GERMANY},
author = {Mallick, Kaniska and Trebs, Ivonne and Boegh, Eva and Giustarini, Laura and Schlerf, Martin and Drewry, Darren T and Hoffmann, Lucien and von Randow, Celso and Kruijt, Bart and Araujo, Alessandro and Saleska, Scott and Ehleringer, James R and Domingues, Tomas F and Ometto, Jean Pierre H B and Nobre, Antonio D and de Moraes, Osvaldo Luiz and Hayek, Matthew and Munger, J William and Wofsy, Steven C},
doi = {10.5194/hess-20-4237-2016},
issn = {1027-5606},
journal = {Hydrology and Earth System Sciences},
month = {oct},
number = {10},
pages = {4237--4264},
publisher = {COPERNICUS GESELLSCHAFT MBH},
title = {{Canopy-scale biophysical controls of transpiration and evaporation in the Amazon Basin}},
type = {Article},
volume = {20},
year = {2016}
}
@article{Manabe1985,
abstract = {The climatic effects of very large changes of CO 2 concentration in the atmosphere are explored using a general circulation model of the coupled ocean-atmosphere system. As a simplification the model has an annual mean insolation and a highly idealized geography, A series of climatic equilibria are obtained for cases with {\&}half;, 1/√2, 1, 2, 4, and 8 times the present CO 2 concentration in the atmosphere. The results from these six numerical experiments indicate the climatic signatures of large CO 2 changes in the atmosphere and in the abyssal and surface waters of the ocean. As the CO 2 concentration in the model atmosphere increased from 1 to 8 times the normal value, the meridional gradient of surface air temperature decreased, while that of upper tropospheric temperature increased in agreement with the results of earlier CO 2 climate sensitivity studies. However, the intensity and latitudinal placement of the atmospheric jet hardly changed. Despite the reduction of meridional temperature gradient, the meridional density gradient of water at the ocean surface changed little because of the increase of thermal expansion coefficient of seawater with increasing temperature. Thus the intensity of thermohaline circulation in the ocean model does not diminish as expected in the range from 1 to 8 times the normal atmospheric CO 2 concentration. As was shown in an earlier study, the CO 2 -induced changes in the deep sea follow the change of sea surface temperature in high latitudes and thus are much larger than the globally averaged changes of sea surface temperature. The model predicts that the area mean rates of precipitation, evaporation, and runoff increase with increasing CO 2 concentration in the atmosphere. The latitudes of the arid zone and the high surface pressure belt in the subtropics are almost constant in the entire range of 1–8 times normal CO 2 . In general, the climatic signature obtained from the model appears to be consistent with a CO 2 hypothesis for the climatic changes in the Cenozoic with the following exception: the tropical sea surface temperature in the model has a small but significant increase with increasing atmospheric CO 2 concentration, while tropical sea surface temperature as deduced from the isotopic record appears to have no systematic trend during the Tertiary. It is found that the climate corresponding to one-half normal CO 2 is markedly different from the normal and high-CO 2 cases. Sea ice extends to middle latitudes, and the thermohaline circulation in the model ocean loses its intensity and is largely confined to an area between the sea ice margin and the equator. The poleward heat transport by ocean currents is very small in high latitudes, markedly reducing the surface air temperature there. It is suggested that a similar process, which enhances the positive albedo feedback effect of sea ice, played a key role in reducing surface air temperatures over the North Atlantic during the last glacial maximum.},
author = {Manabe, Syukuro and Bryan, Kirk},
doi = {10.1029/JC090iC06p11689},
isbn = {2156-2202},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Oceans},
number = {C6},
pages = {11689},
title = {{CO2-induced change in a coupled ocean–atmosphere model and its paleoclimatic implications}},
url = {http://doi.wiley.com/10.1029/JC090iC06p11689},
volume = {90},
year = {1985}
}
@article{Manabe-1975,
abstract = { Abstract An attempt is made to estimate the temperature changes resulting from doubling the present CO2 concentration by the use of a simplified three-dimensional general circulation model. This model contains the following simplications: a limited computational domain, an idealized topography, no beat transport by ocean currents, and fixed cloudiness. Despite these limitations, the results from this computation yield some indication of how the increase of CO2 concentration may affect the distribution of temperature in the atmosphere. It is shown that the CO2 increase raises the temperature of the model troposphere, whereas it lowers that of the model stratosphere. The tropospheric warming is somewhat larger than that expected from a radiative-convective equilibrium model. In particular, the increase of surface temperature in higher latitudes is magnified due to the recession of the snow boundary and the thermal stability of the lower troposphere which limits convective beating to the lowest layer. It is also shown that the doubling of carbon dioxide significantly increases the intensity of the hydrologic cycle of the model. },
author = {Manabe, Syukuro and Wetherald, Richard T},
doi = {10.1175/1520-0469(1975)032<0003:TEODTC>2.0.CO;2},
journal = {Journal of the Atmospheric Sciences},
number = {1},
pages = {3--15},
title = {{The Effects of Doubling the CO2 Concentration on the climate of a General Circulation Model}},
volume = {32},
year = {1975}
}
@article{Manara2016a,
abstract = {A dataset of 54 daily Italian downward surface solar radiation (SSR) records has been set up collecting data for the 1959-2013 period. Special emphasis is given to the quality control and the homogenization of the records in order to ensure the reliability of the resulting trends. This step has been shown as necessary due to the large differences obtained between the raw and homogenized dataset, especially during the first decades of the study period. In addition, SSR series under clear-sky conditions were obtained considering only the cloudless days from corresponding ground-based cloudiness observations. Subsequently, records were interpolated onto a regular grid and clustered into two regions, northern and southern Italy, which were averaged in order to get all-sky and clear-sky regional SSR records. Their temporal evolution is presented, and possible reasons for differences between all-sky and clear-sky conditions and between the two regions are discussed in order to determine to what extent SSR variability depends on aerosols or clouds. Specifically, the all-sky SSR records show a decrease until the mid-1980s (dimming period), and a following increase until the end of the series (brightening period) even though strength and persistence of tendencies are not the same in all seasons. Clear-sky records present stronger tendencies than all-sky records during the dimming period in all seasons and during the brightening period in winter and autumn. This suggests that, under all-sky conditions, the variations caused by the increase/decrease in the aerosol content have been partially masked by cloud cover variations, especially during the dimming period. Under clear sky the observed dimming is stronger in the south than in the north. This peculiarity could be a consequence of a significant contribution of mineral dust variations to the SSR variability.},
address = {Univ Milan, Dept Phys, Milan, Italy Swiss Fed Inst Technol, Inst Atmospher {\&} Climate Sci, Zurich, Switzerland CNR, ISAC, Bologna, Italy Italian Air Force, COMET Ctr Operat Meteorol, Pratica Di Mare, RM, Italy CSIC, IPE, Zaragoza, Spain},
annote = {Dw9ub
Times Cited:0
Cited References Count:89},
author = {Manara, V and Brunetti, M and Celozzi, A and Maugeri, M and Sanchez-Lorenzo, A and Wild, M},
doi = {10.5194/acp-16-11145-2016},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
keywords = {sunshine duration records instrumental time-series},
language = {English},
number = {17},
pages = {11145--11161},
title = {{Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013)}},
volume = {16},
year = {2016}
}
@article{Manara2015a,
abstract = {A data set of quality checked daily sunshine duration measurements was collected from 104 Italian sites over the 1936 to 2013 period. Monthly mean values were homogenized, projected onto a grid, and subjected to principle component analysis, which identified two significantly different regions: North and South. Sunshine duration temporal evolution is presented, and possible reasons for differences between the two regions are discussed in the light of a comparison with the trends found in observations of total cloud cover and with results from two neighboring regions: the Alps and Spain. In addition, trends for irradiance records, estimated from sunshine duration records using the angstrom ngstrom-Prescott formula, are presented too. The major feature of the trends, an increase in sunshine duration from the mid-1980s, was common to both northern and southern Italy; the decrease in the preceding 30 year period was not, as northern Italy had a lower rate of decrease than southern Italy. The few records available during the earliest period of the data set indicate that sunshine duration in Italy increased from the mid-1930s to the mid-1950s. The further steps needed to identify and quantify the mechanisms giving rise to the observed trends and to the reported regional differences in dimming and brightening are outlined.},
address = {Manara, V Univ Milan, Dept Phys, Milan, Italy Univ Milan, Dept Phys, Milan, Italy Univ Milan, Dept Phys, Milan, Italy Consiglio Ric {\&} Sperimentaz Agr, Unita Ric Climatol {\&} Meteorol Applicate Agr, Rome, Italy CNR, Inst Atmospher Sci {\&} Climate, I-40126 Bolo},
annote = {Cj8iy
Times Cited:0
Cited References Count:90},
author = {Manara, V and Beltrano, M C and Brunetti, M and Maugeri, M and Sanchez-Lorenzo, A and Simolo, C and Sorrenti, S},
doi = {10.1002/2014jd022560},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {sunshine duration data homogenization global dimmi},
language = {English},
number = {9},
pages = {3622--3641},
title = {{Sunshine duration variability and trends in Italy from homogenized instrumental time series (1936–2013)}},
volume = {120},
year = {2015}
}
@article{Manaster2017,
abstract = {In this study, observed cloud liquid water path (LWP) trends from the Multisensor Advanced Climatology of Liquid Water Path (MAC-LWP) dataset (1988–2014) are compared to trends computed from the temporally coincident records of 16 global climate models (GCMs) participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5). For many regions, observed trend magnitudes are several times larger than the corresponding model mean trend magnitudes. Muted model mean trends are thought to be the result of cancellation effects arising from differing interannual variability characteristics and differences in model physics–dynamics. In most regions, the majority of modeled trends were statistically consistent with the observed trends. This was thought to be because of large estimated errors in both the observations and the models due to interannual variability. Over the southern oceans (south of 40°S latitude), general agreement between the observed trend and virtually all GCM trends is also found (about 1–2 g m−2 decade−1). Observed trends are also compared to those from the Atmospheric Model Intercomparison Project (AMIP). Like the CMIP5 models, the majority of modeled AMIP trends were statistically consistent with the observed trends. It was also found that, in regions where the AMIP model mean time series better captures observed interannual variability, it tends to better capture the magnitude of the observed trends.},
author = {Manaster, Andrew and O'Dell, Christopher W and Elsaesser, Gregory},
doi = {10.1175/JCLI-D-16-0399.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jul},
number = {15},
pages = {5871--5884},
title = {{Evaluation of Cloud Liquid Water Path Trends Using a Multidecadal Record of Passive Microwave Observations}},
url = {https://doi.org/10.1175/JCLI-D-16-0399.1},
volume = {30},
year = {2017}
}
@article{Manne2001,
abstract = {The Kyoto Protocol permits countries to meet part of their emission reduction obligations by cutting back on gases other than CO2 (ref. 1). This approach requires a definition of trade-offs among the radiatively active gases. The Intergovernmental Panel on Climate Change has suggested global warming potentials for this purpose, which use the accumulated radiative forcing of each gas by a set time horizon to establish emission equivalence. But it has been suggested that this approach has serious shortcomings: damages or abatement costs are not considered and the choice of time horizon for calculating cumulative radiative force is critical, but arbitrary. Here we describe an alternative framework for determining emission equivalence between radiatively active gases that addresses these weaknesses. We focus on limiting temperature change and rate of temperature change, but our framework is also applicable to other objectives. For a proposed ceiling, we calculate how much one should be willing to pay for emitting an additional unit of each gas. The relative prices then determine the trade-off between gases at each point in time, taking into account economical as well as physical considerations. Our analysis shows that the relative prices are sensitive to the lifetime of the gases, the choice of target and the proximity of the target, making short-lived gases more expensive to emit as we approach the prescribed ceiling.},
author = {Manne, Alan S. and Richels, Richard G.},
doi = {10.1038/35070541},
issn = {00280836},
journal = {Nature},
month = {apr},
number = {6829},
pages = {675--677},
publisher = {Macmillan Magazines Ltd.},
title = {{An alternative approach to establishing trade-offs among greenhouse gases}},
url = {http://dx.doi.org/10.1038/35070541 http://10.0.4.14/35070541},
volume = {410},
year = {2001}
}
@article{Marotzke2015a,
abstract = {Most present-generation climate models simulate an increase in global-mean surface temperature (GMST) since 1998, whereas observations suggest a warming hiatus. It is unclear to what extent this mismatch is caused by incorrect model forcing, by incorrect model response to forcing or by random factors. Here we analyse simulations and observations of GMST from 1900 to 2012, and show that the distribution of simulated 15-year trends shows no systematic bias against the observations. Using a multiple regression approach that is physically motivated by surface energy balance, we isolate the impact of radiative forcing, climate feedback and ocean heat uptake on GMST[mdash]with the regression residual interpreted as internal variability[mdash]and assess all possible 15- and 62-year trends. The differences between simulated and observed trends are dominated by random internal variability over the shorter timescale and by variations in the radiative forcings used to drive models over the longer timescale. For either trend length, spread in simulated climate feedback leaves no traceable imprint on GMST trends or, consequently, on the difference between simulations and observations. The claim that climate models systematically overestimate the response to radiative forcing from increasing greenhouse gas concentrations therefore seems to be unfounded.},
author = {Marotzke, Jochem and Forster, Piers M.},
doi = {10.1038/nature14117},
isbn = {0028-0836},
issn = {14764687},
journal = {Nature},
number = {7536},
pages = {565--570},
pmid = {25631444},
publisher = {Nature Publishing Group},
title = {{Forcing, feedback and internal variability in global temperature trends}},
url = {http://dx.doi.org/10.1038/nature14117},
volume = {517},
year = {2015}
}
@article{Marotzke2019,
author = {Marotzke, Jochem},
doi = {10.1002/wcc.563},
issn = {1757-7780},
journal = {WIREs Climate Change},
month = {jan},
number = {1},
pages = {e563},
title = {{Quantifying the irreducible uncertainty in near‐term climate projections}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/wcc.563},
volume = {10},
year = {2019}
}
@article{Marshall2015,
author = {Marshall, John and Scott, Jeffery R. and Armour, Kyle C. and Campin, J.-M. and Kelley, Maxwell and Romanou, Anastasia},
doi = {10.1007/s00382-014-2308-0},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {Antarctic,Arctic,Climate change,Climate feedbacks,Greenhouse gas warming,Ocean},
month = {apr},
number = {7-8},
pages = {2287--2299},
title = {{The ocean's role in the transient response of climate to abrupt greenhouse gas forcing}},
url = {http://link.springer.com/10.1007/s00382-014-2308-0},
volume = {44},
year = {2015}
}
@article{Marshall9999,
abstract = {The relationship between volcanic stratospheric aerosol optical depth (SAOD) and volcanic radiative forcing is key for quantifying volcanic climate impacts. In their Fifth Assessment Report, the Intergovernmental Panel on Climate Change used one scaling factor between volcanic SAOD and volcanic forcing based on climate model simulations of the 1991 Mt. Pinatubo eruption, which may not be appropriate for all eruptions. Using a large ensemble of aerosol-chemistry-climate simulations of eruptions with different sulfur dioxide emissions, latitudes, emission altitudes, and seasons, we find that the effective radiative forcing (ERF) is on average 20{\%} less than the instantaneous radiative forcing, predominantly due to a positive shortwave cloud adjustment. In our model, the volcanic SAOD-ERF relationship is non-unique and varies widely depending on time since an eruption, eruption latitude, and season due to differences in aerosol dispersion and incoming solar radiation. Our revised SAOD-ERF relationships suggest that volcanic forcing has been previously overestimated.},
author = {Marshall, Lauren R. and Smith, Christopher J. and Forster, Piers M. and Aubry, Thomas J. and Andrews, Timothy and Schmidt, Anja},
doi = {10.1029/2020GL090241},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {aerosols,effective radiative forcing,rapid adjustments,volcanic forcing},
month = {oct},
number = {19},
pages = {e2020GL090241},
title = {{Large Variations in Volcanic Aerosol Forcing Efficiency Due to Eruption Source Parameters and Rapid Adjustments}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL090241},
volume = {47},
year = {2020}
}
@article{Martinez-Boti2015a,
abstract = {Theory and climate modelling suggest that the sensitivity of Earth/'s climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth/'s climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2.},
archivePrefix = {arXiv},
arxivId = {arXiv:gr-qc/9809069v1},
author = {Mart{\'{i}}nez-Bot{\'{i}}, M. A. and Foster, G. L. and Chalk, T. B. and Rohling, E. J. and Sexton, P. F. and Lunt, D. J. and Pancost, R. D. and Badger, M. P. S. and Schmidt, D. N.},
doi = {10.1038/nature14145},
eprint = {9809069v1},
isbn = {1476-4687 (Electronic)$\backslash$r0028-0836 (Linking)},
issn = {0028-0836},
journal = {Nature},
pages = {49--54},
pmid = {25652996},
primaryClass = {arXiv:gr-qc},
title = {{Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records}},
url = {http://www.nature.com/doifinder/10.1038/nature14145{\%}5Cnhttp://dx.doi.org/10.1038/nature14145},
volume = {518},
year = {2015}
}
@article{Marvel2015a,
abstract = {Understanding the cloud response to external forcing is a major challenge for climate science. This crucial goal is complicated by intermodel differences in simulating present and future cloud cover and by observational uncertainty. This is the first formal detection and attribution study of cloud changes over the satellite era. Presented herein are CMIP5 model-derived fingerprints of externally forced changes to three cloud properties: the latitudes at which the zonally averaged total cloud fraction (CLT) is maximized or minimized, the zonal average CLT at these latitudes, and the height of high clouds at these latitudes. By considering simultaneous changes in all three properties, the authors define a coherent multivariate fingerprint of cloud response to external forcing and use models from phase 5 of CMIP (CMIP5) to calculate the average time to detect these changes. It is found that given perfect satellite cloud observations beginning in 1983, the models indicate that a detectable multivariat...},
author = {Marvel, Kate and Zelinka, Mark and Klein, Stephen A. and Bonfils, C{\'{e}}line and Caldwell, Peter and Doutriaux, Charles and Santer, Benjamin D. and Taylor, Karl E.},
doi = {10.1175/JCLI-D-14-00734.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Clouds,Pattern detection,Radiative forcing},
number = {12},
pages = {4820--4840},
title = {{External influences on modeled and observed cloud trends}},
volume = {28},
year = {2015}
}
@article{Marvel2018a,
abstract = {{\textcopyright}2018. American Geophysical Union. All Rights Reserved. An emerging literature suggests that estimates of equilibrium climate sensitivity (ECS) derived from recent observations and energy balance models are biased low because models project more positive climate feedback in the far future. Here we use simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to show that across models, ECS inferred from the recent historical period (1979–2005) is indeed almost uniformly lower than that inferred from simulations subject to abrupt increases in CO 2 radiative forcing. However, ECS inferred from simulations in which sea surface temperatures are prescribed according to observations is lower still. ECS inferred from simulations with prescribed sea surface temperatures is strongly linked to changes to tropical marine low clouds. However, feedbacks from these clouds are a weak constraint on long-term model ECS. One interpretation is that observations of recent climate changes constitute a poor direct proxy for long-term sensitivity.},
author = {Marvel, Kate and Pincus, Robert and Schmidt, Gavin A. and Miller, Ron L.},
doi = {10.1002/2017GL076468},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {CMIP5,climate sensitivity,cloud feedback},
number = {3},
pages = {1595--1601},
title = {{Internal Variability and Disequilibrium Confound Estimates of Climate Sensitivity From Observations}},
volume = {45},
year = {2018}
}
@article{Marvel2016b,
abstract = {Climate sensitivity to doubled CO2 is a widely used metric for the large-scale response to external forcing. Climate models predict a wide range for two commonly used definitions: the transient climate response (TCR: the warming after 70 years of CO2 concentrations that rise at 1{\%} per year), and the equilibrium climate sensitivity (ECS: the equilibrium temperature change following a doubling of CO2 concentrations). Many observational data sets have been used to constrain these values, including temperature trends over the recent past, inferences from palaeoclimate and process-based constraints from the modern satellite era. However, as the IPCC recently reported, different classes of observational constraints produce somewhat incongruent ranges. Here we show that climate sensitivity estimates derived from recent observations must account for the efficacy of each forcing active during the historical period. When we use single-forcing experiments to estimate these efficacies and calculate climate sensitivity from the observed twentieth-century warming, our estimates of both TCR and ECS are revised upwards compared to previous studies, improving the consistency with independent constraints.},
author = {Marvel, Kate and Schmidt, Gavin A. and Miller, Ron L. and Nazarenko, Larissa S.},
doi = {10.1038/nclimate2888},
isbn = {1758-6798},
issn = {17586798},
journal = {Nature Climate Change},
number = {4},
pages = {386--389},
title = {{Implications for climate sensitivity from the response to individual forcings}},
volume = {6},
year = {2016}
}
@incollection{Masson-Delmotte2013,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Masson-Delmotte, V and Schulz, M and Abe-Ouchi, A and Beer, J and Ganopolski, A and {González Rouco}, J F and Jansen, E and Lambeck, K and Luterbacher, J and Naish, T and Osborn, T and Otto-Bliesner, B and Quinn, T and Ramesh, R and Rojas, M and Shao, X and Timmermann, A},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {5},
doi = {10.1017/CBO9781107415324.013},
editor = {Stocker, T F and Qin, D and Plattner, G.-K. and Tignor, M and Allen, S K and Boschung, J and Nauels, A and Xia, Y and Bex, V and Midgley, P M},
isbn = {9781107661820},
pages = {383--464},
publisher = {Cambridge University Press},
title = {{Information from Paleoclimate Archives}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Mateos2013,
abstract = {As clouds and aerosols are the main sources of uncertainty in the determination of the energy balance of the Earth, there is a growing interest in the evaluation of their radiative effects. Hence, in this work, long-term data of shortwave radiation from 13 locations over Spain (South-Western Europe) are used to investigate, for the first time, the radiative effects of clouds and aerosols in the period 1985-2010. In particular, monthly radiation data from ground-based observations and radiative transfer simulations fed with reanalysis data of ozone, water vapour and surface albedo, are used to evaluate the cloud and aerosol radiative effect (CARE). Annual values of the CARE become less negative from Northern to Southern stations. For instance, the annual CARE values for Bilbao (North), Valladolid (Centre), and Murcia (South) are -82, -46, and -42 WM-2, respectively. CARE averages exhibit a clear seasonal pattern with the strongest contribution during spring and summer months. Particularly in these seasons, there is a very high correlation between CARE values and sunshine duration, number of cloud-free days, and temperature. Additionally, a significant decrease of the radiative effects of the clouds and aerosols is observed over Spain in the last 26 years. Overall, the linear trend of the mean annual CARE series over Spain is statistically significant with positive sign, 3.1 Wm(-2) per decade. The significant trend values at individual stations range between 2.9 and 5.2 Wm(-2) per decade. Seasonal trends in summer and spring are larger than in autumn and winter. Finally, the radiative effects of water vapour and ozone were also evaluated showing an annual mean over Spain of about - 10 Wm(-2) and -1 Wm(-2), respectively. However, no significant trends were observed for these two variables between 1985 and 2010. (C) 2013 Elsevier B.V. All rights reserved.},
address = {Mateos, D Univ Extremadura, Dept Phys, Avda Elvas S-N, Badajoz 06006, Spain Univ Extremadura, Dept Phys, Avda Elvas S-N, Badajoz 06006, Spain Univ Extremadura, Dept Phys, Badajoz 06006, Spain Univ Girona, Dept Phys, Grp Environm Phys, Girona, Spain ETH, I},
annote = {285FB
Times Cited:6
Cited References Count:46},
author = {Mateos, D and Anton, M and Sanchez-Lorenzo, A and Calbo, J and Wild, M},
doi = {10.1016/J.Gloplacha.2013.10.004},
issn = {0921-8181},
journal = {Global and Planetary Change},
keywords = {cloud and aerosol radiative effect shortwave radia},
language = {English},
pages = {288--295},
title = {{Long-term changes in the radiative effects of aerosols and clouds in a mid-latitude region (1985–2010)}},
volume = {111},
year = {2013}
}
@article{Matus2017,
abstract = {Abstract The radiative impact of clouds strongly depends on their partitioning between liquid and ice phases. Until recently, however, it has been challenging to unambiguously discriminate cloud phase in a number of important global regimes. CloudSat and CALIPSO supply vertically resolved measurements necessary to identify clouds composed of both liquid and ice that are not easily detected using conventional passive sensors. The capability of these active sensors to discriminate cloud phase has been incorporated into the fifth generation of CloudSat's 2B-FLXHR-LIDAR algorithm. Comparisons with Clouds and the Earth's Radiant Energy System fluxes at the top of atmosphere reveal that an improved representation of cloud phase leads to better agreement compared to earlier versions of the algorithm. The RMS differences in annual mean outgoing longwave (LW) radiation gridded at 2.5° resolution are 4.9 W m?2, while RMS differences in outgoing shortwave (SW) are slightly larger at 8.9 W m?2 due to the larger diurnal range of solar insolation. This study documents the relative contributions of clouds composed of only liquid, only ice, and a combination of both phases to global and regional radiation budgets. It is found that mixed-phase clouds exert a global net cloud radiative effect of ?3.4 W m?2, with contributions of ?8.1 W m?2 and 4.7 W m?2 from SW and LW radiation, respectively. When compared with the effects of warm liquid clouds (?11.8 W m?2), ice clouds (3.5 W m?2), and multilayered clouds consisting of distinct liquid and ice layers (?4.6 W m?2), these results reinforce the notion that accurate representation of mixed-phase clouds is essential for quantifying cloud feedbacks in future climate scenarios.},
annote = {doi: 10.1002/2016JD025951},
author = {Matus, Alexander V and L'Ecuyer, Tristan S},
doi = {10.1002/2016JD025951},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {CloudSat,cloud phase,cloud radiative effects,global energy budget,mixed-phase clouds,satellite remote sensing},
month = {mar},
number = {5},
pages = {2559--2578},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{The role of cloud phase in Earth's radiation budget}},
url = {https://doi.org/10.1002/2016JD025951},
volume = {122},
year = {2017}
}
@article{Mauritsen2017,
abstract = {Even if fossil-fuel emissions were to cease immediately, continued anthropogenic warming is expected. Here, observation-based estimates indicate there is a 13{\%} risk that committed warming already exceeds the 1.5 K Paris target.},
author = {Mauritsen, Thorsten and Pincus, Robert},
doi = {10.1038/nclimate3357},
issn = {17586798},
journal = {Nature Climate Change},
number = {9},
pages = {652--655},
title = {{Committed warming inferred from observations}},
volume = {7},
year = {2017}
}
@article{Mauritsen2015,
abstract = {Equilibrium climate sensitivity to a doubling of CO2 falls between 2.0 and 4.6 K in current climate models, and they suggest a weak increase in global mean precipitation. Inferences from the observational record, however, place climate sensitivity near the lower end of this range and indicate that models underestimate some of the changes in the hydrological cycle. These discrepancies raise the possibility that important feedbacks are missing from the models. A controversial hypothesis suggests that the dry and clear regions of the tropical atmosphere expand in a warming climate and thereby allow more infrared radiation to escape to space. This so-called iris effect could constitute a negative feedback that is not included in climate models. We find that inclusion of such an effect in a climate model moves the simulated responses of both temperature and the hydrological cycle to rising atmospheric greenhouse gas concentrations closer to observations. Alternative suggestions for shortcomings of models [mdash] such as aerosol cooling, volcanic eruptions or insufficient ocean heat uptake [mdash] may explain a slow observed transient warming relative to models, but not the observed enhancement of the hydrological cycle. We propose that, if precipitating convective clouds are more likely to cluster into larger clouds as temperatures rise, this process could constitute a plausible physical mechanism for an iris effect.},
author = {Mauritsen, Thorsten and Stevens, Bjorn},
doi = {10.1038/ngeo2414},
isbn = {1752-0894},
issn = {17520908},
journal = {Nature Geoscience},
number = {5},
pages = {346--351},
title = {{Missing iris effect as a possible cause of muted hydrological change and high climate sensitivity in models}},
volume = {8},
year = {2015}
}
@article{Mauritsen2012,
abstract = {During a development stage global climate models have their properties adjusted or tuned in various ways to best match the known state of the Earth's climate system. These desired properties are observables, such as the radiation balance at the top of the atmosphere, the global mean temperature, sea ice, clouds and wind fields. The tuning is typically performed by adjusting uncertain, or even non-observable, parameters related to processes not explicitly represented at the model grid resolution. The practice of climate model tuning has seen an increasing level of attention because key model properties, such as climate sensitivity, have been shown to depend on frequently used tuning parameters. Here we provide insights into how climate model tuning is practically done in the case of closing the radiation balance and adjusting the global mean temperature for the Max Planck Institute Earth System Model (MPI-ESM). We demonstrate that considerable ambiguity exists in the choice of parameters, and present and compare three alternatively tuned, yet plausible configurations of the climate model. The impacts of parameter tuning on climate sensitivity was less than anticipated.},
author = {Mauritsen, Thorste and Stevens, Bjorn and Roeckner, Erich and Crueger, Traute and Esch, Monika and Giorgetta, Marco and Haak, Helmuth and Jungclaus, Johann and Klocke, Daniel and Matei, Daniela and Mikolajewicz, Uwe and Notz, Dirk and Pincus, Robert and Schmidt, Hauke and Tomassini, Lorenzo},
doi = {10.1029/2012MS000154},
isbn = {1942-2466},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
number = {8},
pages = {1--18},
title = {{Tuning the climate of a global model}},
volume = {4},
year = {2012}
}
@article{Mauritsen2013,
abstract = {Earth's climate sensitivity to radiative forcing induced by a doubling of the atmospheric CO2 is deter- mined by feedback mechanisms, including changes in atmospheric water vapor, clouds and surface albedo, that act to either amplify or dampen the response. The climate system is frequently interpreted in terms of a simple energy balance model, in which it is assumed that individual feedback mechanisms are additive and act independently. Here we test these assumptions by systematically control- ling, or locking, the radiative feedbacks in a state-of-the-art climate model. The method is shown to yield a near-perfect decomposition of change into partial temperature contri- butions pertaining to forcing and each of the feedbacks. In the studied model water vapor feedback stands for about half the temperature change, CO2-forcing about one third, while cloud and surface albedo feedback contributions are relatively small. We find a close correspondence between forcing, feedback and partial surface temperature response for the water vapor and surface albedo feedbacks, while the cloud feedback is inefficient in inducing surface tempera- ture change. Analysis suggests that cloud-induced warming in the upper tropical troposphere, consistent with rising convective cloud anvils in a warming climate enhances the negative lapse-rate feedback, thereby offsetting some of the warming that would otherwise be attributable to this positive cloud feedback. By subsequently combining feedback mechanisms we find a positive synergy acting between the water vapor feedback and the cloud feedback; that is, the combined cloud and water vapor feedback is greater than the sum of its parts. Negative synergies sur- round the surface albedo feedback, as associated cloud and water vapor changes dampen the anticipated climate change induced by retreating snow and ice. Our results highlight the importance of treating the coupling between clouds, water vapor and temperature in a deepening troposphere.},
author = {Mauritsen, Thorsten and Graversen, Rune G. and Klocke, Daniel and Langen, Peter L. and Stevens, Bjorn and Tomassini, Lorenzo},
doi = {10.1007/s00382-013-1808-7},
issn = {09307575},
journal = {Climate Dynamics},
keywords = {Climate feedback mechanisms,Climate sensitivity,Synergy},
number = {9-10},
pages = {2539--2554},
title = {{Climate feedback efficiency and synergy}},
volume = {41},
year = {2013}
}
@article{Mauritsen2016,
abstract = {The slow instrumental-record warming is consistent with lower-end climate sensitivity. Simulations and observations now show that changing sea surface temperature patterns could have affected cloudiness and thereby dampened the warming.},
author = {Mauritsen, Thorsten},
doi = {10.1038/ngeo2838},
isbn = {1752-0894},
issn = {17520908},
journal = {Nature Geoscience},
number = {12},
pages = {865--867},
publisher = {Nature Publishing Group},
title = {{Global warming: Clouds cooled the Earth}},
url = {http://dx.doi.org/10.1038/ngeo2838},
volume = {9},
year = {2016}
}
@article{Mauritsen2019,
abstract = {Abstract A new release of the Max Planck Institute for Meteorology Earth System Model (MPI-ESM 1.2) is presented. The development focused on correcting errors in and improving the physical processes representation, as well as improving the computational performance, versatility and overall user friendliness. In addition to new radiation- and aerosol parameterizations of the atmosphere, several relatively large, but partly compensating, coding errors in the model's cloud, convection and turbulence parameterizations were corrected. The representation of land processes was refined by introducing a multi-layer soil hydrology scheme, extending the land biogeochemistry to include the nitrogen cycle, replacing the soil and litter decomposition model, and improving the representation of wildfires. The ocean biogeochemistry now represents cyano-bacteria prognostically in order to capture the response of nitrogen fixation to changing climate conditions, and further includes improved detritus settling and numerous other refinements. As something new, in addition to limiting drift and minimizing certain biases, the instrumental record warming was explicitly taken into account during the tuning process. To this end a very high climate sensitivity of around 7 K caused by low-level clouds in the tropics as found in an intermediate model version was addressed, as it was not deemed possible to match observed warming otherwise. As a result, the model has a climate sensitivity to a doubling of CO2 over pre-industrial conditions of 2.77 K, maintaining the previously identified highly non-linear global mean response to increasing CO2 forcing, which nonetheless can be represented by a simple two-layer model.},
author = {Mauritsen, Thorsten and Bader, J{\"{u}}rgen and Becker, Tobias and Behrens, J{\"{o}}rg and Bittner, Matthias and Brokopf, Renate and Brovkin, Victor and Claussen, Martin and Crueger, Traute and Esch, Monika and Fast, Irina and Fiedler, Stephanie and Fl{\"{a}}schner, Dagmar and Gayler, Veronika and Giorgetta, Marco and Goll, Daniel S and Haak, Helmuth and Hagemann, Stefan and Hedemann, Christopher and Hohenegger, Cathy and Ilyina, Tatiana and Jahns, Thomas and Jimen{\'{e}}z‐de‐la‐Cuesta, Diego and Jungclaus, Johann and Kleinen, Thomas and Kloster, Silvia and Kracher, Daniela and Kinne, Stefan and Kleberg, Deike and Lasslop, Gitta and Kornblueh, Luis and Marotzke, Jochem and Matei, Daniela and Meraner, Katharina and Mikolajewicz, Uwe and Modali, Kameswarrao and M{\"{o}}bis, Benjamin and M{\"{u}}ller, Wolfgang A and Nabel, Julia E M S and Nam, Christine C W and Notz, Dirk and Nyawira, Sarah-Sylvia and Paulsen, Hanna and Peters, Karsten and Pincus, Robert and Pohlmann, Holger and Pongratz, Julia and Popp, Max and Raddatz, Thomas J{\"{u}}rgen and Rast, Sebastian and Redler, Rene and Reick, Christian H and Rohrschneider, Tim and Schemann, Vera and Schmidt, Hauke and Schnur, Reiner and Schulzweida, Uwe and Six, Katharina D and Stein, Lukas and Stemmler, Irene and Stevens, Bjorn and Storch, Jin‐Song and Tian, Fangxing and Voigt, Aiko and Vrese, Philipp and Wieners, Karl-Hermann and Wilkenskjeld, Stiig and Winkler, Alexander and Roeckner, Erich},
doi = {10.1029/2018MS001400},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {Climate sensitivity,Coupled climate model,Model development},
month = {apr},
number = {4},
pages = {998--1038},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Developments in the MPI‐M Earth System Model version 1.2 (MPI‐ESM1.2) and Its Response to Increasing CO2}},
url = {https://doi.org/10.1029/2018MS001400 https://onlinelibrary.wiley.com/doi/10.1029/2018MS001400},
volume = {11},
year = {2019}
}
@article{Mauritsen2020,
abstract = {A climate model's ability to reproduce observed historical warming is sometimes viewed as a measure of quality. Yet, for practical reasons it cannot be considered a purely empirical result of the modeling efforts because the desired result is known in advance and so is a potential target of tuning. Here we report how the latest edition of the Max Planck Institute for Meteorology Earth System Models (MPI-ESM1.2) atmospheric component (ECHAM6.3) had its sensitivity systematically tuned in order to improve the modeled match with the instrumental record. In practice, this was done by targeting an equilibrium climate sensitivity of about 3 K, slightly lower than in the previous model generation (MPI-ESM), which warmed more than observed, and in particular by addressing a climate sensitivity of about 7 K in an intermediate version of the model. In the process we identified several controls on cloud feedback, some of which confirm recently proposed hypotheses. We find the model exhibits excellent fidelity with the observed centennial global warming. We further find that an alternative approach with high climate sensitivity compensated by strong aerosol cooling instead would yield colder than observed results in the second half of the twentieth century.},
author = {Mauritsen, Thorsten and Roeckner, Erich},
doi = {10.1029/2019MS002037},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {Climate,Modeling,Tuning},
number = {5},
pages = {e2019MS002037},
title = {{Tuning the MPI-ESM1.2 Global Climate Model to Improve the Match With Instrumental Record Warming by Lowering Its Climate Sensitivity}},
volume = {12},
year = {2020}
}
@article{ISI:000423299000002,
abstract = {Satellite-based remote sensing has generally necessitated a trade-off between spatial resolution and temporal frequency, affecting the capacity to observe fast hydrological processes and rapidly changing land surface conditions. An avenue for overcoming these spatiotemporal restrictions is the concept of using constellations of satellites, as opposed to the mission focus exemplified by the more conventional space-agency approach to earth observation. Referred to as CubeSats, these platforms offer the potential to provide new insights into a range of earth system variables and processes. Their emergence heralds a paradigm shift from single-sensor launches to an operational approach that envisions tens to hundreds of small, lightweight, and comparatively inexpensive satellites placed into a range of low earth orbits. Although current systems are largely limited to sensing in the optical portion of the electromagnetic spectrum, we demonstrate the opportunity and potential that CubeSats present the hydrological community via the retrieval of vegetation dynamics and terrestrial evaporation and foreshadow future sensing capabilities.},
address = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
author = {McCabe, M F and Aragon, B and Houborg, R and Mascaro, J},
doi = {10.1002/2017WR022240},
issn = {0043-1397},
journal = {Water Resources Research},
month = {dec},
number = {12},
pages = {10017--10024},
publisher = {AMER GEOPHYSICAL UNION},
title = {{CubeSats in Hydrology: Ultrahigh-Resolution Insights Into Vegetation Dynamics and Terrestrial Evaporation}},
type = {Editorial Material},
volume = {53},
year = {2017}
}
@article{ISI:000406660700002,
abstract = {In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically of the order of 1 billion dollars per satellite and with concept-to-launch timelines of the order of 2 decades (for new missions). More recently, the proliferation of smart-phones has helped to miniaturize sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3-5 m) resolution sensing of the Earth on a daily basis. Start-up companies that did not exist a decade ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of traditional satellite missions. With these advances come new space-borne measurements, such as real-time high-definition video for tracking air pollution, storm-cell development, flood propagation, precipitation monitoring, or even for constructing digital surfaces using structure-from-motion techniques. Closer to the surface, measurements from small unmanned drones and tethered balloons have mapped snow depths, floods, and estimated evaporation at sub-metre resolutions, pushing back on spatio-temporal constraints and delivering new process insights. At ground level, precipitation has been measured using signal attenuation between antennae mounted on cell phone towers, while the proliferation of mobile devices has enabled citizen scientists to catalogue photos of environmental conditions, estimate daily average temperatures from battery state, and sense other hydrologically important variables such as channel depths using commercially available wireless devices. Global internet access is being pursued via high-altitude balloons, solar planes, and hundreds of planned satellite launches, providing a means to exploit the ``internet of things{\{}''{\}} as an entirely new measurement domain. Such global access will enable real-time collection of data from billions of smartphones or from remote research platforms. This future will produce petabytes of data that can only be accessed via cloud storage and will require new analytical approaches to interpret. The extent to which today's hydrologic models can usefully ingest such massive data volumes is unclear. Nor is it clear whether this deluge of data will be usefully exploited, either because the measurements are superfluous, inconsistent, not accurate enough, or simply because we lack the capacity to process and analyse them. What is apparent is that the tools and techniques afforded by this array of novel and game-changing sensing platforms present our community with a unique opportunity to develop new insights that advance fundamental aspects of the hydrological sciences. To accomplish this will require more than just an application of the technology: in some cases, it will demand a radical rethink on how we utilize and exploit these new observing systems.},
address = {BAHNHOFSALLEE 1E, GOTTINGEN, 37081, GERMANY},
author = {McCabe, Matthew F and Rodell, Matthew and Alsdorf, Douglas E and Miralles, Diego G and Uijlenhoet, Remko and Wagner, Wolfgang and Lucieer, Arko and Houborg, Rasmus and Verhoest, Niko E C and Franz, Trenton E and Shi, Jiancheng and Gao, Huilin and Wood, Eric F},
doi = {10.5194/hess-21-3879-2017},
issn = {1027-5606},
journal = {Hydrology and Earth System Sciences},
month = {jul},
number = {7},
pages = {3879--3914},
publisher = {COPERNICUS GESELLSCHAFT MBH},
title = {{The future of Earth observation in hydrology}},
type = {Article},
volume = {21},
year = {2017}
}
@article{cp-16-1599-2020,
abstract = {A range of future climate scenarios are projected for high atmospheric CO2 concentrations, given uncertainties over future human actions as well as potential environmental and climatic feedbacks. The geological record offers an opportunity 30 to understand climate system response to a range of forcings and feedbacks which operate over multiple temporal and spatial scales. Here, we examine a single interglacial during the late Pliocene (KM5c, ca. 3.205 +/- 0.01 Ma) when atmospheric CO2 concentrations were higher than pre-industrial, but similar to today and to the lowest emission scenarios for this century. As orbital forcing and continental configurations were almost identical to today, we are able to focus on equilibrium climate system response to modern and near-future CO2. Using proxy data from 32 sites, we demonstrate that global mean sea-surface 35 temperatures were warmer than pre-industrial, by {\~{}}2.3 {\textordmasculine}C for the combined proxy data (foraminifera Mg/Ca and alkenones), or by {\~{}}3.2{\textordmasculine}C (alkenones only). Compared to the pre-industrial, reduced meridional gradients and enhanced warming in the North Atlantic are consistently reconstructed. There is broad agreement between data and models at the global scale, with regional differences reflecting ocean circulation and/or proxy signals. An uneven distribution of proxy data in time and space 2 does, however, add uncertainty to our anomaly calculations. The reconstructed global mean sea-surface temperature anomaly 40 for KM5c is warmer than all but three of the PlioMIP2 model outputs, and the reconstructed North Atlantic data tend to align with the warmest KM5c model values. Our results demonstrate that even under low CO2 emission scenarios, surface ocean warming may be expected to exceed model projections, and will be accentuated in the higher latitudes.},
author = {McClymont, Erin L and Ford, Heather L and Ho, Sze Ling and Tindall, Julia C and Haywood, Alan M and Alonso-Garcia, M and Bailey, Ian and Berke, Melissa A and Littler, Kate and Patterson, Molly O and Petrick, Benjamin and Peterse, Francien and Ravelo, A Christina and Risebrobakken, B and {De Schepper}, S and Swann, G E A and Thirumalai, Kaustubh and Tierney, Jessica E and van der Weijst, C and White, Sarah and Abe-Ouchi, A and Baatsen, M L J and Brady, E C and Chan, W.-L. and Chandan, D and Feng, R and Guo, C and von der Heydt, A S and Hunter, S and Li, X and Lohmann, G and Nisancioglu, K H and Otto-Bliesner, B L and Peltier, W R and Stepanek, C and Zhang, Z and Schepper, Stijn De and George, E A and Thirumalai, Kaustubh and Tierney, Jessica E and {Der Van Weijst}, Carolien and White, Sarah},
doi = {10.5194/cp-16-1599-2020},
journal = {Climate of the Past},
number = {4},
pages = {1599--1615},
title = {{Lessons from a high-CO2 world: an ocean view from {\~{}}3 million years ago}},
url = {https://cp.copernicus.org/articles/16/1599/2020/},
volume = {16},
year = {2020}
}
@article{McComiskey2012,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} A wide range of estimates exists for the radiative forcing of the aerosol effect on cloud albedo. We argue that a component of this uncertainty derives from the use of a wide range of observational scales and platforms. Aerosol influences cloud properties at the microphysical scale, or the "process scale", but observations are most often made of bulk properties over a wide range of resolutions, or "analysis scales". We show that differences between process and analysis scales incur biases in quantification of the albedo effect through the impact that data aggregation and computational approach have on statistical properties of the aerosol or cloud variable, and their covariance. Measures made within this range of scales are erroneously treated as equivalent, leading to a large uncertainty in associated radiative forcing estimates. Issues associated with the coarsening of observational resolution particular to quantifying the albedo effect are discussed. Specifically, the omission of the constraint on cloud liquid water path and the separation in space of cloud and aerosol properties from passive, space-based remote sensors dampen the measured strength of the albedo effect. We argue that, because of this lack of constraints, many of these values are in fact more representative of the full range of aerosol-cloud interactions and their associated feedbacks. Based on our understanding of these biases we propose a new observationally-based and process-model-constrained, method for estimating aerosol-cloud interactions that can be used for radiative forcing estimates as well as a better characterization of the uncertainties associated with those estimates.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {McComiskey, A. and Feingold, G.},
doi = {10.5194/acp-12-1031-2012},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
number = {2},
pages = {1031--1049},
title = {{The scale problem in quantifying aerosol indirect effects}},
url = {https://www.atmos-chem-phys.net/12/1031/2012/},
volume = {12},
year = {2012}
}
@article{McCoy2017,
abstract = {AbstractDecreases in subtropical low cloud cover (LCC) occur in climate model simulations of global warming. In this study 8-day-averaged observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) spanning 2002?14 are combined with European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis to compute the dependence of the observed variability of LCC on various predictor variables. Large-scale thermodynamic and dynamic predictors of LCC are selected based on insight from large-eddy simulations (LESs) and observational analysis. It is found that increased estimated inversion strength (EIS) is associated with increased LCC. Drying of the free troposphere is associated with decreased LCC. Decreased LCC accompanies subsidence in regions of relatively low EIS; the opposite is found in regions of high EIS. Finally, it is found that increasing sea surface temperature (SST) leads to a decrease in LCC. These results are in keeping with previous studies of monthly and annual data. Based upon the observed response of LCC to natural variability of the control parameters, the change in LCC is estimated for an idealized warming scenario where SST increases by 1 K and EIS increases by 0.2 K. For this change in EIS and SST the LCC is inferred to decrease by 0.5{\%}?2.7{\%} when the regression models are trained on data observed between 40°S and 40°N and by 1.1{\%}?1.4{\%} when trained on data from trade cumulus?dominated regions. When the data used to train the regression model are restricted to stratocumulus-dominated regions the change in LCC is highly uncertain and varies between ?1.6{\%} and +1.4{\%}, depending on the stratocumulus-dominated region used to train the regression model.},
annote = {doi: 10.1175/JCLI-D-15-0734.1},
author = {McCoy, Daniel T and Eastman, Ryan and Hartmann, Dennis L and Wood, Robert},
doi = {10.1175/JCLI-D-15-0734.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {feb},
number = {10},
pages = {3609--3620},
publisher = {American Meteorological Society},
title = {{The Change in Low Cloud Cover in a Warmed Climate Inferred from AIRS, MODIS, and ERA-Interim}},
url = {https://doi.org/10.1175/JCLI-D-15-0734.1},
volume = {30},
year = {2017}
}
@article{McCoy2014c,
abstract = {AbstractThe sensitivity of the reflection of shortwave radiation over the Southern Ocean to the cloud properties there is estimated using observations from a suite of passive and active satellite instruments in combination with radiative transfer modeling. A composite cloud property observational data description is constructed that consistently incorporates mean cloud liquid water content, ice water content, liquid and ice particle radius information, vertical structure, vertical overlap, and spatial aggregation of cloud water as measured by optical depth versus cloud-top pressure histograms. The observational datasets used are Moderate Resolution Imaging Spectroradiometer (MODIS) effective radius filtered to mitigate solar zenith angle bias, the Multiangle Imaging Spectroradiometer (MISR) cloud-top height?optical depth (CTH?OD) histogram, the liquid water path from the University of Wisconsin dataset, and ice cloud properties from CloudSat. This cloud database is used to compute reflected shortwave radiation as a function of month and location over the ocean from 40° to 60°S, which compares well with observations of reflected shortwave radiation. This calculation is then used to test the sensitivity of the seasonal variation of shortwave reflection to the observed seasonal variation of cloud properties. Effective radius decreases during the summer season, which results in an increase in reflected solar radiation of 4?8 W m?2 during summer compared to what would be reflected if the effective radius remained constant at its annual-mean value. Summertime increases in low cloud fraction similarly increase the summertime reflection of solar radiation by 9?11 W m?2. In-cloud liquid water path is less in summertime, causing the reflected solar radiation to be 1?4 W m?2 less.},
author = {McCoy, Daniel T and Hartmann, Dennis L and Grosvenor, Daniel P},
doi = {10.1175/JCLI-D-14-00287.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {23},
pages = {8836--8857},
publisher = {American Meteorological Society},
title = {{Observed Southern Ocean Cloud Properties and Shortwave Reflection. Part I: Calculation of SW Flux from Observed Cloud Properties}},
url = {https://doi.org/10.1175/JCLI-D-14-00287.1},
volume = {27},
year = {2014}
}
@article{McCoy2014b,
abstract = {AbstractClimate models produce an increase in cloud optical depth in midlatitudes associated with climate warming, but the magnitude of this increase and its impact on reflected solar radiation vary from model to model. Transition from ice to liquid in midlatitude clouds is thought to be one mechanism for producing increased cloud optical depth. Here observations of cloud properties are used from a suite of remote sensing instruments to estimate the effect of conversion of ice to liquid associated with warming on reflected solar radiation in the latitude band from 40° to 60°S. The calculated increase in upwelling shortwave radiation (SW?) is found to be important and of comparable magnitude to the increase in SW? associated with warming-induced increases of optical depth in climate models. The region where the authors' estimate increases SW? extends farther equatorward than the region where optical depth increases with warming in models. This difference is likely caused by other mechanisms at work in the models but is also sensitive to the amount of ice present in climate models and its susceptibility to warming.},
author = {McCoy, Daniel T and Hartmann, Dennis L and Grosvenor, Daniel P},
doi = {10.1175/JCLI-D-14-00288.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {23},
pages = {8858--8868},
publisher = {American Meteorological Society},
title = {{Observed Southern Ocean Cloud Properties and Shortwave Reflection. Part II: Phase Changes and Low Cloud Feedback}},
url = {https://doi.org/10.1175/JCLI-D-14-00288.1},
volume = {27},
year = {2014}
}
@article{McCoy2018,
abstract = {{\textless}p{\textgreater}{\textless}![CDATA[{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Aerosol–cloud interactions are a major source of uncertainty in inferring the climate sensitivity from the observational record of temperature. The adjustment of clouds to aerosol is a poorly constrained aspect of these aerosol–cloud interactions. Here, we examine the response of midlatitude cyclone cloud properties to a change in cloud droplet number concentration (CDNC). Idealized experiments in high-resolution, convection-permitting global aquaplanet simulations with constant CDNC are compared to 13 years of remote-sensing observations. Observations and idealized aquaplanet simulations agree that increased warm conveyor belt (WCB) moisture flux into cyclones is consistent with higher cyclone liquid water path (CLWP). When CDNC is increased a larger LWP is needed to give the same rain rate. The LWP adjusts to allow the rain rate to be equal to the moisture flux into the cyclone along the WCB. This results in an increased CLWP for higher CDNC at a fixed WCB moisture flux in both observations and simulations. If observed cyclones in the top and bottom tercile of CDNC are contrasted it is found that they have not only higher CLWP but also cloud cover and albedo. The difference in cyclone albedo between the cyclones in the top and bottom third of CDNC is observed by CERES to be between 0.018 and 0.032, which is consistent with a 4.6–8.3{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}Wm{\textless}span class="inline-formula"{\textgreater}{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}{\textless}/span{\textgreater} in-cyclone enhancement in upwelling shortwave when scaled by annual-mean insolation. Based on a regression model to observed cyclone properties, roughly 60{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} of the observed variability in CLWP can be explained by CDNC and WCB moisture flux.{\textless}/p{\textgreater}]]{\textgreater}{\textless}/p{\textgreater}},
author = {McCoy, Daniel T. and Field, Paul R. and Schmidt, Anja and Grosvenor, Daniel P. and Bender, Frida A.-M. and Shipway, Ben J. and Hill, Adrian A. and Wilkinson, Jonathan M. and Elsaesser, Gregory S.},
doi = {10.5194/acp-18-5821-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {apr},
number = {8},
pages = {5821--5846},
title = {{Aerosol midlatitude cyclone indirect effects in observations and high-resolution simulations}},
url = {https://www.atmos-chem-phys.net/18/5821/2018/},
volume = {18},
year = {2018}
}
@article{McCoy2019,
author = {McCoy, Daniel T. and Field, Paul R. and Elsaesser, Gregory S. and Bodas-Salcedo, Alejandro and Kahn, Brian H. and Zelinka, Mark D. and Kodama, Chihiro and Mauritsen, Thorsten and Vanniere, Benoit and Roberts, Malcolm and Vidale, Pier L. and Saint-Martin, David and Voldoire, Aurore and Haarsma, Rein and Hill, Adrian and Shipway, Ben and Wilkinson, Jonathan},
doi = {10.5194/acp-19-1147-2019},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
number = {2},
pages = {1147--1172},
title = {{Cloud feedbacks in extratropical cyclones: insight from long-term satellite data and high-resolution global simulations}},
url = {https://acp.copernicus.org/articles/19/1147/2019/},
volume = {19},
year = {2019}
}
@article{McCoy2016a,
author = {McCoy, Daniel T and Tan, Ivy and Hartmann, Dennis L and Zelinka, Mark D and Storelvmo, Trude},
doi = {10.1002/2015MS000589},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
month = {jun},
number = {2},
pages = {650--668},
title = {{On the relationships among cloud cover, mixed‐phase partitioning, and planetary albedo in GCMs}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2015MS000589},
volume = {8},
year = {2016}
}
@article{McCoy2017a,
author = {McCoy, D. T. and Bender, F. A.-M. and Mohrmann, J. K. C. and Hartmann, D. L. and Wood, R. and Grosvenor, D. P.},
doi = {10.1002/2016JD026141},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aerosol,climate,cloud,microphysics},
month = {feb},
number = {3},
pages = {1779--1796},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{The global aerosol-cloud first indirect effect estimated using MODIS, MERRA, and AeroCom}},
url = {http://doi.wiley.com/10.1002/2016JD026141},
volume = {122},
year = {2017}
}
@article{McCoy2020,
abstract = {The change in planetary albedo due to aerosol-cloud interactions during the industrial era is the leading source of uncertainty in inferring Earth s climate sensitivity to increased greenhouse gases from the historical record. The variable that controls aerosol-cloud interactions in warm clouds is droplet number concentration. Global climate models demonstrate that the present-day hemispheric contrast in cloud droplet number concentration between the pristine Southern Hemisphere and the polluted Northern Hemisphere oceans can be used as a proxy for anthropogenically driven change in cloud droplet number concentration. Remotely sensed estimates constrain this change in droplet number concentration to be between 8 cm-3 and 24 cm-3. By extension, the radiative forcing since 1850 from aerosol-cloud interactions is constrained to be -1.2 W m-2 to -0.6 W m-2. The robustness of this constraint depends upon the assumption that pristine Southern Ocean droplet number concentration is a suitable proxy for preindustrial concentrations. Droplet number concentrations calculated from satellite data over the Southern Ocean are high in austral summer. Near Antarctica, they reach values typical of Northern Hemisphere polluted outflows. These concentrations are found to agree with several in situ datasets. In contrast, climate models show systematic underpredictions of cloud droplet number concentration across the Southern Ocean. Near Antarctica, where precipitation sinks of aerosol are small, the underestimation by climate models is particularly large. This motivates the need for detailed process studies of aerosol production and aerosol-cloud interactions in pristine environments. The hemispheric difference in satellite estimated cloud droplet number concentration implies preindustrial aerosol concentrations were higher than estimated by most models.},
author = {McCoy, Isabel L. and McCoy, Daniel T. and Wood, Robert and Regayre, Leighton and Watson-Parris, Duncan and Grosvenor, Daniel P. and Mulcahy, Jane P. and Hu, Yongxiang and Bender, Frida A.M. and Field, Paul R. and Carslaw, Kenneth S. and Gordon, Hamish},
doi = {10.1073/pnas.1922502117},
issn = {10916490},
journal = {Proceedings of the National Academy of Sciences},
number = {32},
pages = {18998--19006},
pmid = {32719114},
title = {{The hemispheric contrast in cloud microphysical properties constrains aerosol forcing}},
volume = {117},
year = {2020}
}
@article{McGraw2020a,
abstract = {Black carbon (BC) aerosols from incomplete combustion generally warm the climate, but the magnitudes of their various interactions with climate are still uncertain. A key knowledge gap is their role as ice nucleating particles (INPs), enabling ice formation in clouds. Here we assess the global radiative impacts of BC acting as INPs, using simulations with the Community Earth System Model 2 climate model updated to include new laboratory-based ice nucleation parameterizations. Overall, we find a moderate cooling through changes to stratiform cirrus clouds, counteracting the well-known net warming from BC's direct scattering and absorption of radiation. Our best estimates indicate that BC INPs generally thin cirrus by indirectly inhibiting the freezing of solution aerosol, with a global net radiative impact of −0.13 ± 0.07 W/m2. Sensitivity tests of BC amounts and ice nucleating efficiencies, and uncertainties in the environment where ice crystals form, show a potential range of impacts from −0.30 to +0.02 W/m2.},
author = {McGraw, Zachary and Storelvmo, Trude and Samset, Bj{\o}rn Hallvard and Stjern, Camilla Weum},
doi = {10.1029/2020GL089056},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {aerosol indirect effects,black carbon,cirrus,climate,climate modeling},
number = {20},
pages = {1--9},
title = {{Global Radiative Impacts of Black Carbon Acting as Ice Nucleating Particles}},
volume = {47},
year = {2020}
}
@article{McGregor2018,
abstract = {Pacific trade winds have displayed unprecedented strengthening in recent decades1. This strengthening has been associated with east Pacific sea surface cooling2and the early twenty-first-century slowdown in global surface warming2,3, amongst a host of other substantial impacts4–9. Although some climate models produce the timing of these recently observed trends10, they all fail to produce the trend magnitude2,11,12. This may in part be related to the apparent model underrepresentation of low-frequency Pacific Ocean variability and decadal wind trends2,11–13 or be due to a misrepresentation of a forced response1,14–16 or a combination of both. An increasingly prominent connection between the Pacific and Atlantic basins has been identified as a key driver of this strengthening of the Pacific trade winds12,17–20. Here we use targeted climate model experiments to show that combining the recent Atlantic warming trend with the typical climate model bias leads to a substantially underestimated response for the Pacific Ocean wind and surface temperature. The underestimation largely stems from a reduction and eastward shift of the atmospheric heating response to the tropical Atlantic warming trend. This result suggests that the recent Pacific trends and model decadal variability may be better captured by models with improved mean-state climatologies.},
author = {McGregor, Shayne and Stuecker, Malte F. and Kajtar, Jules B. and England, Matthew H. and Collins, Mat},
doi = {10.1038/s41558-018-0163-4},
isbn = {1758-678X 1758-6798},
issn = {17586798},
journal = {Nature Climate Change},
month = {jun},
number = {6},
pages = {493--498},
publisher = {Nature Publishing Group},
title = {{Model tropical Atlantic biases underpin diminished Pacific decadal variability}},
volume = {8},
year = {2018}
}
@article{McGregor2014,
abstract = {An unprecedented strengthening of Pacific trade winds since the late 1990s (ref. 1) has caused widespread climate perturbations, including rapid sea-level rise in the western tropical Pacific, strengthening of Indo-Pacific ocean currents, and an increased uptake of heat in the equatorial Pacific thermocline. The corresponding intensification of the atmospheric Walker circulation is also associated with sea surface cooling in the eastern Pacific, which has been identified as one of the contributors to the current pause in global surface warming. In spite of recent progress in determining the climatic impacts of the Pacific trade wind acceleration, the cause of this pronounced trend in atmospheric circulation remains unknown. Here we analyse a series of climate model experiments along with observational data to show that the recent warming trend in Atlantic sea surface temperature and the corresponding trans-basin displacements of the main atmospheric pressure centres were key drivers of the observed Walker circulation intensification, eastern Pacific cooling, North American rainfall trends and western Pacific sea-level rise. Our study suggests that global surface warming has been partly offset by the Pacific climate response to enhanced Atlantic warming since the early 1990s.},
author = {McGregor, Shayne and Timmermann, Axel and Stuecker, Malte F. and England, Matthew H. and Merrifield, Mark and Jin, Fei-Fei Fei and Chikamoto, Yoshimitsu},
doi = {10.1038/nclimate2330},
isbn = {1758-678X, 1758-6798},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {oct},
number = {10},
pages = {888--892},
title = {{Recent Walker circulation strengthening and Pacific cooling amplified by Atlantic warming}},
volume = {4},
year = {2014}
}
@article{Meehl2020,
abstract = {For the current generation of earth system models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), the range of equilibrium climate sensitivity (ECS, a hypothetical value of global warming at equilibrium for a doubling of CO 2 ) is 1.8°C to 5.6°C, the largest of any generation of models dating to the 1990s. Meanwhile, the range of transient climate response (TCR, the surface temperature warming around the time of CO 2 doubling in a 1{\%} per year CO 2 increase simulation) for the CMIP6 models of 1.7°C (1.3°C to 3.0°C) is only slightly larger than for the CMIP3 and CMIP5 models. Here we review and synthesize the latest developments in ECS and TCR values in CMIP, compile possible reasons for the current values as supplied by the modeling groups, and highlight future directions. Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS in CMIP6.},
author = {Meehl, Gerald A and Senior, Catherine A and Eyring, Veronika and Flato, Gregory and Lamarque, Jean-Francois and Stouffer, Ronald J and Taylor, Karl E and Schlund, Manuel},
doi = {10.1126/sciadv.aba1981},
issn = {2375-2548},
journal = {Science Advances},
month = {jun},
number = {26},
pages = {eaba1981},
title = {{Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models}},
url = {https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aba1981},
volume = {6},
year = {2020}
}
@article{Meinshausen2009,
abstract = {The politically defined threshold of dangerous climate change is an increase of 2 degrees Celsius in the mean global temperature. Simulations here show that when carbon dioxide and a full suite of positive and negative radiative forcings are considered, total emissions from 2000 to 2050 of about 1,400 gigatonnes of carbon dioxide yield a 50{\%} probability of exceeding this threshold by the end of the twenty-first century. 'Business as usual' emissions will probably meet or exceed this 50{\%} probability.},
author = {Meinshausen, Malte and Meinshausen, Nicolai and Hare, William and Raper, Sarah C. B. and Frieler, Katja and Knutti, Reto and Frame, David J. and Allen, Myles R.},
doi = {10.1038/nature08017},
issn = {0028-0836},
journal = {Nature},
month = {apr},
number = {7242},
pages = {1158--1162},
publisher = {Nature Publishing Group},
title = {{Greenhouse-gas emission targets for limiting global warming to 2°C}},
url = {http://www.nature.com/articles/nature08017},
volume = {458},
year = {2009}
}
@article{Meinshausen2020,
abstract = {Anthropogenic increases in atmospheric greenhouse gas concentrations are the main driver of current and future climate change. The integrated assessment community has quantified anthropogenic emissions for the shared socioeconomic pathway (SSP) scenarios, each of which represents a different future socio-economic projection and political environment. Here, we provide the greenhouse gas concentrations for these SSP scenarios - using the reduced-complexity climate-carbon-cycle model MAGICC7.0.We extend historical, observationally based concentration data with SSP concentration projections from 2015 to 2500 for 43 greenhouse gases with monthly and latitudinal resolution. CO2 concentrations by 2100 range from 393 to 1135 ppm for the lowest (SSP1-1.9) and highest (SSP5-8.5) emission scenarios, respectively. We also provide the concentration extensions beyond 2100 based on assumptions regarding the trajectories of fossil fuels and land use change emissions, net negative emissions, and the fraction of non-CO 2 emissions. By 2150, CO2 concentrations in the lowest emission scenario are approximately 350 ppm and approximately plateau at that leveluntil 2500, whereas the highest fossil-fuel-driven scenario projects CO 2 concentrations of 1737 ppm and reaches concentrations beyond 2000 ppm by 2250. We estimate that the share of CO2 in the total radiative forcing contribution of all considered 43 long-lived greenhouse gases increases from 66{\%} for the present day to roughly 68{\%} to 85{\%} by the time of maximum forcing in the 21st century. For this estimation, we updated simple radiative forcing parameterizations that reflect the Oslo Line-By-Line model results. In comparison to the representative concentration pathways (RCPs), the five main SSPs (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) are more evenly spaced and extend to lower 2100 radiative forcing and temperatures. Performing two pairs of six-member historical ensembles with CESM1.2.2, we estimate the effect on surface air temperatures of applying latitudinally and seasonally resolved GHG concentrations. We find that the ensemble differences in the March-April-May (MAM) season provide a regional warming in higher northern latitudes of up to 0.4K over the historical period, latitudinally averaged of about 0.1 K, which we estimate to be comparable to the upper bound (5{\%} level) of natural variability. In comparison to the comparatively straight line of the last 2000 years, the greenhouse gas concentrations since the onset of the industrial period and this studies' projections over the next 100 to 500 years unequivocally depict a "hockey-stick"upwards shape. The SSP concentration time series derived in this study provide a harmonized set of input assumptions for long-term climate science analysis; they also provide an indication of the wide set of futures that societal developments and policy implementations can lead to - ranging from multiple degrees of future warming on the one side to approximately 1.5 °C warming on the other.},
author = {Meinshausen, Malte and Nicholls, Zebedee R.J. and Lewis, Jared and Gidden, Matthew J. and Vogel, Elisabeth and Freund, Mandy and Beyerle, Urs and Gessner, Claudia and Nauels, Alexander and Bauer, Nico and Canadell, Josep G. and Daniel, John S. and John, Andrew and Krummel, Paul B. and Luderer, Gunnar and Meinshausen, Nicolai and Montzka, Stephen A. and Rayner, Peter J. and Reimann, Stefan and Smith, Steven J. and {Van Den Berg}, Marten and Velders, Guus J.M. and Vollmer, Martin K. and Wang, Ray H.J.},
doi = {10.5194/gmd-13-3571-2020},
issn = {19919603},
journal = {Geoscientific Model Development},
month = {aug},
number = {8},
pages = {3571--3605},
publisher = {Copernicus GmbH},
title = {{The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500}},
volume = {13},
year = {2020}
}
@article{Meinshausen2011,
abstract = {Abstract. Current scientific knowledge on the future response of the climate system to human-induced perturbations is comprehensively captured by various model intercomparison efforts. In the preparation of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC), intercomparisons were organized for atmosphere-ocean general circulation models (AOGCMs) and carbon cycle models, named "CMIP3" and "C4MIP", respectively. Despite their tremendous value for the scientific community and policy makers alike, there are some difficulties in interpreting the results. For example, radiative forcings were not standardized across the various AOGCM integrations and carbon cycle runs, and, in some models, key forcings were omitted. Furthermore, the AOGCM analysis of plausible emissions pathways was restricted to only three SRES scenarios. This study attempts to address these issues. We present an updated version of MAGICC, the simple carbon cycle-climate model used in past IPCC Assessment Reports with enhanced representation of time-varying climate sensitivities, carbon cycle feedbacks, aerosol forcings and ocean heat uptake characteristics. This new version, MAGICC6, is successfully calibrated against the higher complexity AOGCMs and carbon cycle models. Parameterizations of MAGICC6 are provided. The mean of the emulations presented here using MAGICC6 deviates from the mean AOGCM responses by only 2.2{\%} on average for the SRES scenarios. This enhanced emulation skill in comparison to previous calibrations is primarily due to: making a "like-with-like comparison" using AOGCM-specific subsets of forcings; employing a new calibration procedure; as well as the fact that the updated simple climate model can now successfully emulate some of the climate-state dependent effective climate sensitivities of AOGCMs. The diagnosed effective climate sensitivity at the time of CO2 doubling for the AOGCMs is on average 2.88 °C, about 0.33 °C cooler than the mean of the reported slab ocean climate sensitivities. In the companion paper (Part 2) of this study, we examine the combined climate system and carbon cycle emulations for the complete range of IPCC SRES emissions scenarios and the new RCP pathways.},
author = {Meinshausen, M. and Raper, S.C.B. and Wigley, T.M.L.},
doi = {10.5194/acp-11-1417-2011},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
language = {English},
month = {feb},
number = {4},
pages = {1417--1456},
title = {{Emulating coupled atmosphere–ocean and carbon cycle models with a simpler model, MAGICC6 – Part 1: Model description and calibration}},
url = {https://acp.copernicus.org/articles/11/1417/2011/},
volume = {11},
year = {2011}
}
@article{Meinshausen2011b,
abstract = {Intercomparisons of coupled atmosphere-ocean general circulation models (AOGCMs) and carbon cycle models are important for galvanizing our current scientific knowledge to project future climate. Interpreting such intercomparisons faces major challenges, not least because different models have been forced with different sets of forcing agents. Here, we show how an emulation approach with MAGICC6 can address such problems. In a companion paper (Meinshausen et al., 2011a), we show how the lower complexity carbon cycle-climate model MAGICC6 can be calibrated to emulate, with considerable accuracy, globally aggregated characteristics of these more complex models. Building on that, we examine here the Coupled Model Intercomparison Project's Phase 3 results (CMIP3). If forcing agents missed by individual AOGCMs in CMIP3 are considered, this reduces ensemble average temperature change from pre-industrial times to 2100 under SRES A1B by 0.4 {\^{A}}°C. Differences in the results from the 1980 to 1999 base period (as reported in IPCC AR4) to 2100 are negligible, however, although there are some differences in the trajectories over the 21st century. In a second part of this study, we consider the new RCP scenarios that are to be investigated under the forthcoming CMIP5 intercomparison for the IPCC Fifth Assessment Report. For the highest scenario, RCP8.5, relative to pre-industrial levels, we project a median warming of around 4.6 {\^{A}}°C by 2100 and more than 7 {\^{A}}°C by 2300. For the lowest RCP scenario, RCP3-PD, the corresponding warming is around 1.5 {\^{A}}°C by 2100, decreasing to around 1.1 {\^{A}}°C by 2300 based on our AOGCM and carbon cycle model emulations. Implied cumulative CO2 emissions over the 21st century for RCP8.5 and RCP3-PD are 1881 GtC (1697 to 2034 GtC, 80{\%} uncertainty range) and 381 GtC (334 to 488 GtC), when prescribing CO2 concentrations and accounting for uncertainty in the carbon cycle. Lastly, we assess the reasons why a previous MAGICC version (4.2) used in IPCC AR4 gave roughly 10{\%} larger warmings over the 21st century compared to the CMIP3 average. We find that forcing differences and the use of slightly too high climate sensitivities inferred from idealized high-forcing runs were the major reasons for this difference. {\textcopyright} Author(s) 2011.},
author = {Meinshausen, M and Wigley, T. M.L. and Raper, S. C.B.},
doi = {10.5194/acp-11-1457-2011},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
number = {4},
pages = {1457--1471},
publisher = {Copernicus GmbH},
title = {{Emulating atmosphere-ocean and carbon cycle models with a simpler model, MAGICC6 - Part 2: Applications}},
volume = {11},
year = {2011}
}
@article{Meraner2013,
abstract = {Equilibrium climate sensitivity (ECS) is a widely accepted measure of Earth's susceptibility to radiative forcing. While ECS is often assumed to be constant to a first order of approximation, recent studies suggested that ECS might depend on the climate state. Here it is shown that the latest generation of climate models consistently exhibits an increasing ECS in warmer climates due to a strengthening of the water-vapor feedback with increasing surface temperatures. The increasing ECS is replicated by a one-dimensional radiative-convective equilibrium model, which further shows that the enhanced water-vapor feedback follows from the rising of the tropopause in a warming climate. This mechanism is potentially important for understanding both warm climates of Earth's past and projections of future high-emission scenarios.},
author = {Meraner, Katharina and Mauritsen, Thorsten and Voigt, Aiko},
doi = {10.1002/2013GL058118},
isbn = {1944-8007},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {CMIP5,climate sensitivity,global warming},
number = {22},
pages = {5944--5948},
title = {{Robust increase in equilibrium climate sensitivity under global warming}},
volume = {40},
year = {2013}
}
@article{Mercado2009a,
abstract = {Plant photosynthesis tends to increase with irradiance. However, recent theoretical and observational studies have demonstrated that photosynthesis is also more efficient under diffuse light conditions. Changes in cloud cover or atmospheric aerosol loadings, arising from either volcanic or anthropogenic emissions, alter both the total photosynthetically active radiation reaching the surface and the fraction of this radiation that is diffuse, with uncertain overall effects on global plant productivity and the land carbon sink. Here we estimate the impact of variations in diffuse fraction on the land carbon sink using a global model modified to account for the effects of variations in both direct and diffuse radiation on canopy photosynthesis. We estimate that variations in diffuse fraction, associated largely with the 'global dimming' period, enhanced the land carbon sink by approximately one-quarter between 1960 and 1999. However, under a climate mitigation scenario for the twenty-first century in which sulphate aerosols decline before atmospheric CO(2) is stabilized, this 'diffuse-radiation' fertilization effect declines rapidly to near zero by the end of the twenty-first century.},
author = {Mercado, Lina M. and Bellouin, Nicolas and Sitch, Stephen and Boucher, Olivier and Huntingford, Chris and Wild, Martin and Cox, Peter M.},
doi = {10.1038/nature07949},
isbn = {0028-0836},
issn = {0028-0836},
journal = {Nature},
month = {apr},
number = {7241},
pages = {1014--1017},
pmid = {19396143},
title = {{Impact of changes in diffuse radiation on the global land carbon sink}},
url = {http://www.nature.com/articles/nature07949},
volume = {458},
year = {2009}
}
@incollection{MeredithM.SommerkornM.CassotaS.DerksenC.EkaykinA.HollowedA2019,
author = {Meredith, M. and Sommerkorn, M. and Cassota, S. and Derksen, C. and Ekaykin, A. and Hollowed, A and Kofinas, G. and Mackintosh, A. and Melbourne-Thomas, J. and Muelbert, M.M.C. and Ottersen, G. and Pritchard, H. and Schuur, E.A.G.},
booktitle = {IPCC Special Report on the Ocean and Cryosphere in a Changing Climate},
editor = {Pörtner, H.-O. and Roberts, D.C. and Masson-Delmotte, V. and Zhai, P. and Tignor, M. and Poloczanska, E. and Mintenbeck, K. and Alegría, A. and Nicolai, M. and Okem, A. and Petzold, J. and Rama, B. and Weyer, N.M.},
pages = {203--320},
publisher = {In Press},
title = {{Polar Regions}},
url = {https://www.ipcc.ch/srocc/chapter/chapter-3-2},
year = {2019}
}
@article{Merlis2014,
abstract = {Coupled climate model simulations of volcanic eruptions and abrupt changes in CO2 concentration are compared in multiple realizations of the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1). The change in global-mean surface temperature (GMST) is analyzed to determine whether a fast component of the climate sensitivity of relevance to the transient climate response (TCR; defined with the 1{\%} yr−1 CO2-increase scenario) can be estimated from shorter-time-scale climate changes. The fast component of the climate sensitivity estimated from the response of the climate model to volcanic forcing is similar to that of the simulations forced by abrupt CO2 changes but is 5{\%}–15{\%} smaller than the TCR. In addition, the partition between the top-of-atmosphere radiative restoring and ocean heat uptake is similar across radiative forcing agents. The possible asymmetry between warming and cooling climate perturbations, which may affect the utility of volcanic eruptions for estimating the TCR, is assessed by comparing simulations of abrupt CO2 doubling to abrupt CO2 halving. There is slightly less ({\~{}}5{\%}) GMST change in 0.5 × CO2 simulations than in 2 × CO2 simulations on the short ({\~{}}10 yr) time scales relevant to the fast component of the volcanic signal. However, inferring the TCR from volcanic eruptions is more sensitive to uncertainties from internal climate variability and the estimation procedure.},
author = {Merlis, Timothy M. and Held, Isaac M. and Stenchikov, Georgiy L. and Zeng, Fanrong and Horowitz, Larry W.},
doi = {10.1175/JCLI-D-14-00214.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {20},
pages = {7781--7795},
title = {{Constraining Transient Climate Sensitivity Using Coupled Climate Model Simulations of Volcanic Eruptions}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-14-00214.1},
volume = {27},
year = {2014}
}
@article{Merlis2018,
abstract = {Diffusive energy balance models (EBMs) that use moist static energy, rather than temperature, as the thermodynamic variable to determine the energy transport provide an idealized framework to understand the pattern of radiatively forced surface warming. These models have a polar amplified warming pattern that is quantitatively similar to general circulation model simulations. Even without surface albedo changes or other spatially varying feedbacks, they simulate polar amplification that results from increased poleward energy transport with warming. Here, two estimates for polar amplification are presented that do not require numerical solution of the EBM governing equation. They are evaluated relative to the results of numerical moist EBM solutions. One estimate considers only changes in a moist thermodynamic quantity (assuming that the increase in energy transport results in a spatially uniform change in moist static energy in the warmed climate) and has more polar amplification than the EBM solution. The other estimate uses a new solution of a truncated form of the moist EBM equation, which allows for a temperature change that is consistent with both the dry and latent energy transport changes, as well as radiative changes. The truncated EBM solution provides an estimate for polar amplification that is nearly identical to that of the numerical EBM solution and only depends on the EBM parameters and climatology of temperature. This solution sheds light on the dependence of polar amplification on the climatological temperature distribution and offers an estimate of the residual polar warming in solar radiation management geoengineered climates.},
author = {Merlis, Timothy M. and Henry, Matthew},
doi = {10.1175/JCLI-D-17-0578.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Climate change,Energy transport},
month = {aug},
number = {15},
pages = {5811--5824},
title = {{Simple Estimates of Polar Amplification in Moist Diffusive Energy Balance Models}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0578.1},
volume = {31},
year = {2018}
}
@article{doi:10.1002/2014GL061700,
abstract = {AbstractThe role of interactions between components of the top-of-atmosphere (TOA) energy balance in determining regional surface temperature changes, such as polar amplification, is examined in diffusive energy balance model (EBM) simulations. These interactions have implications for the interpretation of local feedback analyses when they are applied to regional surface temperature changes. Local feedback analysis succeeds at accounting for the EBM-simulated temperature change given the changes in the radiative forcing, atmospheric energy transport, and radiative feedbacks. However, the inferences about the effect of individual components of the TOA energy balance on regional temperature changes do not account for EBM simulations in which individual components are prescribed or “locked.” As changes in one component of the TOA energy balance affect others, unambiguous attribution statements relating changes in regional temperature or its intermodel spread to individual terms in the TOA energy balance cannot be made.},
author = {Merlis, Timothy M},
doi = {10.1002/2014GL061700},
journal = {Geophysical Research Letters},
keywords = {climate change,climate feedbacks,polar amplification},
number = {20},
pages = {7291--7297},
title = {{Interacting components of the top-of-atmosphere energy balance affect changes in regional surface temperature}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014GL061700},
volume = {41},
year = {2014}
}
@article{Merlis2011,
abstract = {Variations in zonal surface temperature gradients and zonally asymmetric tropical overturning circulations (Walker circulations) are examined over a wide range of climates simulated with an idealized atmospheric general circulation model (GCM). The asymmetry in the tropical climate is generated by an imposed ocean energy flux, which does not vary with climate. The range of climates is simulated by modifying the optical thickness of an idealized longwave absorber (representing greenhouse gases). The zonal surface temperature gradient in low latitudes generally decreases as the climate warms in the idealized GCM simulations. A scaling relationship based on a two-term balance in the surface energy budget accounts for the changes in the zonally asymmetric component of the GCM-simulated surface temperature gradients. The Walker circulation weakens as the climate warms in the idealized simulations, as it does in comprehensive simulations of climate change. The wide range of climates allows a systematic test of energetic arguments that have been proposed to account for these changes in the tropical circulation. The analysis shows that a scaling estimate based on changes in the hydrological cycle (precipitation rate and saturation specific humidity) accounts for the simulated changes in the Walker circulation. However, it must be evaluated locally, with local precipitation rates. If global-mean quantities are used, the scaling estimate does not generally account for changes in the Walker circulation, and the extent to which it does is the result of compensating errors in changes in precipitation and saturation specific humidity that enter the scaling estimate.},
author = {Merlis, Timothy M. and Schneider, Tapio},
doi = {10.1175/2011JCLI4042.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Atmospheric circulation,General circulation models,Surface temperature,Tropics,Walker circulation},
month = {sep},
number = {17},
pages = {4757--4768},
title = {{Changes in zonal surface temperature gradients and Walker circulations in a wide range of climates}},
volume = {24},
year = {2011}
}
@article{Meyer2015,
abstract = {The eruption of the Eritrean Nabro Volcano in June 2011 was the largest eruption since Mount Pinatubo in June 1991. The Nabro volcano emitted 1-1.5 megaton of sulfur dioxide into the lower stratosphere which resulted in a significant rise in the stratospheric sulfate aerosol burden in the months following the eruption. We have analyzed backscatter and extinction from ice clouds, as measured by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite between June 2006 and May 2014, to assess if volcanic aerosol produced by the Nabro eruption had affected ice clouds. We found no significant modifications of either of ice cloud optical properties (i.e., total backscattering and extinction), occurrence frequencies, or residence altitudes on a global scale. Using the analyzed optical properties as indicators of posteruptive ice cloud radiative forcing modifications, we find that the eruption had no significant volcanic aerosol-ice cloud radiative effect. Our results suggest that the investigated optical properties of ice and cirrus clouds are at most weakly dependent on the sulfate droplet number density and size distribution.},
author = {Meyer, A. and Vernier, J. P. and Luo, B. and Lohmann, U. and Peter, T.},
doi = {10.1002/2015JD023326},
issn = {21562202},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {10.1002/2015JD023326 and Volcanic aerosol,CALIPSO,Nabro volcano,aerosol-cloud interactions,ice clouds},
number = {18},
pages = {9500--9513},
title = {{Did the 2011 Nabro eruption affect the optical properties of ice clouds?}},
volume = {120},
year = {2015}
}
@article{10.3389/fmars.2019.00432,
abstract = {The energy radiated by the Earth toward space does not compensate the incoming radiation from the Sun leading to a small positive energy imbalance at the top of the atmosphere (0.4–1 Wm{\textless}sup{\textgreater}–2{\textless}/sup{\textgreater}). This imbalance is coined Earth's Energy Imbalance (EEI). It is mostly caused by anthropogenic greenhouse gas emissions and is driving the current warming of the planet. Precise monitoring of EEI is critical to assess the current status of climate change and the future evolution of climate. But the monitoring of EEI is challenging as EEI is two orders of magnitude smaller than the radiation fluxes in and out of the Earth system. Over 93{\%} of the excess energy that is gained by the Earth in response to the positive EEI accumulates into the ocean in the form of heat. This accumulation of heat can be tracked with the ocean observing system such that today, the monitoring of Ocean Heat Content (OHC) and its long-term change provide the most efficient approach to estimate EEI. In this community paper we review the current four state-of-the-art methods to estimate global OHC changes and evaluate their relevance to derive EEI estimates on different time scales. These four methods make use of: (1) direct observations of in situ temperature; (2) satellite-based measurements of the ocean surface net heat fluxes; (3) satellite-based estimates of the thermal expansion of the ocean and (4) ocean reanalyses that assimilate observations from both satellite and in situ instruments. For each method we review the potential and the uncertainty of the method to estimate global OHC changes. We also analyze gaps in the current capability of each method and identify ways of progress for the future to fulfill the requirements of EEI monitoring. Achieving the observation of EEI with sufficient accuracy will depend on merging the remote sensing techniques with in situ measurements of key variables as an integral part of the Ocean Observing System.},
author = {Meyssignac, Benoit and Boyer, Tim and Zhao, Zhongxiang and Hakuba, Maria Z and Landerer, Felix W and Stammer, Detlef and K{\"{o}}hl, Armin and Kato, Seiji and L'Ecuyer, Tristan and Ablain, Michael and Abraham, John Patrick and Blazquez, Alejandro and Cazenave, Anny and Church, John A and Cowley, Rebecca and Cheng, Lijing and Domingues, Catia M and Giglio, Donata and Gouretski, Viktor and Ishii, Masayoshi and Johnson, Gregory C and Killick, Rachel E and Legler, David and Llovel, William and Lyman, John and Palmer, Matthew Dudley and Piotrowicz, Steve and Purkey, Sarah G and Roemmich, Dean and Roca, R{\'{e}}my and Savita, Abhishek and von Schuckmann, Karina and Speich, Sabrina and Stephens, Graeme and Wang, Gongjie and Wijffels, Susan Elisabeth and Zilberman, Nathalie},
doi = {10.3389/fmars.2019.00432},
issn = {2296-7745},
journal = {Frontiers in Marine Science},
pages = {432},
title = {{Measuring Global Ocean Heat Content to Estimate the Earth Energy Imbalance}},
url = {https://www.frontiersin.org/article/10.3389/fmars.2019.00432},
volume = {6},
year = {2019}
}
@article{Michibata2016,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Aerosol–cloud interactions are one of the most uncertain processes in climate models due to their nonlinear complexity. A key complexity arises from the possibility that clouds can respond to perturbed aerosols in two opposite ways, as characterized by the traditional “cloud lifetime” hypothesis and more recent “buffered system” hypothesis. Their importance in climate simulations remains poorly understood. Here we investigate the response of the liquid water path (LWP) to aerosol perturbations for warm clouds from the perspective of general circulation model (GCM) and A-Train remote sensing, through process-oriented model evaluations. A systematic difference is found in the LWP response between the model results and observations. The model results indicate a near-global uniform increase of LWP with increasing aerosol loading, while the sign of the response of the LWP from the A-Train varies from region to region. The satellite-observed response of the LWP is closely related to meteorological and/or macrophysical factors, in addition to the microphysics. The model does not reproduce this variability of cloud susceptibility (i.e., sensitivity of LWP to perturbed aerosols) because the parameterization of the autoconversion process assumes only suppression of rain formation in response to increased cloud droplet number, and does not consider macrophysical aspects that serve as a mechanism for the negative responses of the LWP via enhancements of evaporation and precipitation. Model biases are also found in the precipitation microphysics, which suggests that the model generates rainwater readily even when little cloud water is present. This essentially causes projections of unrealistically frequent and light rain, with high cloud susceptibilities to aerosol perturbations.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Michibata, Takuro and Suzuki, Kentaroh and Sato, Yousuke and Takemura, Toshihiko},
doi = {10.5194/acp-16-15413-2016},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {dec},
number = {23},
pages = {15413--15424},
title = {{The source of discrepancies in aerosol–cloud–precipitation interactions between GCM and A-Train retrievals}},
volume = {16},
year = {2016}
}
@article{Millar2015,
abstract = {The transient climate response (TCR) is a highly policy-relevant quantity in climate science. We show that recent revisions to TCR in the IPCC 5th Assessment Report have more impact on projections over the next century than revisions to the equilibrium climate sensitivity (ECS). While it is well known that upper bounds on ECS are dependent on model structure, here we show that the same applies to TCR. Our results use observations of the planetary energy budget, updated radiative forcing estimates and a number of simple climate models. We also investigate the ratio TCR:ECS, or realised warming fraction (RWF), a highly policy-relevant quantity. We show that global climate models (GCMs) don't sample a region of low TCR and high RWF consistent with observed climate change under all simple models considered. Whether the additional constraints from GCMs are sufficient to rule out these low climate responses is a matter for further research.},
author = {Millar, Richard J. and Otto, Alexander and Forster, Piers M. and Lowe, Jason A. and Ingram, William J. and Allen, Myles R.},
doi = {10.1007/s10584-015-1384-4},
isbn = {1058401513},
issn = {01650009},
journal = {Climatic Change},
number = {2},
pages = {199--211},
title = {{Model structure in observational constraints on transient climate response}},
volume = {131},
year = {2015}
}
@article{Millar2017a,
abstract = {Abstract. Projections of the response to anthropogenic emission scenarios, evaluation of some greenhouse gas metrics, and estimates of the social cost of carbon often require a simple model that links emissions of carbon dioxide (CO2) to atmospheric concentrations and global temperature changes. An essential requirement of such a model is to reproduce typical global surface temperature and atmospheric CO2 responses displayed by more complex Earth system models (ESMs) under a range of emission scenarios, as well as an ability to sample the range of ESM response in a transparent, accessible and reproducible form. Here we adapt the simple model of the Intergovernmental Panel on Climate Change 5th Assessment Report (IPCC AR5) to explicitly represent the state dependence of the CO2 airborne fraction. Our adapted model (FAIR) reproduces the range of behaviour shown in full and intermediate complexity ESMs under several idealised carbon pulse and exponential concentration increase experiments. We find that the inclusion of a linear increase in 100-year integrated airborne fraction with cumulative carbon uptake and global temperature change substantially improves the representation of the response of the climate system to CO2 on a range of timescales and under a range of experimental designs.},
author = {Millar, Richard J. and Nicholls, Zebedee R. and Friedlingstein, Pierre and Allen, Myles R.},
doi = {10.5194/acp-17-7213-2017},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jun},
number = {11},
pages = {7213--7228},
publisher = {Copernicus GmbH},
title = {{A modified impulse–response representation of the global near-surface air temperature and atmospheric concentration response to carbon dioxide emissions}},
url = {https://acp.copernicus.org/articles/17/7213/2017/},
volume = {17},
year = {2017}
}
@article{Mlynczak2016,
abstract = {The radiative forcing (RF) of carbon dioxide (CO2) is the leading contribution to climate change from anthropogenic activities. Calculating CO2 RF requires detailed knowledge of spectral line parameters for thousands of infrared absorption lines. A reliable spectroscopic characterization of CO2 forcing is critical to scientific and policy assessments of present climate and climate change. Our results show that CO2 RF in a variety of atmospheres is remarkably insensitive to known uncertainties in the three main CO2 spectroscopic parameters: the line shapes, line strengths, and half widths. We specifically examine uncertainty in RF due to line mixing as this process is critical in determining line shapes in the far wings of CO2 absorption lines. RF computed with a Voigt lineshape is also examined. Overall, the spectroscopic uncertainty in present-day CO2 RF is less than one percent, indicating a robust foundation in our understanding of how rising CO2 warms the climate system.},
author = {Mlynczak, Martin G. and Daniels, Taumi S. and Kratz, David P. and Feldman, Daniel R. and Collins, William D. and Mlawer, Eli J. and Alvarado, Matthew J. and Lawler, James E. and Anderson, L. W. and Fahey, David W. and Hunt, Linda A. and Mast, Jeffrey C.},
doi = {10.1002/2016GL068837},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {carbon dioxide,line shape function,radiative forcing,spectroscopy},
month = {may},
number = {10},
pages = {5318--5325},
title = {{The spectroscopic foundation of radiative forcing of climate by carbon dioxide}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2016GL068837},
volume = {43},
year = {2016}
}
@article{Modak2018,
abstract = {In this study, using idealized step-forcing simulations, we examine the effective radiative forcing of CH4relative to that of CO2and compare the effects of CH4and CO2forcing on the climate system. A tenfold increase in CH4concentration in the NCAR CAM5 climate model produces similar long term global mean surface warming ({\~{}} 1.7 K) as a one-third increase in CO2concentration. However, the radiative forcing estimated for CO2using the prescribed-SST method is {\~{}} 81{\%} that of CH4, indicating that the efficacy of CH4forcing is {\~{}} 0.81. This estimate is nearly unchanged when the CO2physiological effect is included in our simulations. Further, for the same long-term global mean surface warming, we simulate a smaller precipitation increase in the CH4case compared to the CO2case. This is because of the fast adjustment processes—precipitation reduction in the CH4case is larger than that of the CO2case. This is associated with a relatively more stable atmosphere and larger atmospheric radiative forcing in the CH4case which occurs because of near-infrared absorption by CH4in the upper troposphere and lower stratosphere. Within a month after an increase in CH4, this shortwave heating results in a temperature increase of {\~{}} 0.8 K in the lower stratosphere and upper troposphere. In contrast, within a month after a CO2increase, longwave cooling results in a temperature decrease of {\~{}} 3 K in the stratosphere and a small change in the upper troposphere. These fast adjustments in the lower stratospheric and upper tropospheric temperature, along with the adjustments in clouds in the troposphere, influence the effective radiative forcing and the fast precipitation response. These differences in fast climate adjustments also produce differences in the climate states from which the slow response begins to evolve and hence they are likely associated with differing feedbacks. We also find that the tropics and subtropics are relatively warmer in the CH4case for the same global mean surface warming because of a larger longwave clear-sky and shortwave cloud forcing over these regions in the CH4case. Further investigation using a multi-model intercomparison framework would permit an assessment of the robustness of our results.},
author = {Modak, Angshuman and Bala, Govindasamy and Caldeira, Ken and Cao, Long},
doi = {10.1007/s00382-018-4102-x},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {nov},
number = {9-10},
pages = {3653--3672},
title = {{Does shortwave absorption by methane influence its effectiveness?}},
url = {http://link.springer.com/10.1007/s00382-018-4102-x},
volume = {51},
year = {2018}
}
@article{Modak2016,
abstract = {Many previous studies have shown that a solar forcing must be greater than a CO2forcing to cause the same global mean surface temperature change but a process-based mechanistic explanation is lacking in the literature. In this study, we investigate the physical mechanisms responsible for the lower efficacy of solar forcing compared to an equivalent CO2forcing. Radiative forcing is estimated using the Gregory method that regresses top-of-atmosphere (TOA) radiative flux against the change in global mean surface temperature. For a 2.25{\%} increase in solar irradiance that produces the same long term global mean warming as a doubling of CO2concentration, we estimate that the efficacy of solar forcing is ∼80{\%} relative to CO2forcing in the NCAR CAM5 climate model. We find that the fast tropospheric cloud adjustments especially over land and stratospheric warming in the first four months cause the slope of the regression between the TOA net radiative fluxes and surface temperature to be steeper in the solar forcing case. This steeper slope indicates a stronger net negative feedback and hence correspondingly a larger solar forcing than CO2forcing for the same equilibrium surface warming. Evidence is provided that rapid land surface warming in the first four months sets up a land-sea contrast that markedly affects radiative forcing and the climate feedback parameter over this period. We also confirm the robustness of our results using simulations from the Hadley Centre climate model. Our study has important implications for estimating the magnitude of climate change caused by volcanic eruptions, solar geoengineering and past climate changes caused by change in solar irradiance such as Maunder minimum.},
author = {Modak, A. and Bala, G. and Cao, L. and Caldeira, K.},
doi = {10.1088/1748-9326/11/4/044013},
journal = {Environmental Research Letters},
number = {4},
pages = {044013},
title = {{Why must a solar forcing be larger than a CO2 forcing to cause the same global mean surface temperature change?}},
volume = {11},
year = {2016}
}
@article{Modak2019,
abstract = {Using idealized climate model simulations, we investigate the effectiveness of black carbon (BC) aerosols in warming the planet relative to CO2 forcing. We find that a 60-fold increase in the BC aerosol mixing ratio from the present-day levels leads to the same equilibrium global mean surface warming (∼4.1 K) as for a doubling of atmospheric CO2 concentration. However, the radiative forcing is larger (∼5.5 Wm-2) in the BC case relative to the doubled CO2 case (∼3.8 Wm-2) for the same surface warming indicating the efficacy (a metric for measuring the effectiveness) of BC aerosols to be less than CO2. The lower efficacy of BC aerosols is related to the differences in the shortwave (SW) cloud feedback: negative in the BC case but positive in the CO2 case. In the BC case, the negative SW cloud feedback is related to an increase in the tropical low clouds which is associated with a northward shift (∼7) of the Intertropical Convergence Zone (ITCZ). Further, we show that in the BC case fast precipitation suppression offsets the surface temperature mediated precipitation response and causes ∼8{\%} net decline in the global mean precipitation. Our study suggests that a feedback between the location of ITCZ and the interhemispheric temperature could exist, and the consequent SW cloud feedback could be contributing to the lower efficacy of BC aerosols. Therefore, an improved representation of low clouds in climate models is likely the key to understand the global climate sensitivity to BC aerosols.},
author = {Modak, Angshuman and Bala, Govindasamy},
doi = {10.1088/1748-9326/ab21e7},
issn = {1748-9326},
journal = {Environmental Research Letters},
keywords = {ITCZ shift,black carbon aerosols,climate feedback,climate sensitivity,cloud feedback,efficacy of forcings,hydrological cycle},
month = {aug},
number = {8},
pages = {084029},
title = {{Efficacy of black carbon aerosols: the role of shortwave cloud feedback}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/ab21e7},
volume = {14},
year = {2019}
}
@article{Morgenstern2017,
abstract = {Abstract. We present an overview of state-of-the-art chemistry–climate and chemistry transport models that are used within phase 1 of the Chemistry–Climate Model Initiative (CCMI-1). The CCMI aims to conduct a detailed evaluation of participating models using process-oriented diagnostics derived from observations in order to gain confidence in the models' projections of the stratospheric ozone layer, tropospheric composition, air quality, where applicable global climate change, and the interactions between them. Interpretation of these diagnostics requires detailed knowledge of the radiative, chemical, dynamical, and physical processes incorporated in the models. Also an understanding of the degree to which CCMI-1 recommendations for simulations have been followed is necessary to understand model responses to anthropogenic and natural forcing and also to explain inter-model differences. This becomes even more important given the ongoing development and the ever-growing complexity of these models. This paper also provides an overview of the available CCMI-1 simulations with the aim of informing CCMI data users.},
author = {Morgenstern, Olaf and Hegglin, Michaela I. and Rozanov, Eugene and O'Connor, Fiona M. and Abraham, N. Luke and Akiyoshi, Hideharu and Archibald, Alexander T. and Bekki, Slimane and Butchart, Neal and Chipperfield, Martyn P. and Deushi, Makoto and Dhomse, Sandip S. and Garcia, Rolando R. and Hardiman, Steven C. and Horowitz, Larry W. and J{\"{o}}ckel, Patrick and Josse, Beatrice and Kinnison, Douglas and Lin, Meiyun and Mancini, Eva and Manyin, Michael E. and Marchand, Marion and Mar{\'{e}}cal, Virginie and Michou, Martine and Oman, Luke D. and Pitari, Giovanni and Plummer, David A. and Revell, Laura E. and Saint-Martin, David and Schofield, Robyn and Stenke, Andrea and Stone, Kane and Sudo, Kengo and Tanaka, Taichu Y. and Tilmes, Simone and Yamashita, Yousuke and Yoshida, Kohei and Zeng, Guang},
doi = {10.5194/gmd-10-639-2017},
issn = {1991-9603},
journal = {Geoscientific Model Development},
month = {feb},
number = {2},
pages = {639--671},
title = {{Review of the global models used within phase 1 of the Chemistry–Climate Model Initiative (CCMI)}},
url = {https://gmd.copernicus.org/articles/10/639/2017/},
volume = {10},
year = {2017}
}
@article{Morgenstern2020,
abstract = {We assess the effective radiative forcing due to ozone-depleting substances using models participating in the Aerosols and Chemistry Model Intercomparison Project (AerChemMIP). A large inter-model spread in this globally averaged quantity necessitates an “emergent constraint” approach whereby we link the radiative forcing to the amount of ozone depletion simulated during 1979-2000, excluding two volcanically perturbed periods. During this period ozone-depleting substances were increasing, and several merged satellite-based climatologies document the ensuing decline of total-column ozone. We use these analyses to come up with effective radiative forcing magnitudes. For all of these satellite climatologies we find an effective radiative forcing outside or on the edge of the previously published “likely” range given by the 5th Assessment Report of IPCC, implying an offsetting effect of ozone depletion and/or other atmospheric feedbacks of -0.4 to -0.25 Wm-2, which is in absolute terms is larger than the previous best estimate of -0.15 Wm-2.},
author = {Morgenstern, Olaf and O'Connor, Fiona M. and Johnson, Ben T. and Zeng, Guang and Mulcahy, Jane Patricia and Williams, Jonny and Teixeira, Jo{\~{a}}o and Michou, Martine and Nabat, Pierre and Horowitz, Larry Wayne and Naik, Vaishali and Sentman, Lori T. and Deushi, Makoto and Bauer, Susanne E. and Tsigaridis, Kostas and Shindell, Drew T. and Kinnison, Douglas Edward},
doi = {10.1029/2020GL088295},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {Atmospheric Sciences,Climatology (Global Change)},
month = {oct},
number = {20},
pages = {e2020GL088295},
title = {{Reappraisal of the Climate Impacts of Ozone‐Depleting Substances}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL088295},
volume = {47},
year = {2020}
}
@article{Morrison2018a,
author = {Morrison, A. L. and Kay, J. E. and Frey, W. R. and Chepfer, H. and Guzman, R.},
doi = {10.1029/2018JD029142},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {jan},
number = {2},
pages = {1003--1020},
title = {{Cloud Response to Arctic Sea Ice Loss and Implications for Future Feedback in the CESM1 Climate Model}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2018JD029142},
volume = {124},
year = {2019}
}
@article{acp-2019-1210,
author = {Moseid, Kine Onsum and Schulz, Michael and Storelvmo, Trude and Julsrud, Ingeborg Rian and Olivi{\'{e}}, Dirk and Nabat, Pierre and Wild, Martin and Cole, Jason N S and Takemura, Toshihiko and Oshima, Naga and Bauer, Susanne E. and Gastineau, Guillaume},
doi = {10.5194/acp-20-16023-2020},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {dec},
number = {24},
pages = {16023--16040},
title = {{Bias in CMIP6 models as compared to observed regional dimming and brightening}},
url = {https://acp.copernicus.org/preprints/acp-2019-1210/ https://acp.copernicus.org/articles/20/16023/2020/},
volume = {20},
year = {2020}
}
@article{Munoz2016,
abstract = {The fifth assessment report by the IPCC includes methane oxidation as an additional indirect effect in the global warming potential (GWP) and global temperature potential (GTP) values for methane. An analysis of the figures provided by the IPCC reveals they lead to different outcomes measured in CO2-eq., depending on whether or not biogenic CO2 emissions are considered neutral. In this article, we discuss this inconsistency and propose a correction.},
author = {Mu{\~{n}}oz, Ivan and Schmidt, Jannick H.},
doi = {10.1007/s11367-016-1091-z},
isbn = {0781769191, 9780781769198},
issn = {0948-3349},
journal = {The International Journal of Life Cycle Assessment},
keywords = {Biogenic carbon,Carbon footprinting,Global temperature change potential,Global warming potential,Life cycle assessment,Methane},
month = {aug},
number = {8},
pages = {1069--1075},
title = {{Methane oxidation, biogenic carbon, and the IPCC's emission metrics. Proposal for a consistent greenhouse-gas accounting}},
url = {http://link.springer.com/10.1007/s11367-016-1091-z},
volume = {21},
year = {2016}
}
@article{ISI:000326603200003,
abstract = {Land evapotranspiration (ET) estimates are available from several global data sets. Here, monthly global land ET synthesis products, merged from these individual data sets over the time periods 1989-1995 (7 yr) and 1989-2005 (17 yr), are presented. The merged synthesis products over the shorter period are based on a total of 40 distinct data sets while those over the longer period are based on a total of 14 data sets. In the individual data sets, ET is derived from satellite and/ or in situ observations (diagnostic data sets) or calculated via land-surface models (LSMs) driven with observations-based forcing or output from atmospheric reanalyses. Statistics for four merged synthesis products are provided, one including all data sets and three including only data sets from one category each (diagnostic, LSMs, and reanalyses). The multi-annual variations of ET in the merged synthesis products display realistic responses. They are also consistent with previous findings of a global increase in ET between 1989 and 1997 (0.13mmyr(-2) in our merged product) followed by a significant decrease in this trend (-0.18mmyr(-2)), although these trends are relatively small compared to the uncertainty of absolute ET values. The global mean ET from the merged synthesis products (based on all data sets) is 493mmyr-1 (1.35mmd-1) for both the 1989-1995 and 1989-2005 products, which is relatively low compared to previously published estimates. We estimate global runoff (precipitation minus ET) to 263mmyr(-1) (34 406 km3 yr-1) for a total land area of 130 922 000 km(2). Precipitation, being an important driving factor and input to most simulated ET data sets, presents uncertainties between single data sets as large as those in the ET estimates. In order to reduce uncertainties in current ET products, improving the accuracy of the input variables, especially precipitation, as well as the parameterizations of ET, are crucial.},
address = {BAHNHOFSALLEE 1E, GOTTINGEN, 37081, GERMANY},
author = {Mueller, B and Hirschi, M and Jimenez, C and Ciais, P and Dirmeyer, P A and Dolman, A J and Fisher, J B and Jung, M and Ludwig, F and Maignan, F and Miralles, D G and McCabe, M F and Reichstein, M and Sheffield, J and Wang, K and Wood, E F and Zhang, Y and Seneviratne, S I},
doi = {10.5194/hess-17-3707-2013},
issn = {1027-5606},
journal = {Hydrology and Earth System Sciences},
number = {10},
pages = {3707--3720},
publisher = {COPERNICUS GESELLSCHAFT MBH},
title = {{Benchmark products for land evapotranspiration: LandFlux-EVAL multi-data set synthesis}},
type = {Article},
volume = {17},
year = {2013}
}
@article{Murphy1995,
abstract = {The roles of surface, atmospheric, and oceanic feedbacks in controlling the global-mean transient response of a coupled ocean-atmosphere general circulation model to increasing carbon dioxide are investigated. The analysis employs a four-box energy balance model and an oceanic box-diffusion model, both tuned to the simulated general circulation model response. The land-sea contrast in the surface warming is explained almost entirely by the shortwave radiative feedbacks associated with changes in cloud and surface albedo. The oceanic thermal inertia delays the response; however, the initial delay is enhanced by increases in Antarctic sea-ice cover, which substantially reduce the effective climate sensitivity of the model in the first half of the 75-year experiment. When driven by the observed anthropogenic greenhouse forcing from the pre-industrial period to present day, the energy balance model overestimates the warming observed over land. However, inclusion of the direct forcing due to anthropogenic tropospheric sulphate aerosol eliminates the land/sea contrast in the response at 1990, leaving the simulated warming over land slightly below the observed value, although the rapid warming observed during the 1980s is well reproduced. The vertical penetration of the oceanic response is small below 1000 m. Within the top 1000 m the effective diffusivities are substantially enhanced by reduced convection and thermohaline overturning, driven by increased precipitation minus evaporation at high latitudes. These changes in ocean heat transport become significant after year 30, whereupon the effective oceanic heat capacity increases substantially, although this increase is partially offset by the effect of changes in the sea-ice margin.},
author = {Murphy, J. M.},
doi = {10.1175/1520-0442(1995)008<0496:TROTHC>2.0.CO;2},
issn = {0894-8755},
journal = {Journal of Climate},
month = {mar},
number = {3},
pages = {496--514},
title = {{Transient Response of the Hadley Centre Coupled Ocean-Atmosphere Model to Increasing Carbon Dioxide. Part III: Analysis of Global-Mean Response Using Simple Models}},
url = {http://journals.ametsoc.org/doi/10.1175/1520-0442(1995)008{\%}3C0496:TROTHC{\%}3E2.0.CO;2},
volume = {8},
year = {1995}
}
@article{Murphy2010a,
abstract = {Changes in outgoing radiation are both a consequence and a cause of changes in the earth's temperature. Spencer and Braswell recently showed that in a simple box model for the earth the regression of outgoing radiation against surface temperature gave a slope that differed from the model's true feedback parameter. They went on to select input parameters for the box model based on observations, computed the difference for those conditions, and asserted that there is a significant bias for climate studies. This paper shows that Spencer and Braswell overestimated the difference. Differences between the regression slope and the true feedback parameter are significantly reduced when 1) a more realistic value for the ocean mixed layer depth is used, 2) a corrected standard deviation of outgoing radiation is used, and 3) the model temperature variability is computed over the same time interval as the observations. When all three changes are made, the difference between the slope and feedback parameter is less than one-tenth of that estimated by Spencer and Braswell. Absolute values of the difference for realistic cases are less than 0.05 W m−2 K−1, which is not significant for climate studies that employ regressions of outgoing radiation against temperature. Previously published results show that the difference is negligible in the Hadley Centre Slab Climate Model, version 3 (HadSM3).},
author = {Murphy, D. M. and Forster, P. M.},
doi = {10.1175/2010JCLI3657.1},
issn = {1520-0442},
journal = {Journal of Climate},
month = {sep},
number = {18},
pages = {4983--4988},
title = {{On the Accuracy of Deriving Climate Feedback Parameters from Correlations between Surface Temperature and Outgoing Radiation}},
url = {http://journals.ametsoc.org/doi/10.1175/2010JCLI3657.1},
volume = {23},
year = {2010}
}
@article{Myers2016,
abstract = {Abstract Large uncertainty remains on how subtropical clouds will respond to anthropogenic climate change and therefore whether they will act as a positive feedback that amplifies global warming or negative feedback that dampens global warming by altering Earth's energy budget. Here we reduce this uncertainty using an observationally constrained formulation of the response of subtropical clouds to greenhouse forcing. The observed interannual sensitivity of cloud solar reflection to varying meteorological conditions suggests that increasing sea surface temperature and atmospheric stability in the future climate will have largely canceling effects on subtropical cloudiness, overall leading to a weak positive shortwave cloud feedback (0.4?±?0.9?W?m?2?K?1). The uncertainty of this observationally based approximation of the cloud feedback is narrower than the intermodel spread of the feedback produced by climate models. Subtropical cloud changes will therefore complement positive cloud feedbacks identified by previous work, suggesting that future global cloud changes will amplify global warming.},
annote = {doi: 10.1002/2015GL067416},
author = {Myers, Timothy A and Norris, Joel R},
doi = {10.1002/2015GL067416},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {clouds,feedbacks},
month = {mar},
number = {5},
pages = {2144--2148},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Reducing the uncertainty in subtropical cloud feedback}},
url = {https://doi.org/10.1002/2015GL067416},
volume = {43},
year = {2016}
}
@incollection{Myhre2013,
abstract = {It is unequivocal that anthropogenic increases in the well-mixed greenhouse gases (WMGHGs) have substantially enhanced the greenhouse effect, and the resulting forcing continues to increase. Aerosols partially offset the forcing of the WMGHGs and dominate the uncertainty associated with the total anthropogenic driving of climate change.},
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Myhre, Gunnar and Shindell, Drew and Br{\'{e}}on, Francois-Marie and Collins, William and Fuglestvedt, Jan and Huang, Jianping and Koch, Dorothy and Lamarque, Jean-Francois and Lee, David and Mendoza, Blanca and Nakajima, Teruyuki and Robock, Alan and Stephens, Graeme and Takemura, Toshihiko and Zhang, Hua},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {8},
doi = {10.1017/ CBO9781107415324.018},
editor = {Stocker, T.F. and Qin, D. and Plattner, G.-K. and Tignor, M. and Allen, S.K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.},
isbn = {9781107661820},
pages = {659--740},
publisher = {Cambridge University Press},
title = {{Anthropogenic and Natural Radiative Forcing}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Myhre2017c,
abstract = {Abstract. Over the past few decades, the geographical distribution of emissions of substances that alter the atmospheric energy balance has changed due to economic growth and air pollution regulations. Here, we show the resulting changes to aerosol and ozone abundances and their radiative forcing using recently updated emission data for the period 1990–2015, as simulated by seven global atmospheric composition models. The models broadly reproduce large-scale changes in surface aerosol and ozone based on observations (e.g. −1 to −3 {\%} yr−1 in aerosols over the USA and Europe). The global mean radiative forcing due to ozone and aerosol changes over the 1990–2015 period increased by +0.17 ± 0.08 W m−2, with approximately one-third due to ozone. This increase is more strongly positive than that reported in IPCC AR5. The main reasons for the increased positive radiative forcing of aerosols over this period are the substantial reduction of global mean SO2 emissions, which is stronger in the new emission inventory compared to that used in the IPCC analysis, and higher black carbon emissions.},
author = {Myhre, Gunnar and Aas, Wenche and Cherian, Ribu and Collins, William and Faluvegi, Greg and Flanner, Mark and Forster, Piers and Hodnebrog, {\O}ivind and Klimont, Zbigniew and Lund, Marianne T. and M{\"{u}}lmenst{\"{a}}dt, Johannes and {Lund Myhre}, Cathrine and Olivi{\'{e}}, Dirk and Prather, Michael and Quaas, Johannes and Samset, Bj{\o}rn H. and Schnell, Jordan L. and Schulz, Michael and Shindell, Drew and Skeie, Ragnhild B. and Takemura, Toshihiko and Tsyro, Svetlana},
doi = {10.5194/acp-17-2709-2017},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {feb},
number = {4},
pages = {2709--2720},
title = {{Multi-model simulations of aerosol and ozone radiative forcing due to anthropogenic emission changes during the period 1990–2015}},
url = {https://acp.copernicus.org/articles/17/2709/2017/},
volume = {17},
year = {2017}
}
@article{Myhre1998a,
abstract = {We have performed new calculations of the radiative forcing due to changes in the concentrations of the most important well mixed greenhouse gases (WMGG) since pre-industrial time. Three radiative transfer models are used. The radiative forcing due to CO2, including shortwave absorption, is 15{\%} lower than the previous IPCC estimate. The radiative forcing due to all the WMGG is calculated to 2.25 Wm−2, which we estimate to be accurate to within about 5{\%}. The importance of the CFCs is increased by about 20{\%} relative to the total effect of all WMGG compared to previous estimates. We present updates to simple forcing-concentration relationships previously used by IPCC.},
author = {Myhre, Gunnar and Highwood, Eleanor J. and Shine, Keith P. and Stordal, Frode},
doi = {10.1029/98GL01908},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {Greenhouse gas,Radiative forcing},
number = {14},
pages = {2715--2718},
title = {{New estimates of radiative forcing due to well mixed greenhouse gases}},
volume = {25},
year = {1998}
}
@article{Myhre2013b,
abstract = {Abstract. We report on the AeroCom Phase II direct aerosol effect (DAE) experiment where 16 detailed global aerosol models have been used to simulate the changes in the aerosol distribution over the industrial era. All 16 models have estimated the radiative forcing (RF) of the anthropogenic DAE, and have taken into account anthropogenic sulphate, black carbon (BC) and organic aerosols (OA) from fossil fuel, biofuel, and biomass burning emissions. In addition several models have simulated the DAE of anthropogenic nitrate and anthropogenic influenced secondary organic aerosols (SOA). The model simulated all-sky RF of the DAE from total anthropogenic aerosols has a range from −0.58 to −0.02 Wm−2, with a mean of −0.27 Wm−2 for the 16 models. Several models did not include nitrate or SOA and modifying the estimate by accounting for this with information from the other AeroCom models reduces the range and slightly strengthens the mean. Modifying the model estimates for missing aerosol components and for the time period 1750 to 2010 results in a mean RF for the DAE of −0.35 Wm−2. Compared to AeroCom Phase I (Schulz et al., 2006) we find very similar spreads in both total DAE and aerosol component RF. However, the RF of the total DAE is stronger negative and RF from BC from fossil fuel and biofuel emissions are stronger positive in the present study than in the previous AeroCom study. We find a tendency for models having a strong (positive) BC RF to also have strong (negative) sulphate or OA RF. This relationship leads to smaller uncertainty in the total RF of the DAE compared to the RF of the sum of the individual aerosol components. The spread in results for the individual aerosol components is substantial, and can be divided into diversities in burden, mass extinction coefficient (MEC), and normalized RF with respect to AOD. We find that these three factors give similar contributions to the spread in results.},
author = {Myhre, G. and Samset, B. H. and Schulz, M. and Balkanski, Y. and Bauer, S. and Berntsen, T. K. and Bian, H. and Bellouin, N. and Chin, M. and Diehl, T. and Easter, R. C. and Feichter, J. and Ghan, S. J. and Hauglustaine, D. and Iversen, T. and Kinne, S. and Kirkev{\aa}g, A. and Lamarque, J.-F. and Lin, G. and Liu, X. and Lund, M. T. and Luo, G. and Ma, X. and van Noije, T. and Penner, J. E. and Rasch, P. J. and Ruiz, A. and Seland, {\O}. and Skeie, R. B. and Stier, P. and Takemura, T. and Tsigaridis, K. and Wang, P. and Wang, Z. and Xu, L. and Yu, H. and Yu, F. and Yoon, J.-H. and Zhang, K. and Zhang, H. and Zhou, C.},
doi = {10.5194/acp-13-1853-2013},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {feb},
number = {4},
pages = {1853--1877},
title = {{Radiative forcing of the direct aerosol effect from AeroCom Phase II simulations}},
url = {https://www.atmos-chem-phys.net/13/1853/2013/},
volume = {13},
year = {2013}
}
@article{Nabat2014b,
abstract = {Since the 1980s anthropogenic aerosols have been considerably reduced in Europe and the Mediterranean area. This decrease is often considered as the likely cause of the brightening effect observed over the same period. This phenomenon is however hardly reproduced by global and regional climate models. Here we use an original approach based on reanalysis-driven coupled regional climate system modeling to show that aerosol changes explain 8116{\%} of the brightening and 235{\%} of the surface warming simulated for the period 1980-2012 over Europe. The direct aerosol effect is found to dominate in the magnitude of the simulated brightening. The comparison between regional simulations and homogenized ground-based observations reveals that observed surface solar radiation and land and sea surface temperature spatiotemporal variations over the Euro-Mediterranean region are only reproduced when simulations include the realistic aerosol variations.},
address = {Nabat, P Meteo France, CNRM GAME, UMR3589, Toulouse, France Meteo France, CNRM GAME, UMR3589, Toulouse, France Meteo France, CNRM GAME, UMR3589, Toulouse, France Lab Aerol, UMR5560, Toulouse, France Univ Girona, Dept Phys, Girona, Spain Swiss Fed Inst Tec},
annote = {Ap0bi
Times Cited:0
Cited References Count:35},
author = {Nabat, P and Somot, S and Mallet, M and Sanchez-Lorenzo, A and Wild, M},
doi = {10.1002/2014gl060798},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {aerosols climate change sulfates mediterranean eur},
language = {English},
number = {15},
pages = {5605--5611},
title = {{Contribution of anthropogenic sulfate aerosols to the changing Euro-Mediterranean climate since 1980}},
volume = {41},
year = {2014}
}
@article{Nakajima2001,
author = {Nakajima, Teruyuki and Higurashi, Akiko and Kawamoto, Kazuaki and Penner, Joyce E.},
doi = {10.1029/2000GL012186},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {apr},
number = {7},
pages = {1171--1174},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{A possible correlation between satellite-derived cloud and aerosol microphysical parameters}},
url = {http://doi.wiley.com/10.1029/2000GL012186},
volume = {28},
year = {2001}
}
@article{acp-15-10887-2015,
author = {Namazi, M and von Salzen, K and Cole, J N S},
doi = {10.5194/acp-15-10887-2015},
journal = {Atmospheric Chemistry and Physics},
number = {18},
pages = {10887--10904},
title = {{Simulation of black carbon in snow and its climate impact in the Canadian Global Climate Model}},
url = {https://www.atmos-chem-phys.net/15/10887/2015/},
volume = {15},
year = {2015}
}
@article{Narenpitak2017,
author = {Narenpitak, Pornampai and Bretherton, Christopher S. and Khairoutdinov, Marat F.},
doi = {10.1002/2016MS000872},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
month = {jun},
number = {2},
pages = {1069--1090},
title = {{Cloud and circulation feedbacks in a near‐global aquaplanet cloud‐resolving model}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2016MS000872},
volume = {9},
year = {2017}
}
@article{Nazarenko2017,
author = {Nazarenko, L. and Rind, D. and Tsigaridis, K. and {Del Genio}, A. D. and Kelley, M. and Tausnev, N.},
doi = {10.1002/2016JD025809},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {mar},
number = {6},
pages = {3457--3480},
title = {{Interactive nature of climate change and aerosol forcing}},
url = {http://doi.wiley.com/10.1002/2016JD025809},
volume = {122},
year = {2017}
}
@article{Neubauer2017a,
abstract = {Abstract. Aerosol–cloud interactions (ACIs) are uncertain and the estimates of the ACI effective radiative forcing (ERFaci) magnitude show a large variability. Within the Aerosol{\_}cci project the susceptibility of cloud properties to changes in aerosol properties is derived from the high-resolution AATSR (Advanced Along-Track Scanning Radiometer) data set using the Cloud–Aerosol Pairing Algorithm (CAPA) (as described in our companion paper) and compared to susceptibilities from the global aerosol climate model ECHAM6-HAM2 and MODIS–CERES (Moderate Resolution Imaging Spectroradiometer – Clouds and the Earth's Radiant Energy System) data. For ECHAM6-HAM2 the dry aerosol is analysed to mimic the effect of CAPA. Furthermore the analysis is done for different environmental regimes. The aerosol–liquid water path relationship in ECHAM6-HAM2 is systematically stronger than in AATSR–CAPA data and cannot be explained by an overestimation of autoconversion when using diagnostic precipitation but rather by aerosol swelling in regions where humidity is high and clouds are present. When aerosol water is removed from the analysis in ECHAM6-HAM2 the strength of the susceptibilities of liquid water path, cloud droplet number concentration and cloud albedo as well as ERFaci agree much better with those of AATSR–CAPA or MODIS–CERES. When comparing satellite-derived to model-derived susceptibilities, this study finds it more appropriate to use dry aerosol in the computation of model susceptibilities. We further find that the statistical relationships inferred from different satellite sensors (AATSR–CAPA vs. MODIS–CERES) as well as from ECHAM6-HAM2 are not always of the same sign for the tested environmental conditions. In particular the susceptibility of the liquid water path is negative in non-raining scenes for MODIS–CERES but positive for AATSR–CAPA and ECHAM6-HAM2. Feedback processes like cloud-top entrainment that are missing or not well represented in the model are therefore not well constrained by satellite observations. In addition to aerosol swelling, wet scavenging and aerosol processing have an impact on liquid water path, cloud albedo and cloud droplet number susceptibilities. Aerosol processing leads to negative liquid water path susceptibilities to changes in aerosol index (AI) in ECHAM6-HAM2, likely due to aerosol-size changes by aerosol processing. Our results indicate that {\ldots}},
author = {Neubauer, David and Christensen, Matthew W. and Poulsen, Caroline A. and Lohmann, Ulrike},
doi = {10.5194/acp-17-13165-2017},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {nov},
number = {21},
pages = {13165--13185},
title = {{Unveiling aerosol–cloud interactions – Part 2: Minimising the effects of aerosol swelling and wet scavenging in ECHAM6-HAM2 for comparison to satellite data}},
url = {https://www.atmos-chem-phys.net/17/13165/2017/},
volume = {17},
year = {2017}
}
@article{Newsom2020,
abstract = {The climate's response to forcing depends on how efficiently heat is absorbed by the ocean. Much, if not most, of this ocean heat uptake results from the passive transport of warm surface waters into the ocean's interior. Here we examine how geographic patterns of surface warming influence the efficiency of this passive heat uptake process. We show that the average pattern of surface warming in CMIP5 damps passive ocean heat uptake efficiency by nearly 25{\%}, as compared to homogeneous surface warming. This “pattern effect” occurs because strong ventilation and weak surface warming are robustly colocated, particularly in the Southern Ocean. However, variations in warming patterns across CMIP5 do not drive significant ensemble spread in passive ocean heat uptake efficiency. This spread is likely linked to intermodel differences in ocean circulation, which our idealized results suggest may be dominated by differences in Southern Ocean and subtropical ventilation processes.},
author = {Newsom, Emily and Zanna, Laure and Khatiwala, Samar and Gregory, Jonathan M.},
doi = {10.1029/2020GL088429},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {Green's functions,climate change,climate modeling,ocean heat uptake efficiency,surface warming patterns},
number = {18},
pages = {e2020GL088429},
title = {{The Influence of Warming Patterns on Passive Ocean Heat Uptake}},
volume = {47},
year = {2020}
}
@article{Nicholls9999,
abstract = {Abstract. Reduced-complexity climate models (RCMs) are critical in the policy and decision making space, and are directly used within multiple Intergovernmental Panel on Climate Change (IPCC) reports to complement the results of more comprehensive Earth system models. To date, evaluation of RCMs has been limited to a few independent studies. Here we introduce a systematic evaluation of RCMs in the form of the Reduced Complexity Model Intercomparison Project (RCMIP). We expect RCMIP will extend over multiple phases, with Phase 1 being the first. In Phase 1, we focus on the RCMs' global-mean temperature responses, comparing them to observations, exploring the extent to which they emulate more complex models and considering how the relationship between temperature and cumulative emissions of CO2 varies across the RCMs. Our work uses experiments which mirror those found in the Coupled Model Intercomparison Project (CMIP), which focuses on complex Earth system and atmosphere–ocean general circulation models. Using both scenario-based and idealised experiments, we examine RCMs' global-mean temperature response under a range of forcings. We find that the RCMs can all reproduce the approximately 1 ∘C of warming since pre-industrial times, with varying representations of natural variability, volcanic eruptions and aerosols. We also find that RCMs can emulate the global-mean temperature response of CMIP models to within a root-mean-square error of 0.2 ∘C over a range of experiments. Furthermore, we find that, for the Representative Concentration Pathway (RCP) and Shared Socioeconomic Pathway (SSP)-based scenario pairs that share the same IPCC Fifth Assessment Report (AR5)-consistent stratospheric-adjusted radiative forcing, the RCMs indicate higher effective radiative forcings for the SSP-based scenarios and correspondingly higher temperatures when run with the same climate settings. In our idealised setup of RCMs with a climate sensitivity of 3 ∘C, the difference for the ssp585–rcp85 pair by 2100 is around 0.23∘C(±0.12 ∘C) due to a difference in effective radiative forcings between the two scenarios. Phase 1 demonstrates the utility of RCMIP's open-source infrastructure, paving the way for further phases of RCMIP to build on the research presented here and deepen our understanding of RCMs.},
author = {Nicholls, Zebedee R. J. and Meinshausen, Malte and Lewis, Jarad Jared and Gieseke, Robert and Dommenget, Dietmar and Dorheim, Kalyn and Fan, Chen-Shuo and Fuglestvedt, Jan S. and Gasser, Thomas and Gol{\"{u}}ke, Ulrich and Goodwin, Philip and Hartin, Corinne and Hope, Austin P. and Kriegler, Elmar and Leach, Nicholas J. and Marchegiani, Davide and McBride, Laura A. and Quilcaille, Yann and Rogelj, Joeri and Salawitch, Ross J. and Samset, Bj{\o}rn H. and Sandstad, Marit and Shiklomanov, Alexey N. and Skeie, Ragnhild B. and Smith, Christopher J. and Smith, Steve and Tanaka, Katsumasa and Tsutsui, Junichi and Xie, Zhiang},
doi = {10.5194/gmd-13-5175-2020},
issn = {19919603},
journal = {Geoscientific Model Development},
number = {11},
pages = {5175--5190},
title = {{Reduced Complexity Model Intercomparison Project Phase 1: introduction and evaluation of global-mean temperature response}},
volume = {13},
year = {2020}
}
@article{Nijsse2020,
abstract = {Abstract. Climate sensitivity to CO2 remains the key uncertainty in projections of future climate change. Transient climate response (TCR) is the metric of temperature sensitivity that is most relevant to warming in the next few decades and contributes the biggest uncertainty to estimates of the carbon budgets consistent with the Paris targets. Equilibrium climate sensitivity (ECS) is vital for understanding longer-term climate change and stabilisation targets. In the IPCC 5th Assessment Report (AR5), the stated “likely” ranges (16 {\%}–84 {\%} confidence) of TCR (1.0–2.5 K) and ECS (1.5–4.5 K) were broadly consistent with the ensemble of CMIP5 Earth system models (ESMs) available at the time. However, many of the latest CMIP6 ESMs have larger climate sensitivities, with 5 of 34 models having TCR values above 2.5 K and an ensemble mean TCR of 2.0±0.4 K. Even starker, 12 of 34 models have an ECS value above 4.5 K. On the face of it, these latest ESM results suggest that the IPCC likely ranges may need revising upwards, which would cast further doubt on the feasibility of the Paris targets. Here we show that rather than increasing the uncertainty in climate sensitivity, the CMIP6 models help to constrain the likely range of TCR to 1.3–2.1 K, with a central estimate of 1.68 K. We reach this conclusion through an emergent constraint approach which relates the value of TCR linearly to the global warming from 1975 onwards. This is a period when the signal-to-noise ratio of the net radiative forcing increases strongly, so that uncertainties in aerosol forcing become progressively less problematic. We find a consistent emergent constraint on TCR when we apply the same method to CMIP5 models. Our constraints on TCR are in good agreement with other recent studies which analysed CMIP ensembles. The relationship between ECS and the post-1975 warming trend is less direct and also non-linear. However, we are able to derive a likely range of ECS of 1.9–3.4 K from the CMIP6 models by assuming an underlying emergent relationship based on a two-box energy balance model. Despite some methodological differences; this is consistent with a previously published ECS constraint derived from warming trends in CMIP5 models to 2005. Our results seem to be part of a growing consensus amongst studies that have applied the emergent constraint approach to different model ensembles and to different aspects of the record of global warming.},
author = {Nijsse, Femke J. M. M. and Cox, Peter M. and Williamson, Mark S.},
doi = {10.5194/esd-11-737-2020},
issn = {2190-4987},
journal = {Earth System Dynamics},
keywords = {Atmospheric sciences,Climate response,Climate sensitivity,Climatology,Earth system science,Ensemble average,Forcing (mathematics),Geology,Global warming},
month = {aug},
number = {3},
pages = {737--750},
title = {{Emergent constraints on transient climate response (TCR) and equilibrium climate sensitivity (ECS) from historical warming in CMIP5 and CMIP6 models}},
url = {https://esd.copernicus.org/articles/11/737/2020/},
volume = {11},
year = {2020}
}
@article{Norris2016a,
abstract = {Clouds substantially affect Earth's energy budget by reflecting solar radiation back to space and by restricting emission of thermal radiation to space1. They are perhaps the largest uncertainty in our understanding of climate change, owing to disagreement among climate models and observational datasets over what cloud changes have occurred during recent decades and will occur in response to global warming2,3. This is because observational systems originally designed for monitoring weather have lacked sufficient stability to detect cloud changes reliably over decades unless they have been corrected to remove artefacts4,5. Here we show that several independent, empirically corrected satellite records exhibit large- scale patterns of cloud change between the 1980s and the 2000s that are similar to those produced by model simulations of climate with recent historical external radiative forcing. Observed and simulated cloud change patterns are consistent with poleward retreat of mid-latitude storm tracks, expansion of subtropical dry zones, and increasing height of the highest cloud tops at all latitudes. The primary drivers of these cloud changes appear to be increasing greenhouse gas concentrations and a recovery from volcanic radiative cooling. These results indicate that the cloud changes most consistently predicted by global climate models are currently occurring in nature.},
author = {Norris, Joel R. and Allen, Robert J. and Evan, Amato T. and Zelinka, Mark D. and O'Dell, Christopher W. and Klein, Stephen A.},
doi = {10.1038/nature18273},
isbn = {1476-4687},
issn = {14764687},
journal = {Nature},
month = {jul},
number = {7614},
pages = {72},
pmid = {27398619},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Evidence for climate change in the satellite cloud record}},
url = {http://dx.doi.org/10.1038/nature18273 http://10.0.4.14/nature18273},
volume = {536},
year = {2016}
}
@article{Notaro2007,
abstract = {Transient simulations are presented of future climate and vegetation$\backslash$nassociated with continued rising levels of CO(2). The model is a fully$\backslash$ncoupled atmosphere-ocean-land-ice model with dynamic vegetation. The$\backslash$nimpacts of the radiative and physiological forcing of CO2 are diagnosed,$\backslash$nalong with the role of vegetation feedbacks. While the radiative effect$\backslash$nof rising CO2 produces most of the warming, the physiological effect$\backslash$ncontributes additional warming by weakening the hydrologic cycle through$\backslash$nreduced evapotranspiration. Both effects cause drying over tropical rain$\backslash$nforests, while the radiative effect enhances Arctic and Indonesian$\backslash$nprecipitation.$\backslash$nA global greening trend is simulated primarily due to the physiological$\backslash$neffect, with an increase in photosynthesis and total tree cover$\backslash$nassociated with enhanced water-use efficiency. In particular, tree cover$\backslash$nis enhanced by the physiological effect over moisture-limited regions.$\backslash$nOver Amazonia, South Africa, and Australia, the radiative forcing$\backslash$nproduces soil drying and reduced forest cover. A poleward shift of the$\backslash$nboreal forest is simulated as both the radiative and physiological$\backslash$neffects enhance vegetation growth in the northern tundra and the$\backslash$nradiative effect induces drying and summertime heat stress on the$\backslash$ncentral and southern boreal forest. Vegetation feedbacks substantially$\backslash$nimpact local temperature trends through changes in albedo and$\backslash$nevapotranspiration. The physiological effect increases net biomass$\backslash$nacross most land areas, while the radiative effect results in an$\backslash$nincrease over the tundra and decrease over tropical forests and portions$\backslash$nof the boreal forest.},
author = {Notaro, Michael and Vavrus, Steve and Liu, Zhengyu},
doi = {10.1175/JCLI3989.1},
isbn = {1520-0442},
issn = {08948755},
journal = {Journal of Climate},
number = {1},
pages = {70--90},
title = {{Global vegetation and climate change due to future increases in CO2 as projected by a fully coupled model with dynamic vegetation}},
volume = {20},
year = {2007}
}
@article{doi:10.1098/rsta.2014.0164,
abstract = { The usefulness of a climate-model simulation cannot be inferred solely from its degree of agreement with observations. Instead, one has to consider additional factors such as internal variability, the tuning of the model, observational uncertainty, the temporal change in dominant processes or the uncertainty in the forcing. In any model-evaluation study, the impact of these limiting factors on the suitability of specific metrics must hence be examined. This can only meaningfully be done relative to a given purpose for using a model. I here generally discuss these points and substantiate their impact on model evaluation using the example of sea ice. For this example, I find that many standard metrics such as sea-ice area or volume only permit limited inferences about the shortcomings of individual models. },
author = {Notz, Dirk},
doi = {10.1098/rsta.2014.0164},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
number = {2052},
pages = {20140164},
title = {{How well must climate models agree with observations?}},
url = {https://royalsocietypublishing.org/doi/abs/10.1098/rsta.2014.0164},
volume = {373},
year = {2015}
}
@article{Nummelin2017,
abstract = {Under greenhouse warming, climate models simulate a weakening of the Atlantic Meridional Overturning Circulation and the associated ocean heat transport at midlatitudes but an increase in the ocean heat transport to the Arctic Ocean. These opposing trends lead to what could appear to be a discrepancy in the reported ocean contribution to Arctic amplification. This study clarifies how ocean heat transport affects Arctic climate under strong greenhouse warming using a set of the 21st century simulations performed within the Coupled Model Intercomparison Project. The results suggest that a future reduction in subpolar ocean heat loss enhances ocean heat transport to the Arctic Ocean, driving an increase in Arctic Ocean heat content and contributing to the intermodel spread in Arctic amplification. The results caution against extrapolating the forced oceanic signal from the midlatitudes to the Arctic.},
author = {Nummelin, Aleksi and Li, Camille and Hezel, Paul J.},
doi = {10.1002/2016GL071333},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {Arctic amplification,CMIP5,RCP8.5,ocean heat content trend,ocean warming trend,transient greenhouse warming},
number = {4},
pages = {1899--1908},
title = {{Connecting ocean heat transport changes from the midlatitudes to the Arctic Ocean}},
url = {http://doi.wiley.com/10.1002/2016GL071333},
volume = {44},
year = {2017}
}
@article{OBrien2014,
abstract = {The western warm pools of the Atlantic and Pacific oceans are a critical source of heat and moisture for the tropical climate system. Over the past five million years, global mean temperatures have cooled by 3-4 °C. Yet, present reconstructions of sea surface temperatures indicate that temperature in the warm pools has remained stable during this time. This stability has been used to suggest that tropical sea surface temperatures are controlled by a thermostat-like mechanism that maintained consistent temperatures. Here we reconstruct sea surface temperatures in the South China Sea, Caribbean Sea and western equatorial Pacific Ocean for the past five million years, using a combination of the Mg/Ca-, TEX86H - and UK′37-surface-temperature proxies. Our data indicate that during the period of Pliocene warmth from about 5 to 2.6 million years ago, the western Pacific and western Atlantic warm pools were about 2 °C warmer than today. We suggest that the apparent lack of warmth seen in the previous reconstructions was an artefact of low seawater Mg/Ca ratios in the Pliocene oceans. Taking this bias into account, our data indicate that tropical sea surface temperatures did change in conjunction with global mean temperatures. We therefore conclude that the temperature of the warm pools of the equatorial oceans during the Pliocene was not limited by a thermostat-like mechanism. {\textcopyright} 2014 Macmillan Publishers Limited.},
author = {O'Brien, Charlotte L. and Foster, Gavin L. and Mart{\'{i}}nez-Bot{\'{i}}, Miguel A. and Abell, Richard and Rae, James W.B. and Pancost, Richard D.},
doi = {10.1038/ngeo2194},
issn = {17520908},
journal = {Nature Geoscience},
month = {jun},
number = {8},
pages = {606--611},
publisher = {Nature Publishing Group},
title = {{High sea surface temperatures in tropical warm pools during the Pliocene}},
url = {http://dx.doi.org/10.1038/ngeo2194 http://10.0.4.14/ngeo2194 https://www.nature.com/articles/ngeo2194{\#}supplementary-information},
volume = {7},
year = {2014}
}
@article{OConnor9999,
abstract = {Abstract. Quantifying forcings from anthropogenic perturbations to the Earth system (ES) is important for understanding changes in climate since the pre-industrial (PI) period. Here, we quantify and analyse a wide range of present-day (PD) anthropogenic effective radiative forcings (ERFs) with the UK's Earth System Model (ESM), UKESM1, following the protocols defined by the Radiative Forcing Model Intercomparison Project (RFMIP) and the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP). In particular, quantifying ERFs that include rapid adjustments within a full ESM enables the role of various chemistry–aerosol–cloud interactions to be investigated. Global mean ERFs for the PD (year 2014) relative to the PI (year 1850) period for carbon dioxide (CO2), nitrous oxide (N2O), ozone-depleting substances (ODSs), and methane (CH4) are 1.89 ± 0.04, 0.25 ± 0.04, −0.18 ± 0.04, and 0.97 ± 0.04 W m−2, respectively. The total greenhouse gas (GHG) ERF is 2.92 ± 0.04 W m−2. UKESM1 has an aerosol ERF of −1.09 ± 0.04 W m−2. A relatively strong negative forcing from aerosol–cloud interactions (ACI) and a small negative instantaneous forcing from aerosol–radiation interactions (ARI) from sulfate and organic carbon (OC) are partially offset by a substantial forcing from black carbon (BC) absorption. Internal mixing and chemical interactions imply that neither the forcing from ARI nor ACI is linear, making the aerosol ERF less than the sum of the individual speciated aerosol ERFs. Ozone (O3) precursor gases consisting of volatile organic compounds (VOCs), carbon monoxide (CO), and nitrogen oxides (NOx), but excluding CH4, exert a positive radiative forcing due to increases in O3. However, they also lead to oxidant changes, which in turn cause an indirect aerosol ERF. The net effect is that the ERF from PD–PI changes in NOx emissions is negligible at 0.03 ± 0.04 W m−2, while the ERF from changes in VOC and CO emissions is 0.33 ± 0.04 W m−2. Together, aerosol and O3 precursors (called near-term climate forcers (NTCFs) in the context of AerChemMIP) exert an ERF of −1.03 ± 0.04 W m−2, mainly due to changes in the cloud radiative effect (CRE). There is also a negative ERF from land use change (−0.17 ± 0.04 W m−2). When adjusted from year 1850 to 1700, it is more negative than the range of previous estimates, and is most likely due to too strong an albedo response. In combination, the net anthropogenic ERF (1.76 ± 0.04 W m−2) is consistent with other estimates. By including interactions between GHGs, stratospheric and tropospheric O3, aerosols, and clouds, this work demonstrates the importance of ES interactions when quantifying ERFs. It also suggests that rapid adjustments need to include chemical as well as physical adjustments to fully account for complex ES interactions.},
author = {O'Connor, Fiona M. and Abraham, N. Luke and Dalvi, Mohit and Folberth, Gerd A. and Griffiths, Paul T. and Hardacre, Catherine and Johnson, Ben T. and Kahana, Ron and Keeble, James and Kim, Byeonghyeon and Morgenstern, Olaf and Mulcahy, Jane P. and Richardson, Mark and Robertson, Eddy and Seo, Jeongbyn and Shim, Sungbo and Teixeira, Jo{\~{a}}o C. and Turnock, Steven T. and Williams, Jonny and Wiltshire, Andrew J. and Woodward, Stephanie and Zeng, Guang},
doi = {10.5194/acp-21-1211-2021},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
number = {2},
pages = {1211--1243},
title = {{Assessment of pre-industrial to present-day anthropogenic climate forcing in UKESM1}},
url = {https://acp.copernicus.org/articles/21/1211/2021/},
volume = {21},
year = {2021}
}
@article{OGorman2013,
abstract = {Warming in climate-change simulations reaches a local maximum in the tropical upper troposphere as expected from moist-adiabatic lapse rates. But the structure of warming varies between models and differs substantially from moist adiabatic in the extratropics. Here, we relate the vertical profile of warming to the climatological temperature profile using the vertical-shift transformation (VST). The VST captures much of the intermodel scatter in the ratio of upper- to middle-tropospheric warming in both the extratropics and tropics of simulations from the Coupled Model Intercomparison Project 5 (CMIP5). Application of the VST to observed climatological temperatures yields warming ratios that are in the range of what is obtained from the model climatological temperatures, although biases in some model climatologies lead to substantial errors when shifted upward. Radiosonde temperature trends are consistent with an upward shift in recent decades in the Northern Hemisphere, with less-robust results in the Southern Hemisphere.},
annote = {doi: 10.1002/grl.50328},
author = {O'Gorman, Paul A and Singh, Martin S},
doi = {10.1002/grl.50328},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {Climate models,Radiosondes,Tropospheric warming,Upward shift},
month = {may},
number = {9},
pages = {1838--1842},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Vertical structure of warming consistent with an upward shift in the middle and upper troposphere}},
url = {https://doi.org/10.1002/grl.50328},
volume = {40},
year = {2013}
}
@article{Oishi2009,
abstract = {An atmosphere-ocean-vegetation coupled model is used to quantify the biogeophysical feedback that emerges as vegetation adjusts dynamically to a quadrupling of atmospheric CO2. This feedback amplifies global warming by 13{\%}. About half of it is due to climatically induced expansion of boreal forest into tundra, reinforced by reductions in snow and sea ice cover. The other half represents a global climatic effect of increased vegetative cover (an indirect consequence of plant physiological responses to CO2) in the semi-arid subtropics. Enhanced absorption of shortwave radiation in these regions produces a net surface warming, which the atmosphere communicates poleward. The greatest vegetation-induced warming is co-located with large, vulnerable carbon stores in the north. These lose carbon, so that in the long term, the biospheric response to CO2 and climate change becomes dominated by positive feedbacks that overwhelm the effect of CO2 fertilization on terrestrial carbon stocks. Citation: O'ishi, R., A. Abe-Ouchi, I. C. Prentice, and S. Sitch (2009), Vegetation dynamics and plant CO2 responses as positive feedbacks in a greenhouse world, Geophys. Res. Lett., 36, L11706, doi: 10.1029/2009GL038217.},
author = {O'ishi, Ryouta and Abe-Ouchi, Ayako and Prentice, I. Colin and Sitch, Stephen},
doi = {10.1029/2009GL038217},
issn = {00948276},
journal = {Geophysical Research Letters},
number = {11},
pages = {1--5},
title = {{Vegetation dynamics and plant CO2 responses as positive feedbacks in a greenhouse world}},
volume = {36},
year = {2009}
}
@article{ISI:000250954200054,
abstract = {The effect of climate change in the 20th century is investigated based on measured massbalance data. Annual, winter and summer mass balances on Claridenfirn, Switzerland, (since 1914/15) Storglaciaren, Sweden, (since 1945/46) Storbreen, Norway, (since 1948/49) Glacier de Sarennes, France, (since 1948/49) and Vernagtferner, Austria, (since 1965/66) are studied with air temperature at high-altitude stations and the longest records of solar global radiation in Europe. The mean mass balances of these glaciers during the 20th century were mostly negative except for the first two decades. The fluctuating mass balance reaches the minimum (largest loss) and maximum (almost equilibrium) around 1940 and 1980, respectively, with a drastic loss in the last 15 years. These variations are mostly steered by the variation in summer mass balance. The change in the summer mass balance is determined to 72{\%} by temperature and the remaining 28{\%} by solar radiation. During the colder period (e.g. 196080), the reduction in solar radiation counteracted the warming trend due to the greenhouse effect. Since 1990 the greenhouse effect of terrestrial radiation and the global brightening effect of solar radiation have both been acting to accelerate the melt, resulting in the unprecedented mass loss of the observational era. The glacier mass balance during the 20th century clearly reacted towards temperature and solar radiation changes, which reflected the greenhouse effect and aerosol and cloud variations.},
author = {Ohmura, Atsumu and Bauder, Andreas and Mueller, Hans and Kappenberger, Giovanni},
doi = {10.3189/172756407782871297},
editor = {Sharp, M},
institution = {Int Glaciol Soc; British Antarct Res; IUGG Commiss Cryospher Sci; World Climate Res Program Climate {\&} Cryosphere Project},
isbn = {978-0-946417-41-4},
issn = {0260-3055},
journal = {Annals of Glaciology},
pages = {367--374},
title = {{Long-term change of mass balance and the role of radiation}},
volume = {46},
year = {2007}
}
@article{Ohno2019,
abstract = {Abstract In this study, the vertical resolution dependency of the high-cloud fraction response on the increase in sea surface temperature was investigated via radiative-convective equilibrium simulations. We performed radiative-convective equilibrium simulations for configurations with a wide range of vertical resolutions using a global nonhydrostatic model including explicit cloud microphysics. It was found that the high-cloud cover almost monotonically decreased as the vertical resolution increased. We also found that the high-cloud cover increased (decreased) as the sea surface temperature increased for higher (lower) vertical resolutions. Budget analyses of ice water condensate in transition states to equilibria were performed using the binned vertical profile method and revealed that the tendencies due to the turbulent mixing near convective cores were strongly dependent on the vertical resolution. Analyses of turbulent diffusivity profiles showed that the diffusivity tended to decrease as the vertical resolution increased. The vertical resolution dependency of turbulent mixing was related to frequently occurring weak stratification near the convective cores. We verified these findings via sensitivity experiments and determined that the contribution of the vertical resolution dependency of other processes was secondary. As substantial variability in vertical diffusivity has been reported in both models and observations, these results suggest that a more thorough understanding of turbulent mixing is needed to comprehend high-cloud changes in warming climates better.},
author = {Ohno, Tomoki and Satoh, Masaki and Noda, Akira},
doi = {10.1029/2019MS001704},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {climate sensitivity,global cloud-resolving model,high-cloud response,radiative-convective equilibrium},
month = {jun},
number = {6},
pages = {1637--1654},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Fine Vertical Resolution Radiative-Convective Equilibrium Experiments: Roles of Turbulent Mixing on the High-Cloud Response to Sea Surface Temperatures}},
url = {https://doi.org/10.1029/2019MS001704},
volume = {11},
year = {2019}
}
@article{Oldenburg2018,
abstract = {Abstract Northward ocean heat transport (OHT) plays a key role in Arctic climate variability and change. Unforced climate model simulations suggest that at decadal and longer timescales, strengthened Atlantic Meridional Overturning Circulation (AMOC) is correlated with increased OHT into the Arctic. Yet, greenhouse-gas (GHG) forced simulations predict increased Arctic OHT while AMOC weakens. Here we partition OHT changes into contributions from ‘dynamic' circulation changes and ‘thermodynamic' temperature advection, as well as meridional overturning and gyre changes. We find that under decadal-scale internal variability, strengthened AMOC converges heat in the subpolar gyre; anomalous heat is advected into the Arctic by both time-mean circulations and strengthened gyre circulations. Under GHG forcing, weakened AMOC reduces subpolar gyre heat convergence; yet Arctic OHT increases as mean overturning and strengthened gyre circulations advect warmed surface waters. Thus, caution should be exercised when inferring Arctic OHT from AMOC, as the relationship between OHT and AMOC changes depends on whether they are internally generated or externally forced.},
author = {Oldenburg, Dylan and Armour, Kyle C. and Thompson, LuAnne and Bitz, Cecilia M.},
doi = {10.1029/2018GL078719},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {aug},
number = {15},
pages = {7692--7700},
title = {{Distinct Mechanisms of Ocean Heat Transport Into the Arctic Under Internal Variability and Climate Change}},
url = {http://doi.wiley.com/10.1029/2018GL078719},
volume = {45},
year = {2018}
}
@article{Olonscheck2019,
abstract = {The anthropogenically forced decline of Arctic sea ice is superimposed on strong internal variability. Possible drivers for this variability include fluctuations in surface albedo, clouds and water vapour, surface winds and poleward atmospheric and oceanic energy transport, but their relative contributions have not been quantified. By isolating the impact of the individual drivers in an Earth system model, we here demonstrate that internal variability of sea ice is primarily caused directly by atmospheric temperature fluctuations. The other drivers together explain only 25{\%} of sea-ice variability. The dominating impact of atmospheric temperature fluctuations on sea ice is consistent across observations, reanalyses and simulations from global climate models. Such atmospheric temperature fluctuations occur due to variations in moist-static energy transport or local ocean heat release to the atmosphere. The fact that atmospheric temperature fluctuations are the key driver for sea-ice variability limits prospects of interannual predictions of sea ice, and suggests that observed record lows in Arctic sea-ice area are a direct response to an unusually warm atmosphere.},
author = {Olonscheck, Dirk and Mauritsen, Thorsten and Notz, Dirk},
doi = {10.1038/s41561-019-0363-1},
issn = {1752-0908},
journal = {Nature Geoscience},
number = {6},
pages = {430--434},
title = {{Arctic sea-ice variability is primarily driven by atmospheric temperature fluctuations}},
url = {https://doi.org/10.1038/s41561-019-0363-1},
volume = {12},
year = {2019}
}
@article{Olonscheck2020,
abstract = {Using seven single-model ensembles and the two multimodel ensembles CMIP5 and CMIP6, we show that observed and simulated trends in sea surface temperature (SST) patterns are globally consistent when accounting for internal variability. Some individual ensemble members simulate trends in large-scale SST patterns that closely resemble the observed ones. Observed regional trends that lie at the outer edge of the models' internal variability range allow two nonexclusive interpretations: (a) Observed trends are unusual realizations of the Earth's possible behavior and/or (b) the models are systematically biased but large internal variability leads to some good matches with the observations. The existing range of multidecadal SST trends is influenced more strongly by large internal variability than by differences in the model formulation or the observational data sets.},
author = {Olonscheck, Dirk and Rugenstein, Maria and Marotzke, Jochem},
doi = {10.1029/2019GL086773},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {global climate models,internal variability,large ensembles,model evaluation,sea surface temperature patterns},
month = {may},
number = {10},
pages = {e2019GL086773},
publisher = {Blackwell Publishing Ltd},
title = {{Broad Consistency Between Observed and Simulated Trends in Sea Surface Temperature Patterns}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2019GL086773},
volume = {47},
year = {2020}
}
@article{Otto2013c,
abstract = {To the Editor — The rate of global mean warming has been lower over the past decade than previously. It has been argued1–5 that this observation might require a downwards revision of estimates of equilibrium climate sensitivity, that is, the long-term (equilibrium) temperature response to a doubling of atmospheric CO2 concentrations. Using up-to-date data on radiative forcing, global mean surface temperature and total heat uptake in the Earth system, we find that the global energy budget6 implies a range of values for the equilibrium climate sensitivity that is in agreement with earlier estimates, within the limits of uncertainty. The energy budget of the most recent decade does, however, indicate a lower range of values for the more policy-relevant7 transient climate response (the temperature increase at the point of doubling of the atmospheric CO2 concentration following a linear ramp of increasing greenhouse gas forcing) than the range obtained by either analysing the energy budget of earlier decades or current climate model simulations8.},
author = {Otto, Alexander and Otto, Friederike E. L. and Boucher, Olivier and Church, John and Hegerl, Gabi and Forster, Piers M. and Gillett, Nathan P. and Gregory, Jonathan and Johnson, Gregory C. and Knutti, Reto and Lewis, Nicholas and Lohmann, Ulrike and Marotzke, Jochem and Myhre, Gunnar and Shindell, Drew and Stevens, Bjorn and Allen, Myles R.},
doi = {10.1038/ngeo1836},
isbn = {1752-0894},
issn = {1752-0894},
journal = {Nature Geoscience},
number = {6},
pages = {415--416},
publisher = {Nature Publishing Group},
title = {{Energy budget constraints on climate response}},
url = {http://www.nature.com/doifinder/10.1038/ngeo1836},
volume = {6},
year = {2013}
}
@article{doi:10.1002/2016GL071805,
abstract = {Abstract Under previous reconstructions of late Pliocene boundary conditions, climate models have failed to reproduce the warm sea surface temperatures reconstructed in the North Atlantic. Using a reconstruction of mid-Piacenzian paleogeography that has the Bering Strait and Canadian Arctic Archipelago Straits closed, however, improves the simulation of the proxy-indicated warm sea surface temperatures in the North Atlantic in the Community Climate System Model. We find that the closure of these small Arctic gateways strengthens the Atlantic Meridional Overturning Circulation, by inhibiting freshwater transport from the Pacific to the Arctic Ocean and from the Arctic Ocean to the Labrador Sea, leading to warmer sea surface temperatures in the North Atlantic. This indicates that the state of the Arctic gateways may influence the sensitivity of the North Atlantic climate in complex ways, and better understanding of the state of these Arctic gateways for past time periods is needed.},
author = {Otto-Bliesner, Bette L and Jahn, Alexandra and Feng, Ran and Brady, Esther C and Hu, Aixue and L{\"{o}}fverstr{\"{o}}m, Marcus},
doi = {10.1002/2016GL071805},
journal = {Geophysical Research Letters},
keywords = {Arctic,Pliocene,climate modeling},
number = {2},
pages = {957--964},
title = {{Amplified North Atlantic warming in the late Pliocene by changes in Arctic gateways}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016GL071805},
volume = {44},
year = {2017}
}
@article{Padilla2011,
abstract = {In this paper, the authors address the impact of uncertainty on estimates of transient climate sensitivity (TCS) of the globally averaged surface temperature, including both uncertainty in past forcing and internal variability in the climate record. This study provides a range of probabilistic estimates of the TCS that combine these two sources of uncertainty for various underlying assumptions about the nature of the uncertainty. The authors also provide estimates of how quickly the uncertainty in the TCS may be expected to diminish in the future as additional observations become available. These estimates are made using a nonlinear Kalman filter coupled to a stochastic, global energy balance model, using the filter and observations to constrain the model parameters. This study verifies that model and filter are able to emulate the evolution of a comprehensive, state-of-the-art atmosphere–ocean general circulation model and to accurately predict the TCS of the model, and then apply the methodology to observed temperature and forcing records of the twentieth century.},
author = {Padilla, Lauren E. and Vallis, Geoffrey K. and Rowley, Clarence W.},
doi = {10.1175/2011JCLI3989.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Carbon dioxide,Climate sensitivity,Energy budget/balance,Forcing,Surface temperature},
month = {nov},
number = {21},
pages = {5521--5537},
title = {{Probabilistic Estimates of Transient Climate Sensitivity Subject to Uncertainty in Forcing and Natural Variability}},
url = {http://journals.ametsoc.org/doi/10.1175/2011JCLI3989.1},
volume = {24},
year = {2011}
}
@article{Palmer2017,
abstract = {The purpose of this review is to summarise the recent literature and scientific challenges on the topic of reconciling estimates of ocean heating rates with satellite-based monitoring of Earth's radiation budget (ERB), including discussion of the satellite record and in situ ocean observing system.},
author = {Palmer, Matthew D},
doi = {10.1007/s40641-016-0053-7},
issn = {2198-6061},
journal = {Current Climate Change Reports},
month = {mar},
number = {1},
pages = {78--86},
title = {{Reconciling Estimates of Ocean Heating and Earth's Radiation Budget}},
url = {https://doi.org/10.1007/s40641-016-0053-7},
volume = {3},
year = {2017}
}
@article{1748-9326-9-3-034016,
abstract = {We analyse a large number of multi-century pre-industrial control simulations from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) to investigate relationships between: net top-of-atmosphere radiation (TOA), globally averaged surface temperature (GST), and globally integrated ocean heat content (OHC) on decadal timescales. Consistent with previous studies, we find that large trends (∼0.3 K dec −1 ) in GST can arise from internal climate variability and that these trends are generally an unreliable indicator of TOA over the same period. In contrast, trends in total OHC explain 95{\%} or more of the variance in TOA for two-thirds of the models analysed; emphasizing the oceans' role as Earth's primary energy store. Correlation of trends in total system energy (TE ≡ time integrated TOA) against trends in OHC suggests that for most models the ocean becomes the dominant term in the planetary energy budget on a timescale of about 12 months. In the context of the recent pause in global surface temperature rise, we investigate the potential importance of internal climate variability in both TOA and ocean heat rearrangement. The model simulations suggest that both factors can account for O (0.1 W m −2 ) on decadal timescales and may play an important role in the recently observed trends in GST and 0–700 m (and 0–1800 m) ocean heat uptake.},
author = {Palmer, M D and McNeall, D J},
doi = {https://doi.org/10.1088/1748-9326/9/3/034016},
journal = {Environmental Research Letters},
number = {3},
pages = {34016},
title = {{Internal variability of Earth's energy budget simulated by CMIP5 climate models}},
volume = {9},
year = {2014}
}
@article{1748-9326-13-8-084003,
abstract = {We present a physically-based emulator approach to extending 21st century CMIP5 model simulations of global mean surface temperature (GMST) and global thermal expansion (TE) to 2300. A two-layer energy balance model that has been tuned to emulate the CO 2 response of individual CMIP5 models is combined with model-specific radiative forcings to generate an emulated ensemble to 2300 for RCP2.6, RCP4.5 and RCP8.5. Errors in the emulated time series are quantified using a subset of CMIP5 models with data available to 2300 and factored into the ensemble uncertainty. The resulting projections show good agreement with 21st century ensemble projections reported in IPCC AR5 and also compare favourably with individual CMIP5 model simulations post-2100. There is a tendency for the two-layer model simulations to overestimate both GMST rise and TE under RCP2.6, which is suggestive of a systematic error in the applied radiative forcings. Overall, the framework shows promise as a basis for extending process-based projections of global sea level rise beyond the 21st century time horizon that typifies CMIP5 simulations. The results also serve to illustrate the differing responses of GMST and Earth's energy imbalance (EEI) to reductions in greenhouse gas emissions. GMST responds relatively quickly to changes in emissions, leading to a negative trend post-2100 for RCP2.6, although temperature remains substantially elevated compared to present day at 2300. In contrast, EEI remains positive under all RCPs, and results in ongoing sea level rise from TE.},
author = {Palmer, Matthew D and Harris, Glen R and Gregory, Jonathan M},
doi = {https://doi.org/10.1088/1748-9326/aad2e4},
journal = {Environmental Research Letters},
number = {8},
pages = {84003},
title = {{Extending CMIP5 projections of global mean temperature change and sea level rise due to thermal expansion using a physically-based emulator}},
volume = {13},
year = {2018}
}
@article{Palmer2020a,
author = {Palmer, M D and Domingues, C M and Slangen, A B A and {Boeira Dias}, F.},
doi = {10.1088/1748-9326/abdaec},
issn = {1748-9326},
journal = {Environmental Research Letters},
month = {apr},
number = {4},
pages = {044043},
title = {{An ensemble approach to quantify global mean sea-level rise over the 20th century from tide gauge reconstructions}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/abdaec},
volume = {16},
year = {2021}
}
@article{Parding2014a,
abstract = {The observed variability of shortwave (SW) irradiance, clouds and temperature and the potential connections between them is studied for the subarctic site Bergen (60.4 degrees N, 5.3 degrees E), located on the Norwegian west coast. Focusing on the quality and spatial representativity of the data, we compare observations from independent instruments and neighbouring measurement sites. The observations indicate that the decrease of sunshine duration and SW irradiance during the 1970s and 80s in Bergen is associated with the increasing frequency of clouds, in particular clouds of low base heights. We argue that the observed cloud changes are indicative of increased frequencies of storms in northern Europe. The annual mean observational time series show an increase in SW irradiance since 1990, which is not accompanied by a cloud cover (NN) decrease. This implies the influence of factors other than clouds, for example, decreasing aerosol emissions. Calculations of the aerosol optical depth (AOD) based on irradiance observations for hours when the sun is unobscured by clouds confirm a decreasing aerosol load after 1990, from 0.15 to 0.10 AOD which corresponds to 2-6 Wm(-2) of brightening. At the same time, a seasonal analysis reveals opposite changes in SW irradiance and NN during the months of strongest changes - March, April and August - also during the recent period of increasing SW irradiance. We conclude that the seasonally decreasing NN also contributes to the recent changes in SW irradiance. Finally, we address the relationship between temperature, SW irradiance and clouds. In winter (December-February), the surface air temperature in Bergen is statistically linked to the warming influence of clouds. In all other seasons, the North Atlantic sea surface temperature variability has a more dominant influence on the air temperature in Bergen compared to local cloud and SW irradiance variability.},
address = {Parding, K Norwegian Meteorol Inst, Oslo, Norway Norwegian Meteorol Inst, Oslo, Norway Univ Bergen, Inst Geophys, Bergen, Norway Norwegian Meteorol Inst, Oslo, Norway NorthWest Res Associates, Redmond, WA USA},
annote = {Ax3ln
Times Cited:0
Cited References Count:34},
author = {Parding, Kajsa and Olseth, Jan A and Dagestad, Knut F and Liepert, Beate G},
doi = {10.3402/tellusb.v66.25897},
issn = {1600-0889},
journal = {Tellus B: Chemical and Physical Meteorology},
keywords = {clouds solar irradiance global dimming and brighte},
language = {English},
month = {jan},
number = {1},
pages = {25897},
title = {{Decadal variability of clouds, solar radiation and temperature at a high-latitude coastal site in Norway}},
url = {https://www.tandfonline.com/doi/full/10.3402/tellusb.v66.25897},
volume = {66},
year = {2014}
}
@article{Park5921,
abstract = {One of the important impacts of marine phytoplankton on climate systems is the geophysical feedback by which chlorophyll and the related pigments in phytoplankton absorb solar radiation and then change sea surface temperature. Yet such biogeophysical impact is still not considered in many climate projections by state-of-the-art climate models, nor is its impact on the future climate quantified. This study shows that, by conducting global warming simulations with and without an active marine ecosystem model, the biogeophysical effect of future phytoplankton changes amplifies Arctic warming by 20{\%}. Given the close linkage between the Arctic and global climate, the biologically enhanced Arctic warming can significantly modify future estimates of global climate change, and therefore it needs to be considered as a possible future scenario.Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical{\{}$\backslash$textendash{\}}ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean-atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes.},
author = {Park, Jong-Yeon and Kug, Jong-Seong and Bader, J{\"{u}}rgen and Rolph, Rebecca and Kwon, Minho},
doi = {10.1073/pnas.1416884112},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {19},
pages = {5921--5926},
publisher = {National Academy of Sciences},
title = {{Amplified Arctic warming by phytoplankton under greenhouse warming}},
url = {https://www.pnas.org/content/112/19/5921},
volume = {112},
year = {2015}
}
@article{Pattyn2018a,
abstract = {Even if anthropogenic warming were constrained to less than 2 °C above pre-industrial, the Greenland and Antarctic ice sheets will continue to lose mass this century, with rates similar to those observed over the past decade. However, nonlinear responses cannot be excluded, which may lead to larger rates of mass loss. Furthermore, large uncertainties in future projections still remain, pertaining to knowledge gaps in atmospheric (Greenland) and oceanic (Antarctica) forcing. On millennial timescales, both ice sheets have tipping points at or slightly above the 1.5–2.0 °C threshold; for Greenland, this may lead to irreversible mass loss due to the surface mass balance–elevation feedback, whereas for Antarctica, this could result in a collapse of major drainage basins due to ice-shelf weakening.},
author = {Pattyn, Frank and Ritz, Catherine and Hanna, Edward and Asay-Davis, Xylar and DeConto, Rob and Durand, Ga{\"{e}}l and Favier, Lionel and Fettweis, Xavier and Goelzer, Heiko and Golledge, Nicholas R and {Kuipers Munneke}, Peter and Lenaerts, Jan T M and Nowicki, Sophie and Payne, Antony J and Robinson, Alexander and Seroussi, H{\'{e}}l{\`{e}}ne and Trusel, Luke D and van den Broeke, Michiel},
doi = {10.1038/s41558-018-0305-8},
issn = {1758-6798},
journal = {Nature Climate Change},
number = {12},
pages = {1053--1061},
title = {{The Greenland and Antarctic ice sheets under 1.5 °C global warming}},
url = {https://doi.org/10.1038/s41558-018-0305-8},
volume = {8},
year = {2018}
}
@article{Pauling2017,
abstract = {The possibility that recent Antarctic sea ice expansion resulted from an increase in freshwater reaching the Southern Ocean is investigated here. The freshwater flux from ice sheet and ice shelf mass imbalance is largely missing in models that participated in phase 5 of the Coupled Model Intercomparison Project (CMIP5). However, on average, precipitation minus evaporation (P − E) reaching the Southern Ocean has increased in CMIP5 models to a present value that is about greater than preindustrial times and 5–22 times larger than estimates of the mass imbalance of Antarctic ice sheets and shelves (119–544 ). Two sets of experiments were conducted from 1980 to 2013 in CESM1(CAM5), one of the CMIP5 models, artificially distributing freshwater either at the ocean surface to mimic iceberg melt or at the ice shelf fronts at depth. An anomalous reduction in vertical advection of heat into the surface mixed layer resulted in sea surface cooling at high southern latitudes and an associated increase in sea i...},
author = {Pauling, Andrew G. and Smith, Inga J. and Langhorne, Patricia J. and Bitz, Cecilia M.},
doi = {10.1002/2017GL075017},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {Antarctica,climate models,freshwater input,latent heat,sea ice,sea ice area trends},
month = {oct},
number = {20},
pages = {10454--10461},
title = {{Time-Dependent Freshwater Input From Ice Shelves: Impacts on Antarctic Sea Ice and the Southern Ocean in an Earth System Model}},
url = {http://doi.wiley.com/10.1002/2017GL075017},
volume = {44},
year = {2017}
}
@article{Paulot2018,
abstract = {We present estimates of changes in the direct aerosol effects (DRE) and its anthropogenic component (DRF) from 2001 to 2015 using the GFDL chemistry-climate model AM3 driven by CMIP6 historical emissions. AM3 is evaluated against observed changes in the clear-sky shortwave direct aerosol effect (DREswclr) derived from the Clouds and the Earth's Radiant Energy System (CERES) over polluted regions. From 2001 to 2015, observations suggest that DREclrsw increases (i.e., less radiation is scattered to space by aerosols) over western Europe (0.7-1Wm'2decade'1) and the eastern US (0.9-1.4Wm'2decade'1), decreases over India ('1 to'1.6Wm'2decade'1), and does not change significantly over eastern China. AM3 captures these observed regional changes in DREclrsw well in the US and western Europe, where they are dominated by the decline of sulfate aerosols, but not in Asia, where the model overestimates the decrease of DREclrsw. Over India, the model bias can be partly attributed to a decrease of the dust optical depth, which is not captured by our model and offsets some of the increase of anthropogenic aerosols. Over China, we find that the decline of SO2 emissions after 2007 is not represented in the CMIP6 emission inventory. Accounting for this decline, using the Modular Emission Inventory for China, and for the heterogeneous oxidation of SO2 significantly reduces the model bias. For both India and China, our simulations indicate that nitrate and black carbon contribute more to changes in DREclrsw than in the US and Europe. Indeed, our model suggests that black carbon (+0.12Wm'2) dominates the relatively weak change in DRF from 2001 to 2015 (+0.03Wm'2). Over this period, the changes in the forcing from nitrate and sulfate are both small and of the same magnitude ('0.03Wm'2 each). This is in sharp contrast to the forcing from 1850 to 2001 in which forcings by sulfate and black carbon largely cancel each other out, with minor contributions from nitrate. The differences between these time periods can be well understood from changes in emissions alone for black carbon but not for nitrate and sulfate; this reflects non-linear changes in the photochemical production of nitrate and sulfate associated with changes in both the magnitude and spatial distribution of anthropogenic emissions.},
author = {Paulot, Fabien and Paynter, David and Ginoux, Paul and Naik, Vaishali and Horowitz, Larry W.},
doi = {10.5194/acp-18-13265-2018},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
month = {sep},
number = {17},
pages = {13265--13281},
publisher = {Copernicus GmbH},
title = {{Changes in the aerosol direct radiative forcing from 2001 to 2015: Observational constraints and regional mechanisms}},
volume = {18},
year = {2018}
}
@article{Payne-2015,
abstract = {Abstract The role of temperature feedbacks in polar amplification of climate change is examined by comparing the response of idealized high- and low-latitude atmospheric columns to greenhouse gas forcing. An analytic expression for the surface polar amplification factor is derived with a one-layer atmospheric model and compared to a more detailed column model with two radiative transfer schemes. The modeled temperature profiles result from competition between the stabilizing influences of atmospheric heat flux convergence and atmospheric solar heating (dominant at high latitudes), and the destabilizing influence of surface solar heating (dominant at low latitudes). For a stable high-latitude radiative-advective atmosphere, the lapse rate increases with greenhouse gas forcing, leading to a positive feedback, and is dependent on the nature of the forcing—pointing to limitations of the traditional forcing-feedback framework. For a low-latitude radiative-convective atmosphere, the lapse rate decreases, leading to a negative feedback.},
author = {Payne, Ashley E and Jansen, Malte F and Cronin, Timothy W},
doi = {10.1002/2015GL065889},
journal = {Geophysical Research Letters},
keywords = {lapse rate feedback,polar amplification,temperature feedbacks},
number = {21},
pages = {9561--9570},
title = {{Conceptual model analysis of the influence of temperature feedbacks on polar amplification}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2015GL065889},
volume = {42},
year = {2015}
}
@article{Paynter2018a,
abstract = {Equilibrium climate sensitivity (ECS), defined as the long-term change in global mean surface air temperature in response to doubling atmospheric CO2, is usually computed from short atmospheric simulations over a mixed layer ocean, or inferred using a linear regression over a short-time period of adjustment. We report the actual ECS from multimillenial simulations of two Geophysical Fluid Dynamics Laboratory (GFDL) general circulation models (GCMs), ESM2M, and CM3 of 3.3 K and 4.8 K, respectively. Both values are {\~{}}1 K higher than estimates for the same models reported in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change obtained by regressing the Earth's energy imbalance against temperature. This underestimate is mainly due to changes in the climate feedback parameter (−$\alpha$) within the first century after atmospheric CO2 has stabilized. For both GCMs it is possible to estimate ECS with linear regression to within 0.3 K by increasing CO2 at 1{\%} per year to doubling and using years 51–350 after CO2 is constant. We show that changes in −$\alpha$ differ between the two GCMs and are strongly tied to the changes in both vertical velocity at 500 hPa ($\omega$500) and estimated inversion strength that the GCMs experience during the progression toward the equilibrium. This suggests that while cloud physics parametrizations are important for determining the strength of −$\alpha$, the substantially different atmospheric state resulting from a changed sea surface temperature pattern may be of equal importance.},
author = {Paynter, D. and Fr{\"{o}}licher, T. L. and Horowitz, L. W. and Silvers, L. G.},
doi = {10.1002/2017JD027885},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {ECS,climate feedback,global warming},
number = {4},
pages = {1921--1941},
title = {{Equilibrium Climate Sensitivity Obtained From Multimillennial Runs of Two GFDL Climate Models}},
volume = {123},
year = {2018}
}
@article{Peng2016a,
abstract = {Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.},
author = {Peng, Jianfei and Hu, Min and Guo, Song and Du, Zhuofei and Zheng, Jing and Shang, Dongjie and {Levy Zamora}, Misti and Zeng, Limin and Shao, Min and Wu, Yu-Sheng and Zheng, Jun and Wang, Yuan and Glen, Crystal R and Collins, Donald R and Molina, Mario J and Zhang, Renyi},
doi = {10.1073/pnas.1602310113},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
keywords = {absorption,air quality,black carbon,climate,radiative forcing},
month = {apr},
number = {16},
pages = {4266--4271},
publisher = {National Academy of Sciences},
title = {{Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments}},
url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1602310113},
volume = {113},
year = {2016}
}
@article{Penner2011,
abstract = {Satellite-based estimates of the aerosol indirect effect (AIE) are consistently smaller than the estimates from global aerosol models, and, partly as a result of these differences, the assessment of this climate forcing includes large uncertainties. Satellite estimates typically use the present-day (PD) relationship between observed cloud drop number concentrations (N(c)) and aerosol optical depths (AODs) to determine the preindustrial (PI) values of N(c). These values are then used to determine the PD and PI cloud albedos and, thus, the effect of anthropogenic aerosols on top of the atmosphere radiative fluxes. Here, we use a model with realistic aerosol and cloud processes to show that empirical relationships for ln(N(c)) versus ln(AOD) derived from PD results do not represent the atmospheric perturbation caused by the addition of anthropogenic aerosols to the preindustrial atmosphere. As a result, the model estimates based on satellite methods of the AIE are between a factor of 3 to more than a factor of 6 smaller than model estimates based on actual PD and PI values for N(c). Using ln(N(c)) versus ln(AI) (Aerosol Index, or the optical depth times angstrom exponent) to estimate preindustrial values for N(c) provides estimates for N(c) and forcing that are closer to the values predicted by the model. Nevertheless, the AIE using ln(N(c)) versus ln(AI) may be substantially incorrect on a regional basis and may underestimate or overestimate the global average forcing by 25 to 35{\%}.},
author = {Penner, Joyce E and Xu, Li and Wang, Minghuai},
doi = {10.1073/pnas.1018526108},
issn = {1091-6490},
journal = {Proceedings of the National Academy of Sciences},
month = {aug},
number = {33},
pages = {13404--13408},
pmid = {21808047},
publisher = {National Academy of Sciences},
title = {{Satellite methods underestimate indirect climate forcing by aerosols}},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21808047 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC3158199},
volume = {108},
year = {2011}
}
@article{Penner2018,
abstract = {We have implemented a parameterization for forming ice in large-scale cirrus clouds that accounts for the changes in updrafts associated with a spectrum of waves acting within each time step in the model. This allows us to account for the frequency of homogeneous and heterogeneous freezing events that occur within each time step of the model and helps to determine more realistic ice number concentrations as well as changes to ice number concentrations. The model is able to fit observations of ice number at the lowest temperatures in the tropical tropopause but is still somewhat high in tropical latitudes with temperatures between 195°K and 215°K. The climate forcings associated with different representations of heterogeneous ice nuclei (IN or INPs) are primarily negative unless large additions of IN are made, such as when we assumed that all aircraft soot acts as an IN. However, they can be close to zero if it is assumed that all background dust can act as an INP irrespective of how much sulfate is deposited on these particles. Our best estimate for the forcing of anthropogenic aircraft soot in this model is −0.2 ± 0.06 W/m 2 , while that from anthropogenic fossil/biofuel soot is −0.093 ± 0.033 W/m 2 . Natural and anthropogenic open biomass burning leads to a net forcing of −0.057 ± 0.05 W/m 2 .},
author = {Penner, Joyce E. and Zhou, Cheng and Garnier, Anne and Mitchell, David L.},
doi = {10.1029/2018JD029204},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {cirrus cloud formation,climate forcing,gravity waves,heterogeneous ice nuclei},
month = {oct},
number = {20},
pages = {11652--11677},
publisher = {Blackwell Publishing Ltd},
title = {{Anthropogenic Aerosol Indirect Effects in Cirrus Clouds}},
volume = {123},
year = {2018}
}
@article{Persad2018a,
abstract = {The distribution of anthropogenic aerosols' climate effects depends on the geographic distribution of the aerosols themselves. Yet many scientific and policy discussions ignore the role of emission location when evaluating aerosols' climate impacts. Here, we present new climate model results demonstrating divergent climate responses to a fixed amount and composition of aerosol—emulating China's present-day emissions—emitted from 8 key geopolitical regions. The aerosols' global-mean cooling effect is fourteen times greater when emitted from the highest impact emitting region (Western Europe) than from the lowest (India). Further, radiative forcing, a widely used climate response proxy, fails as an effective predictor of global-mean cooling for national-scale aerosol emissions in our simulations; global-mean forcing-to-cooling efficacy differs fivefold depending on emitting region. This suggests that climate accounting should differentiate between aerosols emitted from different countries and that aerosol emissions' evolving geographic distribution will impact the global-scale magnitude and spatial distribution of climate change.},
author = {Persad, Geeta G. and Caldeira, Ken},
doi = {10.1038/s41467-018-05838-6},
issn = {2041-1723},
journal = {Nature Communications},
month = {dec},
number = {1},
pages = {3289},
title = {{Divergent global-scale temperature effects from identical aerosols emitted in different regions}},
url = {http://www.nature.com/articles/s41467-018-05838-6},
volume = {9},
year = {2018}
}
@article{Persad2014a,
abstract = {Surface-based observations indicate a significant decreasing trend in clear-sky downward surface solar radiation (SSR) over East Asia since the 1960s. This "dimming" is thought to be driven by the region's long-term increase in aerosol emissions, but little work has been done to quantify the underlying physical mechanisms or the contribution from aerosol absorption within the atmospheric column. Given the distinct climate impacts that absorption-driven dimming may produce, this constitutes an important, but thus far rather neglected, line of inquiry. We examine experiments conducted in the Geophysical Fluid Dynamics Laboratory's atmospheric general circulation models, AM2.1 and AM3, in order to analyze the model-simulated East Asian clear-sky SSR trends. We also use the models' stand-alone radiation module to examine the contribution from various aerosol characteristics in the two models (such as burden, mixing state, hygroscopicity, and seasonal distribution) to the trends. Both models produce trends in clear-sky SSR that are comparable to that observed but via disparate mechanisms. Despite their different aerosol characteristics, the models produce nearly identical increases in aerosol absorption since the 1960s, constituting as much as half of the modeled clear-sky dimming. This is due to a compensation between the differences in aerosol column burden and mixing state assumed in the two models, i.e., plausible clear-sky SSR simulations can be achieved via drastically different aerosol parameterizations. Our novel results indicate that trends in aerosol absorption drive a large portion of East Asian clear-sky solar dimming in the models presented here and for the time periods analyzed and that mechanistic analysis of the factors involved in aerosol absorption is an important diagnostic in evaluating modeled clear-sky solar dimming trends.},
address = {Persad, GG Princeton Univ, Program Atmospher {\&} Ocean Sci, Princeton, NJ 08544 USA Princeton Univ, Program Atmospher {\&} Ocean Sci, Princeton, NJ 08544 USA Princeton Univ, Program Atmospher {\&} Ocean Sci, Princeton, NJ 08544 USA NOAA, Geophys Fluid Dynam Lab,},
annote = {Aq6in
Times Cited:0
Cited References Count:74},
author = {Persad, G G and Ming, Y and Ramaswamy, V},
doi = {10.1002/2014jd021577},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {black carbon hydrological cycle anthropogenic sulf},
language = {English},
number = {17},
pages = {10410--10424},
title = {{The role of aerosol absorption in driving clear-sky solar dimming over East Asia}},
volume = {119},
year = {2014}
}
@article{Peters2011,
abstract = {The Kyoto Protocol compares greenhouse gas emissions (GHGs) using the global warming potential (GWP) with a 100 yr time-horizon. The GWP was developed, however, to illustrate the difficulties in comparing GHGs. In response, there have been many critiques of the GWP and several alternative emission metrics have been proposed. To date, there has been little focus on understanding the linkages between, and interpretations of, different emission metrics. We use an energy balance model to mathematically link the absolute GWP, absolute global temperature change potential (AGTP), absolute ocean heat perturbation (AOHP), and integrated AGTP. For pulse emissions, energy conservation requires that AOHP = AGWP − iAGTP/$\lambda$ and hence AGWP and iAGTP are closely linked and converge as AOHP decays to zero. When normalizing the metrics with CO 2 (GWP, GTP, and iGTP), we find that the iGTP and GWP are similar numerically for a wide range of GHGs and time-horizons, except for very short-lived species. The similarity between the iGTP X and GWP X depends on how well a pulse emission of CO 2 can substitute for a pulse emission of X across a range of time-horizons. The ultimate choice of emission metric(s) and time-horizon(s) depends on policy objectives. To the extent that limiting integrated temperature change over a specific time-horizon is consistent with the broader objectives of climate policy, our analysis suggests that the GWP represents a relatively robust, transparent and policy-relevant emission metric.},
author = {Peters, Glen P and Aamaas, Borgar and Berntsen, Terje and Fuglestvedt, Jan S},
doi = {10.1088/1748-9326/6/4/044021},
issn = {1748-9326},
journal = {Environmental Research Letters},
month = {dec},
number = {4},
pages = {044021},
title = {{The integrated global temperature change potential (iGTP) and relationships between emission metrics}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/6/4/044021},
volume = {6},
year = {2011}
}
@article{Petersik2018,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Atmosphere models with resolutions of several tens of kilometres take subgrid-scale variability in the total specific humidity {\textless}i{\textgreater}q{\textless}/i{\textgreater}{\textless}sub{\textgreater}t{\textless}/sub{\textgreater} into account by using a uniform probability density function (PDF) to predict fractional cloud cover. However, usually only mean relative humidity, {\textless}span style="text-decoration: overline;"{\textgreater}RH{\textless}/span{\textgreater}, or mean clear-sky relative humidity, {\textless}span style="text-decoration: overline;"{\textgreater}RH{\textless}/span{\textgreater}{\textless}sub{\textgreater}cls{\textless}/sub{\textgreater}, is used to compute hygroscopic growth of soluble aerosol particles. While previous studies based on limited-area models and also a global model suggest that subgrid-scale variability in RH should be taken into account for estimating radiative forcing due to aerosol–radiation interactions (RFari), here we present the first estimate of RFari using a global atmospheric model with a parameterization for subgrid-scale variability in RH that is consistent with the assumptions in the model. For this, we sample the subsaturated part of the uniform RH-PDF from the cloud cover scheme for its application in the hygroscopic growth parameterization in the ECHAM6-HAM2 atmosphere model. Due to the non-linear dependence of the hygroscopic growth on RH, this causes an increase in aerosol hygroscopic growth. Aerosol optical depth (AOD) increases by a global mean of 0.009 ( ∼ 7.8 {\textless}i{\textgreater}{\%}{\textless}/i{\textgreater} in comparison to the control run). Especially over the tropics AOD is enhanced with a mean of about 0.013. Due to the increase in AOD, net top of the atmosphere clear-sky solar radiation, SW{\textless}sub{\textgreater}net, cls{\textless}/sub{\textgreater}, decreases by −0.22{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater} ( ∼ −0.08 {\textless}i{\textgreater}{\%}{\textless}/i{\textgreater}). Finally, the RFari changes from −0.15 to −0.19{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}W m{\textless}sup{\textgreater}−2{\textless}/sup{\textgreater}{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater} by about 31{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}. The reason for this very disproportionate effect is that anthropogenic aerosols are disproportionally hygroscopic.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Petersik, Paul and Salzmann, Marc and Kretzschmar, Jan and Cherian, Ribu and Mewes, Daniel and Quaas, Johannes},
doi = {10.5194/acp-18-8589-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jun},
number = {12},
pages = {8589--8599},
title = {{Subgrid-scale variability in clear-sky relative humidity and forcing by aerosol–radiation interactions in an atmosphere model}},
url = {https://www.atmos-chem-phys.net/18/8589/2018/},
volume = {18},
year = {2018}
}
@article{ISI:000426074000016,
abstract = {The incoming solar radiation is the essential climate variable that determines the Earth's energy cycle and climate. As long-term high-quality surface measurements of solar radiation are rare, satellite data are used to derive more information on its spatial pattern and its temporal variability. Recently, the EUMETSAT Satellite Application on Climate Monitoring (CMSAF) has published two satellite-based climate data records: Surface Solar Radiation Data Set-Heliosat, Edition 2 (SARAH-2), and Clouds and Radiation Data Set based on AVHRR (advanced very high resolution radiometer) Satellite Measurements, Edition 2 (CLARA-A2). Both data records provide estimates of surface solar radiation. In this study, these new climate data records are compared to surface measurements in Europe during the period 1983-2015. SARAH-2 and CLARA-A2 show a high accuracy compared to ground-based observations (mean absolute deviations of 6.9 and 7.3W/m(2), respectively) highlighting a good agreement considering the temporal behavior and the spatial distribution. The results show an overall brightening period since the 1980s onward (comprised between 1.9 and 2.4W/m(2)/decade), with substantial decadal and spatial variability. The strongest brightening is found in eastern Europe in spring. An exception is found for northern and southern Europe, where the trends shown by the station data are not completely reproduced by satellite data, especially in summer in southern Europe. We conclude that the major part of the observed trends in surface solar radiation in Europe is caused by changes in clouds and that remaining differences between the satellite- and the station-based data might be connected to changes in the direct aerosol effect and in snow cover. Plain Language Summary The incoming solar radiation is the essential climate variable that determines the Earth's climate. As surface measurements of solar radiation are rare, satellite data are used to derive more information in space and time. Recently, the EUMETSAT Satellite Application on Climate Monitoring (CM SAF) has published two new satellite-based climate data records: Surface Solar Radiation Data Set-Heliosat, Edition 2 (SARAH-2), and Clouds and Radiation Data Set based on AVHRR (advanced very high resolution radiometer) Satellite Measurements, Edition 2 (CLARA-A2). Both satellite-based data records provide estimates of surface solar radiation and can capture what is observed by station measurements in Europe. The proven high accuracy of the CM SAF's climate data records allows the detailed analysis of surface solar radiation during the last three decades. A positive trend is observed by the station and satellite data, meaning surface radiation has increased since the 1980s, mainly in eastern and northwestern Europe. Some discrepancies between satellite and station data are found in the Mediterranean summer likely due to aerosol effects. It is concluded that the main reason for the observed positive trend in surface solar radiation in Europe since the 1980s is a change in clouds.},
address = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
author = {Pfeifroth, Uwe and Sanchez-Lorenzo, Arturo and Manara, Veronica and Trentmann, Joerg and Hollmann, Rainer},
doi = {10.1002/2017JD027418},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {satellite,surface solar radiation,trend analysis},
month = {feb},
number = {3},
pages = {1735--1754},
publisher = {AMER GEOPHYSICAL UNION},
title = {{Trends and Variability of Surface Solar Radiation in Europe Based On Surface- and Satellite-Based Data Records}},
type = {Article},
volume = {123},
year = {2018}
}
@article{Pfister2017,
author = {Pfister, Patrik L. and Stocker, Thomas F.},
doi = {10.1002/2017GL075457},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {ECS,EMIC,climate sensitivity,feedback,sea ice,state dependence},
number = {20},
pages = {10643--10653},
title = {{State-Dependence of the Climate Sensitivity in Earth System Models of Intermediate Complexity}},
volume = {44},
year = {2017}
}
@article{Pierce2017,
author = {Pierce, J. R.},
doi = {10.1002/2017JD027475},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {aug},
number = {15},
pages = {8051--8055},
title = {{Cosmic rays, aerosols, clouds, and climate: Recent findings from the CLOUD experiment}},
url = {http://doi.wiley.com/10.1002/2017JD027475},
volume = {122},
year = {2017}
}
@article{Pierrehumbert2014,
abstract = {Although carbon dioxide emissions are by far the most important mediator of anthropogenic climate disruption, a number of shorter-lived substances with atmospheric lifetimes of under a few decades also contribute significantly to the radiative forcing that drives climate change. In recent years, the argument that early and aggressive mitigation of the emission of these substances or their precursors forms an essential part of any climate protection strategy has gained a considerable following. There is often an implication that such control can in some way make up for the current inaction on carbon dioxide emissions. The prime targets for mitigation, known collectively as short-lived climate pollution (SLCP), are methane, hydrofluo-rocarbons, black carbon, and ozone. A re-examination of the issues shows that the benefits of early SLCP mitigation have been greatly exaggerated, largely because of inadequacies in the methodologies used to compare the climate effects of short-lived substances with those of CO...},
author = {Pierrehumbert, R.T.},
doi = {10.1146/annurev-earth-060313-054843},
isbn = {978-0-8243-2042-3},
issn = {0084-6597},
journal = {Annual Review of Earth and Planetary Sciences},
number = {1},
pages = {341--379},
title = {{Short-Lived Climate Pollution}},
volume = {42},
year = {2014}
}
@article{Pincus2015,
abstract = {Abstract This article reports on the accuracy in aerosol- and cloud-free conditions of the radiation parameterizations used in climate models. Accuracy is assessed relative to observationally validated reference models for fluxes under present-day conditions and forcing (flux changes) from quadrupled concentrations of carbon dioxide. Agreement among reference models is typically within 1 W/m2, while parameterized calculations are roughly half as accurate in the longwave and even less accurate, and more variable, in the shortwave. Absorption of shortwave radiation is underestimated by most parameterizations in the present day and has relatively large errors in forcing. Error in present-day conditions is essentially unrelated to error in forcing calculations. Recent revisions to parameterizations have reduced error in most cases. A dependence on atmospheric conditions, including integrated water vapor, means that global estimates of parameterization error relevant for the radiative forcing of climate change will require much more ambitious calculations.},
annote = {doi: 10.1002/2015GL064291},
author = {Pincus, Robert and Mlawer, Eli J and Oreopoulos, Lazaros and Ackerman, Andrew S and Baek, Sunghye and Brath, Manfred and Buehler, Stefan A and Cady-Pereira, Karen E and Cole, Jason N S and Dufresne, Jean-Louis and Kelley, Maxwell and Li, Jiangnan and Manners, James and Paynter, David J and Roehrig, Romain and Sekiguchi, Miho and Schwarzkopf, Daniel M},
doi = {10.1002/2015GL064291},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {Parameterization,Radiation,Radiative forcing},
month = {jul},
number = {13},
pages = {5485--5492},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Radiative flux and forcing parameterization error in aerosol-free clear skies}},
url = {https://doi.org/10.1002/2015GL064291},
volume = {42},
year = {2015}
}
@article{Pincus2016a,
abstract = {The phrasing of the first of three questions motivating CMIP6 – "How does the Earth system respond to forcing?" – suggests that forcing is always well-known, but in fact forcing has historically been uncertain even in coordinated experiments such as CMIP. The Radiative Forcing Model Intercomparison Project endorsed by CMIP6 seeks to provide a foundation for answering the question for forcing and response through three related activities: (i) accurate characterization of the effective radiative forcing relative to a near pre-industrial baseline, and careful diagnosis of the components of this forcing; (ii) assessment of the absolute accuracy of clear-sky radiative transfer parameterizations against reference models on the global scales relevant for climate modeling; and (iii) identification of robust model responses to a tightly-specified aerosol radiative forcing from 1850 to present. Complete characterization of effective radiative forcing can be accomplished with 180 years (Tier 1) of atmosphere-only simulation using a sea-surface temperature and sea ice concentration climatology derived from the host model's pre-industrial control simulation. Assessment of parameterization error requires trivial amounts of computation but the development of small amounts of infrastructure: new, spectrally-detailed diagnostic output requested as two snapshots at present-day and preindustrial conditions, and results from the model's radiation code applied to specified atmospheric conditions. The search for robust responses to aerosol changes rely on the CMIP6 specification of anthropogenic aerosol properties; models using this specification can contribute to RFMIP with no additional simulation, while those using a full aerosol model are requested to perform at least one, and up to four, 165-year coupled ocean-atmosphere simulations at Tier 1.},
author = {Pincus, Robert and Forster, Piers M. and Stevens, Bjorn},
doi = {10.5194/gmd-9-3447-2016},
isbn = {1991-9603},
issn = {19919603},
journal = {Geoscientific Model Development},
number = {9},
pages = {3447--3460},
title = {{The Radiative Forcing Model Intercomparison Project (RFMIP): Experimental protocol for CMIP6}},
volume = {9},
year = {2016}
}
@article{Pincus9999,
abstract = {Changes in concentrations of greenhouse gases lead to changes in radiative fluxes throughout the atmosphere. The value of this change, the instantaneous radiative forcing, varies across climate models, due partly to differences in the distribution of clouds, humidity, and temperature across models and partly due to errors introduced by approximate treatments of radiative transfer. This paper describes an experiment within the Radiative Forcing Model Intercomparision Project that uses benchmark calculations made with line-by-line models to identify parameterization error in the representation of absorption and emission by greenhouse gases. Clear-sky instantaneous forcing by greenhouse gases is computed using a set of 100 profiles, selected from a reanalysis of present-day conditions, that represent the global annual mean forcing from preindustrial times to the present day with sampling errors of less than 0.01 W m−2. Six contributing line-by-line models agree in their estimate of this forcing to within 0.025 W m−2 while even recently developed parameterizations have typical errors 4 or more times larger, suggesting both that the samples reveal true differences among line-by-line models and that parameterization error will be readily identifiable. Agreement among line-by-line models is better in the longwave than in the shortwave where differing treatments of the water vapor continuum affect estimates of forcing by carbon dioxide and methane. The impacts of clouds on instantaneous radiative forcing are estimated from climate model simulations, and the adjustment due to stratospheric temperature changes estimated by assuming fixed dynamical heating. Adjustments are large only for ozone and for carbon dioxide, for which stratospheric cooling introduces modest nonlinearity.},
author = {Pincus, Robert and Buehler, Stefan A. and Brath, Manfred and Crevoisier, Cyril and Jamil, Omar and {Franklin Evans}, K. and Manners, James and Menzel, Raymond L. and Mlawer, Eli J. and Paynter, David and Pernak, Rick L. and Tellier, Yoann},
doi = {10.1029/2020JD033483},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {CMIP6,RFMIP,effective radiative forcing,line by line},
number = {23},
pages = {1--15},
title = {{Benchmark Calculations of Radiative Forcing by Greenhouse Gases}},
volume = {125},
year = {2020}
}
@article{Piston14,
author = {Pistone, Kristina and Eisenman, Ian and Ramanathan, V},
doi = {10.1073/pnas.1318201111},
journal = {Proceedings of the National Academy of Sciences},
number = {9},
pages = {3322--3326},
title = {{Observational determination of albedo decrease caused by vanishing Arctic sea ice}},
url = {http://www.pnas.org/content/early/2014/02/13/1318201111.abstract},
volume = {111},
year = {2014}
}
@article{Pithan2014b,
abstract = {Climate change is amplified in the Arctic region. Arctic amplification has been found in past warm1 and glacial2 periods, as well as in historical observations3,4 and climate model experiments5,6 . Feedback effects associated with tem- perature, water vapour and clouds have been suggested to contribute to amplified warming in the Arctic, but the surface albedo feedback—the increase in surface absorption of solar radiation when snow and ice retreat—is often cited as the main contributor7–10 . However, Arctic amplification is also found in models without changes in snow and ice cover11,12 . Here we analyse climate model simulations from the Coupled Model Intercomparison Project Phase 5 archive to quantify the contributions of the various feedbacks. We find that in the simulations, the largest contribution to Arctic amplification comes from a temperature feedbacks: as the surface warms, more energy is radiated back to space in low latitudes, compared with the Arctic. This effect can be attributed to both the different vertical structure of the warming in high and low latitudes, and a smaller increase in emitted blackbody radiation per unit warming at colder temperatures. We find that the surface albedo feedback is the second main contributor to Arctic amplification and that other contributions are},
author = {Pithan, Felix and Mauritsen, Thorsten},
doi = {10.1038/ngeo2071},
isbn = {doi:10.1038/ngeo2071},
issn = {17520908},
journal = {Nature Geoscience},
number = {3},
pages = {181--184},
title = {{Arctic amplification dominated by temperature feedbacks in contemporary climate models}},
volume = {7},
year = {2014}
}
@article{Po-Chedley2018a,
abstract = {Sources of intermodel differences in the global lapse rate (LR) and water vapor (WV) feedbacks are assessed using CO2 forcing simulations from 28 general circulation models. Tropical surface warming leads to significant warming and moistening in the tropical and extratropical upper troposphere, signifying a nonlocal, tropical influence on extratropical radiation and feedbacks. Model spread in the locally defined LR and WV feedbacks is pronounced in the Southern Ocean because of large-scale ocean upwelling, which reduces surface warming and decouples the surface from the tropospheric response. The magnitude of local extratropical feedbacks across models and over time is well characterized using the ratio of tropical to extratropical surface warming. It is shown that model differences in locally defined LR and WV feedbacks, particularly over the southern extratropics, drive model variability in the global feedbacks. The cross-model correlation between the global LR and WV feedbacks therefore does not arise from their covariation in the tropics, but rather from the pattern of warming exerting a common control on extratropical feedback responses. Because local feedbacks over the Southern Hemisphere are an important contributor to the global feedback, the partitioning of surface warming between the tropics and the southern extratropics is a key determinant of the spread in the global LR and WV feedbacks. It is also shown that model Antarctic sea ice climatology influences sea ice area changes and southern extratropical surface warming. As a result, model discrepancies in climatological Antarctic sea ice area have a significant impact on the intermodel spread of the global LR and WV feedbacks.},
author = {Po-Chedley, Stephen and Armour, Kyle C. and Bitz, Cecilia M. and Zelinka, Mark D. and Santer, Benjamin D. and Fu, Qiang},
doi = {10.1175/JCLI-D-17-0674.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Climate change,Climate models,Climate sensitivity},
month = {apr},
number = {8},
pages = {3187--3206},
title = {{Sources of Intermodel Spread in the Lapse Rate and Water Vapor Feedbacks}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0674.1},
volume = {31},
year = {2018}
}
@article{Po-Chedley2018,
author = {Po-Chedley, Stephen and Proistosescu, Cristian and Armour, Kyle C and Santer, Benjamin D},
doi = {10.1038/s41586-018-0640-y},
issn = {1476-4687},
journal = {Nature},
number = {7729},
pages = {E6--E9},
title = {{Climate constraint reflects forced signal}},
url = {https://doi.org/10.1038/s41586-018-0640-y},
volume = {563},
year = {2018}
}
@article{Popp2016,
author = {Popp, Max and Schmidt, Hauke and Marotzke, Jochem},
doi = {https://doi.org/10.1038/ncomms10627},
journal = {Nature Communications},
month = {feb},
pages = {10627},
publisher = {The Author(s)},
title = {{Transition to a Moist Greenhouse with CO2 and solar forcing}},
volume = {7},
year = {2016}
}
@article{Port2012,
abstract = {Abstract. In this study, vegetation–climate and vegetation–carbon cycle interactions during anthropogenic climate change are assessed by using the Earth System Model of the Max Planck Institute for Meteorology (MPI ESM) that includes vegetation dynamics and an interactive carbon cycle. We assume anthropogenic CO2 emissions according to the RCP 8.5 scenario in the time period from 1850 to 2120. For the time after 2120, we assume zero emissions to evaluate the response of the stabilising Earth System by 2300. Our results suggest that vegetation dynamics have a considerable influence on the changing global and regional climate. In the simulations, global mean tree cover extends by 2300 due to increased atmospheric CO2 concentration and global warming. Thus, land carbon uptake is higher and atmospheric CO2 concentration is lower by about 40 ppm when considering dynamic vegetation compared to the static pre-industrial vegetation cover. The reduced atmospheric CO2 concentration is equivalent to a lower global mean temperature. Moreover, biogeophysical effects of vegetation cover shifts influence the climate on a regional scale. Expanded tree cover in the northern high latitudes results in a reduced albedo and additional warming. In the Amazon region, declined tree cover causes a regional warming due to reduced evapotranspiration. As a net effect, vegetation dynamics have a slight attenuating effect on global climate change as the global climate cools by 0.22 K due to natural vegetation cover shifts in 2300.},
author = {Port, U. and Brovkin, V. and Claussen, M.},
doi = {10.5194/esd-3-233-2012},
isbn = {2190-4987},
issn = {21904979},
journal = {Earth System Dynamics},
number = {2},
pages = {233--243},
title = {{The influence of vegetation dynamics on anthropogenic climate change}},
volume = {3},
year = {2012}
}
@article{Posselt2014a,
abstract = {Long-term observations of the surface radiation budget are essential for climate monitoring, climate model evaluation and solar energy applications. The Satellite Application Facility on Climate Monitoring (CM SAF) released a climate data record (CDR) of global and direct surface irradiance as well as effective cloud albedo derived from observations of the Meteosat First Generation satellites (MFG, 1983-2005). This study presents an extension of this CDR using measurements from the Meteosat Second Generation satellites (MSG, 2004-present). This extended surface radiation dataset spans nearly 30 years of data and, therefore, is in its uniquely high temporal and spatial resolution a valuable contribution to the climate community. In order to enable climatological consistency and homogeneity, the retrieval algorithm had to be modified for MSG: 1. The two narrowband visible channels of the MSG satellites are combined to simulate the MFG broadband visible channel; 2. The maximum cloud reflectance is empirically adjusted to account for the differences in the dynamic range of MSG compared to MFG. The extended dataset is tested for homogeneity and no significant breaks are detected during the overlap period of 2004-2005. Validation of the extended global radiation dataset against ground based observations from the Baseline Surface Radiation Network yields a mean monthly absolute bias of 8.15 W m(-2). This complies with the target accuracy threshold of 15 W m(-2) defined by the Global Climate Observing System. Global radiation has an overall positive, and significant, trend over the Meteosat disk which is mainly due to a negative trend in the effective cloud albedo, i.e., a decrease in cloudiness. Trends due to changes in the clear sky radiation are small and only induced by trends in the water vapor fields. Trends caused by changes in the direct effects of atmospheric aerosol are not represented because an aerosol climatology is used. (C) 2013 The Authors. Published by Elsevier Inc All rights reserved.},
address = {Posselt, R Fed Off Meteorol {\&} Climatol MeteoSwiss, Zurich, Switzerland Fed Off Meteorol {\&} Climatol MeteoSwiss, Zurich, Switzerland Fed Off Meteorol {\&} Climatol MeteoSwiss, Zurich, Switzerland German Meteorol Serv, Offenbach, Germany},
annote = {Aa3vm
Times Cited:0
Cited References Count:26},
author = {Posselt, R and Mueller, R and Trentrnann, J and Stockli, R and Liniger, M A},
doi = {10.1016/J.Rse.2013.11.007},
issn = {0034-4257},
journal = {Remote Sensing of Environment},
keywords = {solar surface irradiance climate data records sate},
language = {English},
pages = {103--110},
title = {{A surface radiation climatology across two Meteosat satellite generations}},
volume = {142},
year = {2014}
}
@article{doi:10.1029/2019GL084786,
author = {Po‐Chedley, Stephen and Zelinka, Mark D. and Jeevanjee, Nadir and Thorsen, Tyler J. and Santer, Benjamin D.},
doi = {10.1029/2019GL084786},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {nov},
number = {22},
pages = {13399--13409},
title = {{Climatology Explains Intermodel Spread in Tropical Upper Tropospheric Cloud and Relative Humidity Response to Greenhouse Warming}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2019GL084786},
volume = {46},
year = {2019}
}
@article{ISI:000362661800002,
abstract = {The authors evaluate 23 coupled atmosphere-ocean general circulation models from phase 5 of CMIP (CMIP5) in terms of their ability to simulate the observed climatological mean energy budget of the Antarctic atmosphere. While the models are shown to capture the gross features of the energy budget well {\{}[{\}}e.g., the observed two-way balance between the top-of-atmosphere (TOA) net radiation and horizontal convergence of atmospheric energy transport], the simulated TOA absorbed shortwave (SW) radiation is too large during austral summer. In the multimodel mean, this excessive absorption reaches approximately 10 W m(-2), with even larger biases (up to 25-30 W m(-2)) in individual models. Previous studies have identified similar climate model biases in the TOA net SW radiation at Southern Hemisphere midlatitudes and have attributed these biases to errors in the simulated cloud cover. Over the Antarctic, though, model cloud errors are of secondary importance, and biases in the simulated TOA net SW flux are instead driven mainly by biases in the clear-sky SW reflection. The latter are likely related in part to the models' underestimation of the observed annual minimum in Antarctic sea ice extent, thus underscoring the importance of sea ice in the Antarctic energy budget. Finally, substantial differences in the climatological surface energy fluxes between existing observational datasets preclude any meaningful assessment of model skill in simulating these fluxes.},
author = {Previdi, Michael and Smith, Karen L and Polvani, Lorenzo M},
doi = {10.1175/JCLI-D-15-0027.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {20},
pages = {7933--7942},
title = {{How Well Do the CMIP5 Models Simulate the Antarctic Atmospheric Energy Budget?}},
volume = {28},
year = {2015}
}
@article{Proistosescu2018,
abstract = {Estimates of radiative feedbacks obtained by regressing fluctuations in top?of?atmosphere (TOA) energy imbalance and surface temperature depend critically on the sampling interval and on assumptions about the nature of the stochastic forcing driving internal variability. Here we develop an energy balance framework that allows us to model the different impacts of stochastic atmospheric and oceanic forcing on feedback estimates. The contribution of different forcing components is parsed based on their impacts on the covariance structure of near?surface air temperature and TOA energy fluxes, and the framework is validated in a hierarchy of climate model simulations that span a range of oceanic configurations and reproduce the key features seen in observations. We find that at least three distinct forcing sources, feedbacks, and time scales are needed to explain the full covariance structure. Atmospheric and oceanic forcings drive modes of variability with distinct relationships between temperature and TOA radiation, leading to an effect akin to regression dilution. The net regression?based feedback estimate is found to be a weighted average of the distinct feedbacks associated with each mode. Moreover, the estimated feedback depends on whether surface temperature and TOA energy fluxes are sampled at monthly or annual time scales. The results suggest that regression?based feedback estimates reflect contributions from a combination of stochastic forcings and should not be interpreted as providing an estimate of the radiative feedback governing the climate response to greenhouse gas forcing.},
author = {Proistosescu, Cristian and Donohoe, Aaron and Armour, Kyle C. and Roe, Gerard H. and Stuecker, Malte F. and Bitz, Cecilia M.},
doi = {10.1029/2018GL077678},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate sensitivity,natural variability,radiative feedbacks,stochastic processes},
month = {may},
number = {10},
pages = {5082--5094},
title = {{Radiative Feedbacks From Stochastic Variability in Surface Temperature and Radiative Imbalance}},
url = {http://doi.wiley.com/10.1029/2018GL077678},
volume = {45},
year = {2018}
}
@article{Proistosescu2017b,
abstract = {The latest Intergovernmental Panel on Climate Change Assessment Report widened the equilibrium climate sensitivity (ECS) range from 2° to 4.5°C to an updated range of 1.5° to 4.5°C in order to account for the lack of consensus between estimates based on models and historical observations. The historical ECS estimates range from 1.5° to 3°C and are derived assuming a linear radiative response to warming. A Bayesian methodology applied to 24 models, however, documents curvature in the radiative response to warming from an evolving contribution of interannual to centennial modes of radiative response. Centennial modes display stronger amplifying feedbacks and ultimately contribute 28 to 68{\%} (90{\%} credible interval) of equilibrium warming, yet they comprise only 1 to 7{\%} of current warming. Accounting for these unresolved centennial contributions brings historical records into agreement with model-derived ECS estimates.},
archivePrefix = {arXiv},
arxivId = {NIHMS150003},
author = {Proistosescu, Cristian and Huybers, Peter J.},
doi = {10.1126/sciadv.1602821},
eprint = {NIHMS150003},
isbn = {1424410606},
issn = {23752548},
journal = {Science Advances},
number = {7},
pages = {1--7},
pmid = {8629022},
title = {{Slow climate mode reconciles historical and model-based estimates of climate sensitivity}},
volume = {3},
year = {2017}
}
@article{Purich2018,
abstract = {The Southern Ocean surface has freshened in recent decades, increasing water column stability and reducing upwelling of warmer subsurface waters. The majority of CMIP5 models underestimate or fail to capture this historical surface freshening, yet little is known about the impact of this model bias on regional ocean circulation and hydrography. Here experiments are performed using a global coupled climate model with additional freshwater applied to the Southern Ocean to assess the influence of recent surface freshening. The simulations explore the impact of persistent and long-term broad-scale freshening as a result of processes including precipitation minus evaporation changes. Thus, unlike previous studies, the freshening is applied as far north as 55°S, beyond the Antarctic ice margin. It is found that imposing a large-scale surface freshening causes a surface cooling and sea ice increase under preindustrial conditions, because of a reduction in ocean convection and weakened entrainment of warm subsurface waters into the surface ocean. This is consistent with intermodel relationships between CMIP5 models and the simulations, suggesting that models with larger surface freshening also exhibit stronger surface cooling and increased sea ice. Additional experiments are conducted with surface salinity restoration applied to capture observed regional salinity trends. Remarkably, without any mechanical wind trend forcing, these simulations accurately represent the spatial pattern of observed surface temperature and sea ice trends around Antarctica. This study highlights the importance of accurately simulating changes in Southern Ocean salinity to capture changes in ocean circulation, sea surface temperature, and sea ice.},
author = {Purich, Ariaan and England, Matthew H. and Cai, Wenju and Sullivan, Arnold and Durack, Paul J.},
doi = {10.1175/JCLI-D-17-0092.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Antarctica,Coupled models,Precipitation,Southern Ocean},
month = {apr},
number = {7},
pages = {2613--2632},
title = {{Impacts of Broad-Scale Surface Freshening of the Southern Ocean in a Coupled Climate Model}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0092.1},
volume = {31},
year = {2018}
}
@article{Qian2015,
abstract = {Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.},
author = {Qian, Yun and Yasunari, Teppei J. and Doherty, Sarah J. and Flanner, Mark G. and Lau, William K.M. and Ming, Jing and Wang, Hailong and Wang, Mo and Warren, Stephen G. and Zhang, Rudong},
doi = {10.1007/s00376-014-0010-0},
issn = {18619533},
journal = {Advances in Atmospheric Sciences},
keywords = {aerosol,albedo,climate,hydrological cycle,ice,light-absorbing,measurement,modeling,snow},
month = {jan},
number = {1},
pages = {64--91},
publisher = {Science Press},
title = {{Light-absorbing particles in snow and ice: Measurement and modeling of climatic and hydrological impact}},
url = {https://link.springer.com/article/10.1007/s00376-014-0010-0},
volume = {32},
year = {2015}
}
@article{Qu2018,
abstract = {AbstractDifferences among climate models in equilibrium climate sensitivity (ECS, the equilibrium surface temperature response to a doubling of atmospheric CO2) remain a significant barrier to the accurate assessment of societally-important impacts of climate change. Relationships between ECS and observable metrics of the current climate in model ensembles, so-called emergent constraints, have been used to constrain ECS. Here a statistical method (including a backward selection process) is employed to achieve a better statistical understanding of the connections between four recently proposed emergent constraint metrics and individual feedbacks influencing ECS. The relationship between each metric and ECS is largely attributable to a statistical connection with shortwave low cloud feedback, the leading cause of intermodel ECS spread. This result bolsters confidence in some of the metrics, which had assumed such a connection in the first place. Additional analysis is conducted with a few thousand artificia...},
author = {Qu, Xin and Hall, Alex and DeAngelis, Anthony M. and Zelinka, Mark D. and Klein, Stephen A. and Su, Hui and Tian, Baijun and Zhai, Chengxing},
doi = {10.1175/JCLI-D-17-0482.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Climate change,Climate models,Climate sensitivity,Clouds,Feedback},
number = {2},
pages = {863--875},
title = {{On the emergent constraints of climate sensitivity}},
volume = {31},
year = {2018}
}
@article{QuHall07,
abstract = {The strength of snow-albedo feedback (SAF) in transient climate change simulations of the Fourth Assessment of the Intergovernmental Panel on Climate Change is generally determined by the surface-albedo decrease associated with a loss of snow cover rather than the reduction in snow albedo due to snow metamorphosis in a warming climate. The large intermodel spread in SAF strength is likewise attributable mostly to the snow cover component. The spread in the strength of this component is in turn mostly attributable to a correspondingly large spread in mean effective snow albedo. Models with large effective snow albedos have a large surface-albedo contrast between snow-covered and snow-free regions and exhibit a correspondingly large surface-albedo decrease when snow cover decreases. Models without explicit treatment of the vegetation canopy in their surface-albedo calculations typically have high effective snow albedos and strong SAF, often stronger than observed. In models with explicit canopy treatment, completely snow-covered surfaces typically have lower albedos and the simulations have weaker SAF, generally weaker than observed. The authors speculate that in these models either snow albedos or canopy albedos when snow is present are too low, or vegetation shields snow-covered surfaces excessively. Detailed observations of surface albedo in a representative sampling of snow-covered surfaces would therefore be extremely useful in constraining these parameterizations and reducing SAF spread in the next generation of models.},
author = {Qu, Xin and Hall, Alex},
doi = {10.1175/JCLI4186.1},
issn = {1520-0442},
journal = {Journal of Climate},
month = {aug},
number = {15},
pages = {3971--3981},
title = {{What Controls the Strength of Snow-Albedo Feedback?}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI4186.1},
volume = {20},
year = {2007}
}
@article{QuHall14,
author = {Qu, Xin and Hall, Alex},
doi = {10.1007/s00382-013-1774-0},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {jan},
number = {1-2},
pages = {69--81},
title = {{On the persistent spread in snow-albedo feedback}},
url = {http://link.springer.com/10.1007/s00382-013-1774-0},
volume = {42},
year = {2014}
}
@article{Qu2014b,
abstract = {In 36 climate change simulations associated with phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5), changes in marine low cloud cover (LCC) exhibit a large spread, and may be either positive or negative. Here we develop a heuristic model to understand the source of the spread. The model's premise is that simulated LCC changes can be interpreted as a linear combination of contributions from factors shaping the clouds' large-scale environment. We focus primarily on two factors—the strength of the inversion capping the atmospheric boundary layer (measured by the estimated inversion strength, EIS) and sea surface temperature (SST). For a given global model, the respective contributions of EIS and SST are computed. This is done by multiplying (1) the current-climate's sensitivity of LCC to EIS or SST variations, by (2) the climate-change signal in EIS or SST. The remaining LCC changes are then attributed to changes in greenhouse gas and aerosol concentrations, and other environmental factors. The heuristic model is remarkably skillful. Its SST term dominates, accounting for nearly two- thirds of the intermodel variance of LCC changes in CMIP3 models, and about half in CMIP5 models. Of the two factors governing the SST term (the SST increase and the sensitivity of LCC to SST perturbations), the SST sensitivity drives the spread in the SST term and hence the spread in the overall LCC changes. This sensitivity varies a great deal from model to model and is strongly linked to the types of cloud and boundary layer parameterizations used in the models. EIS and SST sensitivities are also estimated using observational cloud and meteorological data. The observed sensitivities are generally consistent with the majority of models as well as expectations from prior research. Based on the observed sensitivities and the relative magnitudes of simulated EIS and SST changes (which we argue are also physically reasonable), the heu- ristic model predicts LCC will decrease over the 21st- century. However, to place a strong constraint, for example on the magnitude of the LCC decrease, will require longer observational records and a careful assessment of other environmental factors producing LCC changes. Mean- while, addressing biases in simulated EIS and SST sensi- tivities will clearly be an important step towards reducing intermodel spread in simulated LCC changes},
author = {Qu, Xin and Hall, Alex and Klein, Stephen A. and Caldwell, Peter M.},
doi = {10.1007/s00382-013-1945-z},
isbn = {0930-7575},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {EIS,Low cloud cover,SST},
month = {may},
number = {9-10},
pages = {2603--2626},
title = {{On the spread of changes in marine low cloud cover in climate model simulations of the 21st century}},
url = {http://link.springer.com/10.1007/s00382-013-1945-z},
volume = {42},
year = {2014}
}
@article{Qu2015,
author = {Qu, Xin and Hall, Alex and Klein, Stephen A. and DeAngelis, Anthony M.},
doi = {10.1002/2015GL065627},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {sep},
number = {18},
pages = {7767--7775},
title = {{Positive tropical marine low‐cloud cover feedback inferred from cloud‐controlling factors}},
url = {https://onlinelibrary.wiley.com/doi/10.1002/2015GL065627},
volume = {42},
year = {2015}
}
@article{Quaas2009,
author = {Quaas, J. and Ming, Y. and Menon, S. and Takemura, T. and Wang, M. and Penner, J. E. and Gettelman, A. and Lohmann, U. and Bellouin, N. and Boucher, O. and Sayer, A. M. and Thomas, G. E. and McComiskey, A. and Feingold, G. and Hoose, C. and Kristj{\'{a}}nsson, J. E. and Liu, X. and Balkanski, Y. and Donner, L. J. and Ginoux, P. A. and Stier, P. and Grandey, B. and Feichter, J. and Sednev, I. and Bauer, S. E. and Koch, D. and Grainger, R. G. and Kirkev{\&}aring;g, A. and Iversen, T. and Seland, {\O}. and Easter, R. and Ghan, S. J. and Rasch, P. J. and Morrison, H. and Lamarque, J.-F. and Iacono, M. J. and Kinne, S. and Schulz, M.},
doi = {10.5194/acp-9-8697-2009},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {nov},
number = {22},
pages = {8697--8717},
title = {{Aerosol indirect effects – general circulation model intercomparison and evaluation with satellite data}},
url = {http://www.atmos-chem-phys.net/9/8697/2009/},
volume = {9},
year = {2009}
}
@article{Quaas2008,
author = {Quaas, Johannes and Boucher, Olivier and Bellouin, Nicolas and Kinne, Stefan},
doi = {10.1029/2007JD008962},
issn = {01480227},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {Climate change,aerosol indirect effects,radiative forcing},
month = {mar},
number = {D5},
pages = {D05204},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Satellite-based estimate of the direct and indirect aerosol climate forcing}},
url = {http://doi.wiley.com/10.1029/2007JD008962},
volume = {113},
year = {2008}
}
@article{Remy2018,
author = {R{\'{e}}my, S. and Bellouin, N. and Benedetti, A. and Boucher, O.},
doi = {10.1175/2018BAMSStateoftheClimate.1.},
journal = {Bulletin of the American Meteorological Society},
number = {8},
pages = {S49--S51},
title = {{Aerosols [in “State of the Climate in 2017”].}},
volume = {99},
year = {2018}
}
@article{Radtke2020,
abstract = {Abstract. The response of shallow trade cumulus clouds to global warming is a leading source of uncertainty in projections of the Earth's changing climate. A setup based on the Rain In Cumulus over the Ocean field campaign is used to simulate a shallow trade wind cumulus field with the Icosahedral Nonhydrostatic Large Eddy Model in a control and a perturbed 4 K warmer climate, while degrading horizontal resolution from 100 m to 5 km. As the resolution is coarsened, the base-state cloud fraction increases substantially, especially near cloud base, lateral mixing is weaker, and cloud tops reach higher. Nevertheless, the overall vertical structure of the cloud layer is surprisingly robust across resolutions. In a warmer climate, cloud cover reduces, alone constituting a positive shortwave cloud feedback: the strength correlates with the amount of base-state cloud fraction and thus is stronger at coarser resolutions. Cloud thickening, resulting from more water vapour availability for condensation in a warmer climate, acts as a compensating feedback, but unlike the cloud cover reduction it is largely resolution independent. Therefore, refining the resolution leads to convergence to a near-zero shallow cumulus feedback. This dependence holds in experiments with enhanced realism including precipitation processes or warming along a moist adiabat instead of uniform warming. Insofar as these findings carry over to other models, they suggest that storm-resolving models may exaggerate the trade wind cumulus cloud feedback.},
author = {Radtke, Jule and Mauritsen, Thorsten and Hohenegger, Cathy},
doi = {10.5194/acp-21-3275-2021},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {mar},
number = {5},
pages = {3275--3288},
title = {{Shallow cumulus cloud feedback in large eddy simulations – bridging the gap to storm-resolving models}},
url = {https://acp.copernicus.org/articles/21/3275/2021/},
volume = {21},
year = {2021}
}
@article{2010JGRD..11512121R,
author = {Raes, Frank and Liao, Hong and Chen, Wei-Ting and Seinfeld, John H},
doi = {10.1029/2009JD013300},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {4801,4906),Atmospheric Composition and Structure: Aerosols a,Atmospheric Composition and Structure: Cloud phys,Atmospheric Composition and Structure: Troposphere,climate feedback},
month = {jun},
number = {D12},
pages = {D12121},
title = {{Atmospheric chemistry-climate feedbacks}},
url = {http://doi.wiley.com/10.1029/2009JD013300},
volume = {115},
year = {2010}
}
@article{ISI:000496622000001,
abstract = {The clear sky greenhouse effect (G) is defined as the trapping of infrared radiation by the atmosphere in the absence of clouds. The magnitude and variability of G is an important element in the understanding of Earth's energy balance; yet the quantification of the governing factors of G is poor. The global mean G averaged over 2000 to 2016 is 130-133 W m(-2) across data sets. We use satellite observations from Clouds and the Earth's Radiant Energy System Energy Balance and Filled (CERES EBAF) to calculate the monthly anomalies in the clear sky greenhouse effect (Delta G). We quantify the contributions to Delta G due to changes in surface temperature, atmospheric temperature, and water vapor by performing partial radiation perturbation experiments using ERA-Interim and Geophysical Fluid Dynamics Laboratory's Atmospheric Model 4.0 climatological data. Water vapor in the middle troposphere and upper troposphere is found to contribute equally to the global mean and tropical mean Delta G. Holding relative humidity (RH) fixed in the radiative transfer calculations captures the temporal variability of global mean Delta G while variations in RH control the regional Delta G signal. The variations in RH are found to help generate the clear sky super greenhouse effect (SGE). Thirty-six percent of Earth's area exhibits SGE, and this disproportionately contributes to 70{\%} of the globally averaged magnitude of Delta G. In the global mean, G's sensitivity to surface temperature is 3.1-4.0 W m(-2) K-1, and the clear sky longwave feedback parameter is 1.5-2.0 W m(-2) K-1. Observations from CERES EBAF lie at the more sensitive ends of these ranges and the spread arises from its cloud removal treatment, suggesting that it is difficult to constrain clear sky feedbacks.},
author = {Raghuraman, Shiv Priyam and Paynter, David and Ramaswamy, V},
doi = {10.1029/2019JD031017},
journal = {Journal of Geophysical Research: Atmospheres},
month = {nov},
number = {21},
pages = {11354--11371},
title = {{Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016}},
volume = {124},
year = {2019}
}
@article{Rahimzadeh2015a,
author = {Rahimzadeh, Fatemeh and Sanchez-Lorenzo, Arturo and Hamedi, Maryam and Kruk, Michael C and Wild, Martin},
doi = {10.1002/joc.4107},
issn = {08998418},
journal = {International Journal of Climatology},
month = {jun},
number = {8},
pages = {2065--2079},
title = {{New evidence on the dimming/brightening phenomenon and decreasing diurnal temperature range in Iran (1961–2009)}},
url = {http://doi.wiley.com/10.1002/joc.4107},
volume = {35},
year = {2015}
}
@article{Ramaswamy2019,
abstract = {We describe the historical evolution of the conceptualization, formulation, quantification, application, and utilization of “radiative forcing” (RF) of Earth's climate. Basic theories of shortwave and longwave radiation were developed through the nineteenth and twentieth centuries and established the analytical framework for defining and quantifying the perturbations to Earth's radiative energy balance by natural and anthropogenic influences. The insight that Earth's climate could be radiatively forced by changes in carbon dioxide, first introduced in the nineteenth century, gained empirical support with sustained observations of the atmospheric concentrations of the gas beginning in 1957. Advances in laboratory and field measurements, theory, instrumentation, computational technology, data, and analysis of well-mixed greenhouse gases and the global climate system through the twentieth century enabled the development and formalism of RF; this allowed RF to be related to changes in global-mean surface temperature with the aid of increasingly sophisticated models. This in turn led to RF becoming firmly established as a principal concept in climate science by 1990. The linkage with surface temperature has proven to be the most important application of the RF concept, enabling a simple metric to evaluate the relative climate impacts of different agents. The late 1970s and 1980s saw accelerated developments in quantification, including the first assessment of the effect of the forcing due to the doubling of carbon dioxide on climate (the “Charney” report). The concept was subsequently extended to a wide variety of agents beyond well-mixed greenhouse gases (WMGHGs; carbon dioxide, methane, nitrous oxide, and halocarbons) to short-lived species such as ozone. The WMO and IPCC international assessments began the important sequence of periodic evaluations and quantifications of the forcings by natural (solar irradiance changes and stratospheric aerosols resulting from volcanic eruptions) and a growing set of anthropogenic agents (WMGHGs, ozone, aerosols, land surface changes, contrails). From the 1990s to the present, knowledge and scientific confidence in the radiative agents acting on the climate system have proliferated. The conceptual basis of RF has also evolved as both our understanding of the way radiative forcing drives climate change and the diversity of the forcing mechanisms have grown. This has led to the current situation where “effective radiative forcing” (ERF) is regarded as the preferred practical definition of radiative forcing in order to better capture the link between forcing and global-mean surface temperature change. The use of ERF, however, comes with its own attendant issues, including challenges in its diagnosis from climate models, its applications to small forcings, and blurring of the distinction between rapid climate adjustments (fast responses) and climate feedbacks; this will necessitate further elaboration of its utility in the future. Global climate model simulations of radiative perturbations by various agents have established how the forcings affect other climate variables besides temperature (e.g., precipitation). The forcing–response linkage as simulated by models, including the diversity in the spatial distribution of forcings by the different agents, has provided a practical demonstration of the effectiveness of agents in perturbing the radiative energy balance and causing climate changes. The significant advances over the past half century have established, with very high confidence, that the global-mean ERF due to human activity since preindustrial times is positive (the 2013 IPCC assessment gives a best estimate of 2.3 W m−2, with a range from 1.1 to 3.3 W m−2; 90{\%} confidence interval). Further, except in the immediate aftermath of climatically significant volcanic eruptions, the net anthropogenic forcing dominates over natural radiative forcing mechanisms. Nevertheless, the substantial remaining uncertainty in the net anthropogenic ERF leads to large uncertainties in estimates of climate sensitivity from observations and in predicting future climate impacts. The uncertainty in the ERF arises principally from the incorporation of the rapid climate adjustments in the formulation, the well-recognized difficulties in characterizing the preindustrial state of the atmosphere, and the incomplete knowledge of the interactions of aerosols with clouds. This uncertainty impairs the quantitative evaluation of climate adaptation and mitigation pathways in the future. A grand challenge in Earth system science lies in continuing to sustain the relatively simple essence of the radiative forcing concept in a form similar to that originally devised, and at the same time improving the quantification of the forcing. This, in turn, demands an accurate, yet increasingly complex and comprehensive, accounting of the relevant processes in the climate system.},
author = {Ramaswamy, V. and Collins, W. and Haywood, J. and Lean, J. and Mahowald, N. and Myhre, G. and Naik, V. and Shine, K. P. and Soden, B. and Stenchikov, G. and Storelvmo, T.},
doi = {10.1175/amsmonographs-d-19-0001.1},
issn = {0065-9401},
journal = {Meteorological Monographs},
month = {jan},
pages = {14.1--14.101},
publisher = {American Meteorological Society},
title = {{Radiative Forcing of Climate: The Historical Evolution of the Radiative Forcing Concept, the Forcing Agents and their Quantification, and Applications}},
url = {http://journals.ametsoc.org/mono/article-pdf/doi/10.1175/AMSMONOGRAPHS-D-19-0001.1/4941541/amsmonographs-d-19-0001{\_}1.pdf},
volume = {59},
year = {2019}
}
@incollection{ch08-IPCC-2007,
address = {Cambridge, United Kingdom and New York, USA},
author = {Randall, D A and Wood, R A and Bony, S and Colman, R and Fichefet, T and Fyfe, J and Kattsov, V and Pitman, A and Shukla, J and Srinivasan, J and Stouffer, R J and Sumi, A and Taylor, K E},
booktitle = {Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {8},
editor = {Solomon, S and Qin, D and Manning, M and Chen, Z and Marquis, M and Averyt, K B and Tignor, M and Miller, H L},
isbn = {9780521880091},
pages = {589--662},
publisher = {Cambridge University Press},
title = {{Climate Models and Their Evaluation}},
url = {https://www.ipcc.ch/report/ar4/wg1},
year = {2007}
}
@article{Randles2017,
abstract = {AbstractThe Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), updates NASA's previous satellite-era (1980 onward) reanalysis system to include additional observations and improvements to the Goddard Earth Observing System, version 5 (GEOS-5), Earth system model. As a major step toward a full Integrated Earth Systems Analysis (IESA), in addition to meteorological observations, MERRA-2 now includes assimilation of aerosol optical depth (AOD) from various ground- and space-based remote sensing platforms. Here, in the first of a pair of studies, the MERRA-2 aerosol assimilation is documented, including a description of the prognostic model (GEOS-5 coupled to the GOCART aerosol module), aerosol emissions, and the quality control of ingested observations. Initial validation and evaluation of the analyzed AOD fields are provided using independent observations from ground, aircraft, and shipborne instruments. The positive impact of the AOD assimilation on simulated aerosols is ...},
author = {Randles, C. A. and da Silva, A. M. and Buchard, V. and Colarco, P. R. and Darmenov, A. and Govindaraju, R. and Smirnov, A. and Holben, B. and Ferrare, R. and Hair, J. and Shinozuka, Y. and Flynn, C. J. and Randles, C. A. and da Silva, A. M. and Buchard, V. and Colarco, P. R. and Darmenov, A. and Govindaraju, R. and Smirnov, A. and Holben, B. and Ferrare, R. and Hair, J. and Shinozuka, Y. and Flynn, C. J.},
doi = {10.1175/JCLI-D-16-0609.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Aerosols,Data assimilation,Model evaluation/performance,Radiative fluxes,Reanalysis data,Satellite observations},
month = {sep},
number = {17},
pages = {6823--6850},
title = {{The MERRA-2 Aerosol Reanalysis, 1980 Onward. Part I: System Description and Data Assimilation Evaluation}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-16-0609.1},
volume = {30},
year = {2017}
}
@article{Raschke2016a,
abstract = {This study examines radiative flux distributions and local spread of values from three major observational datasets (CERES, ISCCP, and SRB) and compares them with results from climate modeling (CMIP3). Examinations of the spread and differences also differentiate among contributions from cloudy and clear-sky conditions. The spread among observational datasets is in large part caused by noncloud ancillary data. Average differences of at least 10 W m(-2) each for clear-sky downward solar, upward solar, and upward infrared fluxes at the surface demonstrate via spatial difference patterns major differences in assumptions for atmospheric aerosol, solar surface albedo and surface temperature, and/or emittance in observational datasets. At the top of the atmosphere (TOA), observational datasets are less influenced by the ancillary data errors than at the surface. Comparisons of spatial radiative flux distributions at the TOA between observations and climate modeling indicate large deficiencies in the strength and distribution of model-simulated cloud radiative effects. Differences are largest for lower-altitude clouds over low-latitude oceans. Global modeling simulates stronger cloud radiative effects (CRE) by +30 W m(-2) over trade wind cumulus regions, yet smaller CRE by about -30 W m(-2) over (smaller in area) stratocumulus regions. At the surface, climate modeling simulates on average about 15 W m(-2) smaller radiative net flux imbalances, as if climate modeling underestimates latent heat release (and precipitation). Relative to observational datasets, simulated surface net fluxes are particularly lower over oceanic trade wind regions (where global modeling tends to overestimate the radiative impact of clouds). Still, with the uncertainty in noncloud ancillary data, observational data do not establish a reliable reference.},
address = {Max Planck Inst Meteorol, Bundesstr 53, D-20146 Hamburg, Germany Univ Hamburg, Bundesstr 53, D-20146 Hamburg, Germany CUNY, NOAA Cooperat Remote Sensing Sci {\&} Technol, New York, NY 10021 USA NASA, Langley Res Ctr, Hampton, VA 23665 USA ETH, Inst Atmospher},
annote = {Dc7kg
Times Cited:1
Cited References Count:57},
author = {Raschke, E and Kinne, S and Rossow, W B and Stackhouse, P W and Wild, M},
doi = {10.1175/Jamc-D-14-0281.1},
issn = {1558-8424},
journal = {Journal of Applied Meteorology and Climatology},
keywords = {aerosols albedo climatology cloud radiative effect},
language = {English},
number = {1},
pages = {93--117},
title = {{Comparison of Radiative Energy Flows in Observational Datasets and Climate Modeling}},
volume = {55},
year = {2016}
}
@article{1989Natur.342..758R,
author = {Raval, A and Ramanathan, V},
doi = {10.1038/342758a0},
journal = {Nature},
keywords = {Atmospheric Physics,Clouds (Meteorology),Earth Observations (From Space),Earth Radiation Budget Experiment,Geophysics,Greenhouse Effect,Sea Surface Temperature,Water Vapor},
pages = {758--761},
title = {{Observational determination of the greenhouse effect}},
volume = {342},
year = {1989}
}
@article{Ravelo1467,
abstract = {Zhang et al. (Reports, 4 April 2014, p. 84) interpret TEX86 and paleotemperature data as providing a fundamentally new view of tropical Pacific climate during the warm Pliocene period. We argue that, within error, their Pliocene data actually support previously published data indicating average western warm-pool temperature similar to today and a reduced zonal gradient, referred to as a permanent El Ni{\~{n}}o{\{}$\backslash$textendash{\}}like state.},
author = {Ravelo, Ana Christina and Lawrence, Kira Trillium and Fedorov, Alexey and Ford, Heather Louise},
doi = {10.1126/science.1257618},
issn = {0036-8075},
journal = {Science},
number = {6216},
pages = {1467},
publisher = {American Association for the Advancement of Science},
title = {{Comment on “A 12-million-year temperature history of the tropical Pacific Ocean”}},
url = {https://science.sciencemag.org/content/346/6216/1467.1},
volume = {346},
year = {2014}
}
@article{Rayner2003,
author = {Rayner, N. A. and Parker, D. E. and Horton, E. B. and Folland, C. K. and Alexander, L. V. and Rowell, D. P. and Kent, E. C. and Kaplan, A.},
doi = {10.1029/2002JD002670},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {bias correction,climate change,climate data reconstruction,night marine air temperature,sea ice,sea surface temperature},
month = {jul},
number = {D14},
pages = {4407},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century}},
url = {http://doi.wiley.com/10.1029/2002JD002670},
volume = {108},
year = {2003}
}
@article{Regayre2018a,
author = {Regayre, Leighton A. and Johnson, Jill S. and Yoshioka, Masaru and Pringle, Kirsty J. and Sexton, David M. H. and Booth, Ben B. B. and Lee, Lindsay A. and Bellouin, Nicolas and Carslaw, Kenneth S.},
doi = {10.5194/acp-18-9975-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jul},
number = {13},
pages = {9975--10006},
title = {{Aerosol and physical atmosphere model parameters are both important sources of uncertainty in aerosol ERF}},
url = {https://www.atmos-chem-phys.net/18/9975/2018/},
volume = {18},
year = {2018}
}
@article{doi:10.1002/jame.20022,
abstract = {The purpose of this paper is to give a rather comprehensive description of the models for natural and anthropogenically driven changes in biogeography as implemented in the land component JSBACH of the Max Planck Institute Earth system model (MPI-ESM). The model for natural land cover change (DYNVEG) features two types of competition: between the classes of grasses and woody types (trees, shrubs) controlled by disturbances (fire, windthrow) and within those vegetation classes between different plant functional types based on relative net primary productivity advantages. As part of this model, the distribution of land unhospitable to vegetation (hot and cold deserts) is determined dynamically from plant productivity under the prevailing climate conditions. The model for anthropogenic land cover change implements the land use transition approach by Hurtt et al. (2006). Our implementation is based on the assumption that historically pastures have been preferentially established on former grasslands (“pasture rule”). We demonstrate that due to the pasture rule, deforestation reduces global forest area between 1850 and 2005 by 15{\%} less than without. Because of the pasture rule the land cover distribution depends on the full history of land use transitions. This has implications for the dynamics of natural land cover change because assumptions must be made on how agriculturalists react to a changing natural vegetation in their environment. A separate model representing this process has been developed so that natural and anthropogenic land cover change can be simulated consistently. Certain aspects of our model implementation are illustrated by selected results from the recent CMIP5 simulations.},
author = {Reick, C H and Raddatz, T and Brovkin, V and Gayler, V},
doi = {10.1002/jame.20022},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {Earth system modeling,dynamic vegetation model,land cover dynamics,land use change},
number = {3},
pages = {459--482},
title = {{Representation of natural and anthropogenic land cover change in MPI-ESM}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/jame.20022},
volume = {5},
year = {2013}
}
@article{Renoult2020,
abstract = {Abstract. In this paper we introduce a Bayesian framework, which is explicit about prior assumptions, for using model ensembles and observations together to constrain future climate change. The emergent constraint approach has seen broad application in recent years, including studies constraining the equilibrium climate sensitivity (ECS) using the Last Glacial Maximum (LGM) and the mid-Pliocene Warm Period (mPWP). Most of these studies were based on ordinary least squares (OLS) fits between a variable of the climate state, such as tropical temperature, and climate sensitivity. Using our Bayesian method, and considering the LGM and mPWP separately, we obtain values of ECS of 2.7 K (0.6–5.2, 5th–95th percentiles) using the PMIP2, PMIP3, and PMIP4 datasets for the LGM and 2.3 K (0.5–4.4) with the PlioMIP1 and PlioMIP2 datasets for the mPWP. Restricting the ensembles to include only the most recent version of each model, we obtain 2.7 K (0.7–5.2) using the LGM and 2.3 K (0.4–4.5) using the mPWP. An advantage of the Bayesian framework is that it is possible to combine the two periods assuming they are independent, whereby we obtain a tighter constraint of 2.5 K (0.8–4.0) using the restricted ensemble. We have explored the sensitivity to our assumptions in the method, including considering structural uncertainty, and in the choice of models, and this leads to 95 {\%} probability of climate sensitivity mostly below 5 K and only exceeding 6 K in a single and most uncertain case assuming a large structural uncertainty. The approach is compared with other approaches based on OLS, a Kalman filter method, and an alternative Bayesian method. An interesting implication of this work is that OLS-based emergent constraints on ECS generate tighter uncertainty estimates, in particular at the lower end, an artefact due to a flatter regression line in the case of lack of correlation. Although some fundamental challenges related to the use of emergent constraints remain, this paper provides a step towards a better foundation for their potential use in future probabilistic estimations of climate sensitivity.},
author = {Renoult, Martin and Annan, James Douglas and Hargreaves, Julia Catherine and Sagoo, Navjit and Flynn, Clare and Kapsch, Marie-Luise and Mikolajewicz, Uwe and Ohgaito, Rumi and Mauritsen, Thorsten},
doi = {https://doi.org/10.5194/cp-16-1715-2020},
issn = {1814-9340},
journal = {Climate of The Past},
keywords = {Bayesian probability,Climate change,Climate sensitivity,Climate state,Climatology,Data set,Econometrics,Geology,Kalman filter,Ordinary least squares,Percentile},
pages = {1715--1735},
title = {{A Bayesian framework for emergent constraints: case studies of climate sensitivity with PMIP}},
volume = {16},
year = {2020}
}
@incollection{IPCCObservationsOceanRhein2013,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Rhein, M and Rintoul, S R and Aoki, S and Campos, E and Chambers, D and Feely, R A and Gulev, S and Johnson, G C and Josey, S A and Kostianoy, A and Mauritzen, C and Roemmich, D and Talley, L D and Wang, F},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
chapter = {3},
doi = {10.1017/CBO9781107415324.010},
editor = {Stocker, T F and Qin, D and Plattner, G.-K. and Tignor, M and Allen, S K and Boschung, J and Nauels, A and Xia, Y and Bex, V and Midgley, P M},
isbn = {9781107661820},
pages = {255--316},
publisher = {Cambridge University Press},
title = {{Observations: Ocean}},
type = {Book Section},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Ribes9999b,
archivePrefix = {arXiv},
arxivId = {eabc0671},
author = {Ribes, Aur{\'{e}}lien and Qasmi, Said and Gillett, Nathan},
doi = {10.1126/sciadv.abc0671},
eprint = {eabc0671},
journal = {Science Advances},
number = {4},
pages = {eabc0671},
title = {{Making climate projections conditional on historical observations}},
volume = {7},
year = {2021}
}
@article{Richardson2018b,
abstract = {{\textcopyright}2018. The Authors. Future projections of east Amazonian precipitation indicate drying, but they are uncertain and poorly understood. In this study we analyze the Amazonian precipitation response to individual atmospheric forcings using a number of global climate models. Black carbon is found to drive reduced precipitation over the Amazon due to temperature-driven circulation changes, but the magnitude is uncertain. CO 2 drives reductions in precipitation concentrated in the east, mainly due to a robustly negative, but highly variable in magnitude, fast response. We find that the physiological effect of CO 2 on plant stomata is the dominant driver of the fast response due to reduced latent heating and also contributes to the large model spread. Using a simple model, we show that CO 2 physiological effects dominate future multimodel mean precipitation projections over the Amazon. However, in individual models temperature-driven changes can be large, but due to little agreement, they largely cancel out in the model mean.},
author = {Richardson, T. B. and Forster, P. M. and Andrews, T. and Boucher, O. and Faluvegi, G. and Fl{\"{a}}schner, D. and Kasoar, M. and Kirkev{\aa}g, A. and Lamarque, J.-F. and Myhre, G. and Olivi{\'{e}}, D. and Samset, B. H. and Shawki, D. and Shindell, D. and Takemura, T. and Voulgarakis, A.},
doi = {10.1002/2017GL076520},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {Amazon,CO forcing 2,Fast response,Physiological forcing,Precipitation,Stomatal response},
month = {mar},
number = {6},
pages = {2815--2825},
title = {{Carbon Dioxide Physiological Forcing Dominates Projected Eastern Amazonian Drying}},
url = {http://doi.wiley.com/10.1002/2017GL076520},
volume = {45},
year = {2018}
}
@article{Richardson2016b,
author = {Richardson, Mark and Cowtan, Kevin and Hawkins, Ed and Stolpe, Martin B.},
doi = {10.1038/nclimate3066},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {oct},
number = {10},
pages = {931--935},
title = {{Reconciled climate response estimates from climate models and the energy budget of Earth}},
url = {http://www.nature.com/articles/nclimate3066},
volume = {6},
year = {2016}
}
@article{Richardson2018,
author = {Richardson, Mark and Cowtan, Kevin and Millar, Richard J},
doi = {10.1088/1748-9326/aab305},
issn = {1748-9326},
journal = {Environmental Research Letters},
month = {may},
number = {5},
pages = {054004},
publisher = {IOP Publishing},
title = {{Global temperature definition affects achievement of long-term climate goals}},
url = {http://stacks.iop.org/1748-9326/13/i=5/a=054004?key=crossref.0ce4fea65c3c516e4cbb008f221e239b},
volume = {13},
year = {2018}
}
@article{Richardson2019,
abstract = {Quantifying the efficacy of different climate forcings is important for understanding the real‐world climate sensitivity. This study presents a systematic multimodel analysis of different climate driver efficacies using simulations from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP). Efficacies calculated from instantaneous radiative forcing deviate considerably from unity across forcing agents and models. Effective radiative forcing (ERF) is a better predictor of global mean near‐surface air temperature (GSAT) change. Efficacies are closest to one when ERF is computed using fixed sea surface temperature experiments and adjusted for land surface temperature changes using radiative kernels. Multimodel mean efficacies based on ERF are close to one for global perturbations of methane, sulfate, black carbon, and insolation, but there is notable intermodel spread. We do not find robust evidence that the geographic location of sulfate aerosol affects its efficacy. GSAT is found to respond more slowly to aerosol forcing than CO2 in the early stages of simulations. Despite these differences, we find that there is no evidence for an efficacy effect on historical GSAT trend estimates based on simulations with an impulse response model, nor on the resulting estimates of climate sensitivity derived from the historical period. However, the considerable intermodel spread in the computed efficacies means that we cannot rule out an efficacy‐induced bias of ±0.4 K in equilibrium climate sensitivity to CO2 doubling when estimated using the historical GSAT trend.},
author = {Richardson, Thomas Benjamin and Forster, Piers M. and Smith, Christopher J. and Maycock, Amanda C. and Wood, Tom and Andrews, Timothy and Boucher, Olivier and Faluvegi, Gregory and Fl{\"{a}}schner, Dagmar and Hodnebrog, {\O}ivind and Kasoar, Matthew and Kirkev{\aa}g, Alf and Lamarque, Jean Fran{\c{c}}ois and M{\"{u}}lmenst{\"{a}}dt, Johannes and Myhre, Gunnar and Olivi{\'{e}}, Dirk and Portmann, Robert W. and Samset, Bj{\o}rn Hallvard and Shawki, Dilshad and Shindell, Drew T. and Stier, Philip and Takemura, Toshihiko and Voulgarakis, Apostolos and Watson-Parris, Dun},
doi = {10.1029/2019JD030581},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {nov},
number = {23},
pages = {12824--12844},
title = {{Efficacy of climate forcings in PDRMIP models}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JD030581},
volume = {124},
year = {2019}
}
@article{Richter2020,
abstract = {In this study, we compare the spatial patterns of simulated geocentric sea-level change to observations from satellite altimetry over the period 1993-2015 to assess whether a forced signal is detectable. This is challenging, as on these time scales internal variability plays an important role and may dominate the observed spatial patterns of regional sea-level change. Model simulations of regional sea-level change associated with sterodynamic sea level, atmospheric loading, glacier mass change, and ice-sheet surface mass balance changes are combined with observations of groundwater depletion, reservoir storage, and dynamic ice-sheet mass changes. The resulting total geocentric regional sea-level change is then compared to independent measurements from satellite altimeter observations. The detectability of the climate-forced signal is assessed by comparing the model ensemble mean of the 'historical' simulations with the characteristics of sea-level variability in pre-industrial control simulations. To further minimize the impact of internal variability, zonal averages were produced. We find that, in all ocean basins, zonally averaged simulated sea-level changes are consistent with observations within sampling uncertainties associated with simulated internal variability of the sterodynamic component. Furthermore, the simulated zonally averaged sea-level change cannot be explained by internal variability alone-thus we conclude that the observations include a forced contribution that is detectable at basin scales.},
author = {Richter, Kristin and Meyssignac, Benoit and Slangen, Aime{\'{e}} B.A. and Melet, Ang{\'{e}}lique and Church, John A. and Fettweis, Xavier and Marzeion, Ben and Agosta, C{\'{e}}cile and Ligtenberg, Stefan R.M. and Spada, Giorgio and Palmer, Matthew D. and Roberts, Christopher D. and Champollion, Nicolas},
doi = {10.1088/1748-9326/ab986e},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {Detection,Forced trends,Internal variability,Sea-level rise},
month = {sep},
number = {9},
pages = {094079},
publisher = {IOP Publishing Ltd},
title = {{Detecting a forced signal in satellite-era sea-level change}},
volume = {15},
year = {2020}
}
@article{Rienecker2011a,
abstract = {AbstractThe Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA's Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA's Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses. Focusing on the satellite era, from 1979 to the present, MERRA has achieved its goals with significant improvements in precipitation and water vapor climatology. Here, a brief overview of the system and some aspects of its performance, including quality assessment diagnostics from innovation and residual statistics, is given.By comparing MERRA with other updated reanalyses [the interim version of the next ECMWF Re-Analysis (ERA-Interim) and the Climate Forecast System Reanalysis (CFSR)], advances made in this new generation of reanalyses, as well as remaining deficiencies, are identified. Although there is little difference between the new reanalyses i...},
author = {Rienecker, Michele M. and Suarez, Max J. and Gelaro, Ronald and Todling, Ricardo and Bacmeister, Julio and Liu, Emily and Bosilovich, Michael G. and Schubert, Siegfried D. and Takacs, Lawrence and Kim, Gi-Kong and Bloom, Stephen and Chen, Junye and Collins, Douglas and Conaty, Austin and da Silva, Arlindo and Gu, Wei and Joiner, Joanna and Koster, Randal D. and Lucchesi, Robert and Molod, Andrea and Owens, Tommy and Pawson, Steven and Pegion, Philip and Redder, Christopher R. and Reichle, Rolf and Robertson, Franklin R. and Ruddick, Albert G. and Sienkiewicz, Meta and Woollen, Jack and Rienecker, Michele M. and Suarez, Max J. and Gelaro, Ronald and Todling, Ricardo and {Julio  Bacmeister} and Liu, Emily and Bosilovich, Michael G. and Schubert, Siegfried D. and Takacs, Lawrence and Kim, Gi-Kong and Bloom, Stephen and Chen, Junye and Collins, Douglas and Conaty, Austin and da Silva, Arlindo and Gu, Wei and Joiner, Joanna and Koster, Randal D. and Lucchesi, Robert and Molod, Andrea and Owens, Tommy and Pawson, Steven and Pegion, Philip and Redder, Christopher R. and Reichle, Rolf and Robertson, Franklin R. and Ruddick, Albert G. and Sienkiewicz, Meta and Woollen, Jack},
doi = {10.1175/JCLI-D-11-00015.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jul},
number = {14},
pages = {3624--3648},
title = {{MERRA: NASA's Modern-Era Retrospective Analysis for Research and Applications}},
url = {http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00015.1},
volume = {24},
year = {2011}
}
@article{Ringer2014,
author = {Ringer, Mark A. and Andrews, Timothy and Webb, Mark J.},
doi = {10.1002/2014GL060347},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {jun},
number = {11},
pages = {4035--4042},
title = {{Global-mean radiative feedbacks and forcing in atmosphere-only and coupled atmosphere–ocean climate change experiments}},
url = {http://doi.wiley.com/10.1002/2014GL060347},
volume = {41},
year = {2014}
}
@article{Riser2016,
abstract = {More than 90{\%} of the heat energy accumulation in the climate system between 1971 and the present has been in the ocean. Thus, the ocean plays a crucial role in determining the climate of the planet. Observing the oceans is problematic even under the most favourable of conditions. Historically, shipboard ocean sampling has left vast expanses, particularly in the Southern Ocean, unobserved for long periods of time. Within the past 15 years, with the advent of the global Argo array of profiling floats, it has become possible to sample the upper 2,000 m of the ocean globally and uniformly in space and time. The primary goal of Argo is to create a systematic global network of profiling floats that can be integrated with other elements of the Global Ocean Observing System. The network provides freely available temperature and salinity data from the upper 2,000 m of the ocean with global coverage. The data are available within 24 hours of collection for use in a broad range of applications that focus on examining climate-relevant variability on seasonal to decadal timescales, multidecadal climate change, improved initialization of coupled ocean-atmosphere climate models and constraining ocean analysis and forecasting systems.},
author = {Riser, Stephen C. and Freeland, Howard J. and Roemmich, Dean and Wijffels, Susan and Troisi, Ariel and Belb{\'{e}}och, Mathieu and Gilbert, Denis and Xu, Jianping and Pouliquen, Sylvie and Thresher, Ann and {Le Traon}, Pierre Yves and Maze, Guillaume and Klein, Birgit and Ravichandran, M. and Grant, Fiona and Poulain, Pierre Marie and Suga, Toshio and Lim, Byunghwan and Sterl, Andreas and Sutton, Philip and Mork, Kjell Arne and V{\'{e}}lez-Belch{\'{i}}, Pedro Joaqu{\'{i}}n and Ansorge, Isabelle and King, Brian and Turton, Jon and Baringer, Molly and Jayne, Steven R.},
doi = {10.1038/nclimate2872},
isbn = {1758-678X},
issn = {17586798},
journal = {Nature Climate Change},
month = {jan},
number = {2},
pages = {145--153},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Fifteen years of ocean observations with the global Argo array}},
url = {http://dx.doi.org/10.1038/nclimate2872 http://10.0.4.14/nclimate2872},
volume = {6},
year = {2016}
}
@article{Roberts2015,
abstract = {The probability of a hiatus in global warming is calculated, with a 10-year event having a probability of ∼10{\%}, but a 20-year event less than 1{\%}. The current 15-year event is found to have up to 25{\%} chance of continuing for another 5 years.},
author = {Roberts, C D and Palmer, M D and McNeall, D and Collins, M},
doi = {10.1038/nclimate2531},
issn = {1758-6798},
journal = {Nature Climate Change},
number = {4},
pages = {337--342},
title = {{Quantifying the likelihood of a continued hiatus in global warming}},
url = {https://doi.org/10.1038/nclimate2531},
volume = {5},
year = {2015}
}
@article{ISI:000433412900040,
abstract = {Freshwater availability is changing worldwide. Here we quantify 34 trends in terrestrial water storage observed by the Gravity Recovery and Climate Experiment (GRACE) satellites during 2002-2016 and categorize their drivers as natural interannual variability, unsustainable groundwater consumption, climate change or combinations thereof. Several of these trends had been lacking thorough investigation and attribution, including massive changes in northwestern China and the Okavango Delta. Others are consistent with climate model predictions. This observation-based assessment of how the world's water landscape is responding to human impacts and climate variations provides a blueprint for evaluating and predicting emerging threats to water and food security.},
address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND},
author = {Rodell, M and Famiglietti, J S and Wiese, D N and Reager, J T and Beaudoing, H K and Landerer, F W and Lo, M -H.},
doi = {10.1038/s41586-018-0123-1},
issn = {0028-0836},
journal = {Nature},
month = {may},
number = {7707},
pages = {651--659},
publisher = {NATURE PUBLISHING GROUP},
title = {{Emerging trends in global freshwater availability}},
type = {Article},
volume = {557},
year = {2018}
}
@article{Roe2011,
abstract = {Estimates of climate sensitivity are typically characterized by highly asymmetric probability density functions (pdfs). The reasons are well known, but the situation leaves open an uncomfortably large possibility that climate sensitivity might exceed 4.5°C. In the contexts of (1) global-mean observations of the Earth's energy budget and (2) a global-mean feedback analysis, we explore what changes in the pdfs of the observations or feedbacks used to estimate climate sensitivity would be needed to remove the asymmetry, or to substantially reduce it, and demonstrate that such changes would be implausibly large. The nonlinearity of climate feedbacks is calculated from a range of studies and is shown also to have very little impact on the asymmetry. The intrinsic relationship between uncertainties in the observed climate forcing and the climate's radiative response to that forcing (i.e., the feedbacks) is emphasized. We also demonstrate that because the pdf of climate forcing is approximately symmetric, there is a strong expectation that the pdf of climate feedbacks should be symmetric as well.},
author = {Roe, G. H. and Armour, K. C.},
doi = {10.1029/2011GL047913},
isbn = {0094-8276},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {jul},
number = {14},
pages = {L14708},
pmid = {293385900004},
title = {{How sensitive is climate sensitivity?}},
url = {http://doi.wiley.com/10.1029/2011GL047913},
volume = {38},
year = {2011}
}
@article{Roe2015,
abstract = {Uncertainty in the spatial pattern of climate change is dominated by divergent predictions among climate models. Model differences are closely linked to their representation of climate feedbacks, that is, the additional radiative fluxes that are caused by changes in clouds, water vapour, surface albedo, and other factors, in response to an external climate forcing. Progress in constraining this uncertainty is therefore predicated on understanding how patterns of individual climate feedbacks aggregate into a regional and global climate response. Here we present a simple, moist energy balance model that combines regional feedbacks and the diffusion of both latent and sensible heat. Our model emulates the relationship between regional feedbacks and temperature response in more comprehensive climate models; the model can therefore be used to understand how uncertainty in feedback patterns drives uncertainty in the patterns of temperature response. We find that whereas uncertainty in tropical feedbacks induces a global response, the impact of uncertainty in polar feedbacks remains predominantly regionally confined.},
author = {Roe, Gerard H. and Feldl, Nicole and Armour, Kyle C. and Hwang, Yen-Ting and Frierson, Dargan M W},
doi = {10.1038/ngeo2346},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {feb},
number = {2},
pages = {135--139},
title = {{The remote impacts of climate feedbacks on regional climate predictability}},
url = {http://www.nature.com/articles/ngeo2346},
volume = {8},
year = {2015}
}
@article{Roe2007a,
abstract = {Uncertainties in projections of future climate change have not lessened substantially in past decades. Both models and observations yield broad probability distributions for long-term increases in global mean temperature expected from the doubling of atmospheric carbon dioxide, with small but finite probabilities of very large increases. We show that the shape of these probability distributions is an inevitable and general consequence of the nature of the climate system, and we derive a simple analytic form for the shape that fits recent published distributions very well. We show that the breadth of the distribution and, in particular, the probability of large temperature increases are relatively insensitive to decreases in uncertainties associated with the underlying climate processes.},
author = {Roe, Gerard H. and Baker, Marcia B.},
doi = {10.1126/science.1144735},
issn = {0036-8075},
journal = {Science},
month = {oct},
number = {5850},
pages = {629--632},
title = {{Why Is Climate Sensitivity So Unpredictable?}},
url = {http://science.sciencemag.org/content/318/5850/629.abstract http://www.sciencemag.org/cgi/doi/10.1126/science.1144735},
volume = {318},
year = {2007}
}
@article{Roe2009,
abstract = {Feedback analysis is a powerful tool for studying the Earth system. It provides a formal framework for evaluating the relative importance of different interactions in a dynamical system. As such, its application is essential for a predictive or even a mechanistic understanding of the complex interplay of processes on the Earth. This paper reviews the basic principles of feedback analysis and tries to highlight the importance of the technique for the interpretation of physical systems. The need for clear and consistent definitions when comparing different interactions is emphasized. It is also demonstrated that feedback analyses can shed light on how uncertainty in physical processes translates into uncertainty in system response, and that the strength of the feedbacks has a very tight connection to the dynamical response time of the system. Copyright {\textcopyright} 2009 by Annual Reviews. All rights reserved.},
author = {Roe, Gerard H.},
doi = {10.1146/annurev.earth.061008.134734},
issn = {0084-6597},
journal = {Annual Review of Earth and Planetary Sciences},
keywords = {Earth systems dynamics,Red noise,Response times},
month = {may},
number = {1},
pages = {93--115},
publisher = {Annual Reviews},
title = {{Feedbacks, Timescales, and Seeing Red}},
url = {http://www.annualreviews.org/doi/10.1146/annurev.earth.061008.134734},
volume = {37},
year = {2009}
}
@incollection{Rogelj2018c,
author = {Rogelj, J and Shindell, D and Jiang, K and Fifita, S and Forster, P and Ginzburg, V and Handa, C and Kheshgi, H and Kobayashi, S and Kriegler, E and Mundaca, L and S{\'{e}}f{\'{e}}rian, R and Vilari{\~{n}}o, M.V.},
booktitle = {Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change,},
chapter = {2},
editor = {Masson-Delmotte, V and Zhai, P and P{\"{o}}rtner, H.-O. and Roberts, D and Skea, J and Shukla, P R and Pirani, A and Moufouma-Okia, W and P{\'{e}}an, C and Pidcock, R and Connors, S and Matthews, J B R and Chen, Y and Zhou, X and Gomis, M I and Lonnoy, E and Maycock, T and Tignor, M and Waterfield, T},
pages = {93--174},
publisher = {In Press},
title = {{Mitigation Pathways Compatible with 1.5°C in the Context of Sustainable Development}},
url = {https://www.ipcc.ch/sr15/chapter/chapter-2},
year = {2018}
}
@article{Rogelj2019,
abstract = {The 2015 Paris Agreement sets out that rapid reductions in greenhouse gas (GHG) emissions are needed to keep global warming to safe levels. A new approach (known as GWP∗) has been suggested to compare contributions of long- and short-lived GHGs, providing a close link between cumulative CO2-equivalent emissions and total warming. However, comparison factors for non-CO2 GHGs under the GWP∗ metric depend on past emissions, and hence raise questions of equity and fairness when applied at any but the global level. The use of GWP∗ would put most developing countries at a disadvantage compared to developed countries, because when using GWP∗ countries with high historical emissions of short-lived GHGs are exempted from accounting for avoidable future warming that is caused by sustaining these emissions. We show that when various established equity or fairness criteria are applied to GWP∗ (defined here as eGWP∗), perceived national non-CO2 emissions vary by more than an order of magnitude, particularly in countries with high methane emissions like New Zealand. We show that national emission estimates that use GWP∗ are very sensitive to arbitrary choices made by countries and therewith facilitate the creation of loopholes when CO2-equivalent emissions based on the GWP∗ concept are traded between countries that use different approaches. In light of such equity-dependent accounting differences, GHG metrics like GWP∗ should only be used at the global level. A common, transparent and equity-neutral accounting metric is vital for the Paris Agreement's effectiveness and its environmental integrity.},
author = {Rogelj, Joeri and Schleussner, Carl Friedrich},
doi = {10.1088/1748-9326/ab4928},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {GWP,Paris agreement,climate policy,emission metrics,equity,fairness,greenhouse gases},
month = {nov},
number = {11},
pages = {114039},
publisher = {Institute of Physics Publishing},
title = {{Unintentional unfairness when applying new greenhouse gas emissions metrics at country level}},
url = {https://doi.org/10.1088/1748-9326/ab4928},
volume = {14},
year = {2019}
}
@article{Rogelj2015,
abstract = {Recently, assessments have robustly linked stabilization of global-mean temperature rise to the necessity of limiting the total amount of emitted carbon-dioxide (CO2). Halting global warming thus requires virtually zero annual CO2 emissions at some point. Policymakers have now incorporated this concept in the negotiating text for a new global climate agreement, but confusion remains about concepts like carbon neutrality, climate neutrality, full decarbonization, and net zero carbon or net zero greenhouse gas (GHG) emissions. Here we clarify these concepts, discuss their appropriateness to serve as a long-term global benchmark for achieving temperature targets, and provide a detailed quantification. We find that with current pledges and for a likely ({\textgreater}66{\%}) chance of staying below 2 °C, the scenario literature suggests net zero CO2 emissions between 2060 and 2070, with net negative CO2 emissions thereafter. Because of residual non-CO2 emissions, net zero is always reached later for total GHG emissions than for CO2. Net zero emissions targets are a useful focal point for policy, linking a global temperature target and socio-economic pathways to a necessary long-term limit on cumulative CO2 emissions.},
author = {Rogelj, Joeri and Schaeffer, Michiel and Meinshausen, Malte and Knutti, Reto and Alcamo, Joseph and Riahi, Keywan and Hare, William},
doi = {10.1088/1748-9326/10/10/105007},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {UNFCCC,carbon dioxide,climate change,climate policy,climate stabilization,global goal,greenhouse gases},
month = {oct},
number = {10},
pages = {105007},
publisher = {Institute of Physics Publishing},
title = {{Zero emission targets as long-term global goals for climate protection}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/10/10/105007 https://iopscience.iop.org/article/10.1088/1748-9326/10/10/105007/meta},
volume = {10},
year = {2015}
}
@article{Rohling2012a,
abstract = {Many palaeoclimate studies have quantified pre-anthropogenic climate change to calculate climate sensitivity (equilibrium temperature change in response to radiative forcing change), but a lack of consistent methodologies produces a wide range of estimates and hinders comparability of results. Here we present a stricter approach, to improve intercomparison of palaeoclimate sensitivity estimates in a manner compatible with equilibrium projections for future climate change. Over the past 65 million years, this reveals a climate sensitivity (in K W−1 m2) of 0.3–1.9 or 0.6–1.3 at 95{\%} or 68{\%} probability, respectively. The latter implies a warming of 2.2–4.8 K per doubling of atmospheric CO2, which agrees with IPCC estimates.},
author = {Rohling, E. J. and Sluijs, A. and Dijkstra, H. A. and K{\"{o}}hler, P. and {Van De Wal}, R. S.W. and {Von Der Heydt}, A. S. and Beerling, D. J. and Berger, A. and Bijl, P. K. and Crucifix, M. and Deconto, R. and Drijfhout, S. S. and Fedorov, A. and Foster, G. L. and Ganopolski, A. and Hansen, J. and H{\"{o}}nisch, B. and Hooghiemstra, H. and Huber, M. and Huybers, P. and Knutti, R. and Lea, D. W. and Lourens, L. J. and Lunt, D. and Masson-Demotte, V. and Medina-Elizalde, M. and Otto-Bliesner, B. and Pagani, M. and P{\"{a}}like, H. and Renssen, H. and Royer, D. L. and Siddall, M. and Valdes, P. and Zachos, J. C. and Zeebe, R. E.},
doi = {10.1038/nature11574},
isbn = {0028-0836},
issn = {00280836},
journal = {Nature},
number = {7426},
pages = {683--691},
pmid = {23192145},
publisher = {Nature Publishing Group},
title = {{Making sense of palaeoclimate sensitivity}},
url = {http://dx.doi.org/10.1038/nature11574},
volume = {491},
year = {2012}
}
@article{Rohrschneider2019,
author = {Rohrschneider, Tim and Stevens, Bjorn and Mauritsen, Thorsten},
doi = {10.1007/s00382-019-04686-4},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {sep},
number = {5-6},
pages = {3131--3145},
title = {{On simple representations of the climate response to external radiative forcing}},
url = {http://link.springer.com/10.1007/s00382-019-04686-4},
volume = {53},
year = {2019}
}
@article{doi:10.1175/JCLI-D-14-00255.1,
author = {Romps, David M},
doi = {10.1175/JCLI-D-14-00255.1},
journal = {Journal of Climate},
number = {19},
pages = {7432--7449},
title = {{An Analytical Model for Tropical Relative Humidity}},
volume = {27},
year = {2014}
}
@article{Rose2014,
abstract = {The effect of ocean heat uptake (OHU) on transient global warming is studied in a multimodel framework. Simple heat sinks are prescribed in shallow aquaplanet ocean mixed layers underlying atmospheric general circulation models independently and combined with CO2 forcing. Sinks are localized to either tropical or high latitudes, representing distinct modes of OHU found in coupled simulations. Tropical OHU produces modest cooling at all latitudes, offsetting only a fraction of CO2 warming. Highlatitude OHU produces three times more global mean cooling in a strongly polar-amplified pattern. Global sensitivities in each scenario are set primarily by large differences in local shortwave cloud feedbacks, robust across models. Differences in atmospheric energy transport set the pattern of temperature change. Results imply that global and regional warming rates depend sensitively on regional ocean processes setting the OHU pattern, and that equilibrium climate sensitivity cannot be reliably estimated from transient observations.},
author = {Rose, Brian E J and Armour, Kyle C. and Battisti, David S. and Feldl, Nicole and Koll, Daniel D B},
doi = {10.1002/2013GL058955},
isbn = {1944-8007},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate sensitivity,feedback,ocean heat uptake},
month = {feb},
number = {3},
pages = {1071--1078},
title = {{The dependence of transient climate sensitivity and radiative feedbacks on the spatial pattern of ocean heat uptake}},
url = {http://doi.wiley.com/10.1002/2013GL058955},
volume = {41},
year = {2014}
}
@article{Rose2016,
abstract = {Transient climate sensitivity tends to increase on multiple timescales in climate models subject to an abrupt CO 2 increase. The interdependence of radiative and ocean heat uptake processes governing this increase are reviewed. Heat uptake tends to be spatially localized to the subpolar oceans, and this pattern emerges rapidly from an initially uniform distribution. Global climatic impact of heat uptake is studied through the lens of the efficacy concept and a linear systems perspective in which responses to individ-ual climate forcing agents are additive. Heat uptake can be treated as a slowly varying forcing on the atmosphere and surface, whose efficacy is strongly determined by its geographical pattern. An illustrative linear model driven by simple prescribed uptake patterns demonstrates the emer-gence of increasing climate sensitivity as a consequence of the slow decay of high-efficacy subpolar heat uptake. Evidence is reviewed for the key role of shortwave cloud feedbacks in setting the high efficacy of ocean heat uptake and thus in increasing climate sensitivity. A causal phys-ical mechanism is proposed, linking subpolar heat uptake to a global-scale increase in lower-tropospheric stability. It is shown that the rate of increase in estimated inversion strength systematically slows as heat uptake decays. Varia-tions in heat uptake should therefore manifest themselves as differences in low cloud feedbacks.},
author = {Rose, Brian E. J. and Rayborn, Lance},
doi = {10.1007/s40641-016-0048-4},
issn = {2198-6061},
journal = {Current Climate Change Reports},
keywords = {Climate sensitivity,Clouds,Efficacy,Feedback,Lower-tropospheric stability,Ocean heat uptake},
month = {dec},
number = {4},
pages = {190--201},
title = {{The Effects of Ocean Heat Uptake on Transient Climate Sensitivity}},
url = {http://link.springer.com/10.1007/s40641-016-0048-4},
volume = {2},
year = {2016}
}
@article{doi:10.1175/JCLI-D-15-0482.1,
abstract = { AbstractChanges in column-integrated water vapor (Q) in response to increased CO2 and ocean heat uptake (OHU) are investigated in slab-ocean aquaplanet simulations. The simulations span a wide range of warming and moistening patterns due to the spatial structures of the imposed OHU. Fractional changes in Q per degree of surface warming range from 0{\%} to 20{\%} K−1 locally and from 3.6{\%} to 11{\%} K−1 globally. A new diagnostic technique decomposes these changes into relative humidity (RH), surface temperature, and lapse rate contributions. Single-column calculations demonstrate substantial departures from apparent (surface temperature based) Clausius–Clapeyron (CC) scaling due to lapse rates changes; a moist-adiabatic column with fixed, uniform RH exceeds the CC rate by 2.5{\%} K−1. The RH contribution is very small in most simulations. The various Q scalings are thus all consistent CC, but result from different patterns of polar amplification and lapse rate change. Lapse rates are sensitive to location and magnitude of OHU, with implications for Q under transient climate change. CO2 with subpolar (tropical) OHU results in higher (lower) Q scalings than CO2 alone. The weakest Q scaling (and largest RH effects) is found for increased poleward ocean heat transport, which causes strongly polar-amplified warming and near-zero tropical temperature change. Despite weak RH changes and fidelity to the CC relation, Q is expected to vary widely on different time scales in nature due to sensitivity of lapse rates to OHU along with the nonlinearity of the diagnostics. },
author = {Rose, Brian E J and Rencurrel, M Cameron},
doi = {10.1175/JCLI-D-15-0482.1},
journal = {Journal of Climate},
number = {11},
pages = {4251--4268},
title = {{The Vertical Structure of Tropospheric Water Vapor: Comparing Radiative and Ocean-Driven Climate Changes}},
url = {https://doi.org/10.1175/JCLI-D-15-0482.1},
volume = {29},
year = {2016}
}
@article{Rosenfeld2019,
abstract = {A lack of reliable estimates of cloud condensation nuclei (CCN) aerosols over oceans has severely limited our ability to quantify their effects on cloud properties and extent of cooling by reflecting solar radiation—a key uncertainty in anthropogenic climate forcing. We introduce a methodology for ascribing cloud properties to CCN and isolating the aerosol effects from meteorological effects. Its application showed that for a given meteorology, CCN explains three-fourths of the variability in the radiative cooling effect of clouds, mainly through affecting shallow cloud cover and water path. This reveals a much greater sensitivity of cloud radiative forcing to CCN than previously reported, which means too much cooling if incorporated into present climate models. This suggests the existence of compensating aerosol warming effects yet to be discovered, possibly through deep clouds.},
author = {Rosenfeld, Daniel and Zhu, Yannian and Wang, Minghuai and Zheng, Youtong and Goren, Tom and Yu, Shaocai},
doi = {10.1126/science.aav0566},
issn = {0036-8075},
journal = {Science},
month = {feb},
number = {6427},
pages = {eaav0566},
pmid = {30655446},
publisher = {American Association for the Advancement of Science},
title = {{Aerosol-driven droplet concentrations dominate coverage and water of oceanic low-level clouds}},
url = {https://www.sciencemag.org/lookup/doi/10.1126/science.aav0566},
volume = {363},
year = {2019}
}
@article{2020ClDy...55..521R,
author = {Rostron, John W and Sexton, David M. H. and McSweeney, Carol F and Yamazaki, Kuniko and Andrews, Timothy and Furtado, Kalli and Ringer, Mark A and Tsushima, Yoko},
doi = {10.1007/s00382-020-05281-8},
journal = {Climate Dynamics},
keywords = {Climate feedbacks,Emergent constraints,Perturbed parameter ensembles,Sensitivity analysis},
number = {3-4},
pages = {521--551},
title = {{The impact of performance filtering on climate feedbacks in a perturbed parameter ensemble}},
volume = {55},
year = {2020}
}
@article{Rotstayn2015,
abstract = {AbstractLinear regression is used to examine the relationship between simulated changes in historical global-mean surface temperature (GMST) and global-mean aerosol effective radiative forcing (ERF) in 14 climate models from CMIP5. The models have global-mean aerosol ERF that ranges from −0.35 to −1.60 W m−2 for 2000 relative to 1850. It is shown that aerosol ERF is the dominant factor that determines intermodel variations in simulated GMST change: correlations between aerosol ERF and simulated changes in GMST exceed 0.9 for linear trends in GMST over all periods that begin between 1860 and 1950 and end between 1995 and 2005. Comparison of modeled and observed GMST trends for these time periods gives an inferred global-mean aerosol ERF of −0.92 W m−2.On average, transient climate sensitivity is roughly 40{\%} larger with respect to historical forcing from aerosols than well-mixed greenhouse gases. This enhanced sensitivity explains the dominant effect of aerosol forcing on simulated changes in GMST: it is es...},
author = {Rotstayn, Leon D. and Collier, Mark A. and Shindell, Drew T. and Boucher, Olivier},
doi = {10.1175/JCLI-D-14-00712.1},
issn = {08948755},
journal = {Journal of Climate},
number = {17},
pages = {6608--6625},
title = {{Why does aerosol forcing control historical global-mean surface temperature change in CMIP5 models?}},
volume = {28},
year = {2015}
}
@article{Rotstayn2001,
abstract = {The component of the indirect aerosol effect related to changes in precipitation efficiency (the second indirect or Albrecht effect) is presently evaluated in climate models by taking the difference in net irradiance between a present-day and a preindustrial simulation using fixed sea surface temperatures (SSTs). This approach gives a "quasi forcing," which differs from a pure forcing in that fields other than the initially perturbed quantity have been allowed to vary. It is routinely used because, in contrast to the first indirect (Twomey) effect, there is no straightforward method of calculating a pure forcing for the second indirect effect. This raises the question of whether evaluation of the second indirect effect in this manner is adequate as an indication of the likely effect of this perturbation on the global-mean surface temperature. An atmospheric global climate model (AGCM) is used to compare the evaluation of different radiative perturbations as both pure forcings (when available) and quasi forcings. Direct and indirect sulfate aerosol effects and a doubling of carbon dioxide (CO2) are considered. For evaluation of the forcings and quasi forcings, the AGCM is run with prescribed SSTs. For evaluation of the equilibrium response to each perturbation, the AGCM is coupled to a mixed layer ocean model. For the global-mean direct and first indirect effects, quasi forcings differ by less than 10{\%} from the corresponding pure forcing. This suggests that any feedbacks contaminating these quasi forcings are small in the global mean. Further, the quasi forcings for the first and second indirect effects are almost identical when based on net irradiance or on cloud-radiative forcing, showing that clear-sky feedbacks are negligible in the global mean. The climate sensitivity parameters obtained for the first and second indirect effects (evaluated as quasi forcings) are almost identical, at 0.78 and 0.79 K m2 W-1, respectively. Climate sensitivity parameters based on pure forcings are 0.69, 0.84, and 1.01 K m2 W-1 for direct sulfate, first indirect, and 2 X CO2 forcings, respectively. The differences are related to the efficiency with which each forcing excites the strong surface-albedo feedback at high latitudes. Closer examination of the calculations of the first indirect effect as a forcing and quasi forcing shows that, although they are in reasonable agreement in the global mean, there are some significant differences in a few regions. Overall, these results suggest that evaluation of the globally averaged second indirect effect as a quasi forcing is satisfactory.},
author = {Rotstayn, Leon D. and Penner, Joyce E.},
doi = {10.1175/1520-0442(2001)014<2960:IAFQFA>2.0.CO;2},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jul},
number = {13},
pages = {2960--2975},
title = {{Indirect Aerosol Forcing, Quasi Forcing, and Climate Response}},
url = {http://journals.ametsoc.org/doi/10.1175/1520-0442(2001)014{\%}3C2960:IAFQFA{\%}3E2.0.CO;2},
volume = {14},
year = {2001}
}
@article{Rowlands2012,
abstract = {Incomplete understanding of three aspects of the climate system-equilibrium climate sensitivity, rate of ocean heat uptake and historical aerosol forcing-and the physical processes underlying them lead to uncertainties in our assessment of the global-mean temperature evolution in the twenty-first century. Explorations of these uncertainties have so far relied on scaling approaches, large ensembles of simplified climate models, or small ensembles of complex coupled atmosphere-ocean general circulation models which under-represent uncertainties in key climate system properties derived from independent sources. Here we present results from a multi-thousand-member perturbed-physics ensemble of transient coupled atmosphere-ocean general circulation model simulations. We find that model versions that reproduce observed surface temperature changes over the past 50 years show global-mean temperature increases of 1.4-3 K by 2050, relative to 1961-1990, under a mid-range forcing scenario. This range of warming is broadly consistent with the expert assessment provided by the Intergovernmental Panel on Climate Change Fourth Assessment Report, but extends towards larger warming than observed in ensembles-of-opportunity typically used for climate impact assessments. From our simulations, we conclude that warming by the middle of the twenty-first century that is stronger than earlier estimates is consistent with recent observed temperature changes and a mid-range 'no mitigation' scenario for greenhouse-gas emissions.},
author = {Rowlands, Daniel J. and Frame, David J. and Ackerley, Duncan and Aina, Tolu and Booth, Ben B. B. and Christensen, Carl and Collins, Matthew and Faull, Nicholas and Forest, Chris E. and Grandey, Benjamin S. and Gryspeerdt, Edward and Highwood, Eleanor J. and Ingram, William J. and Knight, Sylvia and Lopez, Ana and Massey, Neil and McNamara, Frances and Meinshausen, Nicolai and Piani, Claudio and Rosier, Suzanne M. and Sanderson, Benjamin M. and Smith, Leonard A. and Stone, D{\'{a}}ith{\'{i}} A. and Thurston, Milo and Yamazaki, Kuniko and {Hiro Yamazaki}, Y. and Allen, Myles R.},
doi = {10.1038/ngeo1430},
isbn = {1752-0894},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {apr},
number = {4},
pages = {256--260},
title = {{Broad range of 2050 warming from an observationally constrained large climate model ensemble}},
url = {http://www.nature.com/articles/ngeo1430},
volume = {5},
year = {2012}
}
@article{Rowlinson2020,
author = {Rowlinson, Matthew J. and Rap, Alexandru and Hamilton, Douglas S. and Pope, Richard J. and Hantson, Stijn and Arnold, Steve R. and Kaplan, Jed O. and Arneth, Almut and Chipperfield, Martyn P. and Forster, Piers M. and Nieradzik, Lars},
doi = {10.5194/acp-20-10937-2020},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
keywords = {Atmospheric radiative transfer codes,Atmospheric sciences,Chemical transport model,Chemistry,Climatology,Forcing (mathematics),Industrial fire,Ozone,Radiative forcing,Tropospheric ozone,Vegetation},
month = {sep},
number = {18},
pages = {10937--10951},
title = {{Tropospheric ozone radiative forcing uncertainty due to pre-industrial fire and biogenic emissions}},
url = {https://acp.copernicus.org/articles/20/10937/2020/},
volume = {20},
year = {2020}
}
@article{Royer2016a,
abstract = {The response of temperature to CO2 change (climate sensitivity) in the geologic past may help inform future climate predictions. Proxies for CO2 and temperature generally imply high climate sensitivities: ≥3 K per CO2 doubling during ice-free times (fast-feedback sensitivity) and ≥6 K during times with land ice (Earth-system sensitivity). Climate models commonly underpredict the magnitude of climate change and have fast-feedback sensitivities close to 3 K. A better characterization of feedbacks in warm worlds raises climate sensitivity to values more in line with proxies and produces climate simulations that better fit geologic evidence. As CO2 builds in our atmosphere, we should expect both slow (e.g., land ice) and fast (e.g., vegetation, clouds) feedbacks to elevate the long-term temperature response over that predicted from the canonical fast-feedback value of 3 K. Because temperatures will not decline for centuries to millennia, climate sensitivities that integrate slower processes have relevance for...},
author = {Royer, Dana L.},
doi = {10.1146/annurev-earth-100815-024150},
isbn = {978-0-8243-2044-7},
issn = {0084-6597},
journal = {Annual Review of Earth and Planetary Sciences},
keywords = {carbon dioxide,climate,paleoclimate,phanerozoic,proxies,temperature},
number = {1},
pages = {277--293},
title = {{Climate Sensitivity in the Geologic Past}},
url = {http://www.annualreviews.org/doi/10.1146/annurev-earth-100815-024150},
volume = {44},
year = {2016}
}
@article{Rugenstein2016,
abstract = {In most climate models, after an abrupt increase in radiative forcing the climate feedback parameter magnitude decreases with time. We demonstrate how the evolution of the pattern of ocean heat uptake – moving from a more homogeneous toward a heterogeneous and high latitude enhanced pattern – influences not only regional but also global climate feedbacks. We force a slab ocean model with scaled patterns of ocean heat uptake derived from a coupled ocean-atmosphere general circulation model. Steady-state results from the slab-ocean approximate transient results from the dynamic ocean configuration. Our results indicate that cloud radiative effects play an important role in decreasing the magnitude of the climate feedback parameter. The ocean strongly affects atmospheric temperatures through both heat uptake and through influencing atmospheric feedbacks. This highlights the challenges associated with reliably predicting transient or equilibrated climate system states from shorter-term climate simulations and observed climate variability.},
author = {Rugenstein, Maria A. A. and Caldeira, Ken and Knutti, Reto},
doi = {10.1002/2016GL070907},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {climate feedbacks,climate sensitivity,ocean heat uptake,slab ocean,surface heat fluxes},
month = {sep},
number = {18},
pages = {9877--9885},
title = {{Dependence of global radiative feedbacks on evolving patterns of surface heat fluxes}},
url = {http://doi.wiley.com/10.1002/2016GL070907},
volume = {43},
year = {2016}
}
@article{Rugenstein2019a,
abstract = {Abstract The methods to quantify equilibrium climate sensitivity are still debated. We collect millennial-length simulations of coupled climate models and show that the global mean equilibrium warming is higher than those obtained using extrapolation methods from shorter simulations. Specifically, 27 simulations with 15 climate models forced with a range of CO2 concentrations show a median 17{\%} larger equilibrium warming than estimated from the first 150 years of the simulations. The spatial patterns of radiative feedbacks change continuously, in most regions reducing their tendency to stabilizing the climate. In the equatorial Pacific, however, feedbacks become more stabilizing with time. The global feedback evolution is initially dominated by the tropics, with eventual substantial contributions from the mid-latitudes. Time-dependent feedbacks underscore the need of a measure of climate sensitivity that accounts for the degree of equilibration, so that models, observations, and paleo proxies can be adequately compared and aggregated to estimate future warming.},
author = {Rugenstein, Maria A.A. and Bloch‐Johnson, Jonah and Gregory, Jonathan and Andrews, Timothy and Mauritsen, Thorsten and Li, Chao and Fr{\"{o}}licher, Thomas L. and Paynter, David and Danabasoglu, Gokhan and Yang, Shuting and Dufresne, Jean‐Louis and Cao, Long and Schmidt, Gavin A. and Abe‐Ouchi, Ayako and Geoffroy, Olivier and Knutti, Reto},
doi = {10.1029/2019GL083898},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {feb},
number = {4},
pages = {2019GL083898},
title = {{Equilibrium Climate Sensitivity Estimated by Equilibrating Climate Models}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083898 https://onlinelibrary.wiley.com/doi/10.1029/2019GL083898},
volume = {47},
year = {2020}
}
@article{Rugenstein2013a,
abstract = {Climate models simulate a wide range of climate changes at high northern latitudes in response to increased CO2. They also have substantial disagreement on projected changes of the Atlantic meridional overturning circulation (AMOC). Here, two pairs of closely related climate models are used, with each containing members with large and small AMOC declines to explore the influence of AMOC decline on the high-latitude response to increased CO2. The models with larger AMOC decline have less high-latitude warming and sea ice decline than their small AMOC decline counterpart. By examining differences in the perturbation heat budget of the 40°–90°N region, it is shown that AMOC decline diminishes the warming by weakening poleward ocean heat transport and increasing the ocean heat uptake. The cooling impact of this AMOC-forced surface heat flux perturbation difference is enhanced by shortwave feedback and diminished by longwave feedback and atmospheric heat transport differences. The magnitude of the AMOC decline within model pairs is positively related to the magnitudes of control climate AMOC and Labrador and Nordic Seas convection. Because the 40°–90°N region accounts for up to 40{\%} of the simulated global ocean heat uptake over 100 yr, the process described here influences the global heat uptake efficiency.},
author = {Rugenstein, Maria A A and Winton, Michael and Stouffer, Ronald J. and Griffies, Stephen M. and Hallberg, Robert},
doi = {10.1175/JCLI-D-11-00695.1},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
number = {2},
pages = {609--621},
title = {{Northern High-Latitude Heat Budget Decomposition and Transient Warming}},
volume = {26},
year = {2013}
}
@article{Rugenstein2019,
abstract = {We present a model intercomparison project, LongRunMIP, the first collection of millennial-length (1,000+ years) simulations of complex coupled climate models with a representation of ocean, atmosphere, sea ice, and land surface, and their interactions. Standard model simulations are generally only a few hundred years long. However, modeling the long-term equilibration in response to radiative forcing perturbation is important for understanding many climate phenomena, such as the evolution of ocean circulation, time- and temperature-dependent feedbacks, and the differentiation of forced signal and internal variability. The aim of LongRunMIP is to facilitate research into these questions by serving as an archive for simulations that capture as much of this equilibration as possible. The only requirement to participate in LongRunMIP is to contribute a simulation with elevated, constant CO 2 forcing that lasts at least 1,000 years. LongRunMIP is an MIP of opportunity in that the simulations were mostly performed prior to the conception of the archive without an agreed-upon set of experiments. For most models, the archive contains a preindustrial control simulation and simulations with an idealized (typically abrupt) CO 2 forcing. We collect 2D surface and top-of-atmosphere fields and 3D ocean temperature and salinity fields. Here, we document the collection of simulations and discuss initial results, including the evolution of surface and deep ocean temperature and cloud radiative effects. As of October 2019, the collection includes 50 simulations of 15 models by 10 modeling centers. The data of LongRunMIP are publicly available. We encourage submissions of more simulations in the future.},
author = {Rugenstein, Maria A.A. and Bloch-Johnson, Jonah and Abe-Ouchi, Ayako and Andrews, Timothy and Beyerle, Urs and Cao, Long and Chadha, Tarun and Danabasoglu, Gokhan and Dufresne, Jean-Louis and Duan, Lei and Foujols, Marie-Alice and Fr{\"{o}}licher, Thomas and Geoffroy, Olivier and Gregory, Jonathan and Knutti, Reto and Li, Chao and Marzocchi, Alice and Mauritsen, Thorsten and Menary, Matthew and Moyer, Elisabeth and Nazarenko, Larissa and Paynter, David and Saint-Martin, David and Schmidt, Gavin A. and Yamamoto, Akitomo and Yang, Shuting},
doi = {10.1175/BAMS-D-19-0068.1},
issn = {0003-0007},
journal = {Bulletin of the American Meteorological Society},
month = {dec},
number = {12},
pages = {2551--2570},
title = {{LongRunMIP: Motivation and Design for a Large Collection of Millennial-Length AOGCM Simulations}},
url = {https://journals.ametsoc.org/view/journals/bams/100/12/bams-d-19-0068.1.xml},
volume = {100},
year = {2019}
}
@article{Rugenstein2016a,
abstract = {In radiative forcing and climate feedback frameworks, the initial stratospheric and tropospheric adjustments to a forcing agent can be treated as part of the forcing and not as a feedback, as long as the average global surface temperature response is negligible. Here, a very large initial condition ensemble of the Community Earth System Model is used to analyze how the ocean shapes the fast response to radiative forcing. It is shown that not only the stratosphere and troposphere but also the ocean adjusts. This oceanic adjustment includes meridional ocean heat transport convergence anomalies, which are locally as large as the surface heat flux anomalies, and an increase of the Atlantic meridional overturning circulation. These oceanic adjustments set the lower boundary condition for the atmospheric response of the first few years, in particular, the shortwave cloud radiative effect. This cloud adjustment causes a nonlinear relationship between global energy imbalance and temperature. It proceeds with a characteristic time scale of a few years in response to the forcing rather than scaling nonlinearly with global mean temperature anomaly. It is proposed that even very short time scales are treated as a fully coupled problem and encourage other modeling groups to investigate whether our description also suits their models' behavior. A definition of the forcing term ("virtual forcing") including oceanic adjustment processes is introduced and serves as an interpretive idea for longer time scales.},
author = {Rugenstein, Maria A.A. and Gregory, Jonathan M. and Schaller, Nathalie and Sedl{\'{a}}cek, Jan and Knutti, Reto},
doi = {10.1175/JCLI-D-16-0312.1},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Circulation/Dynamics,Coupled models,Feedback,Forcing,Models and modeling,Ocean circulation,Physical Meteorology and Climatology,Radiative forcing},
number = {15},
pages = {5643--5659},
title = {{Multiannual ocean–atmosphere adjustments to radiative forcing}},
volume = {29},
year = {2016}
}
@article{Russotto2020,
abstract = {In the Tropical Rain belts with an Annual cycle and Continent Model Intercomparison Project (TRACMIP) ensemble of aquaplanet climate model experiments, CO2-induced warming is amplified in the poles in 10 out of 12 models, despite the lack of sea ice. We attribute causes of this amplification by perturbing individual radiative forcing and feedback components in a moist energy balance model. We find a strikingly linear pattern of tropical versus polar warming contributions across models and processes, implying that polar amplification is an inherent consequence of diffusion of moist static energy by the atmosphere. The largest contributor to polar amplification is the instantaneous CO2 forcing, followed by the water vapor feedback and, for some models, cloud feedbacks. Extratropical feedbacks affect polar amplification more strongly, but even feedbacks confined to the tropics can cause polar amplification. Our results contradict studies inferring warming contributions directly from the meridional gradient of radiative perturbations, highlighting the importance of interactions between feedbacks and moisture transport for polar amplification.},
author = {Russotto, Rick D. and Biasutti, Michela},
doi = {10.1029/2019GL086771},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {climate feedbacks,climate modeling,energy balance model,polar amplification},
month = {mar},
number = {6},
pages = {e2019GL086771},
publisher = {Blackwell Publishing Ltd},
title = {{Polar Amplification as an Inherent Response of a Circulating Atmosphere: Results From the TRACMIP Aquaplanets}},
volume = {47},
year = {2020}
}
@article{Rypdal2018,
author = {Rypdal, Martin and Fredriksen, Hege-Beate and Rypdal, Kristoffer and Steene, Rebekka J},
doi = {10.1038/s41586-018-0639-4},
issn = {1476-4687},
journal = {Nature},
number = {7729},
pages = {E4--E5},
title = {{Emergent constraints on climate sensitivity}},
url = {https://doi.org/10.1038/s41586-018-0639-4},
volume = {563},
year = {2018}
}
@article{doi:10.1029/2019MS001791,
abstract = {This study introduces CNRM‐ESM 2‐1, the Earth System (ES) model of second generation developed by CNRM‐CERFACS for the 6th phase of the Coupled Model Intercomparison Project (CMIP6). CNRM‐ESM 2‐1 offers a higher model complexity than the Atmosphere‐Ocean General Circulation Model CNRM‐CM6‐1 by adding interactive ES components such as carbon cycle, aerosols and atmospheric chemistry. As both models share the same code, physical parameterizations and grid resolution, they offer a fully‐traceable framework to investigate how far the represented ES processes impact the model performance over present‐day, response to external forcing and future climate projections. Using a large variety of CMIP6 experiments, we show that represented ES processes impact more prominently the model response to external forcing than the model performance over present‐day. Both models display comparable performance at replicating modern observations although the mean climate of CNRM‐ESM 2‐1 is slightly warmer than that of CNRM‐CM6‐1. This difference arises from land cover‐aerosols interactions where the use of different soil‐vegetation distributions between both models impacts the rate of dust emissions. This interaction results in a smaller aerosols burden in CNRM‐ESM 2‐1 than in CNRM‐CM6‐1, leading to a different surface radiative budget and climate. Greater differences are found when comparing the model response to external forcing and future climate projections. Represented ES processes damp future warming by up to 10{\%} in CNRM‐ESM 2‐1 with respect to CNRM‐CM6‐1. The representation of land vegetation and the CO2‐water‐stomatal feedback between both models explain about 60{\%} of this difference. The remainder is driven by other ES feedbacks such as the natural aerosols feedback.},
author = {S{\'{e}}f{\'{e}}rian, Roland and Nabat, P. and Michou, M. and Saint‐Martin, D. and Voldoire, A. and Colin, J. and Decharme, B. and Delire, C. and Berthet, S. and Chevallier, M. and S{\'{e}}n{\'{e}}si, S. and Franchisteguy, L. and Vial, J. and Mallet, M. and Joetzjer, E. and Geoffroy, O. and Gu{\'{e}}r{\'{e}}my, J.‐F. and Moine, M.‐P. and Msadek, R. and Ribes, A. and Rocher, M. and Roehrig, R. and Salas‐y‐M{\'{e}}lia, D. and Sanchez, E. and Terray, L. and Valcke, S. and Waldman, R. and Aumont, O. and Bopp, L. and Deshayes, J. and {\'{E}}th{\'{e}}, C. and Madec, G.},
doi = {10.1029/2019MS001791},
isbn = {0000000204385},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {CMIP6},
pages = {2019MS001791},
title = {{Evaluation of CNRM Earth‐System model, CNRM‐ESM2‐1: role of Earth system processes in present‐day and future climate}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001791},
volume = {11},
year = {2019}
}
@article{Sagoo20130123,
abstract = {Geological data for the Early Eocene (56{\{}$\backslash$textendash{\}}47.8 Ma) indicate extensive global warming, with very warm temperatures at both poles. However, despite numerous attempts to simulate this warmth, there are remarkable data{\{}$\backslash$textendash{\}}model differences in the prediction of these polar surface temperatures, resulting in the so-called {\{}$\backslash$textquoteleft{\}}equable climate problem{\{}$\backslash$textquoteright{\}}. In this paper, for the first time an ensemble with a perturbed climate-sensitive model parameters approach has been applied to modelling the Early Eocene climate. We performed more than 100 simulations with perturbed physics parameters, and identified two simulations that have an optimal fit with the proxy data. We have simulated the warmth of the Early Eocene at 560 ppmv CO2, which is a much lower CO2 level than many other models. We investigate the changes in atmospheric circulation, cloud properties and ocean circulation that are common to these simulations and how they differ from the remaining simulations in order to understand what mechanisms contribute to the polar warming. The parameter set from one of the optimal Early Eocene simulations also produces a favourable fit for the last glacial maximum boundary climate and outperforms the control parameter set for the present day. Although this does not {\{}$\backslash$textquoteleft{\}}prove{\{}$\backslash$textquoteright{\}} that this model is correct, it is very encouraging that there is a parameter set that creates a climate model able to simulate well very different palaeoclimates and the present-day climate. Interestingly, to achieve the great warmth of the Early Eocene this version of the model does not have a strong future climate change Charney climate sensitivity. It produces a Charney climate sensitivity of 2.7{\{}$\backslash$textdegree{\}}C, whereas the mean value of the 18 models in the IPCC Fourth Assessment Report (AR4) is 3.26{\{}$\backslash$textdegree{\}}C{\{}$\backslash$textpm{\}}0.69{\{}$\backslash$textdegree{\}}C. Thus, this value is within the range and below the mean of the models included in the AR4.},
author = {Sagoo, Navjit and Valdes, Paul and Flecker, Rachel and Gregoire, Lauren J and A, Phil Trans R Soc},
doi = {10.1098/rsta.2013.0123},
issn = {1364-503X},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
number = {2001},
pages = {20130123},
publisher = {The Royal Society},
title = {{The Early Eocene equable climate problem: can perturbations of climate model parameters identify possible solutions?}},
url = {http://rsta.royalsocietypublishing.org/content/371/2001/20130123},
volume = {371},
year = {2013}
}
@article{Saint-Lu2020,
abstract = {Abstract Anvil clouds cover extensive areas of the tropics, and their response to global warming can affect cloud feedbacks and climate sensitivity. A growing number of models and theories suggest that when the tropical atmosphere warms, anvil clouds rise and their coverage decreases, but observational support for this behavior remains limited. Here we use 10?years of measurements from the space-borne CALIPSO lidar to analyze the vertical distribution of clouds and isolate the behavior of anvil clouds. On the interannual time scale, we find a strong evidence for anvil rise and coverage decrease in response to tropical warming. Using meteorological reanalyses, we show that this is associated with an increase in static stability and with a reduction in clear-sky radiatively driven mass convergence at the anvil height. These relationships hold over a large range of spatial scales. This is consistent with the stability Iris mechanism suggested by theory and modeling studies.},
annote = {doi: 10.1029/2020GL089059},
author = {Saint-Lu, Marion and Bony, Sandrine and Dufresne, Jean-Louis},
doi = {10.1029/2020GL089059},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {jul},
number = {14},
pages = {e2020GL089059},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Observational Evidence for a Stability Iris Effect in the Tropics}},
url = {https://doi.org/10.1029/2020GL089059},
volume = {47},
year = {2020}
}
@article{Salzmann2013a,
abstract = {Comparing simulations of key warm periods in Earth history with contemporaneous geological proxy data is a useful approach for evaluating the ability of climate models to simulate warm, high-CO2 climates that are unprecedented in the more recent past1–3. Here we use a global data set of confidence-assessed, proxy-based temperature estimates and biome reconstructions to assess the ability of eight models to simulate warm terrestrial climates of the Pliocene epoch. The Late Pliocene, 3.6–2.6 million years ago, is an accessi- ble geological interval to understand climate processes of a warmer world4. We show that model-predicted surface air temperatures reveal a substantial cold bias in the Northern Hemisphere. Particularly strong data–model mismatches in mean annual temperatures (up to 18 ◦C) exist in northern Rus- sia. Our model sensitivity tests identify insufficient temporal constraints hampering the accurate configuration of model boundary conditions as an important factor impacting on data– model discrepancies.We conclude that to allow a more robust evaluation of the ability of present climate models to predict warm climates, future Pliocene data–model comparison studies should focus on orbitally defined time slices5.},
author = {Salzmann, Ulrich and Dolan, Aisling M. and Haywood, Alan M. and Chan, Wing Le and Voss, Jochen and Hill, Daniel J. and Abe-Ouchi, Ayako and Otto-Bliesner, Bette and Bragg, Frances J. and Chandler, Mark A. and Contoux, Camille and Dowsett, Harry J. and Jost, Anne and Kamae, Youichi and Lohmann, Gerrit and Lunt, Daniel J. and Pickering, Steven J. and Pound, Matthew J. and Ramstein, Gilles and Rosenbloom, Nan A. and Sohl, Linda and Stepanek, Christian and Ueda, Hiroaki and Zhang, Zhongshi},
doi = {10.1038/nclimate2008},
isbn = {1758-678X},
issn = {1758678X},
journal = {Nature Climate Change},
number = {11},
pages = {969--974},
publisher = {Nature Publishing Group},
title = {{Challenges in quantifying Pliocene terrestrial warming revealed by data–model discord}},
url = {http://dx.doi.org/10.1038/nclimate2008},
volume = {3},
year = {2013}
}
@article{Salzmann2017a,
abstract = {Previous studies have attributed an overall weaker (or slower) polar amplification in Antarctica compared to the Arctic to a weaker antarctic surface albedo feedback and also to more efficient ocean heat uptake in the Southern Ocean in combination with antarctic ozone depletion. Here, the role of the antarctic surface height for meridional heat transport and local radiative feedbacks including the surface albedo feedback was investigated based on CO2 doubling experiments in a low resolution coupled climate model. If Antarctica was assumed to be flat, the north-south asymmetry of the zonal mean top of the atmosphere radiation budget was significantly reduced. Doubling CO2 in a flat Antarctica ("flat AA") model setup led to a stronger increase of southern hemispheric poleward atmospheric and oceanic heat transport compared to the base model setup. Based on partial radiative perturbation (PRP) computations it was shown that local radiative feedbacks and an increase of the CO2 forcing in the deeper atmospheric column also contributed to stronger antarctic warming in the flat AA model setup, and the roles of the individual radiative feedbacks are discussed in some detail. A significant fraction (between 24 and 80{\&}thinsp;{\%} for three consecutive 25-year time slices starting in year 51 and ending in year 126 after CO2 doubling) of the polar amplification asymmetry was explained by the difference in surface height, but the fraction was subject to transient changes, and might to some extent also depend on model uncertainties.},
author = {Salzmann, Marc},
doi = {10.5194/esd-8-323-2017},
issn = {21904987},
journal = {Earth System Dynamics},
number = {2},
pages = {323--336},
title = {{The polar amplification asymmetry: role of Antarctic surface height}},
volume = {8},
year = {2017}
}
@article{Sanchez-Lorenzo2013a,
abstract = {There is a growing interest in the study of decadal variations in surface solar radiation during the last decades, although the analyses of long-term time series in some areas with major gaps in observations, such as in Spain, are still pending. This work describes for the first time the development of a new dataset of surface solar radiation in Spain based on the longest series with records of global solar radiation (G), most of them starting in the early 1980s. Additional records of diffuse solar radiation (D), which is a component of G much less studied due to the general scarcity of long-term series, are available for some of these series. Particular emphasis is placed upon the homogenization of this dataset in order to ensure the reliability of the trends, which can be affected by non-natural factors such as relocations or changes of instruments. The mean annual G series over Spain shows a tendency to increase during the 1985-2010 period, with a significant linear trend of +3.9 W m(-2) per decade. Similar significant increases are observed in the mean seasonal series, with the highest rate of change during summer (+6.5 W m(-2) per decade) and secondly in autumn (+4.1 W m(-2) per decade) and spring (+3.2 W m(-2) per decade). These results are in line with the widespread increase of G, also known as brightening period, reported at many worldwide observation sites. Furthermore, the annual mean D series starts without relevant variations during the second half of the 1980s, but it is disturbed by a strong increase in 1991 and 1992, which might reflect the signal of the Pinatubo volcanic eruption. Afterwards, the mean series shows a tendency to decrease up to the mid-2000s, with a significant linear trend of -2.1 W m(-2) per decade during the 1985-2010 period. All these results point towards a diminution of clouds and/or aerosols over the area. (C) 2012 Elsevier B.V. All rights reserved.},
address = {Sanchez-Lorenzo, A ETH, Inst Atmospher {\&} Climate Sci, Univ Str 16, CH-8092 Zurich, Switzerland ETH, Inst Atmospher {\&} Climate Sci, Univ Str 16, CH-8092 Zurich, Switzerland ETH, Inst Atmospher {\&} Climate Sci, CH-8092 Zurich, Switzerland Univ Girona, Dept Phy},
annote = {098OF
Times Cited:9
Cited References Count:76},
author = {Sanchez-Lorenzo, A and Calbo, J and Wild, M},
doi = {10.1016/J.Gloplacha.2012.11.010},
issn = {0921-8181},
journal = {Global and Planetary Change},
keywords = {global solar radiation diffuse solar radiation spa},
language = {English},
pages = {343--352},
title = {{Global and diffuse solar radiation in Spain: Building a homogeneous dataset and assessing their trends}},
volume = {100},
year = {2013}
}
@article{Sanchez-Lorenzo2015a,
abstract = {This paper presents trends in downward surface shortwave radiation (SSR) over Europe, which are based on the 56 longest series available from the Global Energy Balance Archive that are mainly concentrated in central Europe. Special emphasis has been placed on both ensuring the temporal homogeneity and including the most recent years in the data set. We have generated, for the first time, composite time series for Europe covering the period 1939-2012, which have been studied by means of running trend analysis. The mean annual SSR series shows an increase from the late 1930s to the early 1950s (i.e., early brightening), followed by a reduction until mid-1980s (i.e., global dimming) and a subsequent increase up to the early 2000s (i.e., global brightening). The series ends with a tendency of stabilization since the early 21st century, but the short time period is insufficient with regard to establishing whether a change in the trend is actually emerging over Europe. Seasonal and regional series are also presented, which highlight that similar variations are obtained for most of the seasons and regions across Europe. In fact, due to the strong spatial correlation in the SSR series, few series are enough to capture almost the same interannual and decadal variability as using a dense network of stations. Decadal variations of the SSR are expected to have an impact on the modulation of the temperatures and other processes over Europe linked with changes in the hydrological cycle, agriculture production, or natural ecosystems. For a better dissemination of the time series developed in this study, the data set is freely available for scientific purposes.},
address = {CSIC, Inst Pirenaico Ecol, Zaragoza, Spain Univ Girona, Dept Phys, Girona, Spain ETH, Inst Atmospher {\&} Climate Sci, Zurich, Switzerland Italian Natl Res Council, Inst Atmospher Sci {\&} Climate, Bologna, Italy State Meteorol Agcy AEMET, Palma De Mallorca, Sp},
annote = {Cu3le
Times Cited:4
Cited References Count:70},
author = {Sanchez-Lorenzo, A and Wild, M and Brunetti, M and Guijarro, J A and Hakuba, M Z and Calbo, J and Mystakidis, S and Bartok, B},
doi = {10.1002/2015jd023321},
issn = {2169-897x},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {global irradiance surface observations homogenizat},
language = {English},
number = {18},
pages = {9555--9569},
title = {{Reassessment and update of long-term trends in downward surface shortwave radiation over Europe (1939–2012)}},
volume = {120},
year = {2015}
}
@article{Santer1551,
abstract = {The month-to-month variability of tropical temperatures is larger in the troposphere than at Earth{\{}$\backslash$textquoteright{\}}s surface. This amplification behavior is similar in a range of observations and climate model simulations and is consistent with basic theory. On multidecadal time scales, tropospheric amplification of surface warming is a robust feature of model simulations, but it occurs in only one observational data set. Other observations show weak, or even negative, amplification. These results suggest either that different physical mechanisms control amplification processes on monthly and decadal time scales, and models fail to capture such behavior; or (more plausibly) that residual errors in several observational data sets used here affect their representation of long-term trends.},
author = {Santer, B D and Wigley, T M L and Mears, C and Wentz, F J and Klein, S A and Seidel, D J and Taylor, K E and Thorne, P W and Wehner, M F and Gleckler, P J and Boyle, J S and Collins, W D and Dixon, K W and Doutriaux, C and Free, M and Fu, Q and Hansen, J E and Jones, G S and Ruedy, R and Karl, T R and Lanzante, J R and Meehl, G A and Ramaswamy, V and Russell, G and Schmidt, G A},
doi = {10.1126/science.1114867},
issn = {0036-8075},
journal = {Science},
number = {5740},
pages = {1551--1556},
publisher = {American Association for the Advancement of Science},
title = {{Amplification of Surface Temperature Trends and Variability in the Tropical Atmosphere}},
url = {http://science.sciencemag.org/content/309/5740/1551},
volume = {309},
year = {2005}
}
@article{Sato2018,
abstract = {Aerosols affect climate by modifying cloud properties through their role as cloud condensation nuclei or ice nuclei, called aerosol–cloud interactions. In most global climate models (GCMs), the aerosol–cloud interactions are represented by empirical parameterisations, in which the mass of cloud liquid water (LWP) is assumed to increase monotonically with increasing aerosol loading. Recent satellite observations, however, have yielded contradictory results: LWP can decrease with increasing aerosol loading. This difference implies that GCMs overestimate the aerosol effect, but the reasons for the difference are not obvious. Here, we reproduce satellite-observed LWP responses using a global simulation with explicit representations of cloud microphysics, instead of the parameterisations. Our analyses reveal that the decrease in LWP originates from the response of evaporation and condensation processes to aerosol perturbations, which are not represented in GCMs. The explicit representation of cloud microphysics in global scale modelling reduces the uncertainty of climate prediction.},
author = {Sato, Yousuke and Goto, Daisuke and Michibata, Takuro and Suzuki, Kentaroh and Takemura, Toshihiko and Tomita, Hirofumi and Nakajima, Teruyuki},
doi = {10.1038/s41467-018-03379-6},
issn = {2041-1723},
journal = {Nature Communications},
month = {dec},
number = {1},
pages = {985},
publisher = {Nature Publishing Group},
title = {{Aerosol effects on cloud water amounts were successfully simulated by a global cloud-system resolving model}},
volume = {9},
year = {2018}
}
@article{Schleussner2019,
author = {Schleussner, Carl-Friedrich and Nauels, Alexander and Schaeffer, Michiel and Hare, William and Rogelj, Joeri},
doi = {10.1088/1748-9326/ab56e7},
issn = {1748-9326},
journal = {Environmental Research Letters},
month = {dec},
number = {12},
pages = {124055},
title = {{Inconsistencies when applying novel metrics for emissions accounting to the Paris agreement}},
url = {http://iopscience.iop.org/article/10.1088/1748-9326/ab56e7 https://iopscience.iop.org/article/10.1088/1748-9326/ab56e7},
volume = {14},
year = {2019}
}
@article{Schleussner2016,
abstract = {The Paris Agreement sets a long-term temperature goal of holding the global average temperature increase to well below 2 °C, and pursuing efforts to limit this to 1.5 °C above pre-industrial levels. Here, we present an overview of science and policy aspects related to this goal and analyse the implications for mitigation pathways. We show examples of discernible differences in impacts between 1.5 °C and 2 °C warming. At the same time, most available low emission scenarios at least temporarily exceed the 1.5 °C limit before 2100. The legacy of temperature overshoots and the feasibility of limiting warming to 1.5 °C, or below, thus become central elements of a post-Paris science agenda. The near-term mitigation targets set by countries for the 2020-2030 period are insufficient to secure the achievement of the temperature goal. An increase in mitigation ambition for this period will determine the Agreement's effectiveness in achieving its temperature goal.},
author = {Schleussner, Carl-Friedrich and Rogelj, Joeri and Schaeffer, Michiel and Lissner, Tabea and Licker, Rachel and Fischer, Erich M. and Knutti, Reto and Levermann, Anders and Frieler, Katja and Hare, William},
doi = {10.1038/nclimate3096},
issn = {17586798},
journal = {Nature Climate Change},
keywords = {Climate,change mitigation,change policy},
month = {aug},
number = {9},
pages = {827--835},
publisher = {Nature Publishing Group},
title = {{Science and policy characteristics of the Paris Agreement temperature goal}},
url = {www.nature.com/natureclimatechange},
volume = {6},
year = {2016}
}
@article{Schlund2020,
author = {Schlund, Manuel and Lauer, Alex and Gentine, Pierre and Sherwood, Steven and Eyring, Veronika},
doi = {https://doi.org/10.5194/esd-11-1233-2020},
journal = {Earth System Dynamics},
pages = {1233--1258},
title = {{Emergent constraints on Equilibrium Climate Sensitivity in CMIP5: do they hold for CMIP6?}},
volume = {11},
year = {2020}
}
@article{Schmidt2014b,
abstract = {We present a selection of methodologies for using the palaeo-climate model component of the Coupled Model Intercomparison Project (Phase 5) (CMIP5) to attempt to constrain future climate projections using the same models. The constraints arise from measures of skill in hindcasting palaeo-climate changes from the present over three periods: the Last Glacial Maximum (LGM) (21 000 yr before present, ka), the mid-Holocene (MH) (6 ka) and the Last Millennium (LM) (850–1850 CE). The skill measures may be used to val- idate robust patterns of climate change across scenarios or to distinguish between models that have differing outcomes in future scenarios. We find that the multi-model ensemble of palaeo-simulations is adequate for addressing at least some of these issues. For example, selected benchmarks for the LGM andMHare correlated to the rank of future projections of precipitation/temperature or sea ice extent to indicate that models that produce the best agreement with palaeo-climate information give demonstrably different future results than the rest of the models. We also explore cases where com- parisons are strongly dependent on uncertain forcing time series or show important non-stationarity, making direct in- ferences for the future problematic. Overall, we demonstrate that there is a strong potential for the palaeo-climate simu- lations to help inform the future projections and urge all the modelling groups to complete this subset of the CMIP5 runs.},
author = {Schmidt, G. A. and Annan, J. D. and Bartlein, P. J. and Cook, B. I. and Guilyardi, E. and Hargreaves, J. C. and Harrison, S. P. and Kageyama, M. and Legrande, A. N. and Konecky, B. and Lovejoy, S. and Mann, M. E. and Masson-Delmotte, V. and Risi, C. and Thompson, D. and Timmermann, A. and Yiou, P.},
doi = {10.5194/cp-10-221-2014},
isbn = {1814-9332},
issn = {18149324},
journal = {Climate of the Past},
number = {1},
pages = {221--250},
title = {{Using palaeo-climate comparisons to constrain future projections in CMIP5}},
volume = {10},
year = {2014}
}
@article{Schmidt2017b,
abstract = {Model calibration (or "tuning") is a necessary part of developing and testing coupled ocean-atmosphere climate models regardless of their main scientific purpose. There is an increasing recognition that this process needs to become more transparent for both users of climate model output and other developers. Knowing how and why climate models are tuned and which targets are used is essential to avoiding possible misattributions of skillful predictions to data accommodation and vice versa. This paper describes the approach and practice of model tuning for the six major U.S. climate modeling centers. While details differ among groups in terms of scientific missions, tuning targets and tunable parameters, there is a core commonality of approaches. However, practices differ significantly on some key aspects, in particular, in the use of initialized forecast analyses as a tool, the explicit use of the historical transient record, and the use of the present day radiative imbalance vs. the implied balance in the pre-industrial as a target.},
author = {Schmidt, Gavin A. and Bader, David and Donner, Leo J. and Elsaesser, Gregory S. and Golaz, Jean Christophe and Hannay, Cecile and Molod, Andrea and Neale, Richard B. and Saha, Suranjana},
doi = {10.5194/gmd-10-3207-2017},
issn = {19919603},
journal = {Geoscientific Model Development},
number = {9},
pages = {3207--3223},
title = {{Practice and philosophy of climate model tuning across six US modeling centers}},
volume = {10},
year = {2017}
}
@article{Schmidt2017c,
abstract = {Palaeoclimate variations are an essential component in constraining future projections of climate change as a function of increasing abundances of anthropogenic greenhouse gases1. The Earth system sensitivity (ESS) describes the multi-millennial response of Earth (in terms of the change in global-mean temperature) to a doubling of atmospheric CO2 concentrations. A recent study2 used a correlation of inferred temperatures and radiative forcing from greenhouse gases over the past 800,000 years3 to estimate that the ESS from present-day CO2 concentrations is about 9 °C and to imply a long-term commitment of 3–7 °C even if greenhouse gas concentrations remain at present-day levels. However, we demonstrate that the methodology of ref. 2 does not reliably estimate the ESS in the presence of orbital forcing of ice-age cycles and therefore conclude that the inferred2 present-day committed warming is considerably overestimated. There is a Reply to this Comment by Snyder, C. W. Nature 547, http://dx.doi.org/10.1038/nature22804 (2017). The previous analysis2 was based on the assumption that greenhouse gases were solely responsible for long-term global-mean glacial–interglacial temperature changes. This is not correct4, 5, 6, 7. Although it is clear that greenhouse gases have a large role, quantifying that role is difficult because of simultaneous changes in many factors that also influence the energy balance of Earth (such as the extent of the ice sheets, snow cover, vegetation, dust load and cloud cover)4. However, it is widely accepted that orbital forcing is the ultimate trigger for glacial–interglacial cycles4, 5, 6, 7, enhanced by fast and slow feedbacks that involve the ice albedo, clouds, the carbon cycle, vegetation, and so on1, sometimes resulting in hysteresis behaviour6. Therefore, the strong correlation that is seen in the datasets analysed in ref. 2 is a conflation of the sensitivity of the climate to CO2 and the response of the carbon cycle to variations in temperature and ice-sheet extent. The Charney climate sensitivity (which includes fast atmospheric feedbacks, but not long-term changes in ice-sheet extent or in vegetation) can be constrained by these data by treating the long-term factors as forcings8. However, estimating the long-term sensitivity to greenhouse gas forcing alone requires constraints from periods that are not affected by the interaction between orbital forcing and ice sheets, or that include a model-based assessment of the response to other forcings1, 9, 10, 11.},
author = {Schmidt, Gavin A. and Severinghaus, Jeff and Abe-Ouchi, Ayako and Alley, Richard B. and Broecker, Wallace and Brook, Ed and Etheridge, David and Kawamura, Kenji and Keeling, Ralph F. and Leinen, Margaret and Marvel, Kate and Stocker, Thomas F.},
doi = {10.1038/nature22803},
issn = {14764687},
journal = {Nature},
number = {7662},
pages = {E16--E17},
publisher = {Nature Publishing Group},
title = {{Overestimate of committed warming}},
url = {http://dx.doi.org/10.1038/nature22803},
volume = {547},
year = {2017}
}
@article{Schmidt2018,
abstract = {Abstract Using volcanic sulfur dioxide emissions in an aerosol-climate model we derive a time-series of global-mean volcanic effective radiative forcing (ERF) from 1979 to 2015. For 2005-2015, we calculate a global multi-annual mean volcanic ERF of -0.08 W m-2 relative to the volcanically quiescent 1999-2002 period, due to a high frequency of small-to-moderate-magnitude explosive eruptions after 2004. For eruptions of large magnitude such as 1991 Mt. Pinatubo, our model-simulated volcanic ERF, which accounts for rapid adjustments including aerosol perturbations of clouds, is less negative than that reported in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) that only accounted for stratospheric temperature adjustments. We find that, when rapid adjustments are considered, the relation between volcanic forcing and volcanic stratospheric optical depth (SAOD) is 13-21{\%} weaker than reported in IPCC AR5 for large-magnitude eruptions. Further, our analysis of the recurrence frequency of eruptions reveals that sulfur-rich small-to-moderate-magnitude eruptions with column heights ≥10 km occur frequently, with periods of volcanic quiescence being statistically rare. Small-to-moderate-magnitude eruptions should therefore be included in climate model simulations, given the {\textgreater}50{\%} chance of one or two eruptions to occur in any given year. Not all of these eruptions affect the stratospheric aerosol budget, but those that do increase the non-volcanic background SAOD by {\~{}}0.004 on average, contributing {\~{}}50{\%} to the total SAOD in the absence of large-magnitude eruptions. This equates to a volcanic ERF of about -0.10 W m-2, which is about two-thirds of the ERF from ozone changes induced by ozone-depleting substances.},
author = {Schmidt, Anja and Mills, Michael J. and Ghan, Steven and Gregory, Jonathan M. and Allan, Richard P. and Andrews, Timothy and Bardeen, Charles G. and Conley, Andrew and Forster, Piers M. and Gettelman, Andrew and Portmann, Robert W. and Solomon, Susan and Toon, Owen B.},
doi = {10.1029/2018JD028776},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aerosol-cloud interactions,climate change,volcanic aerosol,volcanic emissions,volcanic eruptions,volcanic radiative forcing},
month = {nov},
number = {22},
pages = {12491--12508},
title = {{Volcanic Radiative Forcing From 1979 to 2015}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2018JD028776},
volume = {123},
year = {2018}
}
@article{Schndr18,
abstract = {Previous studies quantify surface albedo feedback (SAF) in climate change, but few assess its variability on decadal time scales. Using the Coupled Model Intercomparison Project Version 5 (CMIP5) multimodel ensemble data set, we calculate time evolving SAF in multiple decades from surface albedo and temperature linear regressions. Results are meaningful when temperature change exceeds 0.5 K. Decadal-scale SAF is strongly correlated with century-scale SAF during the 21st century. Throughout the 21st century, multimodel ensemble mean SAF increases from 0.37 to 0.42 W m−2 K−1. These results suggest that models' mean decadal-scale SAFs are good estimates of their century-scale SAFs if there is at least 0.5 K temperature change. Persistent SAF into the late 21st century indicates ongoing capacity for Arctic albedo decline despite there being less sea ice. If the CMIP5 multimodel ensemble results are representative of the Earth, we cannot expect decreasing Arctic sea ice extent to suppress SAF in the 21st century.},
annote = {2017GL076293},
author = {Schneider, Adam and Flanner, Mark and Perket, Justin},
doi = {10.1002/2017GL076293},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {Arctic sea ice,albedo,climate change,climate feedbacks,climate sensitivity,cryosphere},
number = {4},
pages = {1972--1980},
title = {{Multidecadal Variability in Surface Albedo Feedback Across CMIP5 Models}},
url = {http://dx.doi.org/10.1002/2017GL076293},
volume = {45},
year = {2018}
}
@article{Schneider2019,
abstract = {Stratocumulus clouds cover 20{\%} of the low-latitude oceans and are especially prevalent in the subtropics. They cool the Earth by shading large portions of its surface from sunlight. However, as their dynamical scales are too small to be resolvable in global climate models, predictions of their response to greenhouse warming have remained uncertain. Here we report how stratocumulus decks respond to greenhouse warming in large-eddy simulations that explicitly resolve cloud dynamics in a representative subtropical region. In the simulations, stratocumulus decks become unstable and break up into scattered clouds when CO2 levels rise above 1,200 ppm. In addition to the warming from rising CO2 levels, this instability triggers a surface warming of about 8 K globally and 10 K in the subtropics. Once the stratocumulus decks have broken up, they only re-form once CO2 concentrations drop substantially below the level at which the instability first occurred. Climate transitions that arise from this instability may have contributed importantly to hothouse climates and abrupt climate changes in the geological past. Such transitions to a much warmer climate may also occur in the future if CO2 levels continue to rise.},
author = {Schneider, Tapio and Kaul, Colleen M and Pressel, Kyle G},
doi = {10.1038/s41561-019-0310-1},
issn = {1752-0908},
journal = {Nature Geoscience},
number = {3},
pages = {163--167},
title = {{Possible climate transitions from breakup of stratocumulus decks under greenhouse warming}},
url = {https://doi.org/10.1038/s41561-019-0310-1},
volume = {12},
year = {2019}
}
@article{bg-9-649-2012,
author = {{Schneider von Deimling}, T and Meinshausen, M and Levermann, A and Huber, V and Frieler, K and Lawrence, D M and Brovkin, V},
doi = {10.5194/bg-9-649-2012},
journal = {Biogeosciences},
number = {2},
pages = {649--665},
title = {{Estimating the near-surface permafrost-carbon feedback on global warming}},
url = {https://bg.copernicus.org/articles/9/649/2012/},
volume = {9},
year = {2012}
}
@article{SchneidervonDeimling2015,
abstract = {High-latitude soils store vast amounts of perennially frozen and therefore inert organic matter. With rising global temperatures and consequent permafrost degradation, a part of this carbon stock will become available for microbial decay and eventual release to the atmosphere. We have developed a simplified, two-dimensional multi-pool model to estimate the strength and timing of future carbon dioxide (CO 2) and methane (CH 4) fluxes from newly thawed per-mafrost carbon (i.e. carbon thawed when temperatures rise above pre-industrial levels). We have especially simulated carbon release from deep deposits in Yedoma regions by describing abrupt thaw under newly formed thermokarst lakes. The computational efficiency of our model allowed us to run large, multi-centennial ensembles under various scenarios of future warming to express uncertainty inherent to simulations of the permafrost carbon feedback. Under moderate warming of the representative concentration pathway (RCP) 2.6 scenario, cumulated CO 2 fluxes from newly thawed permafrost carbon amount to 20 to 58 peta-grams of carbon (Pg-C) (68 {\%} range) by the year 2100 and reach 40 to 98 Pg-C in 2300. The much larger permafrost degradation under strong warming (RCP8.5) results in cu-mulated CO 2 release of 42 to 141 Pg-C and 157 to 313 Pg-C (68 {\%} ranges) in the years 2100 and 2300, respectively. Our estimates only consider fluxes from newly thawed per-mafrost, not from soils already part of the seasonally thawed active layer under pre-industrial climate. Our simulated CH 4 fluxes contribute a few percent to total permafrost carbon release yet they can cause up to 40 {\%} of total permafrost-affected radiative forcing in the 21st century (upper 68 {\%} range). We infer largest CH 4 emission rates of about 50 Tg-CH 4 per year around the middle of the 21st century when simulated thermokarst lake extent is at its maximum and when abrupt thaw under thermokarst lakes is taken into account. CH 4 release from newly thawed carbon in wetland-affected deposits is only discernible in the 22nd and 23rd century because of the absence of abrupt thaw processes. We further show that release from organic matter stored in deep deposits of Yedoma regions crucially affects our simulated circumpolar CH 4 fluxes. The additional warming through the release from newly thawed permafrost carbon proved only slightly dependent on the pathway of anthropogenic emission and amounts to about 0.03-0.14 • C (68 {\%} ranges) by end of the century. The warming increased further in the 22nd and 23rd century and was most pronounced under the RCP6.0 scenario, adding 0.16 to 0.39 • C (68 {\%} range) to simulated global mean surface air temperatures in the year 2300.},
author = {{Schneider von Deimling}, T and Grosse, G and Strauss, J and Schirrmeister, L and Morgenstern, A and Schaphoff, S and Meinshausen, M and Boike, J},
doi = {10.5194/bg-12-3469-2015},
isbn = {12/3469/2015},
journal = {Biogeosciences},
pages = {3469--3488},
title = {{Observation-based modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity}},
url = {www.biogeosciences.net/12/3469/2015/},
volume = {12},
year = {2015}
}
@article{Schr_der_2019,
author = {Schr{\"{o}}der, Marc and Lockhoff, Maarit and Shi, Lei and August, Thomas and Bennartz, Ralf and Brogniez, Helene and Calbet, Xavier and Fell, Frank and Forsythe, John and Gambacorta, Antonia and Al., Et},
doi = {10.3390/rs11030251},
issn = {2072-4292},
journal = {Remote Sensing},
month = {jan},
number = {3},
pages = {251},
publisher = {MDPI AG},
title = {{The GEWEX Water Vapor Assessment: Overview and Introduction to Results and Recommendations}},
url = {http://dx.doi.org/10.3390/rs11030251},
volume = {11},
year = {2019}
}
@article{Schulz2006,
author = {Schulz, M. and Textor, C. and Kinne, S. and Balkanski, Y. and Bauer, S. and Berntsen, T. and Berglen, T. and Boucher, O. and Dentener, F. and Guibert, S. and Isaksen, I. S. A. and Iversen, T. and Koch, D. and Kirkev{\aa}g, A. and Liu, X. and Montanaro, V. and Myhre, G. and Penner, J. E. and Pitari, G. and Reddy, S. and Seland, {\O}. and Stier, P. and Takemura, T.},
doi = {10.5194/acp-6-5225-2006},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {nov},
number = {12},
pages = {5225--5246},
title = {{Radiative forcing by aerosols as derived from the AeroCom present-day and pre-industrial simulations}},
url = {http://www.atmos-chem-phys.net/6/5225/2006/},
volume = {6},
year = {2006}
}
@article{Schurer2018,
abstract = { AbstractThe transient climate response (TCR) quantifies the warming expected during a transient doubling of greenhouse gas concentrations in the atmosphere. Many previous studies quantifying the observed historic response to greenhouse gases, and with it the TCR, use multimodel mean fingerprints and found reasonably constrained values, which contributed to the IPCC estimated ({\textgreater}66{\%}) range from 1° to 2.5°C. Here, it is shown that while the multimodel mean fingerprint is statistically more powerful than any individual model's fingerprint, it does lead to overconfident results when applied to synthetic data, if model uncertainty is neglected. Here, a Bayesian method is used that estimates TCR, accounting for climate model and observational uncertainty with indices of global temperature that aim at constraining the aerosol contribution to the historical record better. Model uncertainty in the aerosol response was found to be large. Nevertheless, an overall TCR estimate of 0.4°–3.1°C ({\textgreater}90{\%}) was calculated from the historical record, which reduces to 1.0°–2.6°C when using prior information that rules out negative TCR values and model misestimates of more than a factor of 3, and to 1.2°–2.4°C when using the multimodel mean fingerprints with a variance correction. Modeled temperature, like in the observations, is calculated as a blend of sea surface and air temperatures. },
author = {Schurer, Andrew and Hegerl, Gabi and Ribes, Aur{\'{e}}lien and Polson, Debbie and Morice, Colin and Tett, Simon},
doi = {10.1175/JCLI-D-17-0717.1},
journal = {Journal of Climate},
number = {20},
pages = {8645--8663},
title = {{Estimating the Transient Climate Response from Observed Warming}},
volume = {31},
year = {2018}
}
@article{Schwartz2007a,
abstract = {The equilibrium sensitivity of Earth's climate is determined as the quotient of the relaxation time constant of the system and the pertinent global heat capacity. The heat capacity of the global ocean, obtained from regression of ocean heat content versus global mean surface temperature, GMST, is 14 +/- 6 W a m(-2) K-1, equivalent to 110 m of ocean water; other sinks raise the effective planetary heat capacity to 17 +/- 7 W a m(-2) K-1 ( all uncertainties are 1- sigma estimates). The time constant pertinent to changes in GMST is determined from autocorrelation of that quantity over 1880 - 2004 to be 5 +/- 1 a. The resultant equilibrium climate sensitivity, 0.30 +/- 0.14 K/(W m(-2)), corresponds to an equilibrium temperature increase for doubled CO2 of 1.1 +/- 0.5 K. The short time constant implies that GMST is in near equilibrium with applied forcings and hence that net climate forcing over the twentieth century can be obtained from the observed temperature increase over this period, 0.57 +/- 0.08 K, as 1.9 +/- 0.9 W m(-2). For this forcing considered the sum of radiative forcing by incremental greenhouse gases, 2.2 +/- 0.3 W m(-2), and other forcings, other forcing agents, mainly incremental tropospheric aerosols, are inferred to have exerted only a slight forcing over the twentieth century of -0.3 +/- 1.0 W m(-2).},
author = {Schwartz, Stephen E.},
doi = {10.1029/2007JD008746},
isbn = {0148-0227},
issn = {01480227},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {climate sensitivity,doi:10.1029/2007JD008746,energy balance model,http://dx.doi.org/10.1029/2007JD008746},
number = {24},
pages = {1--12},
title = {{Heat capacity, time constant, and sensitivity of Earth's climate system}},
volume = {112},
year = {2007}
}
@article{Schwartz2018,
author = {Schwartz, Stephen E.},
doi = {10.1002/2017JD028121},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {apr},
number = {7},
pages = {3462--3482},
title = {{Unrealized Global Temperature Increase: Implications of Current Uncertainties}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2017JD028121},
volume = {123},
year = {2018}
}
@article{Schwartz2012,
author = {Schwartz, Stephen E.},
doi = {10.1007/s10712-012-9180-4},
issn = {0169-3298},
journal = {Surveys in Geophysics},
month = {jul},
number = {3-4},
pages = {745--777},
publisher = {Springer Netherlands},
title = {{Determination of Earth's Transient and Equilibrium Climate Sensitivities from Observations Over the Twentieth Century: Strong Dependence on Assumed Forcing}},
url = {http://link.springer.com/10.1007/s10712-012-9180-4},
volume = {33},
year = {2012}
}
@article{ISI:000519214500005,
abstract = {The amount of solar (shortwave) radiation that reaches the Earth's surface underwent substantial variations over recent decades. Since the 1950s, surface shortwave radiation gradually decreased at widespread locations. In Europe, this so-called surface dimming continued until the late 1980s, when surface brightening set in and surface shortwave radiation increased again. In China, the dimming levelled off in the 1980s, but did not turn into brightening until 2005. Changes in clouds and aerosol are the prime potential causes for the phenomenon, but the scientific community has not yet reached a consensus about the relative role of the different potential forcing agents. Here we bring together co-located long-term observational data from surface and space to study decadal changes of the shortwave energy balance in Europe and China from 1985 to 2015. Within this observation-based framework, we show that an increasing net shortwave radiation at the top of the atmosphere and a decreasing atmospheric shortwave absorption each contribute roughly half of the observed brightening trends in Europe. For China, we find that the continued dimming until 2005 and the subsequent brightening occurred despite opposing trends in the top-of-the-atmosphere net shortwave radiation. This shows that changes in atmospheric shortwave absorption are a major driver of European brightening and the dominant cause for the Chinese surface trends. Although the observed variations cannot be attributed unambiguously, we discuss potential causes for the observed changes.},
author = {Schwarz, M and Folini, D and Yang, S and Allan, R P and Wild, M},
doi = {10.1038/s41561-019-0528-y},
issn = {1752-0894},
journal = {Nature Geoscience},
month = {feb},
number = {2},
pages = {110--115},
title = {{Changes in atmospheric shortwave absorption as important driver of dimming and brightening}},
volume = {13},
year = {2020}
}
@article{ISI:000455876300014,
abstract = {The representativeness of surface solar radiation (SSR) point observations is an important issue when using them in combination with gridded data. We conduct a comprehensive near-global (50 degrees Sto55 degrees N) analysis on the representativeness of SSR point observations on the monthly mean time scale. Thereto, we apply the existing concepts of decorrelation lengths (), spatial sampling biases (), and spatial sampling errors (epsilon) to three high-resolution gridded monthly mean SSR data sets (CLARA, SARAH-P, and SARAH-E) provided by the Satellite Application Facility on Climate Monitoring. While quantifies the area for which a point observation is representative, and epsilon are uncertainty estimates with respect to the 1-degree reference grid (G). For this grid we find a near-global average (G)=3.4 degrees, (G)=1.4W/m(2), and epsilon(G)=7.6W/m(2) with substantial regional differences. Disregarding tropical, mountainous, and some coastal regions, monthly SSR point observations can largely be considered representative of a 1-degree grid. Since epsilon is an uncorrectable error the total uncertainty when combining point with 1-degree gridded data is roughly 40{\%} higher than the uncertainty of station-based SSR measurements alone if a rigorous bias correction is applied. Cloud cover and terrain data can at maximum explain 50{\%} of the patterns of the representativeness metrics. We apply our methodology to the stations of the Baseline Surface Radiation Network. Overall, this study shows that representativeness is strongly dependent on local conditions and that all three metrics (, , and epsilon) must be considered for a comprehensive assessment of representativeness. Plain Language Summary Station-based observations are the most robust way to measure the amount of solar radiation reaching the Earth's surface (surface solar radiation {\{}[{\}}SSR]). These measurements are point observations yet are often used in combination with satellite or model data (e.g., for validation or for derivation of other quantities). The latter have a typical spatial extent up to a few hundred kilometers. Thus, it is important that the point observations are representative of this large area. In this paper, we show that the representativeness of SSR point observations varies regionally and is strongly dependent on local conditions. We find that some regions are problematic in terms of representativeness. However, in most regions SSR point observations can be considered representative for a 1-degree grid. We quantified additional uncertainties, which have to be taken into account when combining point and gridded data.},
author = {Schwarz, M and Folini, D and Hakuba, M Z and Wild, M},
doi = {10.1029/2018JD029169},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {dec},
number = {24},
pages = {13857--13874},
title = {{From Point to Area: Worldwide Assessment of the Representativeness of Monthly Surface Solar Radiation Records}},
volume = {123},
year = {2018}
}
@article{doi:10.1029/2011JC007084,
abstract = {Uncertainty in the Pan-Arctic Ice-Ocean Modeling and Assimilation System (PIOMAS) Arctic sea ice volume record is characterized. A range of observations and approaches, including in situ ice thickness measurements, ICESat retrieved ice thickness, and model sensitivity studies, yields a conservative estimate for October Arctic ice volume uncertainty of 1.35 103 km3 and an uncertainty of the ice volume trend over the 1979{\&}8211;2010 period of 1.0 103 km3 decade{\&}8211;1. A conservative estimate of the trend over this period is {\&}8722;2.8 103 km3 decade{\&}8211;1. PIOMAS ice thickness estimates agree well with ICESat ice thickness retrievals ({\textless}0.1 m mean difference) for the area for which submarine data are available, while difference outside this area are larger. PIOMAS spatial thickness patterns agree well with ICESat thickness estimates with pattern correlations of above 0.8. PIOMAS appears to overestimate thin ice thickness and underestimate thick ice, yielding a smaller downward trend than apparent in reconstructions from observations. PIOMAS ice volume uncertainties and trends are examined in the context of climate change attribution and the declaration of record minima. The distribution of 32 year trends in a preindustrial coupled model simulation shows no trends comparable to those seen in the PIOMAS retrospective, even when the trend uncertainty is accounted for. Attempts to label September minima as new record lows are sensitive to modeling error. However, the September 2010 ice volume anomaly did in fact exceed the previous 2007 minimum by a large enough margin to establish a statistically significant new record.},
author = {Schweiger, Axel and Lindsay, Ron and Zhang, Jinlun and Steele, Mike and Stern, Harry and Kwok, Ron},
doi = {10.1029/2011JC007084},
issn = {0148-0227},
journal = {Journal of Geophysical Research},
keywords = {Arctic,climate change,ice volume,modelling,sea ice},
month = {sep},
number = {C8},
pages = {C00D06},
title = {{Uncertainty in modeled Arctic sea ice volume}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2011JC007084 http://doi.wiley.com/10.1029/2011JC007084},
volume = {116},
year = {2011}
}
@article{Scott2017,
abstract = {More than one quarter of natural forests have been cleared by humans to make way for other land-uses, with changes to forest cover projected to continue. The climate impact of land-use change (LUC) is dependent upon the relative strength of several biogeophysical and biogeochemical effects. In addition to affecting the surface albedo and exchanging carbon dioxide (CO 2 ) and moisture with the atmosphere, vegetation emits biogenic volatile organic compounds (BVOCs), altering the formation of short-lived climate forcers (SLCFs) including aerosol, ozone (O 3 ) and methane (CH 4 ). Once emitted, BVOCs are rapidly oxidised by O 3 , and the hydroxyl (OH) and nitrate (NO 3 ) radicals. These oxidation reactions yield secondary organic products which are implicated in the formation and growth of aerosol particles and are estimated to have a negative radiative effect on the climate ( i.e. a cooling). These reactions also deplete OH, increasing the atmospheric lifetime of CH 4 , and directly affect concentrations of O 3 ; the latter two being greenhouse gases which impose a positive radiative effect ( i.e. a warming) on the climate. Our previous work assessing idealised deforestation scenarios found a positive radiative effect due to changes in SLCFs; however, since the radiative effects associated with changes to SLCFs result from a combination of non-linear processes it may not be appropriate to scale radiative effects from complete deforestation scenarios according to the deforestation extent. Here we combine a land-surface model, a chemical transport model, a global aerosol model, and a radiative transfer model to assess the net radiative effect of changes in SLCFs due to historical LUC between the years 1850 and 2000.},
author = {Scott, C. E. and Monks, S. A. and Spracklen, D. V. and Arnold, S. R. and Forster, P. M. and Rap, A. and Carslaw, K. S. and Chipperfield, M. P. and Reddington, C. L. S. and Wilson, C.},
doi = {10.1039/C7FD00028F},
issn = {1359-6640},
journal = {Faraday Discussions},
pages = {101--120},
title = {{Impact on short-lived climate forcers (SLCFs) from a realistic land-use change scenario via changes in biogenic emissions}},
url = {http://xlink.rsc.org/?DOI=C7FD00028F},
volume = {200},
year = {2017}
}
@article{doi:10.1029/2012GL051598,
abstract = {The Arctic is warming two to four times faster than the global average. Debate continues on the relative roles of local factors, such as sea ice reductions, versus remote factors in driving, or amplifying, Arctic warming. This study examines the vertical profile and seasonality of observed tropospheric warming, and addresses its causes using atmospheric general circulation model simulations. The simulations enable the isolation and quantification of the role of three controlling factors of Arctic warming: 1) observed Arctic sea ice concentration (SIC) and sea surface temperature (SST) changes; 2) observed remote SST changes; and 3) direct radiative forcing (DRF) due to observed changes in greenhouse gases, ozone, aerosols, and solar output. Local SIC and SST changes explain a large portion of the observed Arctic near-surface warming, whereas remote SST changes explain the majority of observed warming aloft. DRF has primarily contributed to Arctic tropospheric warming in summer.},
author = {Screen, J A and Deser, C and Simmonds, I},
doi = {10.1029/2012GL051598},
journal = {Geophysical Research Letters},
keywords = {Arctic,Arctic amplification,climate change,forcing,sea ice,sea surface temperature},
number = {10},
pages = {L10709},
title = {{Local and remote controls on observed Arctic warming}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2012GL051598},
volume = {39},
year = {2012}
}
@article{Seager2019,
abstract = {As exemplified by El Ni{\~{n}}o, the tropical Pacific Ocean strongly influences regional climates and their variability worldwide1–3. It also regulates the rate of global temperature rise in response to rising GHGs4. The tropical Pacific Ocean response to rising GHGs impacts all of the world's population. State-of-the-art climate models predict that rising GHGs reduce the west-to-east warm-to-cool sea surface temperature gradient across the equatorial Pacific5. In nature, however, the gradient has strengthened in recent decades as GHG concentrations have risen sharply5. This stark discrepancy between models and observations has troubled the climate research community for two decades. Here, by returning to the fundamental dynamics and thermodynamics of the tropical ocean–atmosphere system, and avoiding sources of model bias, we show that a parsimonious formulation of tropical Pacific dynamics yields a response that is consistent with observations and attributable to rising GHGs. We use the same dynamics to show that the erroneous warming in state-of-the-art models is a consequence of the cold bias of their equatorial cold tongues. The failure of state-of-the-art models to capture the correct response introduces critical error into their projections of climate change in the many regions sensitive to tropical Pacific sea surface temperatures.},
author = {Seager, Richard and Cane, Mark and Henderson, Naomi and Lee, Dong-Eun and Abernathey, Ryan and Zhang, Honghai},
doi = {10.1038/s41558-019-0505-x},
issn = {1758-6798},
journal = {Nature Climate Change},
number = {7},
pages = {517--522},
title = {{Strengthening tropical Pacific zonal sea surface temperature gradient consistent with rising greenhouse gases}},
url = {https://doi.org/10.1038/s41558-019-0505-x},
volume = {9},
year = {2019}
}
@article{Seeley2021,
abstract = {Abstract Recent explorations of the state-dependence of Earth?s equilibrium climate sensitivity (ECS) have revealed a pronounced peak in ECS at a surface temperature of ?310 K. This ECS peak has been observed in models spanning the model hierarchy, suggesting a robust physical source. Here, we propose an explanation for this ECS peak using a novel spectrally resolved decomposition of clear-sky longwave feedbacks. We show that the interplay between spectral feedbacks in H2O-dominated and CO2-dominated portions of the longwave spectrum, along with moist-adiabatic amplification of upper-tropospheric warming, conspire to produce a minimum in the feedback parameter, and a corresponding peak in ECS, at a surface temperature of 310 K. Mechanism-denial tests highlight three key ingredients for the ECS peak: (1) H2O continuum absorption to quickly close spectral windows at high surface temperature; (2) moist-adiabatic tropospheric temperatures to enhance upper-tropospheric warming; and (3) energetically consistent increases of CO2 with surface temperature.},
author = {Seeley, Jacob T. and Jeevanjee, Nadir},
doi = {10.1029/2020GL089609},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {equilibrium climate sensitivity,longwave feedbacks,radiative transfer,runaway greenhouse},
month = {feb},
number = {4},
pages = {e2020GL089609},
publisher = {American Geophysical Union (AGU)},
title = {{H2O Windows and CO2 Radiator Fins: A Clear‐Sky Explanation for the Peak in Equilibrium Climate Sensitivity}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL089609},
volume = {48},
year = {2021}
}
@article{Seifert2015,
author = {Seifert, Axel and Heus, Thijs and Pincus, Robert and Stevens, Bjorn},
doi = {10.1002/2015MS000489},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
month = {dec},
number = {4},
pages = {1918--1937},
publisher = {Wiley-Blackwell},
title = {{Large-eddy simulation of the transient and near-equilibrium behavior of precipitating shallow convection}},
url = {http://doi.wiley.com/10.1002/2015MS000489},
volume = {7},
year = {2015}
}
@article{Seneviratne2016a,
abstract = {Global temperature targets, such as the widely accepted limit of an increase above pre-industrial temperatures of two degrees Celsius, may fail to communicate the urgency of reducing carbon dioxide (CO2) emissions. The translation of CO2 emissions into regional- and impact-related climate targets could be more powerful because such targets are more directly aligned with individual national interests. We illustrate this approach using regional changes in extreme temperatures and precipitation. These scale robustly with global temperature across scenarios, and thus with cumulative CO2 emissions. This is particularly relevant for changes in regional extreme temperatures on land, which are much greater than changes in the associated global mean.},
author = {Seneviratne, Sonia I. and Donat, Markus G. and Pitman, Andy J. and Knutti, Reto and Wilby, Robert L.},
doi = {10.1038/nature16542},
isbn = {doi:10.1038/nature16542},
journal = {Nature},
pages = {477--483},
pmid = {26789252},
title = {{Allowable CO2 emissions based on regional and impact-related climate targets}},
volume = {529},
year = {2016}
}
@article{Shaffer2016a,
abstract = {Future global warming from anthropogenic greenhouse gas emissions will depend on climate feedbacks, the effect of which is expressed by climate sensitivity, the warming for a doubling of atmospheric CO2 content. It is not clear how feedbacks, sensitivity, and temperature will evolve in our warming world, but past warming events may provide insight. Here we employ paleoreconstructions and new climate-carbon model simulations in a novel framework to explore a wide scenario range for the Paleocene-Eocene Thermal Maximum (PETM) carbon release and global warming event 55.8 Ma ago, a possible future warming analogue. We obtain constrained estimates of CO2 and climate sensitivity before and during the PETM and of the PETM carbon input amount and nature. Sensitivity increased from 3.3–5.6 to 3.7–6.5 K (Kelvin) into the PETM. When taken together with Last Glacial Maximum and modern estimates, this result indicates climate sensitivity increase with global warming.},
author = {Shaffer, Gary and Huber, Matthew and Rondanelli, Roberto and {Pepke Pedersen}, Jens Olaf},
doi = {10.1002/2016GL069243},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {carbon cycle,climate sensitivity,paleoclimate},
number = {12},
pages = {6538--6545},
title = {{Deep time evidence for climate sensitivity increase with warming}},
volume = {43},
year = {2016}
}
@article{2011A&A...529A..67S,
archivePrefix = {arXiv},
arxivId = {astro-ph.SR/1102.4763},
author = {Shapiro, A.I. and Schmutz, W and Rozanov, E and Schoell, M and Haberreiter, M and Shapiro, A.V. V. and Nyeki, S},
doi = {10.1051/0004-6361/201016173},
eprint = {1102.4763},
issn = {0004-6361},
journal = {Astronomy {\&} Astrophysics},
keywords = {Astrophysics - Solar and Stellar Astrophysics,Sun: UV radiation,Sun: atmosphere,Sun: surface magnetism,line: formation,radiative transfer,solar-terrestrial relations},
month = {may},
pages = {A67},
primaryClass = {astro-ph.SR},
title = {{A new approach to the long-term reconstruction of the solar irradiance leads to large historical solar forcing}},
url = {http://www.aanda.org/10.1051/0004-6361/201016173},
volume = {529},
year = {2011}
}
@article{Sherwood2015a,
abstract = {The traditional forcing-feedback framework has provided an indispensable basis for discussing global climate changes. However, as analysis of model behavior has become more detailed, shortcomings and ambiguities in the framework have become more evident and physical effects unaccounted for by the traditional framework have become interesting. In particular, the new concept of adjustments, which are responses to forcings that are not mediated by the global mean temperature, has emerged. This concept, related to the older ones of climate efficacy and stratospheric adjustment, is a more physical way of capturing unique responses to specific forcings. We present a pedagogical review of the adjustment concept, why it is important, and how it can be used. The concept is particularly useful for aerosols, where it helps to organize what has become a complex array of forcing mechanisms. It also helps clarify issues around cloud and hydrological response, transient vs. equilibrium climate change, and geoengineering.},
author = {Sherwood, Steven C. and Bony, Sandrine and Boucher, Olivier and Bretherton, Chris and Forster, Piers M. and Gregory, Jonathan M. and Stevens, Bjorn},
doi = {10.1175/BAMS-D-13-00167.1},
issn = {00030007},
journal = {Bulletin of the American Meteorological Society},
number = {2},
pages = {217--228},
title = {{Adjustments in the forcing-feedback framework for understanding climate change}},
volume = {96},
year = {2015}
}
@article{Sherwood2018,
abstract = {Water vapour is the most abundant and powerful greenhouse gas in Earth's atmosphere, and is emitted by human activities. Yet the global warming potential (GWP) and radiative forcing (RF) of emitted water vapour have not been formally quantified in the literature. Here these quantities are estimated for surface emission using idealised experiments conducted with the CAM5 global atmospheric model at fixed ocean temperatures. Water is introduced in vapour form at rates matching total anthropogenic emissions (mainly from irrigation) but omitting the local evaporative cooling seen in irrigation simulations. A 100 year GWP for H2O of -10-3 to 5 × 10-4 is found, and an effective radiative forcing of -0.1 to 0.05 W m-2 for the given emissions. Increases in water vapour greenhouse effect are small because additional vapour cannot reach the upper troposphere, and greenhouse-gas warming is outweighed by increases in reflectance from humidity-induced low cloud cover, leading to a near-zero or small cooling effect. Near-surface temperature decreases over land are implied even without evaporative cooling at the surface, due to cooling by low clouds and vapour-induced changes to the moist lapse rate. These results indicate that even large increases in anthropogenic water vapour emissions would have negligible warming effects on climate, but that possible negative RF may deserve more attention.},
author = {Sherwood, Steven C. and Dixit, Vishal and Salomez, Chrys{\'{e}}is},
doi = {10.1088/1748-9326/aae018},
issn = {1748-9326},
journal = {Environmental Research Letters},
keywords = {climate change,global warming,radiative forcing,water vapour},
month = {sep},
number = {10},
pages = {104006},
title = {{The global warming potential of near-surface emitted water vapour}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/aae018},
volume = {13},
year = {2018}
}
@article{doi:10.1029/2009JD012585,
author = {Sherwood, Steven C and Ingram, William and Tsushima, Yoko and Satoh, Masaki and Roberts, Malcolm and Vidale, Pier Luigi and O'Gorman, Paul A},
doi = {10.1029/2009JD012585},
issn = {0148-0227},
journal = {Journal of Geophysical Research},
keywords = {climate feedbacks,climate models,water vapor},
month = {may},
number = {D9},
pages = {D09104},
title = {{Relative humidity changes in a warmer climate}},
url = {http://doi.wiley.com/10.1029/2009JD012585},
volume = {115},
year = {2010}
}
@article{Sherwood2014a,
abstract = {Equilibrium climate sensitivity refers to the ultimate change in global mean temperature in response to a change in external forcing. Despite decades of research attempting to narrow uncertainties, equilibrium climate sensitivity estimates from climate models still span roughly 1.5 to 5 degrees Celsius for a doubling of atmospheric carbon dioxide concentration, precluding accurate projections of future climate. The spread arises largely from differences in the feedback from low clouds, for reasons not yet understood. Here we show that differences in the simulated strength of convective mixing between the lower and middle tropical troposphere explain about half of the variance in climate sensitivity estimated by 43 climate models. The apparent mechanism is that such mixing dehydrates the low-cloud layer at a rate that increases as the climate warms, and this rate of increase depends on the initial mixing strength, linking the mixing to cloud feedback. The mixing inferred from observations appears to be sufficiently strong to imply a climate sensitivity of more than 3 degrees for a doubling of carbon dioxide. This is significantly higher than the currently accepted lower bound of 1.5 degrees, thereby constraining model projections towards relatively severe future warming.},
author = {Sherwood, Steven C. and Bony, Sandrine and Dufresne, Jean-Louis},
doi = {10.1038/nature12829},
isbn = {0028-0836},
issn = {00280836},
journal = {Nature},
month = {jan},
number = {7481},
pages = {37--42},
pmid = {24380952},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Spread in model climate sensitivity traced to atmospheric convective mixing}},
url = {http://dx.doi.org/10.1038/nature12829 http://10.0.4.14/nature12829},
volume = {505},
year = {2014}
}
@article{Sherwood.ea-2010-wv,
abstract = {Recent progress is reviewed in the understanding of convective interaction with water vapor and changes associated with water vapor in warmer climates. Progress includes new observing techniques (including isotopic methods) that are helping to illuminate moisture-convection interaction, better observed humidity trends, new modeling approaches, and clearer expectations as to the hydrological consequences of increased specific humidity in a warmer climate. A theory appears to be in place to predict humidity in the free troposphere if winds are known at large scales, providing a crucial link between small-scale behavior and large-scale mass and energy constraints. This, along with observations, supports the anticipated water vapor feedback on climate, though key uncertainties remain connected to atmospheric dynamics and the hydrological consequences of a moister atmosphere. More work is called for to understand how circulations on all scales are governed and what role water vapor plays. Suggestions are given for future research.},
author = {Sherwood, S C and Roca, R and Weckwerth, T M and Andronova, N G},
doi = {10.1029/2009RG000301},
issn = {8755-1209},
journal = {Reviews of Geophysics},
keywords = {climate change,climate feedbacks,convection,water vapor},
month = {apr},
number = {2},
pages = {RG2001},
title = {{Tropospheric water vapor, convection, and climate}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2009RG000301 http://doi.wiley.com/10.1029/2009RG000301},
volume = {48},
year = {2010}
}
@article{Sherwood2020c,
abstract = {Abstract We assess evidence relevant to Earth's equilibrium climate sensitivity per doubling of atmospheric CO2, characterized by an effective sensitivity S. This evidence includes feedback process understanding, the historical climate record, and the paleoclimate record. An S value lower than 2 K is difficult to reconcile with any of the three lines of evidence. The amount of cooling during the Last Glacial Maximum provides strong evidence against values of S greater than 4.5 K. Other lines of evidence in combination also show that this is relatively unlikely. We use a Bayesian approach to produce a probability density (PDF) for S given all the evidence, including tests of robustness to difficult-to-quantify uncertainties and different priors. The 66{\%} range is 2.6-3.9 K for our Baseline calculation, and remains within 2.3-4.5 K under the robustness tests; corresponding 5-95{\%} ranges are 2.3-4.7 K, bounded by 2.0-5.7 K (although such high-confidence ranges should be regarded more cautiously). This indicates a stronger constraint on S than reported in past assessments, by lifting the low end of the range. This narrowing occurs because the three lines of evidence agree and are judged to be largely independent, and because of greater confidence in understanding feedback processes and in combining evidence. We identify promising avenues for further narrowing the range in S, in particular using comprehensive models and process understanding to address limitations in the traditional forcing-feedback paradigm for interpreting past changes.},
author = {Sherwood, S. C. and Webb, M. J. and Annan, J. D. and Armour, K. C. and Forster, P. M. and Hargreaves, J. C. and Hegerl, G. and Klein, S. A. and Marvel, K. D. and Rohling, E. J. and Watanabe, M. and Andrews, T. and Braconnot, P. and Bretherton, C. S. and Foster, G. L. and Hausfather, Z. and Heydt, A. S. and Knutti, R. and Mauritsen, T. and Norris, J. R. and Proistosescu, C. and Rugenstein, M. and Schmidt, G. A. and Tokarska, K. B. and Zelinka, M. D.},
doi = {10.1029/2019RG000678},
isbn = {0000000153492},
issn = {8755-1209},
journal = {Reviews of Geophysics},
month = {dec},
number = {4},
pages = {e2019RG000678},
title = {{An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2019RG000678},
volume = {58},
year = {2020}
}
@article{Shindell2017a,
abstract = {Methane emissions contribute to global warming, damage public health and reduce the yield of agricultural and forest ecosystems. Quantifying these damages to the planetary commons by calculating the social cost of methane (SCM) facilitates more comprehensive cost-benefit analyses of methane emissions control measures and is the first step to potentially incorporating them into the marketplace. Use of a broad measure of social welfare is also an attractive alternative or supplement to emission metrics focused on a temperature target in a given year as it incentivizes action to provide benefits over a broader range of impacts and timescales. Calculating the SCM using consistent temporal treatment of physical and economic processes and incorporating climate- and air quality-related impacts, we find large SCM values, e.g. ∼{\$}2400 per ton and ∼{\$}3600 per ton with 5{\%} and 3{\%} discount rates respectively. These values are ∼100 and 50 times greater than corresponding social costs for carbon dioxide. Our results suggest that ∼110 of 140 Mt of identified methane abatement via scaling up existing technology and policy options provide societal benefits that outweigh implementation costs. Within the energy sector, renewables compare far better against use of natural gas in electricity generation when incorporating these social costs for methane. In the agricultural sector, changes in livestock management practices, promoting healthy diets including reduced beef and dairy consumption, and reductions in food waste have been promoted as ways to mitigate emissions, and these are shown here to indeed have the potential to provide large societal benefits (∼{\$}50–150 billion per year). Examining recent trends in methane and carbon dioxide, we find that increases in methane emissions may have offset much of the societal benefits from a slowdown in the growth rate of carbon dioxide emissions. The results indicate that efforts to reduce methane emissions via policies spanning a wide range of technical, regulatory and behavioural options provide benefits at little or negative net cost. Recognition of the full SCM, which has typically been undervalued, may help catalyze actions to reduce emissions and thereby provide a broad set of societal benefits.},
author = {Shindell, D. T. and Fuglestvedt, J. S. and Collins, W. J.},
doi = {10.1039/C7FD00009J},
issn = {1359-6640},
journal = {Faraday Discussions},
pages = {429--451},
pmid = {28581559},
title = {{The social cost of methane: theory and applications}},
url = {http://xlink.rsc.org/?DOI=C7FD00009J},
volume = {200},
year = {2017}
}
@article{Shindell2014a,
abstract = {Understanding climate sensitivity is critical to projecting climate change in response to a given forcing scenario. Recent analyses1–3 have suggested that transient climate sensitivity is at the low end of the present model range taking into account the reducedwarming rates during the past 10–15 years during which forcing has increased markedly4 . In contrast, comparisons of modelled feedback processes with observations indicate that the most realistic models have higher sensitivities5,6 . Here I analyse results from recent climate modelling intercomparison projects to demonstrate that transient climate sensitivity to historical aerosols and ozone is substantially greater than the transient climate sensitivitytoCO2 .Thisenhancedsensitivityis primarilycaused by more of the forcing being located at Northern Hemisphere middle to high latitudes where it triggers more rapid land responses and stronger feedbacks. I find that accounting for thisenhancementlargely reconciles the twosets of results,and I conclude that the lowest end of the range of transient climate responsetoCO2 in presentmodelsandassessments7 ({\textless}1.3 ◦ C) is very unlikely. Modelled},
author = {Shindell, Drew T.},
doi = {10.1038/nclimate2136},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {apr},
number = {4},
pages = {274--277},
title = {{Inhomogeneous forcing and transient climate sensitivity}},
url = {http://www.nature.com/articles/nclimate2136},
volume = {4},
year = {2014}
}
@article{Shindell2015,
author = {Shindell, Drew T. and Faluvegi, Greg and Rotstayn, Leon and Milly, George},
doi = {10.1002/2014JD022752},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {jun},
number = {11},
pages = {5385--5403},
title = {{Spatial patterns of radiative forcing and surface temperature response}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2014JD022752},
volume = {120},
year = {2015}
}
@article{Shindell2013c,
abstract = {The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercompari- son Project phase 5 (CMIP5). The models reproduce present-day total aerosol opti- cal depth (AOD) relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980–2000 Ocean Science AOD trends well, but underpredict increases over the Yel- low/Eastern Sea. They strongly underestimate absorbing Open Access AOD in many regions. We examine both the direct radiative forcing (RF) and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects). The Solid Earth models' all-sky 1850 to 2000 global mean annual average},
author = {Shindell, D. T. and Lamarque, J. F. and Schulz, M. and Flanner, M. and Jiao, C. and Chin, M. and Young, P. J. and Lee, Y. H. and Rotstayn, L. and Mahowald, N. and Milly, G. and Faluvegi, G. and Balkanski, Y. and Collins, W. J. and Conley, A. J. and Dalsoren, S. and Easter, R. and Ghan, S. and Horowitz, L. and Liu, X. and Myhre, G. and Nagashima, T. and Naik, V. and Rumbold, S. T. and Skeie, R. and Sudo, K. and Szopa, S. and Takemura, T. and Voulgarakis, A. and Yoon, J. H. and Lo, F.},
doi = {10.5194/acp-13-2939-2013},
isbn = {1680-7316},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
number = {6},
pages = {2939--2974},
title = {{Radiative forcing in the ACCMIP historical and future climate simulations}},
volume = {13},
year = {2013}
}
@article{Shindell2009a,
abstract = {Evaluating multicomponent climate change mitigation strategies requires knowledge of the diverse direct and indirect effects of emissions. Methane, ozone, and aerosols are linked through atmospheric chemistry so that emissions of a single pollutant can affect several species. We calculated atmospheric composition changes, historical radiative forcing, and forcing per unit of emission due to aerosol and tropospheric ozone precursor emissions in a coupled compositionclimate model. We found that gas-aerosol interactions substantially alter the relative importance of the various emissions. In particular, methane emissions have a larger impact than that used in current carbon-trading schemes or in the Kyoto Protocol. Thus, assessments of muLtigas mitigation policies, as well as any separate efforts to mitigate warming from short-lived pollutants, should include gas-aerosol interactions.},
author = {Shindell, Drew T. and Faluvegi, Greg and Koch, Dorothy M. and Schmidt, Gavin A. and Unger, Nadine and Bauer, Susanne E.},
doi = {10.1126/science.1174760},
issn = {0036-8075},
journal = {Science},
month = {oct},
number = {5953},
pages = {716--718},
title = {{Improved Attribution of Climate Forcing to Emissions}},
url = {https://www.science.org/doi/10.1126/science.1174760},
volume = {326},
year = {2009}
}
@incollection{Shine1990,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Shine, K. P. and Derwent, R. G. and Wuebbles, D. J. and Morcrette, J.-J.},
booktitle = {Climate Change: The IPCC Scientific Assessment},
editor = {Houghton, J. T. and Jenkins, J. G. and Ephraums, J. J.},
pages = {41--68},
publisher = {Cambridge University Press},
title = {{Radiative Forcing of Climate}},
url = {https://www.ipcc.ch/report/ar1/wg1},
year = {1990}
}
@article{Shine2005,
abstract = {The Global Warming Potential (GWP) is used within the Kyoto Protocol to the United Nations Framework Convention on Climate Change as a metric for weighting the climatic impact of emissions of different greenhouse gases. The GWP has been subjected to many criticisms because of its formulation, but nevertheless it has retained some favour because of the simplicity of its design and application, and its transparency compared to proposed alternatives. Here, two new metrics are proposed, which are based on a simple analytical climate model. The first metric is called the Global Temperature Change Potential and represents the temperature change at a given time due to a pulse emission of a gas (GTPP); the second is similar but represents the effect of a sustainedemission change (hence GTPS). Both GTPPand GTPSare presented as relative to the temperature change due to a similar emission change of a reference gas, here taken to be carbon dioxide. Both metrics are compared against an upwelling-diffusion energy balance model that resolves land and ocean and the hemispheres. The GTPPdoes not perform well, compared to the energy balance model, except for long-lived gases. By contrast, the GTPSis shown to perform well relative to the energy balance model, for gases with a wide variety of lifetimes. It is also shown that for time horizons in excess of about 100 years, the GTPSand GWP produce very similar results, indicating an alternative interpretation for the GWP. The GTPSretains the advantage of the GWP in terms of transparency, and the relatively small number of input parameters required for calculation. However, it has an enhanced relevance, as it is further down the cause-effect chain of the impacts of greenhouse gases emissions and has an unambiguous interpretation. It appears to be robust to key uncertainties and simplifications in its derivation and may be an attractive alternative to the GWP. {\textcopyright} Springer 2005.},
author = {Shine, K.P. and Fuglestvedt, J.S. and Hailemariam, K. and Stuber, N.},
doi = {10.1007/s10584-005-1146-9},
journal = {Climatic Change},
number = {3},
pages = {281--302},
title = {{Alternatives to the Global Warming Potential for comparing climate impacts of emissions of greenhouse gases}},
volume = {68},
year = {2005}
}
@article{Shine2015a,
abstract = {Abstract. Recent advances in understanding have made it possible to relate global precipitation changes directly to emissions of particular gases and aerosols that influence climate. Using these advances, new indices are developed here called the Global Precipitation-change Potential for pulse (GPPP) and sustained (GPPS) emissions, which measure the precipitation change per unit mass of emissions. The GPP can be used as a metric to compare the effects of different emissions. This is akin to the global warming potential (GWP) and the global temperature-change potential (GTP) which are used to place emissions on a common scale. Hence the GPP provides an additional perspective of the relative or absolute effects of emissions. It is however recognised that precipitation changes are predicted to be highly variable in size and sign between different regions and this limits the usefulness of a purely global metric. The GPPP and GPPS formulation consists of two terms, one dependent on the surface temperature change and the other dependent on the atmospheric component of the radiative forcing. For some forcing agents, and notably for CO2, these two terms oppose each other – as the forcing and temperature perturbations have different timescales, even the sign of the absolute GPPP and GPPS varies with time, and the opposing terms can make values sensitive to uncertainties in input parameters. This makes the choice of CO2 as a reference gas problematic, especially for the GPPS at time horizons less than about 60 years. In addition, few studies have presented results for the surface/atmosphere partitioning of different forcings, leading to more uncertainty in quantifying the GPP than the GWP or GTP. Values of the GPPP and GPPS for five long- and short-lived forcing agents (CO2, CH4, N2O, sulphate and black carbon – BC) are presented, using illustrative values of required parameters. The resulting precipitation changes are given as the change at a specific time horizon (and hence they are end-point metrics) but it is noted that the GPPS can also be interpreted as the time-integrated effect of a pulse emission. Using CO2 as a references gas, the GPPP and GPPS for the non-CO2 species are larger than the corresponding GTP values. For BC emissions, the atmospheric forcing is sufficiently strong that the GPPS is opposite in sign to the GPPS. The sensitivity of these values to a number of input parameters is explored. The GPP can also be used to evaluate the contribution of different emissions to precipitation change during or after a period of emissions. As an illustration, the precipitation changes resulting from emissions in 2008 (using the GPPP) and emissions sustained at 2008 levels (using the GPPS) are presented. These indicate that for periods of 20 years (after the 2008 emissions) and 50 years (for sustained emissions at 2008 levels) methane is the dominant driver of positive precipitation changes due to those emissions. For sustained emissions, the sum of the effect of the five species included here does not become positive until after 50 years, by which time the global surface temperature increase exceeds 1 K.},
author = {Shine, K.P. and Allan, R.P. and Collins, W.J. and Fuglestvedt, J.S.},
doi = {10.5194/esd-6-525-2015},
issn = {2190-4987},
journal = {Earth System Dynamics},
month = {aug},
number = {2},
pages = {525--540},
title = {{Metrics for linking emissions of gases and aerosols to global precipitation changes}},
url = {https://www.earth-syst-dynam.net/6/525/2015/ https://esd.copernicus.org/articles/6/525/2015/},
volume = {6},
year = {2015}
}
@article{Shine2003,
abstract = {Radiative forcing is widely used to measure the relative efficacy of climate change mechanisms. Earlier general circulation model (GCM) experiments showed that the global-mean radiative forcing could be used to predict, with useful accuracy, the consequent global-mean surface temperature change regardless of whether the forcing was due to, for example, changes in greenhouse gases or solar output. More recent experiments indicate that for changes in absorbing aerosols and ozone, the predictive ability of radiative forcing is much worse. Building on a suggestion from Hansen and co-workers, we propose an alternative, the "adjusted troposphere and stratosphere forcing". We present GCM calculations showing that it is a significantly more reliable predictor of this GCM's surface temperature change than radiative forcing. It is a candidate to supplement radiative forcing as a metric for comparing different mechanisms and provides a framework for understanding the circumstances in which radiative forcing is less reliable. {\textcopyright} 2003 by the American Geophysical Union.},
author = {Shine, Keith P. and Cook, Jolene and Highwood, Eleanor J. and Joshi, Manoj M.},
doi = {10.1029/2003GL018141},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {oct},
number = {20},
pages = {2003GL018141},
title = {{An alternative to radiative forcing for estimating the relative importance of climate change mechanisms}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2003GL018141},
volume = {30},
year = {2003}
}
@article{Siler2018,
abstract = {Despite the increasing sophistication of climate models, the amount of surface warming expected from a doubling of atmospheric CO{\$}{\$}{\_}2{\$}{\$}2(equilibrium climate sensitivity) remains stubbornly uncertain, in part because of differences in how models simulate the change in global albedo due to clouds (the shortwave cloud feedback). Here, model differences in the shortwave cloud feedback are found to be closely related to the spatial pattern of the cloud contribution to albedo ({\$}{\$}$\backslash$alpha{\$}{\$}$\alpha$) in simulations of the current climate: high-feedback models exhibit lower (higher) {\$}{\$}$\backslash$alpha{\$}{\$}$\alpha$in regions of warm (cool) sea-surface temperatures, and therefore predict a larger reduction in global-mean {\$}{\$}$\backslash$alpha{\$}{\$}$\alpha$as temperatures rise and warm regions expand. The spatial pattern of {\$}{\$}$\backslash$alpha{\$}{\$}$\alpha$is found to be strongly predictive ({\$}{\$}r=0.84{\$}{\$}r=0.84) of a model's global cloud feedback, with satellite observations indicating a most-likely value of {\$}{\$}0.58$\backslash$pm 0.31{\$}{\$}0.58±0.31Wm{\$}{\$}{\^{}}{\{}-2{\}}{\$}{\$}-2K{\$}{\$}{\^{}}{\{}-1{\}}{\$}{\$}-1(90{\%} confidence). This estimate is higher than the model-average cloud feedback of 0.43 Wm{\$}{\$}{\^{}}{\{}-2{\}}{\$}{\$}-2K{\$}{\$}{\^{}}{\{}-1{\}}{\$}{\$}-1, with half the range of uncertainty. The observational constraint on climate sensitivity is weaker but still significant, suggesting a likely value of 3.68 ± 1.30 K (90{\%} confidence), which also favors the upper range of model estimates. These results suggest that uncertainty in model estimates of the global cloud feedback may be substantially reduced by ensuring a realistic distribution of clouds between regions of warm and cool SSTs in simulations of the current climate.},
author = {Siler, Nicholas and Po-Chedley, Stephen and Bretherton, Christopher S},
doi = {10.1007/s00382-017-3673-2},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {3},
pages = {1209--1220},
title = {{Variability in modeled cloud feedback tied to differences in the climatological spatial pattern of clouds}},
url = {https://doi.org/10.1007/s00382-017-3673-2},
volume = {50},
year = {2018}
}
@article{Siler2018a,
abstract = {Recent studies have shown that the change in poleward energy transport under global warming is well approximated by downgradient transport of near-surface moist static energy (MSE) modulated by the spatial pattern of radiative forcing, feedbacks, and ocean heat uptake. Here we explore the implications of downgradient MSE transport for changes in the vertically integrated moisture flux and thus the zonal-mean pattern of evaporation minus precipitation ( E − P). Using a conventional energy balance model that we have modified to represent the Hadley cell, we find that downgradient MSE transport implies changes in E − P that mirror those simulated by comprehensive global climate models (GCMs), including a poleward expansion of the subtropical belt where E {\textgreater} P, and a poleward shift in the extratropical minimum of E − P associated with the storm tracks. The surface energy budget imposes further constraints on E and P independently: E increases almost everywhere, with relatively little spatial variability, while P must increase in the deep tropics, decrease in the subtropics, and increase in middle and high latitudes. Variations in the spatial pattern of radiative forcing, feedbacks, and ocean heat uptake across GCMs modulate these basic features, accounting for much of the model spread in the zonal-mean response of E and P to climate change. Thus, the principle of downgradient energy transport appears to provide a simple explanation for the basic structure of hydrologic cycle changes in GCM simulations of global warming.},
author = {Siler, Nicholas and Roe, Gerard H. and Armour, Kyle C.},
doi = {10.1175/JCLI-D-18-0081.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Eddies,Energy transport,Hadley circulation,Hydrologic cycle},
month = {sep},
number = {18},
pages = {7481--7493},
title = {{Insights into the Zonal-Mean Response of the Hydrologic Cycle to Global Warming from a Diffusive Energy Balance Model}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-18-0081.1},
volume = {31},
year = {2018}
}
@article{Silvers2018,
author = {Silvers, Levi G. and Paynter, David and Zhao, Ming},
doi = {10.1002/2017GL075583},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {jan},
number = {1},
pages = {391--400},
title = {{The Diversity of Cloud Responses to Twentieth Century Sea Surface Temperatures}},
url = {http://doi.wiley.com/10.1002/2017GL075583},
volume = {45},
year = {2018}
}
@article{Singarayer2011,
abstract = {The question of how long humans have influenced global climate by greenhouse-gas emissions is fundamental to understanding climate system sensitivity. Hence the interest in an apparent anomalous increase in atmospheric methane concentrations that occurred about 5,000 years ago — as recorded in polar ice cores. Explanations offered for the rise in methane levels include very early agricultural activity and increased natural wetland emissions. A new series of climate and wetland simulations of global methane levels during the last glacial cycle now suggests that the increase in methane concentrations can be explained by natural changes in Earth's orbital configuration, with enhanced emissions in the Southern Hemisphere tropics linked to precession-induced modification of seasonal precipitation.},
author = {Singarayer, Joy S and Valdes, Paul J and Friedlingstein, Pierre and Nelson, Sarah and Beerling, David J},
doi = {10.1038/nature09739},
issn = {1476-4687},
journal = {Nature},
number = {7332},
pages = {82--85},
title = {{Late Holocene methane rise caused by orbitally controlled increase in tropical sources}},
url = {https://doi.org/10.1038/nature09739},
volume = {470},
year = {2011}
}
@article{Singh2017,
abstract = {We isolate the role of the ocean in polar climate change by directly evaluating how changes in ocean dynamics with quasi?equilibrium CO2 doubling impact high?latitude climate. With CO2 doubling, the ocean heat flux convergence (OHFC) shifts poleward in winter in both hemispheres. Imposing this pattern of perturbed OHFC in a global climate model results in a poleward shift in ocean?to?atmosphere turbulent heat fluxes (both sensible and latent) and sea ice retreat; the high latitudes warm, while the midlatitudes cool, thereby amplifying polar warming. Furthermore, midlatitude cooling is propagated to the polar midtroposphere on isentropic surfaces, augmenting the (positive) lapse rate feedback at high latitudes. These results highlight the key role played by the partitioning of meridional energy transport changes between the atmosphere and ocean in high?latitude climate change.},
author = {Singh, H. A. and Rasch, P. J. and Rose, B. E. J.},
doi = {10.1002/2017GL074561},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {Bjerknes feedback,lapse rate feedback,ocean dynamics,polar amplification,polar climate change,winter sea ice retreat},
month = {oct},
number = {20},
pages = {10,583--10,591},
title = {{Increased Ocean Heat Convergence Into the High Latitudes With CO2 Doubling Enhances Polar-Amplified Warming}},
url = {http://doi.wiley.com/10.1002/2017GL074561},
volume = {44},
year = {2017}
}
@article{Sitch2008,
abstract = {This study tests the ability of five Dynamic Global Vegetation Models (DGVMs), forced with observed climatology and atmospheric CO2, to model the contemporary global carbon cycle. The DGVMs are also coupled to a fast 'climate analogue model', based on the Hadley Centre General Circulation Model (GCM), and run into the future for four Special Report Emission Scenarios (SRES): A1FI, A2, B1, B2. Results show that all DGVMs are consistent with the contemporary global land carbon budget. Under the more extreme projections of future environmental change, the responses of the DGVMs diverge markedly. In particular, large uncertainties are associated with the response of tropical vegetation to drought and boreal ecosystems to elevated temperatures and changing soil moisture status. The DGVMs show more divergence in their response to regional changes in climate than to increases in atmospheric CO2 content. All models simulate a release of land carbon in response to climate, when physiological effects of elevated atmospheric CO2 on plant production are not considered, implying a positive terrestrial climate-carbon cycle feedback. All DGVMs simulate a reduction in global net primary production (NPP) and a decrease in soil residence time in the tropics and extra-tropics in response to future climate. When both counteracting effects of climate and atmospheric CO2 on ecosystem function are considered, all the DGVMs simulate cumulative net land carbon uptake over the 21st century for the four SRES emission scenarios. However, for the most extreme A1FI emissions scenario, three out of five DGVMs simulate an annual net source of CO2 from the land to the atmosphere in the final decades of the 21st century. For this scenario, cumulative land uptake differs by 494 Pg C among DGVMs over the 21st century. This uncertainty is equivalent to over 50 years of anthropogenic emissions at current levels.},
author = {Sitch, Stephan and Huntingford, C. and Gedney, N. and Levy, P. E. and Lomas, M. and Piao, S. L. and Betts, R. and Ciais, P. and Cox, P. and Friedlingstein, P. and Jones, C. D. and Prentice, I. C. and Woodward, F. I.},
doi = {10.1111/j.1365-2486.2008.01626.x},
isbn = {1354-1013},
issn = {13541013},
journal = {Global Change Biology},
number = {9},
pages = {2015--2039},
title = {{Evaluation of the terrestrial carbon cycle, future plant geography and climate–carbon cycle feedbacks using five Dynamic Global Vegetation Models (DGVMs)}},
volume = {14},
year = {2008}
}
@article{esd-9-879-2018,
abstract = {Inferred effective climate sensitivity (ECSinf) is estimated using a method combining radiative forcing (RF) time series and several series of observed ocean heat content (OHC) and near-surface temperature change in a Bayesian framework using a simple energy balance model and a stochastic model. The model is updated compared to our previous analysis by using recent forcing estimates from IPCC, including OHC data for the deep ocean, and extending the time series to 2014. In our main analysis, the mean value of the estimated ECSinf is 2.0°C, with a median value of 1.9°C and a 90{\%} credible interval (CI) of 1.2-3.1°C. The mean estimate has recently been shown to be consistent with the higher values for the equilibrium climate sensitivity estimated by climate models. The transient climate response (TCR) is estimated to have a mean value of 1.4°C (90{\%} CI 0.9-2.0°C), and in our main analysis the posterior aerosol effective radiative forcing is similar to the range provided by the IPCC. We show a strong sensitivity of the estimated ECSinf to the choice of a priori RF time series, excluding pre-1950 data and the treatment of OHC data. Sensitivity analysis performed by merging the upper (0-700m) and the deep-ocean OHC or using only one OHC dataset (instead of four in the main analysis) both give an enhancement of the mean ECSinf by about 50{\%} from our best estimate.},
author = {Skeie, Ragnhild Bieltvedt and Berntsen, Terje and Aldrin, Magne and Holden, Marit and Myhre, Gunnar},
doi = {10.5194/esd-9-879-2018},
issn = {21904987},
journal = {Earth System Dynamics},
number = {2},
pages = {879--894},
title = {{Climate sensitivity estimates – Sensitivity to radiative forcing time series and observational data}},
url = {https://www.earth-syst-dynam.net/9/879/2018/},
volume = {9},
year = {2018}
}
@article{Skeie2020a,
abstract = {Radiative forcing (RF) time series for total ozone from 1850 up to the present day are calculated based on historical simulations of ozone from 10 climate models contributing to the Coupled Model Intercomparison Project Phase 6 (CMIP6). In addition, RF is calculated for ozone fields prepared as an input for CMIP6 models without chemistry schemes and from a chemical transport model simulation. A radiative kernel for ozone is constructed and used to derive the RF. The ozone RF in 2010 (2005–2014) relative to 1850 is 0.35 W m −2 [0.08–0.61] (5–95{\%} uncertainty range) based on models with both tropospheric and stratospheric chemistry. One of these models has a negative present-day total ozone RF. Excluding this model, the present-day ozone RF increases to 0.39 W m −2 [0.27–0.51] (5–95{\%} uncertainty range). The rest of the models have RF close to or stronger than the RF time series assessed by the Intergovernmental Panel on Climate Change in the fifth assessment report with the primary driver likely being the new precursor emissions used in CMIP6. The rapid adjustments beyond stratospheric temperature are estimated to be weak and thus the RF is a good measure of effective radiative forcing.},
author = {Skeie, Ragnhild Bieltvedt and Myhre, Gunnar and Hodnebrog, {\O}ivind and Cameron-Smith, Philip J. and Deushi, Makoto and Hegglin, Michaela I. and Horowitz, Larry W. and Kramer, Ryan J. and Michou, Martine and Mills, Michael J. and Olivi{\'{e}}, Dirk J. L. and Connor, Fiona M. O' and Paynter, David and Samset, Bj{\o}rn H. and Sellar, Alistair and Shindell, Drew and Takemura, Toshihiko and Tilmes, Simone and Wu, Tongwen},
doi = {10.1038/s41612-020-00131-0},
issn = {2397-3722},
journal = {npj Climate and Atmospheric Science},
month = {dec},
number = {1},
pages = {32},
title = {{Historical total ozone radiative forcing derived from CMIP6 simulations}},
url = {https://www.nature.com/articles/s41612-020-00131-0},
volume = {3},
year = {2020}
}
@article{Skeie2021,
abstract = {Countries' historical contributions to climate change have been on the agenda for more than two decades and will most likely continue to be an element in future international discussions and negotiations on climate. Previous studies have quantified the historical contributions to climate change across a range of choices and assumptions. In contrast, we quantify how historical contributions to changes in global mean surface temperature (GMST) may change in the future for a broad set of choices using the quantification of the shared socioeconomic pathways (SSPs). We calculate the contributions for five coarse geographical regions used in the SSPs. Historical emissions of long-lived gases remain important for future contributions to warming, due to their accumulation and the inertia of climate system, and historical emissions are even more important for strong mitigation scenarios. When only accounting for future emissions, from 2015 to 2100, there is surprisingly little variation in the regional contributions to GMST change between the different SSPs and different mitigation targets. The largest variability in the regional future contributions is found across the different integrated assessment models (IAMs). This suggests the characteristics of the IAMs are more important for calculated future historical contributions than variations across SSP or forcing target.},
author = {Skeie, Ragnhild B. and Peters, Glen P. and Fuglestvedt, Jan and Andrew, Robbie},
doi = {10.1007/s10584-021-02982-9},
issn = {15731480},
journal = {Climatic Change},
keywords = {Brazilian proposal,Equity,Historical contribution,Paris Agreement,Shared socioeconomic pathways},
month = {jan},
number = {1-2},
pages = {1--13},
publisher = {Springer Science and Business Media B.V.},
title = {{A future perspective of historical contributions to climate change}},
url = {https://doi.org/10.1007/s10584-021-02982-9},
volume = {164},
year = {2021}
}
@article{Skeie2017,
abstract = {The politically contentious issue of calculating countries' contributions to climate change is strongly dependent on methodological choices. Different principles can be applied for distributing efforts for reducing human-induced global warming. According to the 'Brazilian Proposal', industrialized countries would reduce emissions proportional to their historical contributions to warming. This proposal was based on the assumption that the political process would lead to a global top-down agreement. The Paris Agreement changed the role of historical responsibilities. Whereas the agreement refers to equity principles, differentiation of mitigation efforts is delegated to each country, as countries will submit new national contributions every five years without any international negotiation. It is likely that considerations of historical contributions and distributive fairness will continue to play a key role, but increasingly so in a national setting. Contributions to warming can be used as a background for negotiations to inform and justify positions, and may also be useful for countries' own assessment of what constitutes reasonable and fair contributions to limiting warming. Despite the fact that the decision from COP21 explicitly rules out compensation in the context of loss and damage, it is likely that considerations of historical responsibility will also play a role in future discussions. However, methodological choices have substantial impacts on calculated contributions to warming, including rank-ordering of contributions, and thus support the view that there is no single correct answer to the question of how much each country has contributed. There are fundamental value-related and ethical questions that cannot be answered through a single set of calculated contributions. Thus, analyses of historical contributions should not present just one set of results, but rather present a spectrum of results showing how the calculated contributions vary with a broad set of choices. Our results clearly expose some of the core issues related to climate responsibility.},
author = {Skeie, Ragnhild B. and Fuglestvedt, Jan and Berntsen, Terje and Peters, Glen P. and Andrew, Robbie and Allen, Myles and Kallbekken, Steffen},
doi = {10.1088/1748-9326/aa5b0a},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {Brazilian proposal,Paris agreement,ethics,responsibility,short-lived climate forcers,time horizon},
month = {feb},
number = {2},
pages = {024022},
publisher = {Institute of Physics Publishing},
title = {{Perspective has a strong effect on the calculation of historical contributions to global warming}},
url = {https://doi.org/10.1088/1748-9326/aa5b0a},
volume = {12},
year = {2017}
}
@article{Skinner2012,
abstract = {Humanity is engaged in an unprecedented climate experiment, the outcome of which is often framed in terms of an equilibrium “climate sensitivity.” This parameter encapsulates the amount of global warming that may be expected as a result of a doubling of the atmospheric carbon dioxide (CO2) concentration, which is equivalent to an additional 3.7 W m−2 of energy available to warm Earth's surface. The current best estimate of climate sensitivity is similar to the earliest estimates by Arrhenius and Callendar, ranging from 2° to 4.5°C. Constraints on the lower limit of this range are much tighter than they are on the upper limit, with small but finite probabilities for very large climate sensitivities. Although the geological record provides strong support for climate sensitivities in this range, it also reminds us that a single value of climate sensitivity is unlikely to provide a complete picture of the climate system's response to forcing.},
author = {Skinner, L.},
doi = {10.1126/science.1224011},
isbn = {0036-8075 1095-9203},
issn = {0036-8075},
journal = {Science},
number = {6097},
pages = {917--919},
pmid = {22923566},
title = {{A Long View on Climate Sensitivity}},
url = {http://www.sciencemag.org/cgi/doi/10.1126/science.1224011},
volume = {337},
year = {2012}
}
@article{tc-15-233-2021,
author = {Slater, T and Lawrence, I R and Otosaka, I N and Shepherd, A and Gourmelen, N and Jakob, L and Tepes, P and Gilbert, L and Nienow, P},
doi = {10.5194/tc-15-233-2021},
journal = {The Cryosphere},
number = {1},
pages = {233--246},
title = {{Review article: Earth's ice imbalance}},
url = {https://tc.copernicus.org/articles/15/233/2021/},
volume = {15},
year = {2021}
}
@article{Smith2012,
abstract = {Climate policies address emissions of many greenhouse gases including carbon dioxide, methane, nitrous oxide and various halogen-containing compounds. These are aggregated and traded on a CO2-equivalent basis using the 100-year global warming potential (GWP100); however, the GWP100has received scientific and economic criticism as a tool for policy1-4. In particular, given international agreement to limit global average warming to 2°C, the GWP100does not measure temperature and does not clearly signal the need to limit cumulative CO2emissions5-7. Here, we show that future peak temperature is constrained by cumulative emissions of several long-lived gases (including CO2and N2O) and emission rates of a separate basket of shorter-lived species (including CH 4). For each basket we develop an emissions-equivalence metric allowing peak temperature to be estimated directly for any emissions scenario. Today's emissions of shorter-lived species have a lesser impact on ultimate peak temperature than those nearer the time of peaking. The 2°C limit could therefore be met by setting a limit to cumulative long-lived CO2-equivalent emissions while setting a maximum future rate for shorter-lived emissions. {\textcopyright} 2012 Macmillan Publishers Limited. All rights reserved.},
author = {Smith, S.M. and Lowe, J.A. and Bowerman, N.H.A. and Gohar, L.K. and Huntingford, C. and Allen, M.R.},
doi = {10.1038/nclimate1496},
journal = {Nature Climate Change},
number = {7},
pages = {535--538},
title = {{Equivalence of greenhouse-gas emissions for peak temperature limits}},
volume = {2},
year = {2012}
}
@article{Smith2018a,
author = {Smith, Christopher J. and Forster, Piers M. and Allen, Myles and Leach, Nicholas and Millar, Richard J. and Passerello, Giovanni A. and Regayre, Leighton A.},
doi = {10.5194/gmd-11-2273-2018},
issn = {1991-9603},
journal = {Geoscientific Model Development},
month = {jun},
number = {6},
pages = {2273--2297},
title = {{FAIR v1.3: a simple emissions-based impulse response and carbon cycle model}},
url = {https://gmd.copernicus.org/articles/11/2273/2018/},
volume = {11},
year = {2018}
}
@article{Smith2018b,
author = {Smith, C. J. and Kramer, R. J. and Myhre, G. and Forster, P. M. and Soden, B. J. and Andrews, T. and Boucher, O. and Faluvegi, G. and Fl{\"{a}}schner, D. and Hodnebrog, {\O}. and Kasoar, M. and Kharin, V. and Kirkev{\aa}g, A. and Lamarque, J.‐F. and M{\"{u}}lmenst{\"{a}}dt, J. and Olivi{\'{e}}, D. and Richardson, T. and Samset, B. H. and Shindell, D. and Stier, P. and Takemura, T. and Voulgarakis, A. and Watson‐Parris, D.},
doi = {10.1029/2018GL079826},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {PDRMIP,kernels,radiative forcing,rapid adjustments},
month = {nov},
number = {21},
pages = {12023--12031},
pmid = {21516461},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Understanding Rapid Adjustments to Diverse Forcing Agents}},
url = {http://doi.wiley.com/10.1029/2018GL079826 https://onlinelibrary.wiley.com/doi/10.1029/2018GL079826},
volume = {45},
year = {2018}
}
@article{Smith2019,
author = {Smith, Christopher J and Forster, Piers M and Allen, Myles and Fuglestvedt, Jan and Millar, Richard J and Rogelj, Joeri and Zickfeld, Kirsten},
doi = {10.1038/s41467-018-07999-w},
issn = {2041-1723},
journal = {Nature Communications},
month = {dec},
number = {1},
pages = {101},
title = {{Current fossil fuel infrastructure does not yet commit us to 1.5°C warming}},
url = {https://doi.org/10.1038/s41467-018-07999-w http://www.nature.com/articles/s41467-018-07999-w},
volume = {10},
year = {2019}
}
@article{Smith9999,
abstract = {We present top-of-atmosphere and surface radiative kernels based on the atmospheric component (GA7.1) of the HadGEM3 general circulation model developed by the UK Met Office. We show that the utility of radiative kernels for forcing adjustments in idealised CO2 perturbation experiments is greatest where there is sufficiently high resolution in the stratosphere in both the target climate model and the radiative kernel. This is because stratospheric cooling to a CO2 perturbation continues to increase with height, and low-resolution or low-top kernels or climate model output are unable to fully resolve the full stratospheric temperature adjustment. In the sixth phase of the Coupled Model Intercomparison Project (CMIP6), standard atmospheric model data are available up to 1 hPa on 19 pressure levels, which is a substantial advantage compared to CMIP5. We show in the IPSL-CM6A-LR model where a full set of climate diagnostics are available that the HadGEM3-GA7.1 kernel exhibits linear behaviour and the residual error term is small, as well as from a survey of kernels available in the literature that in general low-top radiative kernels underestimate the stratospheric temperature response. The HadGEM3-GA7.1 radiative kernels are available at https://doi.org/10.5281/zenodo.3594673 (Smith, 2019).},
author = {Smith, Christopher J. and Kramer, Ryan J. and Sima, Adriana},
doi = {10.5194/essd-12-2157-2020},
issn = {18663516},
journal = {Earth System Science Data},
month = {sep},
number = {3},
pages = {2157--2168},
title = {{The HadGEM3-GA7.1 radiative kernel: The importance of a well-resolved stratosphere}},
url = {https://essd.copernicus.org/articles/12/2157/2020/},
volume = {12},
year = {2020}
}
@article{Smith2016,
abstract = {The rate of global mean surface temperature (GMST) warming has slowed this century despite the increasing concentrations of greenhouse gases. Climate model experiments show that this slowdown was largely driven by a negative phase of the Pacific Decadal Oscillation (PDO), with a smaller external contribution from solar variability, and volcanic and anthropogenic aerosols. The prevailing view is that this negative PDO occurred through internal variability. However, here we show that coupled models from the Fifth Coupled Model Intercomparison Project robustly simulate a negative PDO in response to anthropogenic aerosols implying a potentially important role for external human influences. The recovery from the eruption of Mount Pinatubo in 1991 also contributed to the slowdown in GMST trends. Our results suggest that a slowdown in GMST trends could have been predicted in advance, and that future reduction of anthropogenic aerosol emissions, particularly from China, would promote a positive PDO and increased GMST trends over the coming years. Furthermore, the overestimation of the magnitude of recent warming by models is substantially reduced by using detection and attribution analysis to rescale their response to external factors, especially cooling following volcanic eruptions. Improved understanding of external influences on climate is therefore crucial to constrain near-term climate predictions.},
author = {Smith, Doug M. and Booth, Ben B.B. and Dunstone, Nick J. and Eade, Rosie and Hermanson, Leon and Jones, Gareth S. and Scaife, Adam A. and Sheen, Katy L. and Thompson, Vikki},
doi = {10.1038/nclimate3058},
issn = {17586798},
journal = {Nature Climate Change},
month = {sep},
number = {10},
pages = {936--940},
publisher = {Nature Publishing Group},
title = {{Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown}},
volume = {6},
year = {2016}
}
@article{Smith2021,
author = {Smith, M. A. and Cain, M. and Allen, M. R.},
doi = {10.1038/s41612-021-00169-8},
issn = {2397-3722},
journal = {npj Climate and Atmospheric Science},
month = {dec},
number = {1},
pages = {19},
title = {{Further improvement of warming-equivalent emissions calculation}},
url = {http://www.nature.com/articles/s41612-021-00169-8},
volume = {4},
year = {2021}
}
@article{Smith9999a,
abstract = {Abstract. The effective radiative forcing, which includes the instantaneous forcing plus adjustments from the atmosphere and surface, has emerged as the key metric of evaluating human and natural influence on the climate. We evaluate effective radiative forcing and adjustments in 17 contemporary climate models that are participating in the Coupled Model Intercomparison Project (CMIP6) and have contributed to the Radiative Forcing Model Intercomparison Project (RFMIP). Present-day (2014) global-mean anthropogenic forcing relative to pre-industrial (1850) levels from climate models stands at 2.00 (±0.23) W m−2, comprised of 1.81 (±0.09) W m−2 from CO2, 1.08 (± 0.21) W m−2 from other well-mixed greenhouse gases, −1.01 (± 0.23) W m−2 from aerosols and −0.09 (±0.13) W m−2 from land use change. Quoted uncertainties are 1 standard deviation across model best estimates, and 90 {\%} confidence in the reported forcings, due to internal variability, is typically within 0.1 W m−2. The majority of the remaining 0.21 W m−2 is likely to be from ozone. In most cases, the largest contributors to the spread in effective radiative forcing (ERF) is from the instantaneous radiative forcing (IRF) and from cloud responses, particularly aerosol–cloud interactions to aerosol forcing. As determined in previous studies, cancellation of tropospheric and surface adjustments means that the stratospherically adjusted radiative forcing is approximately equal to ERF for greenhouse gas forcing but not for aerosols, and consequentially, not for the anthropogenic total. The spread of aerosol forcing ranges from −0.63 to −1.37 W m−2, exhibiting a less negative mean and narrower range compared to 10 CMIP5 models. The spread in 4×CO2 forcing has also narrowed in CMIP6 compared to 13 CMIP5 models. Aerosol forcing is uncorrelated with climate sensitivity. Therefore, there is no evidence to suggest that the increasing spread in climate sensitivity in CMIP6 models, particularly related to high-sensitivity models, is a consequence of a stronger negative present-day aerosol forcing and little evidence that modelling groups are systematically tuning climate sensitivity or aerosol forcing to recreate observed historical warming.},
author = {Smith, Christopher J. and Kramer, Ryan J. and Myhre, Gunnar and Alterskj{\ae}r, Kari and Collins, William and Sima, Adriana and Boucher, Olivier and Dufresne, Jean-Louis and Nabat, Pierre and Michou, Martine and Yukimoto, Seiji and Cole, Jason and Paynter, David and Shiogama, Hideo and O'Connor, Fiona M. and Robertson, Eddy and Wiltshire, Andy and Andrews, Timothy and Hannay, C{\'{e}}cile and Miller, Ron and Nazarenko, Larissa and Kirkev{\aa}g, Alf and Olivi{\'{e}}, Dirk and Fiedler, Stephanie and Lewinschal, Anna and Mackallah, Chloe and Dix, Martin and Pincus, Robert and Forster, Piers M.},
doi = {10.5194/acp-20-9591-2020},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {aug},
number = {16},
pages = {9591--9618},
publisher = {Copernicus GmbH},
title = {{Effective radiative forcing and adjustments in CMIP6 models}},
url = {https://acp.copernicus.org/articles/20/9591/2020/},
volume = {20},
year = {2020}
}
@article{Snyder2016a,
abstract = {Reconstructions of Earth's past climate strongly influence our understanding of the dynamics and sensitivity of the climate system. Yet global temperature has been reconstructed for only a few isolated windows of time1, 2, and continuous reconstructions across glacial cycles remain elusive. Here I present a spatially weighted proxy reconstruction of global temperature over the past 2 million years estimated from a multi-proxy database of over 20,000 sea surface temperature point reconstructions. Global temperature gradually cooled until roughly 1.2 million years ago and cooling then stalled until the present. The cooling trend probably stalled before the beginning of the mid-Pleistocene transition3, and pre-dated the increase in the maximum size of ice sheets around 0.9 million years ago4, 5, 6. Thus, global cooling may have been a pre-condition for, but probably is not the sole causal mechanism of, the shift to quasi-100,000-year glacial cycles at the mid-Pleistocene transition. Over the past 800,000 years, polar amplification (the amplification of temperature change at the poles relative to global temperature change) has been stable over time, and global temperature and atmospheric greenhouse gas concentrations have been closely coupled across glacial cycles. A comparison of the new temperature reconstruction with radiative forcing from greenhouse gases estimates an Earth system sensitivity of 9 degrees Celsius (range 7 to 13 degrees Celsius, 95 per cent credible interval) change in global average surface temperature per doubling of atmospheric carbon dioxide over millennium timescales. This result suggests that stabilization at today's greenhouse gas levels may already commit Earth to an eventual total warming of 5 degrees Celsius (range 3 to 7 degrees Celsius, 95 per cent credible interval) over the next few millennia as ice sheets, vegetation and atmospheric dust continue to respond to global warming.},
author = {Snyder, Carolyn W.},
doi = {10.1038/nature19798},
isbn = {1476-4687},
issn = {14764687},
journal = {Nature},
number = {7624},
pages = {226--228},
pmid = {27669024},
publisher = {Nature Publishing Group},
title = {{Evolution of global temperature over the past two million years}},
volume = {538},
year = {2016}
}
@article{Snyder2019,
abstract = {This study evaluates paleoclimate sensitivity over the past 800,000 years from proxy-based reconstructions of changes in global temperature, ice sheets and sea level, vegetation, dust, and greenhouse gases. This analysis uses statistical methods that are not biased by the variable (heteroscedastic) uncertainty in the reconstructions, and applies a Monte Carlo-style probabilistic framework to quantify several sources of measurement and structural uncertainty. Not addressing the heteroscedastic uncertainty would result in regression results that underestimate paleoclimate sensitivity by over 30{\%}, and not using a probabilistic framework could underestimate the credible interval by fivefold. A comparison of changes in global temperature ($\Delta$T) and changes in radiative forcing from greenhouse gases, ice sheets, dust, and vegetation ($\Delta$R[GHG,LI,AE,VG]) over the past 800 kyr finds that the two are closely coupled across glacial cycles with a correlation of 0.81 (0.6 to 0.9, 95{\%} credible interval). The variation of $\Delta$T with $\Delta$R over the past 800 kyr is non-linear, with lower correlation and lower responsiveness at colder temperatures. The paleoclimate sensitivity parameter estimates (S[GHG,LI,AE,VG]) are 0.84 °C/W/m2 (0.20 to 1.9 °C/W/m2, 95{\%} interval) for interglacial periods and intermediate glacial climates and 0.53 °C/W/m2 (0.08 to 1.5 °C/W/m2, 95{\%} interval) for full glacial climates, 37{\%} lower at the median. The estimates of S[GHG,LI,AE,VG] and the pattern of state dependence are similar across glacial cycles over the past 800 kyr. This analysis explicitly includes several sources of uncertainty and is still able to provide a strong upper bound for the paleoclimate sensitivity parameter for interglacial periods and intermediate glacial climates: over 1.5 °C/W/m2 is {\textless} 10{\%} probability, 1.7 °C/W/m2 is {\textless} 5{\%} probability, and over 1.9 °C/W/m2 is {\textless} 2.5{\%} probability.},
author = {Snyder, Carolyn W},
doi = {10.1007/s10584-019-02536-0},
issn = {1573-1480},
journal = {Climatic Change},
number = {1},
pages = {121--138},
title = {{Revised estimates of paleoclimate sensitivity over the past 800,000 years}},
url = {https://doi.org/10.1007/s10584-019-02536-0},
volume = {156},
year = {2019}
}
@article{2008JCli...21.3504S,
abstract = {The extent to which the climate will change due to an external forcing depends largely on radiative feedbacks, which act to amplify or damp the surface temperature response. There are a variety of issues that complicate the analysis of radiative feedbacks in global climate models, resulting in some confusion regarding their strengths and distributions. In this paper, the authors present a method for quantifying climate feedbacks based on "radiative kernels" that describe the differential response of the top-of-atmosphere radiative fluxes to incremental changes in the feedback variables. The use of radiative kernels enables one to decompose the feedback into one factor that depends on the radiative transfer algorithm and the unperturbed climate state and a second factor that arises from the climate response of the feedback variables. Such decomposition facilitates an understanding of the spatial characteristics of the feedbacks and the causes of intermodel differences. This technique provides a simple and accurate way to compare feedbacks across different models using a consistent methodology. Cloud feedbacks cannot be evaluated directly from a cloud radiative kernel because of strong nonlinearities, but they can be estimated from the change in cloud forcing and the difference between the full-sky and clear-sky kernels. The authors construct maps to illustrate the regional structure of the feedbacks and compare results obtained using three different model kernels to demonstrate the robustness of the methodology. The results confirm that models typically generate globally averaged cloud feedbacks that are substantially positive or near neutral, unlike the change in cloud forcing itself, which is as often negative as positive. {\textcopyright} 2008 American Meteorological Society.},
author = {Soden, Brian J. and Held, Isaac M. and Colman, Robert C. and Shell, Karen M. and Kiehl, Jeffrey T. and Shields, Christine A.},
doi = {10.1175/2007JCLI2110.1},
issn = {08948755},
journal = {Journal of Climate},
number = {14},
pages = {3504--3520},
title = {{Quantifying climate feedbacks using radiative kernels}},
volume = {21},
year = {2008}
}
@article{doi:10.1175/JCLI3799.1,
abstract = { Abstract The climate feedbacks in coupled ocean–atmosphere models are compared using a coordinated set of twenty-first-century climate change experiments. Water vapor is found to provide the largest positive feedback in all models and its strength is consistent with that expected from constant relative humidity changes in the water vapor mixing ratio. The feedbacks from clouds and surface albedo are also found to be positive in all models, while the only stabilizing (negative) feedback comes from the temperature response. Large intermodel differences in the lapse rate feedback are observed and shown to be associated with differing regional patterns of surface warming. Consistent with previous studies, it is found that the vertical changes in temperature and water vapor are tightly coupled in all models and, importantly, demonstrate that intermodel differences in the sum of lapse rate and water vapor feedbacks are small. In contrast, intermodel differences in cloud feedback are found to provide the largest source of uncertainty in current predictions of climate sensitivity. },
author = {Soden, Brian J and Held, Isaac M},
doi = {10.1175/JCLI3799.1},
journal = {Journal of Climate},
number = {14},
pages = {3354--3360},
title = {{An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models}},
url = {https://doi.org/10.1175/JCLI3799.1},
volume = {19},
year = {2006}
}
@article{Soden2018,
abstract = {Radiative forcing is a fundamental quantity for understanding both anthropogenic and natural changes in climate. It measures the extent to which human activities [such as the emission of carbon dioxide (CO2), see the image] and natural events (such as volcanic eruptions) perturb the flow of energy into and out of the climate system. This perturbation initiates all other changes of the climate in response to external forcings. Inconsistencies in the calculation of radiative forcing by CO2 introduce uncertainties in model projections of climate change, a problem that has persisted for more than two decades. The explicit calculation of radiative forcing and a careful vetting of radiative transfer parameterizations provide a straightforward means to substantially reduce these uncertainties and improve the projections.},
author = {Soden, Brian J. and Collins, William D. and Feldman, Daniel R.},
doi = {10.1126/science.aau1864},
issn = {0036-8075},
journal = {Science},
month = {jul},
number = {6400},
pages = {326--327},
title = {{Reducing uncertainties in climate models}},
url = {http://science.sciencemag.org/content/sci/361/6400/326.full.pdf https://www.sciencemag.org/lookup/doi/10.1126/science.aau1864},
volume = {361},
year = {2018}
}
@article{Soden841,
abstract = {Climate models predict that the concentration of water vapor in the upper troposphere could double by the end of the century as a result of increases in greenhouse gases. Such moistening plays a key role in amplifying the rate at which the climate warms in response to anthropogenic activities, but has been difficult to detect because of deficiencies in conventional observing systems. We use satellite measurements to highlight a distinct radiative signature of upper tropospheric moistening over the period 1982 to 2004. The observed moistening is accurately captured by climate model simulations and lends further credence to model projections of future global warming.},
author = {Soden, Brian J and Jackson, Darren L and Ramaswamy, V and Schwarzkopf, M D and Huang, Xianglei},
doi = {10.1126/science.1115602},
issn = {0036-8075},
journal = {Science},
number = {5749},
pages = {841--844},
publisher = {American Association for the Advancement of Science},
title = {{The Radiative Signature of Upper Tropospheric Moistening}},
url = {https://science.sciencemag.org/content/310/5749/841},
volume = {310},
year = {2005}
}
@article{Sohn2013,
abstract = {In order to examine the changes in Walker circulation over the recent decades, we analyzed the sea surface temperature (SST), deep convective activities, upper tropospheric moistening, sea level pressure (SLP), and effective wind in the boundary layer over the 30-year period of 1979-2008. The analysis showed that the eastern tropical Pacific has undergone cooling while the western Pacific has undergone warming over the past three decades, causing an increase in the east-west SST gradient. It is indicated that the tropical atmosphere should have responded to these SST changes; increased deep convective activities and associated upper tropospheric moistening over the western Pacific ascending region, increased SLP over the eastern Pacific descending region in contrast to decreased SLP over the western Pacific ascending region, and enhanced easterly wind in the boundary layer in response to the SLP change. These variations, recognized from different data sets, occur in tandem with each other, strongly supporting the intensified Walker circulation over the tropical Pacific Ocean. Since the SST trend was attributed to more frequent occurrences of central Pacific-type El Ni{\~{n}}o in recent decades, it is suggested that the decadal variation of El Ni{\~{n}}o caused the intensified Walker circulation over the past 30 years. An analysis of current climate models shows that model results deviate greatly from the observed intensified Walker circulation. The uncertainties in the current climate models may be due to the natural variability dominating the forced signal over the tropical Pacific during the last three decades in the twentieth century climate scenario runs by CMIP3 CGCMs. {\textcopyright} 2012 The Author(s).},
author = {Sohn, B. J. and Yeh, Sang Wook and Schmetz, Johannes and Song, Hwan Jin},
doi = {10.1007/s00382-012-1484-z},
issn = {09307575},
journal = {Climate Dynamics},
keywords = {Climate change over the tropics,Decadal variation,El Nino,Walker circulation},
number = {7-8},
pages = {1721--1732},
title = {{Observational evidences of Walker circulation change over the last 30 years contrasting with GCM results}},
volume = {40},
year = {2013}
}
@article{ISI:000366879100021,
abstract = {Recent observational studies show that solar radiation incident on ground has not been stable over the last several decades but underwent significant multi-decadal variations. From the 1950s, solar radiation has had a general decreasing trend, named dimming. Since the late 1980s, a trend reversal and partial recovery has been observed at many observations sites across the globe; it is the so-called brightening. The present study examined temporal and spatial trends in surface solar radiation (global and diffuse) and sunshine duration in India using a 40-year data set (1971-2010) of the twelve stations of solar radiation network of the India Meteorological Department. The research work examines the global solar radiation trends in all-sky and cloud-free sky conditions. The long-term variability in the diffuse components of solar radiation, bright sunshine duration, and cloud cover has also been studied over India. India is one of the few regions that showed a continuous and steady decline in global solar radiation from the 1970s to 2000. The declining trend of all-sky global irradiance over India as a whole was 0.6 Wm(-2) year(-1) during 1971-2000 and 0.2 Wm(-2) year(-1) during 2001-2010. A third-order polynomial fit to the data indicated a reversal in all-sky global irradiance around 2001 at some sites. Reversal or stabilization of global irradiance is also seen in seasonal mean values at some of the stations. The reversal in clear-sky global irradiance was clearly evident from 2001. Similar trend is also observed in bright sunshine duration. This confirms the well-known phenomenon of global dimming and global brightening over India. The analysis of global irradiance data highlights the fact that in general the dimming/brightening is station dependent because of regional sources and meteorology which contribute to the variation in solar irradiance. (C) 2015 Elsevier B.V. All rights reserved.},
address = {360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA},
author = {Soni, V K and Pandithurai, G and Pai, D S},
doi = {10.1016/j.atmosres.2015.10.010},
issn = {0169-8095},
journal = {Atmospheric Research},
keywords = {Brightening,Di,Global dimming,Global irradiance},
month = {mar},
number = {A},
pages = {209--224},
publisher = {ELSEVIER SCIENCE INC},
title = {{Is there a transition of solar radiation from dimming to brightening over India?}},
type = {Article},
volume = {169},
year = {2016}
}
@article{Spencer2011,
abstract = {The sensitivity of the climate system to an imposed radiative imbalance remains the largest source of uncertainty in projections of future anthropogenic climate change. Here we present further evidence that this uncertainty from an observational perspective is largely due to the masking of the radiative feedback signal by internal radiative forcing, probably due to natural cloud variations. That these internal radiative forcings exist and likely corrupt feedback diagnosis is demonstrated with lag regression analysis of satellite and coupled climate model data, interpreted with a simple forcing-feedback model. While the satellite-based metrics for the period 2000–2010 depart substantially in the direction of lower climate sensitivity from those similarly computed from coupled climate models, we find that, with traditional methods, it is not possible to accurately quantify this discrepancy in terms of the feedbacks which determine climate sensitivity. It is concluded that atmospheric feedback diagnosis of the climate system remains an unsolved problem, due primarily to the inability to distinguish between radiative forcing and radiative feedback in satellite radiative budget observations.},
author = {Spencer, Roy W. and Braswell, William D.},
doi = {10.3390/rs3081603},
issn = {2072-4292},
journal = {Remote Sensing},
keywords = {CERES,Climate,Clouds,Feedback,Models,Sensitivity,Temperature,Warming},
month = {jul},
number = {8},
pages = {1603--1613},
title = {{On the Misdiagnosis of Surface Temperature Feedbacks from Variations in Earth's Radiant Energy Balance}},
url = {http://www.mdpi.com/2072-4292/3/8/1603},
volume = {3},
year = {2011}
}
@article{Spencer2010,
abstract = {The impact of time-varying radiative forcing on the diagnosis of radiative feedback from satellite observations of the Earth is explored. Phase space plots of variations in global average temperature versus radiative flux reveal linear striations and spiral patterns in both satellite measurements and in output from coupled climate models. A simple forcing-feedback model is used to demonstrate that the linear striations represent radiative feedback upon nonradiatively forced temperature variations, while the spiral patterns are the result of time-varying radiative forcing generated internal to the climate system. Only in the idealized special case of instantaneous and then constant radiative forcing, a situation that probably never occurs either naturally or anthropogenically, can feedback be observed in the presence of unknown radiative forcing. This is true whether the unknown radiative forcing is generated internal or external to the climate system. In the general case, a mixture of both unknown radiative and nonradiative forcings can be expected, and the challenge for feedback diagnosis is to extract the signal of feedback upon nonradiatively forced temperature change in the presence of the noise generated by unknown time-varying radiative forcing. These results underscore the need for more accurate methods of diagnosing feedback from satellite data and for quantitatively relating those feedbacks to long-term climate sensitivity.},
author = {Spencer, Roy W. and Braswell, William D.},
doi = {10.1029/2009JD013371},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
month = {aug},
number = {D16},
pages = {D16109},
title = {{On the diagnosis of radiative feedback in the presence of unknown radiative forcing}},
url = {http://doi.wiley.com/10.1029/2009JD013371},
volume = {115},
year = {2010}
}
@article{ISI:000344052800018,
abstract = {Analysis of the Angstrom-Prescott relationship between normalized values of global radiation and sunshine duration measured during the last 50 years made at five sites with a wide range of climate and aerosol emissions showed few significant differences in atmospheric transmissivity under clear or cloud-covered skies between years when global dimming occurred and years when global brightening was measured, nor in most cases were there any significant changes in the parameters or in their relationships to annual rates of fossil fuel combustion in the surrounding 1 degrees cells. It is concluded that at the sites studied changes in cloud cover rather than anthropogenic aerosols emissions played the major role in determining solar dimming and brightening during the last half century and that there are reasons to suppose that these findings may have wider relevance.},
address = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
author = {Stanhill, Gerald and Achiman, Ori and Rosa, Rafael and Cohen, Shabtai},
doi = {10.1002/2013JD021308},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {sep},
number = {18},
pages = {10902--10911},
publisher = {AMER GEOPHYSICAL UNION},
title = {{The cause of solar dimming and brightening at the Earth's surface during the last half century: Evidence from measurements of sunshine duration}},
type = {Article},
volume = {119},
year = {2014}
}
@article{Stap2019,
abstract = {Abstract. The influence of long-term processes in the climate system, such as land ice changes, has to be compensated for when comparing climate sensitivity derived from paleodata with equilibrium climate sensitivity (ECS) calculated by climate models, which is only generated by a CO2 change. Several recent studies found that the impact these long-term processes have on global temperature cannot be quantified directly through the global radiative forcing they induce. This renders the approach of deconvoluting paleotemperatures through a partitioning based on radiative forcings inaccurate. Here, we therefore implement an efficacy factor $\epsilon$[LI], that relates the impact of land ice changes on global temperature to that of CO2 changes, in our calculation of climate sensitivity from paleodata. We apply our new approach to a proxy-inferred paleoclimate dataset, and find an equivalent ECS of 5.6{\&}thinsp;±{\&}thinsp;1.3{\&}thinsp;K per CO2 doubling. The substantial uncertainty herein is generated by the range in $\epsilon$[LI] we use, which is based on a multi-model assemblage of simulated relative influences of land ice changes on the Last Glacial Maximum (LGM) temperature anomaly (46{\&}thinsp;±{\&}thinsp;14{\&}thinsp;{\%}). The low end of our ECS estimate, which concurs with estimates from other approaches, tallies with a large influence for land ice changes. To separately assess this influence, we analyse output of the PMIP3 climate model intercomparison project. From this data, we infer a functional intermodel relation between global and high-latitude temperature changes at the LGM with respect to the pre-industrial climate, and the temperature anomaly caused by a CO2 change. Applying this relation to our dataset, we find a considerable 64{\&}thinsp;{\%} influence for land ice changes on the LGM temperature anomaly. This is even higher than the range used before, and leads to an equivalent ECS of 3.8{\&}thinsp;K per CO2 doubling. Together, our results suggest that land ice changes play a key role in the variability of Late Pleistocene temperatures.},
author = {Stap, Lennert B. and K{\"{o}}hler, Peter and Lohmann, Gerrit},
doi = {10.5194/esd-10-333-2019},
issn = {21904987},
journal = {Earth System Dynamics},
number = {2},
pages = {333--345},
title = {{Including the efficacy of land ice changes in deriving climate sensitivity from paleodata}},
volume = {10},
year = {2019}
}
@article{Steffen2018a,
abstract = {We explore the risk that self-reinforcing feedbacks could push the Earth System toward a planetary threshold that, if crossed, could prevent stabilization of the climate at intermediate temperature rises and cause continued warming on a "Hothouse Earth" pathway even as human emissions are reduced. Crossing the threshold would lead to a much higher global average temperature than any interglacial in the past 1.2 million years and to sea levels significantly higher than at any time in the Holocene. We examine the evidence that such a threshold might exist and where it might be. If the threshold is crossed, the resulting trajectory would likely cause serious disruptions to ecosystems, society, and economies. Collective human action is required to steer the Earth System away from a potential threshold and stabilize it in a habitable interglacial-like state. Such action entails stewardship of the entire Earth System-biosphere, climate, and societies-and could include decarbonization of the global economy, enhancement of biosphere carbon sinks, behavioral changes, technological innovations, new governance arrangements, and transformed social values.},
archivePrefix = {arXiv},
arxivId = {arXiv:1408.1149},
author = {Steffen, Will and Rockstr{\"{o}}m, Johan and Richardson, Katherine and Lenton, Timothy M. and Folke, Carl and Liverman, Diana and Summerhayes, Colin P. and Barnosky, Anthony D. and Cornell, Sarah E. and Crucifix, Michel and Donges, Jonathan F. and Fetzer, Ingo and Lade, Steven J. and Scheffer, Marten and Winkelmann, Ricarda and Schellnhuber, Hans Joachim},
doi = {10.1073/pnas.1810141115},
eprint = {arXiv:1408.1149},
isbn = {9111267038},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {33},
pages = {8252--8259},
pmid = {30082409},
title = {{Trajectories of the Earth System in the Anthropocene}},
url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1810141115},
volume = {115},
year = {2018}
}
@article{Stein2016,
abstract = {AbstractUsing the satellite-infrared-based Simple Convective Aggregation Index (SCAI) to determine the degree of aggregation, 5 years of CloudSat?CALIPSO cloud profiles are composited at a spatial scale of 10 degrees to study the relationship between cloud vertical structure and aggregation. For a given large-scale vertical motion and domain-averaged precipitation rate, there is a large decrease in anvil cloud (and in cloudiness as a whole) and an increase in clear sky and low cloud as aggregation increases. The changes in thick anvil cloud are proportional to the changes in total areal cover of brightness temperatures below 240 K [cold cloud area (CCA)], which is negatively correlated with SCAI. Optically thin anvil cover decreases significantly when aggregation increases, even for a fixed CCA, supporting previous findings of a higher precipitation efficiency for aggregated convection. Cirrus, congestus, and midlevel clouds do not display a consistent relationship with the degree of aggregation. Lidar-observed low-level cloud cover (where the lidar is not attenuated) is presented herein as the best estimate of the true low-level cloud cover, and it is shown that it increases as aggregation increases. Qualitatively, the relationships between cloud distribution and SCAI do not change with sea surface temperature, while cirrus clouds are more abundant and low-level clouds less at higher sea surface temperatures. For the observed regimes, the vertical cloud profile varies more evidently with SCAI than with mean precipitation rate. These results confirm that convective scenes with similar vertical motion and rainfall can be associated with vastly different cloudiness (both high and low cloud) and humidity depending on the degree of convective aggregation.},
author = {Stein, T H M and Holloway, C E and Tobin, I and Bony, S},
doi = {10.1175/JCLI-D-16-0125.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {dec},
number = {6},
pages = {2187--2207},
publisher = {American Meteorological Society},
title = {{Observed Relationships between Cloud Vertical Structure and Convective Aggregation over Tropical Ocean}},
url = {https://doi.org/10.1175/JCLI-D-16-0125.1},
volume = {30},
year = {2017}
}
@article{Steiner2020,
abstract = {Temperature observations of the upper-air atmosphere are now available for more than 40 years from both ground- and satellite-based observing systems. Recent years have seen substantial improvements in reducing long-standing discrepancies among datasets through major reprocessing efforts. The advent of radio occultation (RO) observations in 2001 has led to further improvements in vertically resolved temperature measurements, enabling a detailed analysis of upper-troposphere/lower-stratosphere trends. This paper presents the current state of atmospheric temperature trends from the latest available observational records. We analyze observations from merged operational satellite measurements, radiosondes, lidars, and RO, spanning a vertical range from the lower troposphere to the upper stratosphere. The focus is on assessing climate trends and on identifying the degree of consistency among the observational systems. The results show a robust cooling of the stratosphere of about 1–3 K, and a robust warming of the troposphere of about 0.6–0.8 K over the last four decades (1979–2018). Consistent results are found between the satellite-based layer-average temperatures and vertically resolved radiosonde records. The overall latitude–altitude trend patterns are consistent between RO and radiosonde records. Significant warming of the troposphere is evident in the RO measurements available after 2001, with trends of 0.25–0.35 K per decade. Amplified warming in the tropical upper-troposphere compared to surface trends for 2002–18 is found based on RO and radiosonde records, in approximate agreement with moist adiabatic lapse rate theory. The consistency of trend results from the latest upper-air datasets will help to improve understanding of climate changes and their drivers.},
author = {Steiner, A. K. and Ladst{\"{a}}dter, F. and Randel, W. J. and Maycock, A. C. and Fu, Q. and Claud, C. and Gleisner, H. and Haimberger, L. and Ho, S.-P. and Keckhut, P. and Leblanc, T. and Mears, C. and Polvani, L. M. and Santer, B. D. and Schmidt, T. and Sofieva, V. and Wing, R. and Zou, C.-Z.},
doi = {10.1175/JCLI-D-19-0998.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {19},
pages = {8165--8194},
title = {{Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-19-0998.1},
volume = {33},
year = {2020}
}
@article{Steinhilber5967,
abstract = {Understanding the temporal variation of cosmic radiation and solar activity during the Holocene is essential for studies of the solar-terrestrial relationship. Cosmic-ray produced radionuclides, such as 10Be and 14C which are stored in polar ice cores and tree rings, offer the unique opportunity to reconstruct the history of cosmic radiation and solar activity over many millennia. Although records from different archives basically agree, they also show some deviations during certain periods. So far most reconstructions were based on only one single radionuclide record, which makes detection and correction of these deviations impossible. Here we combine different 10Be ice core records from Greenland and Antarctica with the global 14C tree ring record using principal component analysis. This approach is only possible due to a new high-resolution 10Be record from Dronning Maud Land obtained within the European Project for Ice Coring in Antarctica in Antarctica. The new cosmic radiation record enables us to derive total solar irradiance, which is then used as a proxy of solar activity to identify the solar imprint in an Asian climate record. Though generally the agreement between solar forcing and Asian climate is good, there are also periods without any coherence, pointing to other forcings like volcanoes and greenhouse gases and their corresponding feedbacks. The newly derived records have the potential to improve our understanding of the solar dynamics and to quantify the solar influence on climate.},
author = {Steinhilber, Friedhelm and Abreu, Jose A and Beer, J{\"{u}}rg and Brunner, Irene and Christl, Marcus and Fischer, Hubertus and Heikkil{\"{a}}, Ulla and Kubik, Peter W and Mann, Mathias and McCracken, Ken G and Miller, Heinrich and Miyahara, Hiroko and Oerter, Hans and Wilhelms, Frank},
doi = {10.1073/pnas.1118965109},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {16},
pages = {5967--5971},
publisher = {National Academy of Sciences},
title = {9,400 years of cosmic radiation and solar activity from ice cores and tree rings},
url = {https://www.pnas.org/content/109/16/5967},
volume = {109},
year = {2012}
}
@article{Steinthorsdottir2020,
abstract = {Key Points: • Miocene floras, faunas, and paleogeography were similar to today and provide plausible analogues for future climatic warming. • The Miocene saw great dynamism in biotic and climate systems, but the reasons for these shifts are still not well understood. • The pCO2-temperature-ice relationships during major Miocene climate oscillations and transitions warrant further research. Abstract The Miocene epoch (23.03-5.33 Ma) was a time interval of global warmth, relative to today. Continental configurations and mountain topography transitioned towards modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a {\~{}}2 Myr greenhouse interval-the Miocene Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, pCO2, and ocean and atmospheric circulation mostly (but not ubiquitously) covaried with these large changes in climate. With higher temperatures and moderately higher pCO2 ({\~{}}400-600 ppm), the MCO has been suggested as a particularly appropriate analogue for future climate scenarios, and for assessing the predictive accuracy of numerical climate models-the same models that are used to simulate future climate. Yet, Miocene conditions have proved difficult to reconcile with models. This implies either missing positive feedbacks in the models, a lack of knowledge of past climate forcings, or the need for re-interpretation of proxies, which might mitigate the model-data discrepancy. Our understanding of Miocene climatic, biogeochemical, and oceanic changes on broad spatial and temporal scales is still developing. New records documenting the physical, chemical, and biotic aspects of the Earth system are emerging, and together provide a more comprehensive understanding of this important time interval. Here we review the state-of-the-art in Miocene climate, ocean circulation, biogeochemical cycling, ice sheet dynamics, and biotic adaptation research as inferred through proxy observations and modelling studies. Plain Language Summary During the Miocene time period ({\~{}}23-5 million years ago), Planet Earth looked similar to today, atmospheric CO2 was not much higher. Continental-sized ice sheets were only present on Antarctica, but not in the northern hemisphere. The continents drifted to near their modern-day positions, and plants and animals evolved into the many (near) modern species. Scientists study the Miocene because present-day and projected future CO2 levels are in the same range as those reconstructed for the Miocene. Therefore, if we can understand climate changes and their biotic responses from the Miocene past, we are able to better predict current and future global changes. By comparing Miocene climate reconstructions from fossil and chemical data to climate simulations produced by computer models, scientists are able to test their understanding of the Earth system under higher CO2 and warmer conditions than those of today. This helps in constraining future warming scenarios for the coming decades. In this review paper, we summarize the current understanding of the Miocene world from data and models. We also identify gaps in our understanding that need further research attention in the future.},
author = {Steinthorsdottir, M. and Coxall, H. K. and de Boer, A. M. and Huber, M. and Barbolini, N. and Bradshaw, C. D. and Burls, N. J. and Feakins, S. J. and Gasson, E. and Henderiks, J. and Holbourn, A. E. and Kiel, S. and Kohn, M. J. and Knorr, G. and K{\"{u}}rschner, W. M. and Lear, C. H. and Liebrand, D. and Lunt, D. J. and M{\"{o}}rs, T. and Pearson, P. N. and Pound, M. J. and Stoll, H. and Str{\"{o}}mberg, C. A. E.},
doi = {10.1029/2020PA004037},
issn = {2572-4517},
journal = {Paleoceanography and Paleoclimatology},
keywords = {Climate modelling,Paleo‐biota,Paleo‐climate,Paleo‐environments,Review,The Miocene},
month = {apr},
number = {4},
pages = {e2020PA004037},
publisher = {American Geophysical Union (AGU)},
title = {{The Miocene: The Future of the Past}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020PA004037},
volume = {36},
year = {2021}
}
@article{doi:10.1002/2014RG000449,
abstract = {Abstract The fraction of the incoming solar energy scattered by Earth back to space is referred to as the planetary albedo. This reflected energy is a fundamental component of the Earth's energy balance, and the processes that govern its magnitude, distribution, and variability shape Earth's climate and climate change. We review our understanding of Earth's albedo as it has progressed to the current time and provide a global perspective of our understanding of the processes that define it. Joint analyses of surface solar flux data that are a complicated mix of measurements and model calculations with top-of-atmosphere (TOA) flux measurements from current orbiting satellites yield a number of surprising results including (i) the Northern and Southern Hemispheres (NH, SH) reflect the same amount of sunlight within {\~{}} 0.2 W m−2. This symmetry is achieved by increased reflection from SH clouds offsetting precisely the greater reflection from the NH land masses. (ii) The albedo of Earth appears to be highly buffered on hemispheric and global scales as highlighted by both the hemispheric symmetry and a remarkably small interannual variability of reflected solar flux ({\~{}}0.2{\%} of the annual mean flux). We show how clouds provide the necessary degrees of freedom to modulate the Earth's albedo setting the hemispheric symmetry. We also show that current climate models lack this same degree of hemispheric symmetry and regulation by clouds. The relevance of this hemispheric symmetry to the heat transport across the equator is discussed.},
author = {Stephens, Graeme L and O'Brien, Denis and Webster, Peter J and Pilewski, Peter and Kato, Seiji and Li, Jui-lin},
doi = {10.1002/2014RG000449},
journal = {Reviews of Geophysics},
keywords = {albedo,energy balance,solar radiation},
number = {1},
pages = {141--163},
title = {{The albedo of Earth}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014RG000449},
volume = {53},
year = {2015}
}
@article{Sterner2014,
abstract = {Here we present two new metrics used for comparing climate impacts of emissions of different climate forcers: the Global Sea level rise Potential (GSP) and the Integrated Global Sea level rise Potential (IGSP). The GSP represents the Sea Level Rise (SLR) at a given time horizon due to an emission pulse of a forcer; the IGSP is similar but represents the time integrated SLR up to a given point in time. The GSP and IGSP are presented relative to the SLR caused by a comparable emission pulse of carbon dioxide. The metrics are assessed using an Upwelling-Diffusion Energy Balance Model (UDEBM). We focus primarily on the thermosteric part of SLR, denoted GSPth. All of the examined climate forcers – even black carbon, a very Short-Lived Climate Forcer (SLCF) – have considerable influence on the thermosteric SLR on the century time scale. For a given time horizon and forcer, GSPth lies in between the corresponding metric values obtained using Global Warming Potential (GWP) and Global Temperature change Potential (GTP), whereas IGSPth ends up in the opposite end to GTP in the spectrum of compared metrics. GSPth and IGSPth are more sensitive for SLCFs than for the long-lived Greenhouse Gases (GHGs) to changes in the parameterization of the model (under the time horizons considered here). We also use a Semi-Empirical (SE) model to estimate the full SLR, and corresponding GSPSE and IGSPSE, as alternatives to the thermosteric approach. For SLCFs, GSPSE is greater than GSPth for all time horizons considered, while the opposite holds for long-lived GHGs such as SF6.},
author = {Sterner, Erik O. and Johansson, Daniel J.A. and Azar, Christian},
doi = {10.1007/s10584-014-1258-1},
issn = {15731480},
journal = {Climatic Change},
number = {2},
pages = {335--351},
title = {{Emission metrics and sea level rise}},
volume = {127},
year = {2014}
}
@article{Sterner2017,
abstract = {The Climate–Carbon cycle Feedback (CCF) affects emission metric values. In the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change metric values for Global Warming Potentials (GWP) and Global Temperature Potentials (GTP) are reported both with and without CCF for non-CO2 climate forcers, while CCF is always included for CO2. The estimation of CCF for non-CO2 climate forcers in AR5 is based on a linear feedback analysis. This study compares that approach with an explicit approach that uses a temperature dependent carbon cycle model. The key difference in the CCF results for non-CO2 climate forcers is that, with the approach used in AR5, a fraction of the CO2 signal induced by non-CO2 forcers will persist in the atmosphere basically forever, while, with the approach based on an explicit carbon cycle model, the atmospheric CO2 signal induced by non-CO2 forcers eventually vanishes. The differences in metric values between the two model approaches are within ±10{\%} for all well-mixed greenhouse gases when the time horizon is limited to 100 yr or less, for both GWP and GTP. However, for long time horizons, such as 500 yr, metric values are substantially lower with the explicit CCF model than with the linear feedback approach, up to 30{\%} lower for GWP and up to 90{\%} lower for GTP.},
author = {Sterner, Erik O. and Johansson, Daniel J A},
doi = {10.1088/1748-9326/aa61dc},
issn = {1748-9326},
journal = {Environmental Research Letters},
keywords = {climate-carbon cycle feedback,emission metrics,energy balance,greenhouse gases,short-lived climate forcers,upwelling diffusion},
month = {mar},
number = {3},
pages = {034019},
title = {{The effect of climate–carbon cycle feedbacks on emission metrics}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/aa61dc},
volume = {12},
year = {2017}
}
@article{Stevens2009a,
abstract = {It is thought that changes in the concentration of cloud-active aerosol can alter the precipitation efficiency of clouds, thereby changing cloud amount and, hence, the radiative forcing of the climate system. Despite decades of research, it has proved frustratingly difficult to establish climatically meaningful relationships among the aerosol, clouds and precipitation. As a result, the climatic effect of the aerosol remains controversial. We propose that the difficulty in untangling relationships among the aerosol, clouds and precipitation reflects the inadequacy of existing tools and methodologies and a failure to account for processes that buffer cloud and precipitation responses to aerosol perturbations.},
author = {Stevens, Bjorn and Feingold, Graham},
doi = {https://doi.org/10.1038/nature08281},
journal = {Nature},
number = {7264},
pages = {607--613},
publisher = {Nature Publishing Group},
title = {{Untangling aerosol effects on clouds and precipitation in a buffered system}},
volume = {461},
year = {2009}
}
@article{Stevens2015,
abstract = {Based on research showing that in the case of a strong aerosol forcing, this forcing establishes itself early in the historical record, a simple model is constructed to explore the implications of a strongly negative aerosol forcing on the early (pre-1950) part of the instrumental record. This model, which contains terms representing both aerosol–radiation and aerosol–cloud interactions, well represents the known time history of aerosol radiative forcing as well as the effect of the natural state on the strength of aerosol forcing. Model parameters, randomly drawn to represent uncertainty in understanding, demonstrate that a forcing more negative than −1.0 W m−2 is implausible, as it implies that none of the approximately 0.3-K temperature rise between 1850 and 1950 can be attributed to Northern Hemisphere forcing. The individual terms of the model are interpreted in light of comprehensive modeling, constraints from observations, and physical understanding to provide further support for the less negative (−1.0 W m−2) lower bound. These findings suggest that aerosol radiative forcing is less negative and more certain than is commonly believed.},
author = {Stevens, Bjorn},
doi = {10.1175/JCLI-D-14-00656.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Aerosols,Climate change,Climate models,Climate sensitivity,Coupled models,Radiative forcing},
month = {jun},
number = {12},
pages = {4794--4819},
pmid = {23033315},
title = {{Rethinking the Lower Bound on Aerosol Radiative Forcing}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-14-00656.1},
volume = {28},
year = {2015}
}
@article{Stevens2016a,
abstract = {The concept of Earth's Equilibrium Climate Sensitivity (ECS) is reviewed. A particular problem in quantifying plausible bounds for ECS has been how to account for all of the diverse lines of relevant scientific evidence. It is argued that developing and refuting physical storylines (hypotheses) for values outside any proposed range has the potential to better constrain these bounds and to help articulate the science needed to narrow the range further. A careful reassessment of all important lines of evidence supporting these storylines, their limitations, and the assumptions required to combine them is therefore required urgently.},
author = {Stevens, Bjorn and Sherwood, Steven C. and Bony, Sandrine and Webb, Mark J.},
doi = {10.1002/2016EF000376},
issn = {23284277},
journal = {Earth's Future},
keywords = {Climate change,Climate sensitivity},
number = {11},
pages = {512--522},
title = {{Prospects for narrowing bounds on Earth's equilibrium climate sensitivity}},
volume = {4},
year = {2016}
}
@article{Stier2016,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Aerosol–cloud interactions are considered a key uncertainty in our understanding of climate change (Boucher et al., 2013). Knowledge of the global abundance of cloud condensation nuclei (CCN) is fundamental to determine the strength of the anthropogenic climate perturbation. Direct measurements are limited and sample only a very small fraction of the globe so that remote sensing from satellites and ground-based instruments is widely used as a proxy for cloud condensation nuclei (Nakajima et al., 2001; Andreae, 2009; Clarke and Kapustin, 2010; Boucher et al., 2013). However, the underlying assumptions cannot be robustly tested with the small number of measurements available so that no reliable global estimate of cloud condensation nuclei exists. This study overcomes this limitation using a self-consistent global model (ECHAM-HAM) of aerosol radiative properties and cloud condensation nuclei. An analysis of the correlation of simulated aerosol radiative properties and cloud condensation nuclei reveals that common assumptions about their relationships are violated for a significant fraction of the globe: 71{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} of the area of the globe shows correlation coefficients between CCN{\textless}sub{\textgreater}0.2{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%}{\textless}/sub{\textgreater} at cloud base and aerosol optical depth (AOD) below 0.5, i.e. AOD variability explains only 25{\textless}span class="thinspace"{\textgreater}{\textless}/span{\textgreater}{\%} of the CCN variance. This has significant implications for satellite based studies of aerosol–cloud interactions. The findings also suggest that vertically resolved remote-sensing techniques, such as satellite-based high spectral resolution lidars, have a large potential for global monitoring of cloud condensation nuclei.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Stier, Philip},
doi = {10.5194/acp-16-6595-2016},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {may},
number = {10},
pages = {6595--6607},
title = {{Limitations of passive remote sensing to constrain global cloud condensation nuclei}},
url = {https://www.atmos-chem-phys.net/16/6595/2016/},
volume = {16},
year = {2016}
}
@article{Stjern2017,
abstract = {We investigate the climate response to increased concentrations of black carbon (BC), as part of the Precipitation Driver Response Model Intercomparison Project (PDRMIP). A tenfold increase in BC is simulated by nine global coupled-climate models, producing a model median effective radiative forcing of 0.82 (ranging from 0.41 to 2.91) W m −2 , and a warming of 0.67 (0.16 to 1.66) K globally and 1.24 (0.26 to 4.31) K in the Arctic. A strong positive instantaneous radiative forcing (median of 2.10 W m −2 based on five of the models) is countered by negative rapid adjustments (−0.64 W m −2 for the same five models), which dampen the total surface temperature signal. Unlike other drivers of climate change, the response of temperature and cloud profiles to the BC forcing is dominated by rapid adjustments. Low-level cloud amounts increase for all models, while higher-level clouds are diminished. The rapid temperature response is particularly strong above 400 hPa, where increased atmospheric stabilization and reduced cloud cover contrast the response pattern of the other drivers. In conclusion, we find that this substantial increase in BC concentrations does have considerable impacts on important aspects of the climate system. However, some of these effects tend to offset one another, leaving a relatively small median global warming of 0.47 K per W m −2 —about 20{\%} lower than the response to a doubling of CO 2 . Translating the tenfold increase in BC to the present-day impact of anthropogenic BC (given the emissions used in this work) would leave a warming of merely 0.07 K.},
author = {Stjern, Camilla Weum and Samset, Bj{\o}rn Hallvard and Myhre, Gunnar and Forster, Piers M. and Hodnebrog, {\O}ivind and Andrews, Timothy and Boucher, Olivier and Faluvegi, Gregory and Iversen, Trond and Kasoar, Matthew and Kharin, Viatcheslav and Kirkev{\aa}g, Alf and Lamarque, Jean-Fran{\c{c}}ois and Olivi{\'{e}}, Dirk and Richardson, Thomas and Shawki, Dilshad and Shindell, Drew and Smith, Christopher J. and Takemura, Toshihiko and Voulgarakis, Apostolos},
doi = {10.1002/2017JD027326},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {black carbon,climate,rapid adjustments,semidirect},
month = {nov},
number = {21},
pages = {11462--11481},
title = {{Rapid Adjustments Cause Weak Surface Temperature Response to Increased Black Carbon Concentrations}},
url = {http://doi.wiley.com/10.1002/2017JD027326},
volume = {122},
year = {2017}
}
@article{Stjern2019,
abstract = {The Arctic is experiencing rapid climate change in response to changes in greenhouse gases, aerosols, and other climate drivers. Emission changes in general, as well as geographical shifts in emissions and transport pathways of short-lived climate forcers, make it necessary to understand the influence of each climate driver on the Arctic. In the Precipitation Driver Response Model Intercomparison Project, 10 global climate models perturbed five different climate drivers separately (CO2, CH4, the solar constant, black carbon, and SO4). We show that the annual mean Arctic amplification (defined as the ratio between Arctic and the global mean temperature change) at the surface is similar between climate drivers, ranging from 1.9 (± an intermodel standard deviation of 0.4) for the solar to 2.3 (±0.6) for the SO4 perturbations, with minimum amplification in the summer for all drivers. The vertical and seasonal temperature response patterns indicate that the Arctic is warmed through similar mechanisms for all climate drivers except black carbon. For all drivers, the precipitation change per degree global temperature change is positive in the Arctic, with a seasonality following that of the Arctic amplification. We find indications that SO4 perturbations produce a slightly stronger precipitation response than the other drivers, particularly compared to CO2.},
author = {Stjern, Camilla Weum and Lund, Marianne Tronstad and Samset, Bj{\o}rn Hallvard and Myhre, Gunnar and Forster, Piers M. and Andrews, Timothy and Boucher, Olivier and Faluvegi, Gregory and Fl{\"{a}}schner, Dagmar and Iversen, Trond and Kasoar, Matthew and Kharin, Viatcheslav and Kirkev{\aa}g, Alf and Lamarque, Jean Fran{\c{c}}ois and Olivi{\'{e}}, Dirk and Richardson, Thomas and Sand, Maria and Shawki, Dilshad and Shindell, Drew and Smith, Christopher J. and Takemura, Toshihiko and Voulgarakis, Apostolos},
doi = {10.1029/2018JD029726},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {Arctic amplification,aerosols,climate change,climate drivers,greenhouse gases},
month = {jul},
number = {13},
pages = {6698--6717},
publisher = {Blackwell Publishing Ltd},
title = {{Arctic Amplification Response to Individual Climate Drivers}},
volume = {124},
year = {2019}
}
@article{Stocker2013c,
abstract = {The sensitivity of the terrestrial biosphere to changes in climate constitutes a feedback mechanism with the potential to accentuate global warming. Process-based modelling experiments now indicate that under a business-as-usual emissions scenario the biosphere on land is expected to be an increasingly positive feedback to anthropogenic climate change, potentially amplifying equilibrium climate sensitivity by 22–27{\%}.},
author = {Stocker, Benjamin D and Roth, Raphael and Joos, Fortunat and Spahni, Renato and Steinacher, Marco and Zaehle, Soenke and Bouwman, Lex and Xu-Ri and Prentice, Iain Colin},
doi = {10.1038/nclimate1864},
issn = {1758-6798},
journal = {Nature Climate Change},
number = {7},
pages = {666--672},
title = {{Multiple greenhouse-gas feedbacks from the land biosphere under future climate change scenarios}},
url = {https://doi.org/10.1038/nclimate1864},
volume = {3},
year = {2013}
}
@article{Stolpe2019,
abstract = {It is debated whether the global mean transient temperature response to forcing is largely independent of biases in the simulated base state climate. To test this, we run the Community Earth System Model (CESM1) into new quasi-equilibria by altering the solar constant by{\{}$\backslash$thinspace{\}}{\{}$\backslash$textpm{\}}{\{}$\backslash$thinspace{\}}25 Wm−2 and initialize idealized CO2 climate change experiments from these climate states. The simulations branched off from the warm and control states, with increased and unaltered solar constant, respectively, show similar global mean feedback parameters, effective CO2 radiative forcings (ERF) and ocean heat uptake efficiencies and therefore simulate indiscernibly different amounts of global warming. The experiments starting from the cold climate state behave differently: The CO2 ERF is lower mostly because of rapid adjustments in the clouds, and the climate sensitivity is enhanced, mainly due to a large surface albedo feedback caused by the increased sea ice and snow coverage that extends to lower latitudes. The global heat uptake efficiency is reduced in the cold state. While taking up more heat in the Southern Ocean than the experiments from the warmer states much less heat is taken up by the North Atlantic. The less stabilizing net climate feedback parameter and the decreased ocean heat uptake efficiency dominate over the reduced CO2 ERF, and the simulations initialized from the cold state show{\{}$\backslash$thinspace{\}}{\{}$\backslash$textasciitilde{\}}{\{}$\backslash$thinspace{\}}10{\%} more global warming compared to those from the control state. This enhanced warming mainly occurs at higher-latitudes over sea ice and snow-covered areas and the North Atlantic. While the local climate response may depend strongly on the base state, the future global mean temperature increase simulated by CESM1 is remarkably independent on the initial climate state.},
author = {Stolpe, Martin B and Medhaug, Iselin and Beyerle, Urs and Knutti, Reto},
doi = {10.1007/s00382-019-04849-3},
issn = {1432-0894},
journal = {Climate Dynamics},
month = {oct},
number = {7},
pages = {5079--5099},
title = {{Weak dependence of future global mean warming on the background climate state}},
url = {https://doi.org/10.1007/s00382-019-04849-3},
volume = {53},
year = {2019}
}
@article{Storelvmo2016a,
abstract = {Earth's climate sensitivity has long been subject to heated debate and has spurred renewed interest after the latest IPCC assessment report suggested a downward adjustment of its most likely range1 . Recent observational studies have produced estimates of transient climate sensitivity, that is, the global mean surface temperature increase at the time of CO2 doubling, as low as 1.3K (refs 2,3), well below the best estimate produced by global climate models (1.8 K). Here, we present an observation-based study of the time period 1964 to 2010, which does not rely on climate models. The method incorporates observations of greenhouse gas concentrations, temperature and radiation from approximately 1,300 surface sites into an energy balance framework. Statistical methods commonly applied to economic time series are then used to decompose observed temperature trends into components attributable to changes in greenhouse gas concentrations and surface radiation.We find that surface radiation trends, which have been largely explained by changes in atmospheric aerosol loading, caused a cooling that masked approximately one-third of the continental warming due to increasing greenhouse gas concentrations over the past half-century. In consequence, the method yields a higher transient climate sensitivity (2.0 ± 0.8 K) than other observational studies.},
author = {Storelvmo, T. and Leirvik, T. and Lohmann, U. and Phillips, P. C.B. and Wild, M.},
doi = {10.1038/ngeo2670},
isbn = {1752-0894},
issn = {17520908},
journal = {Nature Geoscience},
number = {4},
pages = {286--289},
title = {{Disentangling greenhouse warming and aerosol cooling to reveal Earth's climate sensitivity}},
volume = {9},
year = {2016}
}
@article{Storelvmo2018,
author = {Storelvmo, Trude and Heede, Ulla K. and Leirvik, Thomas and Phillips, Peter C. B. and Arndt, Philipp and Wild, Martin},
doi = {10.1029/2018GL078298},
journal = {Geophysical Research Letters},
number = {18},
pages = {9},
title = {{Lethargic response to aerosol emissions in current climate models}},
volume = {45},
year = {2018}
}
@article{Storelvmo2017,
abstract = {Clouds in Earth's atmosphere can be composed of liquid droplets, ice crystals , or a combination of the two. Clouds' thermodynamic phase is largely controlled by temperature, but other factors can also have a significant effect. Aerosols-i.e., particles suspended in Earth's atmosphere-affect cloud properties differently depending on cloud phase and can potentially have a strong influence on climate via any cloud type. Aerosol-cloud-climate interactions have been a topic of active research for more than two decades, but these interactions nevertheless currently represent one of the most uncertain forcings of climate change over the past century. Most research to date has focused on how aerosols can impact climate via liquid clouds, which are better understood and observed than their ice-containing counterparts. Thus, the problem of how liquid clouds mediate aerosols' effects on climate is a more tractable one. However, there is no a priori reason to think that mixed-phase and ice clouds are any less affected by changes in atmospheric aerosol composition than liquid clouds, and estimates of how aerosols can influence these ice-containing clouds have started to emerge. Laboratory and field work, as well as satellite observations, is now shifting attention to this new frontier in the field of aerosol-cloud-climate interactions, allowing for improved representation of ice processes in numerical models. Here, we review this recent progress in our understanding of aerosol effects on mixed-phase and ice clouds, focusing on the four underpinning research pillars of laboratory experiments, field observations, satellite retrievals, and numerical modeling of global climate. Evident from this review is the possibility of a powerful yet poorly constrained climate forcing, which is uncertain in terms of both its magnitude and its sign.},
author = {Storelvmo, T.},
doi = {10.1146/annurev-earth-060115-012240},
issn = {0084-6597},
journal = {Annual Review of Earth and Planetary Sciences},
title = {{Aerosol Effects on Climate via Mixed-Phase and Ice Clouds}},
year = {2017}
}
@article{Stouffer2003,
abstract = {This study evaluates the equilibrium response of a coupled ocean-atmosphere model to the doubling, quadrupling, and halving of CO2 concentration in the atmosphere. Special emphasis in the study is placed upon the response of the thermohaline circulation in the Atlantic Ocean to the changes in CO2 concentration of the atmosphere. The simulated intensity of the thermohaline circulation (THC) is similar among three quasi-equilibrium states with the standard, double the standard, and quadruple the standard amounts of CO2 concentration in the atmosphere. When the model atmosphere has half the standard concentration of CO2, however, the THC is very weak and shallow in the Atlantic Ocean. Below a depth of 3 km, the model oceans maintain very thick layer of cold bottom water with temperature close to -2 degreesC, preventing the deeper penetration of the THC in the Atlantic Ocean. In the Circumpolar Ocean of the Southern Hemisphere, sea ice extends beyond the Antarctic Polar front, almost entirely covering the regions of deepwater ventilation. In addition to the active mode of the THC, there exists another stable mode of the THC for the standard, possibly double the standard (not yet confirmed), and quadruple the standard concentration of atmospheric carbon dioxide. This second mode is characterized by the weak, reverse overturning circulation over the entire Atlantic basin, and has no ventilation of the entire subsurface water in the North Atlantic Ocean. At one half the standard CO, concentration, however, the intensity of the first mode is so weak that it is not certain whether there are two distinct stable modes or not. The paleoceanographic implications of the results obtained here are discussed as they relate to the signatures of the Cenozoic changes in the oceans.},
author = {Stouffer, R. J. and Manabe, S.},
doi = {10.1007/s00382-002-0302-4},
isbn = {0930-7575},
issn = {09307575},
journal = {Climate Dynamics},
number = {7-8},
pages = {759--773},
title = {{Equilibrium response of thermohaline circulation to large changes in atmospheric CO2 concentration}},
volume = {20},
year = {2003}
}
@article{ISI:000239597000006,
abstract = {Global average trends in solar radiation reaching the Earth's surface show a transition from dimming to brightening that occurred in about 1990. We show that the inter-annual trend in solar radiation between 1980 and 2000 mirrors the trend in primary emissions of SO2 and black carbon, which together contribute about one-third of global average aerosol optical depth. Combined global emissions of these two species peaked in 1988 - 1989. The two-decadal rate of decline in aerosol loading resulting from these emission changes, 0.13{\%} yr(-1), can be compared with the reported increase in solar radiation of 0.10{\%} yr(-1) in 1983 - 2001. Regional patterns of aerosol and radiation changes are also qualitatively consistent. We conclude that changes in the aerosol burden due to changing patterns of anthropogenic emissions are likely contributing to the trends in surface solar radiation.},
author = {Streets, David G and Wu, Ye and Chin, Mian},
doi = {10.1029/2006GL026471},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {aug},
number = {15},
pages = {L15806},
title = {{Two-decadal aerosol trends as a likely explanation of the global dimming/brightening transition}},
url = {http://doi.wiley.com/10.1029/2006GL026471},
volume = {33},
year = {2006}
}
@article{Strove12,
author = {Stroeve, Julienne C and Kattsov, Vladimir and Barrett, Andrew and Serreze, Mark and Pavlova, Tatiana and Holland, Marika and Meier, Walter N},
doi = {10.1029/2012GL052676},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {aug},
number = {16},
pages = {L16502},
title = {{Trends in Arctic sea ice extent from CMIP5, CMIP3 and observations}},
url = {http://doi.wiley.com/10.1029/2012GL052676},
volume = {39},
year = {2012}
}
@article{Stuber2005,
abstract = {Radiative forcing has been widely used as a metric of climate change, i.e. as a measure by which various contributors to a net surface temperature change can be quantitatively compared. The extent to which this concept is valid for spatially inhomogeneous perturbations to the climate system is tested. A series of climate model simulations involving ozone changes of different spatial structure reveals that the climate sensitivity parameter $\gamma$ is highly variable: for an ozone increase in the northern hemisphere lower stratosphere, it is more than twice as large as for a homogeneous CO2 perturbation. A global ozone perturbation in the upper troposphere, however, causes a significantly smaller surface temperature response than CO2. The variability of the climate sensitivity parameter is shown to be mostly due to the varying strength of the stratospheric water vapour feedback. The variability of the sea-ice albedo feedback modifies climate sensitivity of perturbations with the same vertical structure but a different horizontal structure. This feedback is also the origin of the comparatively larger climate sensitivity to perturbations restricted to the northern hemisphere extratropics. As cloud feedback does not operate independently from the other feedbacks, quantifying its effect is rather difficult. However, its effect on the variability of $\gamma$ for horizontally and vertically inhomogeneous perturbations within one model framework seems to be comparatively small. {\textcopyright} Springer-Verlag 2005.},
author = {Stuber, Nicola and Ponater, Michael and Sausen, Robert},
doi = {10.1007/s00382-004-0497-7},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {Climate feedbacks,Radiative forcing},
month = {apr},
number = {5},
pages = {497--510},
title = {{Why radiative forcing might fail as a predictor of climate change}},
url = {http://link.springer.com/10.1007/s00382-004-0497-7},
volume = {24},
year = {2005}
}
@article{Stuecker2018,
abstract = {The surface temperature response to greenhouse gas forcing displays a characteristic pattern of polar-amplified warming1–5, particularly in the Northern Hemisphere. However, the causes of this polar amplification are still debated. Some studies highlight the importance of surface-albedo feedback6–8, while others find larger contributions from longwave feedbacks4,9,10, with changes in atmospheric and oceanic heat transport also thought to play a role11–16. Here, we determine the causes of polar amplification using climate model simulations in which CO2 forcing is prescribed in distinct geographical regions, with the linear sum of climate responses to regional forcings replicating the response to global forcing. The degree of polar amplification depends strongly on the location of CO2 forcing. In particular, polar amplification is found to be dominated by forcing in the polar regions, specifically through positive local lapse-rate feedback, with ice-albedo and Planck feedbacks playing subsidiary roles. Extra-polar forcing is further shown to be conducive to polar warming, but given that it induces a largely uniform warming pattern through enhanced poleward heat transport, it contributes little to polar amplification. Therefore, understanding polar amplification requires primarily a better insight into local forcing and feedbacks rather than extra-polar processes.},
author = {Stuecker, Malte F. and Bitz, Cecilia M. and Armour, Kyle C. and Proistosescu, Cristian and Kang, Sarah M. and Xie, Shang Ping and Kim, Doyeon and McGregor, Shayne and Zhang, Wenjun and Zhao, Sen and Cai, Wenju and Dong, Yue and Jin, Fei Fei},
doi = {10.1038/s41558-018-0339-y},
issn = {17586798},
journal = {Nature Climate Change},
number = {12},
pages = {1076--1081},
title = {{Polar amplification dominated by local forcing and feedbacks}},
volume = {8},
year = {2018}
}
@article{Su2014a,
abstract = {It has long been recognized that differences in climate model-simulated cloud feedbacks are a primary source of uncertainties for the model-predicted surface temperature change induced by increasing greenhouse gases such as CO2. Large-scale circulation broadly determines when and where clouds form and how they evolve. However, the linkage between large-scale circulation change and cloud radiative effect (CRE) change under global warming has not been thoroughly studied. By analyzing 15 climate models, we show that the change of the Hadley Circulation exhibits meridionally varying weakening and strengthening structures, physically consistent with the cloud changes in distinct cloud regimes. The regions that experience a weakening (strengthening) of the zonal-mean circulation account for 54{\%} (46{\%}) of the multimodel-mean top-of-atmosphere (TOA) CRE change integrated over 45°S–40°N. The simulated Hadley Circulation structure changes per degree of surface warming differ greatly between the models, and the intermodel spread in the Hadley Circulation change is well correlated with the intermodel spread in the TOA CRE change. This correlation underscores the close interactions between large-scale circulation and clouds and suggests that the uncertainties of cloud feedbacks and climate sensitivity reside in the intimate coupling between large-scale circulation and clouds. New model performance metrics proposed in this work, which emphasize how models reproduce satellite-observed spatial variations of zonal-mean cloud fraction and relative humidity associated with the Hadley Circulation, indicate that the models closer to the satellite observations tend to have equilibrium climate sensitivity higher than the multimodel mean.},
author = {Su, Hui and Jiang, Jonathan H. and Zhai, Chengxing and Shen, Tsaepyng J. and Neelin, J. David and Stephens, Graeme L. and Yung, Yuk L.},
doi = {10.1002/2014JD021642},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {may},
number = {10},
pages = {5787--5805},
title = {{Weakening and strengthening structures in the Hadley Circulation change under global warming and implications for cloud response and climate sensitivity}},
url = {http://doi.wiley.com/10.1002/2014JD021642},
volume = {119},
year = {2014}
}
@article{Su2017a,
abstract = {The change of global-mean precipitation under global warming and interannual variability is predominantly controlled by the change of atmospheric longwave radiative cooling. Here we show that tightening of the ascending branch of the Hadley Circulation coupled with a decrease in tropical high cloud fraction is key in modulating precipitation response to surface warming. The magnitude of high cloud shrinkage is a primary contributor to the intermodel spread in the changes of tropical-mean outgoing longwave radiation (OLR) and global-mean precipitation per unit surface warming (dP/dTs) for both interannual variability and global warming. Compared to observations, most Coupled Model Inter-comparison Project Phase 5 models underestimate the rates of interannual tropical-mean dOLR/dTs and global-mean dP/dTs, consistent with the muted tropical high cloud shrinkage. We find that the five models that agree with the observation-based interannual dP/dTs all predict dP/dTs under global warming higher than the ensemble mean dP/dTs from the ∼20 models analysed in this study.},
author = {Su, Hui and Jiang, Jonathan H and Neelin, J David and Shen, T Janice and Zhai, Chengxing and Yue, Qing and Wang, Zhien and Huang, Lei and Choi, Yong-Sang and Stephens, Graeme L and Yung, Yuk L},
doi = {10.1038/ncomms15771},
issn = {2041-1723},
journal = {Nature Communications},
number = {1},
pages = {15771},
title = {{Tightening of tropical ascent and high clouds key to precipitation change in a warmer climate}},
url = {https://doi.org/10.1038/ncomms15771},
volume = {8},
year = {2017}
}
@article{Sun2017,
abstract = {Observational analysis suggests that the western tropical Pacific (WTP) sea surface temperature (SST) shows predominant variability over multidecadal time scales, which is unlikely to be explained by the Interdecadal Pacific Oscillation. Here we show that this variability is largely explained by the remote Atlantic multidecadal oscillation (AMO). A suite of Atlantic Pacemaker experiments successfully reproduces the WTP multidecadal variability and the AMO-WTP SST connection. The AMO warm SST anomaly generates an atmospheric teleconnection to the North Pacific, which weakens the Aleutian low and subtropical North Pacific westerlies. The wind changes induce a subtropical North Pacific SST warming through wind-evaporation-SST effect, and in response to this warming, the surface winds converge towards the subtropical North Pacific from the tropics, leading to anomalous cyclonic circulation and low pressure over the WTP region. The warm SST anomaly further develops due to the SST-sea level pressure-cloud-longwave radiation positive feedback. Our findings suggest that the Atlantic Ocean acts as a key pacemaker for the western Pacific decadal climate variability.},
author = {Sun, Cheng and Kucharski, Fred and Li, Jianping and Jin, Fei-Fei and Kang, In-Sik and Ding, Ruiqiang},
doi = {10.1038/ncomms15998},
isbn = {2041-1723 (Electronic) 2041-1723 (Linking)},
issn = {2041-1723},
journal = {Nature Communications},
month = {dec},
number = {1},
pages = {15998},
pmid = {28685765},
publisher = {Nature Publishing Group},
title = {{Western tropical Pacific multidecadal variability forced by the Atlantic multidecadal oscillation}},
url = {http://www.nature.com/articles/ncomms15998},
volume = {8},
year = {2017}
}
@article{10.1130/G40228.1,
abstract = {Climate proxies indicate coupling between changes in atmospheric pCO2, global temperatures, and ice volume over much of the Cenozoic. Evidence has been presented for decoupling of these factors in the Miocene, though the cause of the apparent decoupling was uncertain. Here, we revisit Deep Sea Drilling Program (DSDP) Site 608 (24–9 Ma) in the North Atlantic Ocean, to provide improved constraints on sea-surface temperatures (SSTs) using the TEX86 and proxies, and use these to recalculate atmospheric pCO2. From the Oligocene/Miocene boundary to the middle Miocene Climatic Optimum (MCO, ca. 23.03 to ca. 14.5 Ma), SSTs at Site 608 were upward of 30 °C, nearly 15 °C warmer than modern. During the Middle Miocene Climatic Transition (MMCT), ca. 14.5 to ca. 12.5 Ma), SSTs cooled by ∼6 °C. Lower SSTs persisted until the end of our record at 9 Ma. Our organic proxy derived SST estimates are considerably higher than those previously calculated from planktonic foraminiferal oxygen isotope data, leading to reassessed alkenone pCO2 estimates ∼65 to ∼175 ppm higher than previously calculated, with other assumptions held constant. A pCO2 decrease from an average of ∼430 ppm in MCO to ∼305 ppm after the MMCT, in step with the ∼6 °C SST cooling, demonstrates coupling of climate and the carbon cycle, as well as a highly sensitive climate system.},
author = {Super, James R and Thomas, Ellen and Pagani, Mark and Huber, Matthew and O'Brien, Charlotte and Hull, Pincelli M},
doi = {10.1130/G40228.1},
issn = {0091-7613},
journal = {Geology},
number = {6},
pages = {519--522},
title = {{North Atlantic temperature and pCO2 coupling in the early-middle Miocene}},
url = {https://doi.org/10.1130/G40228.1},
volume = {46},
year = {2018}
}
@article{Sutton2018c,
abstract = {The purpose of the Intergovernmental Panel on Climate Change (IPCC) is to provide policy-relevant assessments of the scientific evidence about climate change. Policymaking necessarily involves risk assessments, so it is important that IPCC reports are designed accordingly. This paper proposes a specific idea, illustrated with examples, to improve the contribution of IPCC Working Group I to informing climate risk assessments.},
author = {Sutton, Rowan T.},
doi = {10.5194/esd-9-1155-2018},
issn = {21904987},
journal = {Earth System Dynamics},
number = {4},
pages = {1155--1158},
title = {{ESD Ideas: A simple proposal to improve the contribution of IPCC WGI to the assessment and communication of climate change risks}},
volume = {9},
year = {2018}
}
@article{PhysRevLett.81.5027,
author = {Svensmark, Henrik},
doi = {10.1103/PhysRevLett.81.5027},
journal = {Physical Review Letters},
month = {nov},
number = {22},
pages = {5027--5030},
publisher = {American Physical Society},
title = {{Influence of Cosmic Rays on Earth's Climate}},
url = {https://link.aps.org/doi/10.1103/PhysRevLett.81.5027},
volume = {81},
year = {1998}
}
@article{Svensmark2009,
author = {Svensmark, Henrik and Bondo, Torsten and Svensmark, Jacob},
doi = {10.1029/2009GL038429},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {aug},
number = {15},
pages = {L15101},
title = {{Cosmic ray decreases affect atmospheric aerosols and clouds}},
url = {http://doi.wiley.com/10.1029/2009GL038429},
volume = {36},
year = {2009}
}
@article{Svensmark2016,
author = {Svensmark, J. and Enghoff, M. B. and Shaviv, N. J. and Svensmark, H.},
doi = {10.1002/2016JA022689},
issn = {2169-9380},
journal = {Journal of Geophysical Research: Space Physics},
month = {sep},
number = {9},
pages = {8152--8181},
title = {{The response of clouds and aerosols to cosmic ray decreases}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2016JA022689},
volume = {121},
year = {2016}
}
@article{Svensmark2017,
abstract = {Ions produced by cosmic rays have been thought to influence aerosols and clouds. In this study, the effect of ionization on the growth of aerosols into cloud condensation nuclei is investigated theoretically and experimentally. We show that the mass-flux of small ions can constitute an important addition to the growth caused by condensation of neutral molecules. Under atmospheric conditions the growth from ions can constitute several percent of the neutral growth. We performed experimental studies which quantify the effect of ions on the growth of aerosols between nucleation and sizes {\textgreater}20 nm and find good agreement with theory. Ion-induced condensation should be of importance not just in Earth's present day atmosphere for the growth of aerosols into cloud condensation nuclei under pristine marine conditions, but also under elevated atmospheric ionization caused by increased supernova activity.},
author = {Svensmark, H. and Enghoff, M. B. and Shaviv, N. J. and Svensmark, J.},
doi = {10.1038/s41467-017-02082-2},
issn = {20411723},
journal = {Nature Communications},
keywords = {Atmospheric chemistry,Climate sciences,Physical chemistry,Space physics},
month = {dec},
number = {1},
pages = {1--9},
pmid = {29259163},
publisher = {Nature Publishing Group},
title = {{Increased ionization supports growth of aerosols into cloud condensation nuclei}},
url = {www.nature.com/naturecommunications},
volume = {8},
year = {2017}
}
@article{Swingedouw2008a,
abstract = {We show by using a three-dimensional climate model, which includes a comprehensive representation of polar ice sheets, that on centennial to millennial time scales Antarctic Ice Sheet (AIS) can melt and moderate warming in the Southern Hemisphere, by up to 10°C regionally, in a 4 × CO2 scenario. This behaviour stems from the formation of a cold halocline in the Southern Ocean, which limits sea-ice cover retreat under global warming and increases surface albedo, reducing local surface warming. Furthermore, we show that AIS melting, by decreasing Antarctic Bottom Water formation, restrains the weakening of the Atlantic meridional overturning circulation, which is a new illustration of the effect of the bi-polar oceanic seesaw. Consequently, it appears that AIS melting strongly interacts with climate and ocean circulation globally. It is therefore necessary to account for this coupling in future climate and sea-level rise scenarios.},
author = {Swingedouw, D and Fichefet, T and Huybrechts, P and Goosse, H and Driesschaert, E and Loutre, M.-F.},
doi = {10.1029/2008GL034410},
journal = {Geophysical Research Letters},
number = {17},
title = {{Antarctic ice-sheet melting provides negative feedbacks on future climate warming}},
volume = {35},
year = {2008}
}
@article{Takahashi2016a,
abstract = {The Pacific trade winds, coupled with the zonal sea surface temperature gradient in the equatorial Pacific Ocean, control regional sea levels, and therefore their trend is a great concern in the Pacific Rim. Over the past two decades, easterly winds have been accelerated in association with eastern tropical Pacific cooling. They may represent natural interdecadal variability in the Pacific and possibly explain the recent global warming hiatus. However, the intensification of the winds has been the strongest ever observed in the past century, the reason for which is still unclear. Here we show, using multiple climate simulations for 1921-2014 by a global climate model, that approximately one-third of the trade-wind intensification for 1991-2010 can be attributed to changes in sulfate aerosols. The multidecadal sea surface temperature anomaly induced mostly by volcanic aerosols dominates in the western North Pacific, and its sign changed rapidly from negative to positive in the 1990s, coherently with Atlantic multidecadal variability. The western North Pacific warming resulted in intensification of trade winds to the west of the dateline. These trends have not contributed much to the global warming hiatus, but have greatly impacted rainfall over the western Pacific islands.},
author = {Takahashi, Chiharu and Watanabe, Masahiro},
doi = {10.1038/nclimate2996},
issn = {17586798},
journal = {Nature Climate Change},
month = {apr},
number = {8},
pages = {768--772},
publisher = {Nature Publishing Group},
title = {{Pacific trade winds accelerated by aerosol forcing over the past two decades}},
url = {http://dx.doi.org/10.1038/nclimate2996 http://10.0.4.14/nclimate2996 https://www.nature.com/articles/nclimate2996{\#}supplementary-information},
volume = {6},
year = {2016}
}
@article{Takahashi2016,
author = {Takahashi, Hanii and Su, Hui and Jiang, Jonathan H},
doi = {10.1007/s00382-016-3035-5},
journal = {Climate Dynamics},
number = {12},
pages = {3673--3691},
title = {{Water vapor changes under global warming and the linkage to present-day interannual variabilities in CMIP5 models}},
volume = {47},
year = {2016}
}
@article{Takemura2019,
abstract = {Reducing black carbon (BC), i.e. soot, in the atmosphere is a potential mitigation measure for climate change before revealing the effect of reducing anthropogenic carbon dioxide (CO 2 ) because BC with shorter lifetime than CO 2 absorbs solar and infrared radiation. BC has a strong positive radiative forcing in the atmosphere, as indicated in many previous studies. Here, we show that the decline in surface air temperatures with reduced BC emissions is weaker than would be expected from the magnitude of its instantaneous radiative forcing at the top of the atmosphere (TOA). Climate simulations show that the global mean change in surface air temperature per unit of instantaneous radiative forcing of BC at the TOA is about one-eighth that of sulphate aerosols, which cool the climate through scattering solar radiation, without absorption. This is attributed to the positive radiation budget of BC being largely compensated for by rapid atmospheric adjustment, whereas the radiative imbalance due to sulphate aerosols drives a slow response of climate over a long timescale. Regional climate responses to short-lived species are shown to exhibit even more complex characteristics due to their heterogeneous spatial distributions, requiring further analysis in future studies.},
author = {Takemura, Toshihiko and Suzuki, Kentaroh},
doi = {10.1038/s41598-019-41181-6},
issn = {2045-2322},
journal = {Scientific Reports},
month = {dec},
number = {1},
pages = {4419},
publisher = {Nature Publishing Group},
title = {{Weak global warming mitigation by reducing black carbon emissions}},
url = {http://www.nature.com/articles/s41598-019-41181-6},
volume = {9},
year = {2019}
}
@article{Tan2016,
abstract = {Global climate model (GCM) estimates of the equilibrium global mean surface temperature response to a doubling of atmospheric CO2, measured by the equilibrium climate sensitivity (ECS), range from 2.0° to 4.6°C. Clouds are among the leading causes of this uncertainty. Here we show that the ECS can be up to 1.3°C higher in simulations where mixed-phase clouds consisting of ice crystals and supercooled liquid droplets are constrained by global satellite observations. The higher ECS estimates are directly linked to a weakened cloud-phase feedback arising from a decreased cloud glaciation rate in a warmer climate. We point out the need for realistic representations of the supercooled liquid fraction in mixed-phase clouds in GCMs, given the sensitivity of the ECS to the cloud-phase feedback.},
author = {Tan, Ivy and Storelvmo, Trude and Zelinka, Mark D.},
doi = {10.1126/science.aad5300},
issn = {10959203},
journal = {Science},
month = {apr},
number = {6282},
pages = {224--227},
title = {{Observational constraints on mixed-phase clouds imply higher climate sensitivity}},
url = {http://science.sciencemag.org/content/352/6282/224.abstract},
volume = {352},
year = {2016}
}
@article{Tan2019,
abstract = {Abstract We present a novel method that identifies the contributions of thermodynamic phase shifts and processes governing supercooled liquid and ice clouds to cloud optical depth variations with temperature using Moderate Resolution Imaging Spectroradiometer observations. Our findings suggest that thermodynamic phase shifts outweigh the net influence of processes governing supercooled liquid and ice clouds in causing increases in midlatitudinal cold cloud optical depth with temperature. Cloud regime analysis suggests that dynamical conditions appear to have little influence on the contribution of thermodynamic phase shifts to cloud optical depth variations with temperature. Thermodynamic phase shifts also contribute more to increases in cloud optical depth during colder seasons due to the enhanced optical thickness contrast between liquid and ice clouds. The results of this study highlight the importance of thermodynamic phase shifts in explaining cold cloud optical depth increases with temperature in the current climate and may elucidate their role in the cloud optical depth feedback.},
annote = {doi: 10.1029/2018GL081590},
author = {Tan, Ivy and Oreopoulos, Lazaros and Cho, Nayeong},
doi = {10.1029/2018GL081590},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {apr},
number = {8},
pages = {4502--4511},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{The Role of Thermodynamic Phase Shifts in Cloud Optical Depth Variations With Temperature}},
url = {https://doi.org/10.1029/2018GL081590},
volume = {46},
year = {2019}
}
@article{ISI:000387453900003,
abstract = {Worldwide observations indicate secular trends of all-sky surface solar radiation on a decadal time scale, termed global dimming and brightening. Accordingly, the observed surface radiation in Japan generally shows a strong decline until the end of the 1980s and then a recovery until around 2000. Because a substantial number of measurement stations are located within or close to populated areas, one may speculate that the observed trends are strongly influenced by local air pollution and are thus not of large-scale significance. This hypothesis poses a serious question as to what regional extent the global dimming and brightening are significant: are the global dimming and brightening truly global phenomena, or regional, or even only local? Our study focused on 14 meteorological observatories that measured all-sky surface solar radiation, zenith transmittance, and maximum transmittance. On the basis of municipality population time series, historical land use maps, recent satellite images, and actual site visits, we concluded that eight stations have been significantly influenced by urbanization, with the remaining six stations being left pristine. Between the urban and rural areas, no marked differences were identified in the temporal trends of the aforementioned meteorological parameters. Our findings suggest that global dimming and brightening in Japan occurred on a large scale, independently of urbanization.},
author = {Tanaka, Katsumasa and Ohmura, Atsumu and Folini, Doris and Wild, Martin and Ohkawara, Nozomu},
doi = {10.5194/acp-16-13969-2016},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
month = {nov},
number = {21},
pages = {13969--14001},
title = {{Is global dimming and brightening in Japan limited to urban areas?}},
volume = {16},
year = {2016}
}
@article{Tanaka2013,
abstract = {In multi-gas climate policies such as the Kyoto Protocol one has to decide how to compare the emissions of different greenhouse gases. The choice of metric could have significant implications for mitigation priorities considered under the prospective negotiations for climate mitigation agreements. Several metrics have been proposed for this task with the Global Warming Potential (GWP) being the most common. However, these metrics have not been systematically compared to each other in the context of the 2 °C climate stabilization target. Based on a single unified modeling framework, we demonstrate that metric values span a wide range, depending on the metric structure and the treatment of the time dimension. Our finding confirms the basic salient point that metrics designed to represent different aspects of the climate and socio-economic system behave differently. Our result also reflects a complex interface between science and policy surrounding metrics. Thus, it is important to select or design a metric suitable for climate stabilization based on an interaction among practitioners, policymakers, and scientists. {\textcopyright} 2013 Springer Science+Business Media Dordrecht.},
author = {Tanaka, Katsumasa and Johansson, Daniel J. A. and O'Neill, Brian C. and Fuglestvedt, Jan S.},
doi = {10.1007/s10584-013-0693-8},
issn = {0165-0009},
journal = {Climatic Change},
month = {apr},
number = {4},
pages = {933--941},
title = {{Emission metrics under the 2°C climate stabilization target}},
url = {http://link.springer.com/10.1007/s10584-013-0693-8},
volume = {117},
year = {2013}
}
@article{Tanaka2018,
abstract = {The Paris Agreement stipulates that global warming be stabilized at well below 2 °C above pre-industrial levels, with aims to further constrain this warming to 1.5 °C. However, it also calls for reducing net anthropogenic greenhouse gas (GHG) emissions to zero during the second half of this century. Here, we use a reduced-form integrated assessment model to examine the consistency between temperature- and emission-based targets. We find that net zero GHG emissions are not necessarily required to remain below 1.5 °C or 2 °C, assuming either target can be achieved without overshoot. With overshoot, however, the emissions goal is consistent with the temperature targets, and substantial negative emissions are associated with reducing warming after it peaks. Temperature targets are put at risk by late achievement of emissions goals and the use of some GHG emission metrics. Refinement of Paris Agreement emissions goals should include a focus on net zero CO2 - not GHG - emissions, achieved early in the second half of the century.},
author = {Tanaka, Katsumasa and O'Neill, Brian C.},
doi = {10.1038/s41558-018-0097-x},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {apr},
number = {4},
pages = {319--324},
title = {{The Paris Agreement zero-emissions goal is not always consistent with the 1.5°C and 2°C temperature targets}},
url = {http://www.nature.com/articles/s41558-018-0097-x},
volume = {8},
year = {2018}
}
@article{Tang2019,
abstract = {We compare six methods of estimating effective radiative forcing (ERF) using a set of atmosphere-ocean general circulation models. This is the first multiforcing agent, multimodel evaluation of ERF values calculated using different methods. We demonstrate that previously reported apparent consistency between the ERF values derived from fixed sea surface temperature simulations and linear regression holds for most climate forcings, excluding black carbon (BC). When land adjustment is accounted for, however, the fixed sea surface temperature ERF values are generally 10–30{\%} larger than ERFs derived using linear regression across all forcing agents, with a much larger ({\~{}}70–100{\%}) discrepancy for BC. Except for BC, this difference can be largely reduced by either using radiative kernel techniques or by exponential regression. Responses of clouds and their effects on shortwave radiation show the strongest variability in all experiments, limiting the application of regression-based ERF in small forcing simulations.},
author = {Tang, T. and Shindell, D. and Faluvegi, G. and Myhre, Gunnar and Olivi{\'{e}}, Dirk and Voulgarakis, Apostolos and Kasoar, Matthew and Andrews, Timothy and Boucher, Olivi{\'{e}}r and Forster, Piers M. and Hodnebrog and Iversen, Trond and Kirkev{\aa}g, Alf and Lamarque, Jean Fran{\c{c}}ois and Richardson, T. and Samset, Bj{\o}rn Hallvard and Stjern, Camilla Weum and Takemura, Toshihiko and Smith, C.},
doi = {10.1029/2018JD030188},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {PDRMIP,aerosol,effective radiative forcing,regression},
number = {8},
pages = {4382--4394},
title = {{Comparison of Effective Radiative Forcing Calculations Using Multiple Methods, Drivers, and Models}},
volume = {124},
year = {2019}
}
@article{Tao2012,
abstract = {Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosol effects on clouds could further extend to precipitation, both through the formation of cloud particles and by exerting persistent radiative forcing on the climate system that disturbs dynamics. However, the various mechanisms behind these effects, in particular, the ones connected to precipitation, are not yet well understood. The atmospheric and climate communities have long been working to gain a better grasp of these critical effects and hence to reduce the significant uncertainties in climate prediction resulting from such a lack of adequate knowledge. Here we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes from theoretical analysis of microphysics, observational evidence, and a range of numerical model simulations. In addition, the discrepancies between results simulated by models, as well as those between simulations and observations, are presented. Specifically, this paper addresses the following topics: (1) fundamental theories of aerosol effects on microphysics and precipitation processes, (2) observational evidence of the effect of aerosols on precipitation processes, (3) signatures of the aerosol impact on precipitation from large-scale analyses, (4) results from cloud-resolving model simulations, and (5) results from large-scale numerical model simulations. Finally, several future research directions for gaining a better understanding of aerosol-cloud-precipitation interactions are suggested.},
author = {Tao, Wei-Kuo and Chen, Jen-Ping and Li, Zhanqing and Wang, Chien and Zhang, Chidong},
doi = {10.1029/2011RG000369},
issn = {87551209},
journal = {Reviews of Geophysics},
month = {jun},
number = {2},
pages = {RG2001},
title = {{Impact of aerosols on convective clouds and precipitation}},
url = {http://doi.wiley.com/10.1029/2011RG000369},
volume = {50},
year = {2012}
}
@article{doi:10.1175/JCLI-D-12-00696.1,
abstract = { AbstractPolar surface temperatures are expected to warm 2–3 times faster than the global-mean surface temperature: a phenomenon referred to as polar warming amplification. Therefore, understanding the individual process contributions to the polar warming is critical to understanding global climate sensitivity. The Coupled Feedback Response Analysis Method (CFRAM) is applied to decompose the annual- and zonal-mean vertical temperature response within a transient 1{\%} yr−1 CO2 increase simulation of the NCAR Community Climate System Model, version 4 (CCSM4), into individual radiative and nonradiative climate feedback process contributions. The total transient annual-mean polar warming amplification (amplification factor) at the time of CO2 doubling is +2.12 (2.3) and +0.94 K (1.6) in the Northern and Southern Hemisphere, respectively. Surface albedo feedback is the largest contributor to the annual-mean polar warming amplification accounting for +1.82 and +1.04 K in the Northern and Southern Hemisphere, respectively. Net cloud feedback is found to be the second largest contributor to polar warming amplification (about +0.38 K in both hemispheres) and is driven by the enhanced downward longwave radiation to the surface resulting from increases in low polar water cloud. The external forcing and atmospheric dynamic transport also contribute positively to polar warming amplification: +0.29 and +0.32 K, respectively. Water vapor feedback contributes negatively to polar warming amplification because its induced surface warming is stronger in low latitudes. Ocean heat transport storage and surface turbulent flux feedbacks also contribute negatively to polar warming amplification. Ocean heat transport and storage terms play an important role in reducing the warming over the Southern Ocean and Northern Atlantic Ocean. },
author = {Taylor, Patrick C and Cai, Ming and Hu, Aixue and Meehl, Jerry and Washington, Warren and Zhang, Guang J},
doi = {10.1175/JCLI-D-12-00696.1},
journal = {Journal of Climate},
number = {18},
pages = {7023--7043},
title = {{A Decomposition of Feedback Contributions to Polar Warming Amplification}},
url = {https://doi.org/10.1175/JCLI-D-12-00696.1},
volume = {26},
year = {2013}
}
@article{Taylor2015,
abstract = {Abstract Understanding the cloud response to sea ice change is necessary for modeling Arctic climate. Previous work has primarily addressed this problem from the interannual variability perspective. This paper provides a refined perspective of sea ice-cloud relationship in the Arctic using a satellite footprint-level quantification of the covariance between sea ice and Arctic low cloud properties from NASA A-Train active remote sensing data. The covariances between Arctic low cloud properties and sea ice concentration are quantified by first partitioning each footprint into four atmospheric regimes defined using thresholds of lower tropospheric stability and midtropospheric vertical velocity. Significant regional variability in the cloud properties is found within the atmospheric regimes indicating that the regimes do not completely account for the influence of meteorology. Regional anomalies are used to account for the remaining meteorological influence on clouds. After accounting for meteorological regime and regional influences, a statistically significant but weak covariance between cloud properties and sea ice is found in each season for at least one atmospheric regime. Smaller average cloud fraction and liquid water are found within footprints with more sea ice. The largest-magnitude cloud-sea ice covariance occurs between 500?m and 1.2?km when the lower tropospheric stability is between 16 and 24?K. The covariance between low cloud properties and sea ice is found to be largest in fall and is accompanied by significant changes in boundary layer temperature structure where larger average near-surface static stability is found at larger sea ice concentrations.},
author = {Taylor, Patrick C and Kato, Seiji and Xu, Kuan-Man and Cai, Ming},
doi = {10.1002/2015JD023520},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {Arctic clouds,sea ice,sea ice-cloud interaction},
month = {dec},
number = {24},
pages = {12656--12678},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Covariance between Arctic sea ice and clouds within atmospheric state regimes at the satellite footprint level}},
url = {https://doi.org/10.1002/2015JD023520},
volume = {120},
year = {2015}
}
@article{Tebaldi2014,
abstract = {Abstract We review the ideas behind the pattern scaling technique, and focus on its value and limitations given its use for impact assessment and within integrated assessment models. We present estimates of patterns for temperature and precipitation change from the latest transient simulations available from the Coupled Model Inter-comparison Project Phase 5 (CMIP5), focusing on multi-model mean patterns, and characterizing the sources of variability of these patterns across models and scenarios. The patterns are compared to those obtained from the previous set of experiments, under CMIP3. We estimate the significance of the emerging differences between CMIP3 and CMIP5 results through a bootstrap exercise, while also taking into account the fundamental differences in scenario and model ensemble composition. All in all, the robustness of the geographical features in patterns of temperature and precipitation, when computed as multi-model means, is confirmed by this comparison. The intensity of the change (in both the warmer and cooler areas with respect to global temperature change, and the drier and wetter regions) is overall heightened per degree of global warming in the ensemble mean of the newsimulations. The presence of stabilized scenarios in the new set of simulations allows investigation of the performance of the technique once the system has gotten close to equilibrium. Overall, the well established validity of the technique in approximating the forced signal of change under increasing concentrations of greenhouse gases is confirmed. This},
author = {Tebaldi, Claudia and Arblaster, Julie M.},
doi = {10.1007/s10584-013-1032-9},
isbn = {0165-0009 1573-1480},
issn = {0165-0009},
journal = {Climatic Change},
month = {feb},
number = {3},
pages = {459--471},
title = {{Pattern scaling: Its strengths and limitations, and an update on the latest model simulations}},
url = {http://link.springer.com/10.1007/s10584-013-1032-9},
volume = {122},
year = {2014}
}
@article{Tebaldi_2018,
abstract = {Global climate policy is increasingly debating the value of very low warming targets, yet not many experiments conducted with global climate models in their fully coupled versions are currently available to help inform studies of the corresponding impacts. This raises the question whether a map of warming or precipitation change in a world 1.5 °C warmer than preindustrial can be emulated from existing simulations that reach higher warming targets, or whether entirely new simulations are required. Here we show that also for this type of low warming in strong mitigation scenarios, climate change signals are quite linear as a function of global temperature. Therefore, emulation techniques amounting to linear rescaling on the basis of global temperature change ratios (like simple pattern scaling) provide a viable way forward. The errors introduced are small relative to the spread in the forced response to a given scenario that we can assess from a multi-model ensemble. They are also small relative to the noise introduced into the estimates of the forced response by internal variability within a single model, which we can assess from either control simulations or initial condition ensembles. Challenges arise when scaling inadvertently reduces the inter-model spread or suppresses the internal variability, both important sources of uncertainty for impact assessment, or when the scenarios have very different characteristics in the composition of the forcings. Taking advantage of an available suite of coupled model simulations under low-warming and intermediate scenarios, we evaluate the accuracy of these emulation techniques and show that they are unlikely to represent a substantial contribution to the total uncertainty.},
author = {Tebaldi, Claudia and Knutti, Reto},
doi = {10.1088/1748-9326/aabef2},
journal = {Environmental Research Letters},
number = {5},
pages = {55006},
publisher = {{\{}IOP{\}} Publishing},
title = {{Evaluating the accuracy of climate change pattern emulation for low warming targets}},
url = {https://doi.org/10.1088{\%}2F1748-9326{\%}2Faabef2},
volume = {13},
year = {2018}
}
@article{Terai2016a,
author = {Terai, C. R. and Klein, S. A. and Zelinka, M. D.},
doi = {10.1002/2016JD025233},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {aug},
number = {16},
pages = {9696--9716},
title = {{Constraining the low-cloud optical depth feedback at middle and high latitudes using satellite observations}},
url = {http://doi.wiley.com/10.1002/2016JD025233},
volume = {121},
year = {2016}
}
@article{Terai2019,
abstract = {Abstract Ground-based observations from three middle- and high-latitude sites managed by the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program are used to determine the sensitivity of the low-cloud optical depth to temperature and to test whether observations support mechanisms previously proposed to affect the optical depth feedback. Analysis of cloud optical depth retrievals support previous satellite findings that the optical depth decreases or stays constant with increases in temperature when the cloud is warm but increases when the cloud is cold. The cloud liquid water path sensitivity to warming largely explains the optical depth sensitivity at all sites. Mechanisms examined in this study involve the temperature dependence of (a) the moist-adiabatic lapse rate, (b) cloud phase partitioning, (c) drying efficiency of cloud top mixing, (d) cloud top inversion strength, and (e) boundary layer decoupling. Mechanism (a) is present across all clouds and explains 30{\%} to 50{\%} of the increase in liquid water path with warming at temperatures below 0 °C. However, the cloud's adiabaticity, the ratio between the liquid water path and its theoretical maximum, is at least as important and determines how the liquid water path sensitivity to temperature varies with temperature. At temperatures below 0 °C, the adiabaticity increases with warming, and the data support mechanism (b). At warmer temperatures, the adiabaticity decreases with warming, overwhelming mechanism (a) and resulting in the liquid water path decreasing with warming. This adiabaticity decrease arises primarily because of mechanism (d), and to a lesser degree because of mechanism (e). No evidence is found supporting mechanism (c).},
author = {Terai, C R and Zhang, Y and Klein, S A and Zelinka, M D and Chiu, J C and Min, Q},
doi = {10.1029/2018JD029359},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {cloud feedback,clouds,ground observation,optical depth feedback},
month = {feb},
number = {4},
pages = {2127--2147},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Mechanisms Behind the Extratropical Stratiform Low-Cloud Optical Depth Response to Temperature in ARM Site Observations}},
url = {https://doi.org/10.1029/2018JD029359},
volume = {124},
year = {2019}
}
@article{Thackeray-Hall-ncc-2019,
abstract = {Arctic sea ice has decreased substantially over recent decades, a trend projected to continue. Shrinking ice reduces surface albedo, leading to greater surface solar absorption, thus amplifying warming and driving further melt. This sea-ice albedo feedback (SIAF) is a key driver of Arctic climate change and an important uncertainty source in climate model projections. Using an ensemble of models, we demonstrate an emergent relationship between future SIAF and an observable version of SIAF in the current climate's seasonal cycle. This relationship is robust in constraining SIAF over the coming decades (Pearson's r = 0.76), and then it degrades. The degradation occurs because some models begin producing ice-free conditions, signalling a transition to a new ice regime. The relationship is strengthened when models with unrealistically thin historical ice are excluded. Because of this tight relationship, reducing model errors in the current climate's seasonal SIAF and ice thickness can narrow SIAF spread under climate change.},
author = {Thackeray, Chad W. and Hall, Alex},
doi = {10.1038/s41558-019-0619-1},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {dec},
number = {12},
pages = {972--978},
title = {{An emergent constraint on future Arctic sea-ice albedo feedback}},
url = {http://www.nature.com/articles/s41558-019-0619-1},
volume = {9},
year = {2019}
}
@article{Thomas2020,
abstract = {The NASA Energy and Water Cycle Study (NEWS) climatology is a self-consistent coupled annual and seasonal cycle solution for radiative, turbulent, and water fluxes over Earth's surface using Earth observation data covering 2000-09. Here we seek to improve the NEWS solution, particularly over the ocean basins, by considering spatial covariances in the observation errors (some evidence for which is found by comparing five turbulent flux products over the oceans) and by introducing additional horizontal transports from ocean reanalyses as weak constraints. By explicitly representing large error covariances between surface heat flux components over the major ocean basins we retain the flux contrasts present in the original data and infer additional heat losses over the North Atlantic Ocean, more consistent with a strong Atlantic overturning. This change does not alter the global flux balance but if only the errors in evaporation and precipitation are correlated then those fluxes experience larger adjustments (e.g., the surface latent heat flux increases to 85 6 2Wm22). Replacing SeaFlux v1 with J-OFURO v3 (Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations) ocean fluxes also leads to a considerable increase in the global latent heat loss as well as a larger North Atlantic heat loss. Furthermore, including a weak constraint on the horizontal transports of heat and freshwater from high-resolution ocean reanalyses improves the net fluxes over the North Atlantic, Caribbean Sea, andArcticOcean,without any impact on the global flux balances. These results suggest that better characterized flux uncertainties can greatly improve the quality of the optimized flux solution.},
author = {Thomas, Christopher M. and Dong, Bo and Haines, Keith},
doi = {10.1175/JCLI-D-19-0343.1},
issn = {08948755},
journal = {Journal of Climate},
month = {mar},
number = {5},
pages = {1707--1723},
publisher = {American Meteorological Society},
title = {{Inverse modeling of global and regional energy and water cycle fluxes using earth observation data}},
url = {http://creativecommons.},
volume = {33},
year = {2020}
}
@article{Thompson2017,
abstract = {The study explores two fundamental problems in climate science: (i) The physical factors that govern the depth of the troposphere, and (ii) the response of clouds to climate change. Previous research has argued that tropical anvil temperatures are strongly constrained by the fundamental thermodynamic properties of water vapor. Here we argue that the same basic thermodynamic properties strongly constrain the depth of the troposphere, the temperature of high clouds, and the amplitude of large-scale dynamics throughout the globe. The results suggest that the positive climate feedbacks associated with tropical high clouds also operate in the extratropics, and that the top of the troposphere should remain at roughly the same temperature throughout the globe as the climate system warms.The troposphere is the region of the atmosphere characterized by low static stability, vigorous diabatic mixing, and widespread condensational heating in clouds. Previous research has argued that in the tropics, the upper bound on tropospheric mixing and clouds is constrained by the rapid decrease with height of the saturation water vapor pressure and hence radiative cooling by water vapor in clear-sky regions. Here the authors contend that the same basic physics play a key role in constraining the vertical structure of tropospheric mixing, tropopause temperature, and cloud-top temperature throughout the globe. It is argued that radiative cooling by water vapor plays an important role in governing the depth and amplitude of large-scale dynamics at extratropical latitudes.},
author = {Thompson, David W J and Bony, Sandrine and Li, Ying},
doi = {10.1073/pnas.1620493114},
journal = {Proceedings of the National Academy of Sciences},
month = {aug},
number = {31},
pages = {8181--8186},
title = {{Thermodynamic constraint on the depth of the global tropospheric circulation}},
url = {http://www.pnas.org/content/114/31/8181.abstract},
volume = {114},
year = {2017}
}
@article{Thornhill9999,
author = {Thornhill, Gillian D. and Collins, William J. and Kramer, Ryan J. and Olivi{\'{e}}, Dirk and Skeie, Ragnhild B. and O'Connor, Fiona M. and Abraham, Nathan Luke and Checa-Garcia, Ramiro and Bauer, Susanne E. and Deushi, Makoto and Emmons, Louisa K. and Forster, Piers M. and Horowitz, Larry W. and Johnson, Ben and Keeble, James and Lamarque, Jean-Francois and Michou, Martine and Mills, Michael J. and Mulcahy, Jane P. and Myhre, Gunnar and Nabat, Pierre and Naik, Vaishali and Oshima, Naga and Schulz, Michael and Smith, Christopher J. and Takemura, Toshihiko and Tilmes, Simone and Wu, Tongwen and Zeng, Guang and Zhang, Jie},
doi = {10.5194/acp-21-853-2021},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
number = {2},
pages = {853--874},
title = {{Effective radiative forcing from emissions of reactive gases and aerosols – a multi-model comparison}},
url = {https://acp.copernicus.org/articles/21/853/2021/},
volume = {21},
year = {2021}
}
@article{Thornhill9999a,
abstract = {Abstract. Feedbacks play a fundamental role in determining the magnitude of the response of the climate system to external forcing, such as from anthropogenic emissions. The latest generation of Earth system models includes aerosol and chemistry components that interact with each other and with the biosphere. These interactions introduce a complex web of feedbacks that is important to understand and quantify. This paper addresses multiple pathways for aerosol and chemical feedbacks in Earth system models. These focus on changes in natural emissions (dust, sea salt, dimethyl sulfide, biogenic volatile organic compounds (BVOCs) and lightning) and changes in reaction rates for methane and ozone chemistry. The feedback terms are then given by the sensitivity of a pathway to climate change multiplied by the radiative effect of the change. We find that the overall climate feedback through chemistry and aerosols is negative in the sixth Coupled Model Intercomparison Project (CMIP6) Earth system models due to increased negative forcing from aerosols in a climate with warmer surface temperatures following a quadrupling of CO2 concentrations. This is principally due to increased emissions of sea salt and BVOCs which are sensitive to climate change and cause strong negative radiative forcings. Increased chemical loss of ozone and methane also contributes to a negative feedback. However, overall methane lifetime is expected to increase in a warmer climate due to increased BVOCs. Increased emissions of methane from wetlands would also offset some of the negative feedbacks. The CMIP6 experimental design did not allow the methane lifetime or methane emission changes to affect climate, so we found a robust negative contribution from interactive aerosols and chemistry to climate sensitivity in CMIP6 Earth system models.},
author = {Thornhill, Gillian D. and Collins, William and Olivi{\'{e}}, Dirk and Skeie, Ragnhild B. and Archibald, Alex and Bauer, Susanne and Checa-Garcia, Ramiro and Fiedler, Stephanie and Folberth, Gerd and Gjermundsen, Ada and Horowitz, Larry and Lamarque, Jean-Francois and Michou, Martine and Mulcahy, Jane and Nabat, Pierre and Naik, Vaishali and O'Connor, Fiona M. and Paulot, Fabien and Schulz, Michael and Scott, Catherine E. and S{\'{e}}f{\'{e}}rian, Roland and Smith, Chris and Takemura, Toshihiko and Tilmes, Simone and Tsigaridis, Kostas and Weber, James},
doi = {10.5194/acp-21-1105-2021},
issn = {16807324},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
number = {2},
pages = {1105--1126},
title = {{Climate-driven chemistry and aerosol feedbacks in CMIP6 Earth system models}},
url = {https://acp.copernicus.org/articles/21/1105/2021/},
volume = {21},
year = {2021}
}
@article{Tian2015,
abstract = {Despite decades of climate research and model development, two outstanding problems still plague the latest global climate models (GCMs): the double-Intertropical Convergence Zone (ITCZ) bias and the 2-5°C spread of equilibrium climate sensitivity (ECS). Here we show that the double-ITCZ bias and ECS in 44 GCMs from Coupled Model Intercomparison Project Phases 3/5 are negatively correlated. The models with weak (strong) double-ITCZ biases have high (low)-ECS values of ∼4.1(2.2)°C. This indicates that the double-ITCZ bias is a new emergent constraint for ECS based on which ECS might be in the higher end of its range (∼4.0°C) and most models might have underestimated ECS. In addition, we argue that the double-ITCZ bias can physically affect both cloud and water vapor feedbacks (thus ECS) and is a more easily measured emergent constraint for ECS than previous ones. It can be used as a performance metric for evaluating and comparing different GCMs.},
author = {Tian, Baijun},
doi = {10.1002/2015GL064119},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {Coupled Model Intercomparison Project (CMIP5),double-ITCZ bias,emergent constraint,equilibrium climate sensitivity (ECS),global climate models (GCMs)},
number = {10},
pages = {4133--4141},
title = {{Spread of model climate sensitivity linked to double-Intertropical Convergence Zone bias}},
volume = {42},
year = {2015}
}
@article{doi:10.1029/2019GL083802,
abstract = {Abstract With CO2 concentrations similar to today (410 ppm), the Pliocene Epoch offers insights into climate changes under a moderately warmer world. Previous work suggested a low zonal sea surface temperature (SST) gradient in the tropical Pacific during the Pliocene, the so-called “permanent El Ni{\~{n}}o.” Here, we recalculate SSTs using the alkenone proxy and find moderate reductions in both the zonal and meridional SST gradients during the mid-Piacenzian warm period. These reductions are captured by coupled climate model simulations of the Pliocene, especially those that simulate weaker Walker circulation. We also produce a spatial reconstruction of mid-Piacenzian warm period Pacific SSTs that closely resembles both Pliocene and future, low-emissions simulations, a pattern that is, to a first order, diagnostic of weaker Walker circulation. Therefore, Pliocene warmth does not require drastic changes in the climate system—rather, it supports the expectation that the Walker circulation will weaken in the future under higher CO2.},
author = {Tierney, Jessica E and Haywood, Alan M and Feng, Ran and Bhattacharya, Tripti and Otto-Bliesner, Bette L},
doi = {10.1029/2019GL083802},
journal = {Geophysical Research Letters},
keywords = {Pliocene,Walker circulation,alkenones,climate change,tropical Pacific},
number = {15},
pages = {9136--9144},
title = {{Pliocene Warmth Consistent With Greenhouse Gas Forcing}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083802},
volume = {46},
year = {2019}
}
@article{Tierney2020a,
abstract = {The Last Glacial Maximum (LGM), one of the best studied palaeoclimatic intervals, offers an excellent opportunity to investigate how the climate system responds to changes in greenhouse gases and the cryosphere. Previous work has sought to constrain the magnitude and pattern of glacial cooling from palaeothermometers1,2, but the uneven distribution of the proxies, as well as their uncertainties, has challenged the construction of a full-field view of the LGM climate state. Here we combine a large collection of geochemical proxies for sea surface temperature with an isotope-enabled climate model ensemble to produce a field reconstruction of LGM temperatures using data assimilation. The reconstruction is validated with withheld proxies as well as independent ice core and speleothem $\delta$18O measurements. Our assimilated product provides a constraint on global mean LGM cooling of −6.1 degrees Celsius (95 per cent confidence interval: −6.5 to −5.7 degrees Celsius). Given assumptions concerning the radiative forcing of greenhouse gases, ice sheets and mineral dust aerosols, this cooling translates to an equilibrium climate sensitivity of 3.4 degrees Celsius (2.4–4.5 degrees Celsius), a value that is higher than previous LGM-based estimates but consistent with the traditional consensus range of 2–4.5 degrees Celsius3,4.},
author = {Tierney, Jessica E and Zhu, Jiang and King, Jonathan and Malevich, Steven B and Hakim, Gregory J and Poulsen, Christopher J},
doi = {10.1038/s41586-020-2617-x},
issn = {1476-4687},
journal = {Nature},
number = {7822},
pages = {569--573},
title = {{Glacial cooling and climate sensitivity revisited}},
url = {https://doi.org/10.1038/s41586-020-2617-x},
volume = {584},
year = {2020}
}
@article{Tierney2020,
abstract = {As the world warms, there is a profound need to improve projections of climate change. Although the latest Earth system models offer an unprecedented number of features, fundamental uncertainties continue to cloud our view of the future. Past climates provide the only opportunity to observe how the Earth system responds to high carbon dioxide, underlining a fundamental role for paleoclimatology in constraining future climate change. Here, we review the relevancy of paleoclimate information for climate prediction and discuss the prospects for emerging methodologies to further insights gained from past climates. Advances in proxy methods and interpretations pave the way for the use of past climates for model evaluation—a practice that we argue should be widely adopted.},
author = {Tierney, Jessica E. and Poulsen, Christopher J. and Monta{\~{n}}ez, Isabel P. and Bhattacharya, Tripti and Feng, Ran and Ford, Heather L. and H{\"{o}}nisch, B{\"{a}}rbel and Inglis, Gordon N. and Petersen, Sierra V. and Sagoo, Navjit and Tabor, Clay R. and Thirumalai, Kaustubh and Zhu, Jiang and Burls, Natalie J. and Foster, Gavin L. and Godd{\'{e}}ris, Yves and Huber, Brian T. and Ivany, Linda C. and {Kirtland Turner}, Sandra and Lunt, Daniel J. and McElwain, Jennifer C. and Mills, Benjamin J. W. and Otto-Bliesner, Bette L. and Ridgwell, Andy and Zhang, Yi Ge},
doi = {10.1126/science.aay3701},
issn = {0036-8075},
journal = {Science},
keywords = {Christopher J Poulsen,Jessica E Tierney,MEDLINE,NCBI,NIH,NLM,National Center for Biotechnology Information,National Institutes of Health,National Library of Medicine,Non-U.S. Gov't,PubMed Abstract,Research Support,Review,Yi Ge Zhang,doi:10.1126/science.aay3701,pmid:33154110},
month = {nov},
number = {6517},
pages = {eaay3701},
publisher = {American Association for the Advancement of Science},
title = {{Past climates inform our future}},
url = {https://www.science.org/doi/10.1126/science.aay3701},
volume = {370},
year = {2020}
}
@article{Tokarska2018,
abstract = {{\textcopyright} 2018 The Author(s). Published by IOP Publishing Ltd. Carbon budgets provide a useful tool for policymakers to help meet the global climate targets, as they specify total allowable carbon emissions consistent with limiting warming to a given temperature threshold. Non-CO2forcings have a net warming effect in the Representative Concentration Pathways (RCP) scenarios, leading to reductions in remaining carbon budgets based on CO2forcing alone. Carbon budgets consistent with limiting warming to below 2.0 C, with and without accounting for the effects of non-CO2forcings, were assessed in inconsistent ways by the Intergovernmental Panel on Climate Change (IPCC), making the effects of non-CO2forcings hard to identify. Here we use a consistent approach to compare 1.5 C and 2.0 C carbon budgets with and without accounting for the effects of non-CO2forcings, using CO2-only and RCP8.5 simulations. The median allowable carbon budgets for 1.5 C and 2.0 C warming are reduced by 257 PgC and 418 PgC, respectively, and the uncertainty ranges on the budgets are reduced by more than a factor of two when accounting for the net warming effects of non-CO2forcings. While our overall results are consistent with IPCC, we use a more robust methodology, and explain the narrower uncertainty ranges of carbon budgets when non-CO2forcings are included. We demonstrate that most of the reduction in carbon budgets is a result of the direct warming effect of the non-CO2forcings, with a secondary contribution from the influence of the non-CO2forcings on the carbon cycle. Such carbon budgets are expected to play an increasingly important role in climate change mitigation, thus understanding the influence of non-CO2forcings on these budgets and their uncertainties is critical.},
author = {Tokarska, Katarzyna B. and Gillett, Nathan P. and Arora, Vivek K. and Lee, Warren G. and Zickfeld, Kirsten},
doi = {10.1088/1748-9326/aaafdd},
issn = {17489326},
journal = {Environmental Research Letters},
pages = {034039},
title = {{The influence of non-CO2 forcings on cumulative carbon emissions budgets}},
volume = {13},
year = {2018}
}
@article{Tokarska2020a,
abstract = {Future global warming estimates have been similar across past assessments, but several climate models of the latest Sixth Coupled Model Intercomparison Project (CMIP6) simulate much stronger warming, apparently inconsistent with past assessments. Here, we show that projected future warming is correlated with the simulated warming trend during recent decades across CMIP5 and CMIP6 models, enabling us to constrain future warming based on consistency with the observed warming. These findings carry important policy-relevant implications: The observationally constrained CMIP6 median warming in high emissions and ambitious mitigation scenarios is over 16 and 14{\%} lower by 2050 compared to the raw CMIP6 median, respectively, and over 14 and 8{\%} lower by 2090, relative to 1995-2014. Observationally constrained CMIP6 warming is consistent with previous assessments based on CMIP5 models, and in an ambitious mitigation scenario, the likely range is consistent with reaching the Paris Agreement target.},
author = {Tokarska, Katarzyna B. and Stolpe, Martin B. and Sippel, Sebastian and Fischer, Erich M. and Smith, Christopher J. and Lehner, Flavio and Knutti, Reto},
doi = {10.1126/sciadv.aaz9549},
issn = {23752548},
journal = {Science Advances},
number = {12},
pages = {1--14},
pmid = {32206725},
title = {{Past warming trend constrains future warming in CMIP6 models}},
volume = {6},
year = {2020}
}
@article{Toll2017,
author = {Toll, Velle and Christensen, Matthew and Gass{\'{o}}, Santiago and Bellouin, Nicolas},
doi = {10.1002/2017GL075280},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {dec},
number = {24},
pages = {12492--12500},
publisher = {Wiley-Blackwell},
title = {{Volcano and Ship Tracks Indicate Excessive Aerosol-Induced Cloud Water Increases in a Climate Model}},
volume = {44},
year = {2017}
}
@article{Toll2019,
abstract = {The cooling of the Earth's climate through the effects of anthropogenic aerosols on clouds offsets an unknown fraction of greenhouse gas warming. An increase in the amount of water inside liquid-phase clouds induced by aerosols, through the suppression of rain formation, has been postulated to lead to substantial cooling, which would imply that the Earth's surface temperature is highly sensitive to anthropogenic forcing. Here we provide direct observational evidence that, instead of a strong increase, aerosols cause a relatively weak average decrease in the amount of water in liquid-phase clouds compared with unpolluted clouds. Measurements of polluted clouds downwind of various anthropogenic sources—such as oil refineries, smelters, coal-fired power plants, cities, wildfires and ships—reveal that aerosol-induced cloud-water increases, caused by suppressed rain formation, and decreases, caused by enhanced evaporation of cloud water, partially cancel each other out. We estimate that the observed decrease in cloud water offsets 23{\%} of the global climate-cooling effect caused by aerosol-induced increases in the concentration of cloud droplets. These findings invalidate the hypothesis that increases in cloud water cause a substantial climate cooling effect and translate into reduced uncertainty in projections of future climate.},
author = {Toll, Velle and Christensen, Matthew and Quaas, Johannes and Bellouin, Nicolas},
doi = {10.1038/s41586-019-1423-9},
issn = {14764687},
journal = {Nature},
number = {7767},
pages = {51--55},
publisher = {Springer US},
title = {{Weak average liquid-cloud-water response to anthropogenic aerosols}},
url = {http://dx.doi.org/10.1038/s41586-019-1423-9},
volume = {572},
year = {2019}
}
@article{2015QJRMS.141.1404T,
author = {Tomassini, L and Voigt, A and Stevens, B},
doi = {10.1002/qj.2450},
journal = {Quarterly Journal of the Royal Meteorological Society},
number = {689},
pages = {1404--1416},
title = {{On the connection between tropical circulation, convective mixing, and climate sensitivity}},
volume = {141},
year = {2015}
}
@article{essd-9-809-2017,
abstract = {The injection of sulfur into the stratosphere by explosive volcanic eruptions is the cause of significant climate variability. Based on sulfate records from a suite of ice cores from Greenland and Antarctica, the eVolv2k database includes estimates of the magnitudes and approximate source latitudes of major volcanic stratospheric sulfur injection (VSSI) events from 500ĝ€BCE to 1900ĝ€CE, constituting an update of prior reconstructions and an extension of the record by 1000 years. The database incorporates improvements to the ice core records (in terms of synchronisation and dating) and refinements to the methods used to estimate VSSI from ice core records, and it includes first estimates of the random uncertainties in VSSI values. VSSI estimates for many of the largest eruptions, including Samalas (1257), Tambora (1815), and Laki (1783), are within 10ĝ€{\%} of prior estimates. A number of strong events are included in eVolv2k which are largely underestimated or not included in earlier VSSI reconstructions, including events in 540, 574, 682, and 1108ĝ€CE. The long-term annual mean VSSI from major volcanic eruptions is estimated to be ĝ1/4 0.5ĝ€Tgĝ€†[S]ĝ€†yrĝ'1, ĝ1/4 50ĝ€{\%} greater than a prior reconstruction due to the identification of more events and an increase in the magnitude of many intermediate events. A long-term latitudinally and monthly resolved stratospheric aerosol optical depth (SAOD) time series is reconstructed from the eVolv2k VSSI estimates, and the resulting global mean SAOD is found to be similar (within 33ĝ€{\%}) to a prior reconstruction for most of the largest eruptions. The long-term (500ĝ€BCE-1900ĝ€CE) average global mean SAOD estimated from the eVolv2k VSSI estimates including a constant background injection of stratospheric sulfur is ĝ1/4 0.014, 30ĝ€{\%} greater than a prior reconstruction. These new long-term reconstructions of past VSSI and SAOD variability give context to recent volcanic forcing, suggesting that the 20th century was a period of somewhat weaker than average volcanic forcing, with current best estimates of 20th century mean VSSI and SAOD values being 25 and 14ĝ€{\%} less, respectively, than the mean of the 500ĝ€BCE to 1900ĝ€CE period. The reconstructed VSSI and SAOD data are available at https://doi.org/10.1594/WDCC/eVolv2k-v2. .},
author = {Toohey, Matthew and Sigl, Michael},
doi = {10.5194/essd-9-809-2017},
issn = {18663516},
journal = {Earth System Science Data},
month = {nov},
number = {2},
pages = {809--831},
title = {{Volcanic stratospheric sulfur injections and aerosol optical depth from 500 BCE to 1900 CE}},
url = {https://essd.copernicus.org/articles/9/809/2017/},
volume = {9},
year = {2017}
}
@article{ISI:000337272700004,
abstract = {Climate change from increased greenhouse gases arises from a global energy imbalance at the top of the atmosphere (TOA). TOA measurements of radiation from space can track changes over time but lack absolute accuracy. An inventory of energy storage changes shows that over 90{\%} of the imbalance is manifested as a rise in ocean heat content (OHC). Data from the Ocean Reanalysis System, version 4 (ORAS4), and other OHC-estimated rates of change are used to compare with model-based estimates of TOA energy imbalance [from the Community Climate System Model, version 4 (CCSM4)] and with TOA satellite measurements for the year 2000 onward. Most ocean-only OHC analyses extend to only 700-m depth, have large discrepancies among the rates of change of OHC, and do not resolve interannual variability adequately to capture ENSO and volcanic eruption effects, all aspects that are improved with assimilation of multivariate data. ORAS4 rates of change of OHC quantitatively agree with the radiative forcing estimates of impacts of the three major volcanic eruptions since 1960 (Mt. Agung, 1963; El Chich{\'{o}}n, 1982; and Mt. Pinatubo, 1991). The natural variability of the energy imbalance is substantial from month to month, associated with cloud and weather variations, and interannually mainly associated with ENSO, while the sun affects 15{\%} of the climate change signal on decadal time scales. All estimates (OHC and TOA) show that over the past decade the energy imbalance ranges between about 0.5 and 1 W m−2. By using the full-depth ocean, there is a better overall accounting for energy, but discrepancies remain at interannual time scales between OHC- and TOA-based estimates, notably in 2008/09.},
address = {45 BEACON ST, BOSTON, MA 02108-3693 USA},
author = {Trenberth, Kevin E and Fasullo, John T and Balmaseda, Magdalena A},
doi = {10.1175/JCLI-D-13-00294.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Climate,Climate change,ENSO,Heating,Volcanoes},
month = {may},
number = {9},
pages = {3129--3144},
publisher = {AMER METEOROLOGICAL SOC},
title = {{Earth's Energy Imbalance}},
type = {Article},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-13-00294.1},
volume = {27},
year = {2014}
}
@article{Trenberth2015c,
abstract = {Abstract The monthly global and regional variability in Earth's radiation balance is examined using correlations and regressions between atmospheric temperatures and water vapor with top-of-atmosphere outgoing longwave (OLR), absorbed shortwave (ASR), and net radiation (RT?=?ASR???OLR). Anomalous global mean monthly variability in the net radiation is surprisingly large, often more than ±1?W?m?2, and arises mainly from clouds and transient weather systems. Relationships are strongest and positive between OLR and temperatures, especially over land for tropospheric temperatures, except in the deep tropics where high sea surface temperatures are associated with deep convection, high cold cloud tops and thus less OLR but also less ASR. Tropospheric vertically averaged temperatures (surface = 150?hPa) are thus negatively correlated globally with net radiation (?0.57), implying 2.18?±?0.10?W?m?2 extra net radiation to space for 1°C increase in temperature. Water vapor is positively correlated with tropospheric temperatures and thus also negatively correlated with net radiation; however, when the temperature dependency of water vapor is statistically removed, a significant positive feedback between water vapor and net radiation is revealed globally with 0.87?W?m?2 less OLR to space per millimeter of total column water vapor. The regression coefficient between global RT and tropospheric temperature becomes ?2.98?W?m?2?K?1 if water vapor effects are removed, slightly less than expected from blackbody radiation (?3.2?W?m?2?K?1), suggesting a positive feedback from clouds and other processes. Robust regional structures provide additional physical insights. The observational record is too short, weather noise too great, and forcing too small to make reliable estimates of climate sensitivity.},
annote = {doi: 10.1002/2014JD022887},
author = {Trenberth, Kevin E and Zhang, Yongxin and Fasullo, John T and Taguchi, Shoichi},
doi = {10.1002/2014JD022887},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {climate feedbacks,climate variability,radiation,temperatures},
month = {may},
number = {9},
pages = {3642--3659},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Climate variability and relationships between top-of-atmosphere radiation and temperatures on Earth}},
url = {https://doi.org/10.1002/2014JD022887},
volume = {120},
year = {2015}
}
@article{ISI:000273555500014,
abstract = {The energy budget of the modern-day Southern Hemisphere is poorly simulated in both state-of-the-art reanalyses and coupled global climate models. The ocean-dominated Southern Hemisphere has low surface reflectivity and therefore its albedo is particularly sensitive to cloud cover. In modern-day climates, mainly because of systematic deficiencies in cloud and albedo at mid- and high latitudes, too much solar radiation enters the ocean. Along with too little radiation absorbed at lower latitudes because of clouds that are too bright, unrealistically weak poleward transports of energy by both the ocean and atmosphere are generally simulated in the Southern Hemisphere. This implies too little baroclinic eddy development and deficient activity in storm tracks. However, projections into the future by coupled climate models indicate that the Southern Ocean features a robust and unique increase in albedo, related to clouds, in association with an intensification and poleward shift in storm tracks that is not observed at any other latitude. Such an increase in cloud may be untenable in nature, as it is likely precluded by the present-day ubiquitous cloud cover that models fail to capture. There is also a remarkably strong relationship between the projected changes in clouds and the simulated current-day cloud errors. The model equilibrium climate sensitivity is also significantly negatively correlated with the Southern Hemisphere energy errors, and only the more sensitive models are in the range of observations. As a result, questions loom large about how the Southern Hemisphere will actually change as global warming progresses, and a better simulation of the modern-day climate is an essential first step.},
author = {Trenberth, Kevin E and Fasullo, John T},
doi = {10.1175/2009JCLI3152.1},
issn = {1520-0442},
journal = {Journal of Climate},
month = {jan},
number = {2},
pages = {440--454},
title = {{Simulation of Present-Day and Twenty-First-Century Energy Budgets of the Southern Oceans}},
url = {http://journals.ametsoc.org/doi/10.1175/2009JCLI3152.1},
volume = {23},
year = {2010}
}
@article{TselioudisG.LipatB.R.KonstaD.GriseK.M.andPolvaniL.M.2016,
abstract = {We investigate the interannual relationship among clouds, their radiative effects, and two key indices of the atmospheric circulation: the latitudinal positions of the Hadley cell edge and the midlatitude jet. From reanalysis data and satellite observations, we find a clear and consistent relationship between the width of the Hadley cell and the high cloud field, statistically significant in nearly all regions and seasons. In contrast, shifts of the midlatitude jet correlate significantly with high cloud shifts only in the North Atlantic region during the winter season. While in that region and season poleward high cloud shifts are associated with shortwave radiative warming, over the Southern Oceans during all seasons they are associated with shortwave radiative cooling. Finally, a trend analysis reveals that poleward high cloud shifts observed over the 1983–2009 period are more likely related to Hadley cell expansion, rather than poleward shifts of the midlatitude jets.},
author = {Tselioudis, George and Lipat, Bernard R. and Konsta, Dimitra and Grise, Kevin M. and Polvani, Lorenzo M.},
doi = {10.1002/2016GL068242},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {may},
number = {9},
pages = {4594--4601},
title = {{Midlatitude cloud shifts, their primary link to the Hadley cell, and their diverse radiative effects}},
url = {http://doi.wiley.com/10.1002/2016GL068242},
volume = {43},
year = {2016}
}
@article{Tsushima2013,
abstract = {In the climate system, two types of radiative feedback are in operation. The feedback of the first kind involves the radiative damping of the vertically uniform temperature perturbation of the troposphere and Earth's surface that approximately follows the Stefan-Boltzmann law of blackbody radiation. The second kind involves the change in the vertical lapse rate of temperature, water vapor, and clouds in the troposphere and albedo of the Earth's surface. Using satellite observations of the annual variation of the outgoing flux of longwave radiation and that of reflected solar radiation at the top of the atmosphere, this study estimates the so-called "gain factor," which characterizes the strength of radiative feedback of the second kind that operates on the annually varying, global-scale perturbation of temperature at the Earth's surface. The gain factor is computed not only for all sky but also for clear sky. The gain factor of so-called "cloud radiative forcing" is then computed as the difference between the two. The gain factors thus obtained are compared with those obtained from 35 models that were used for the fourth and fifth Intergovernmental Panel on Climate Change assessment. Here, we show that the gain factors obtained from satellite observations of cloud radiative forcing are effective for identifying systematic biases of the feedback processes that control the sensitivity of simulated climate, providing useful information for validating and improving a climate model.},
author = {Tsushima, Y. and Manabe, S.},
doi = {10.1073/pnas.1216174110},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
month = {may},
number = {19},
pages = {7568--7573},
pmid = {23613585},
title = {{Assessment of radiative feedback in climate models using satellite observations of annual flux variation}},
url = {http://www.pnas.org/cgi/doi/10.1073/pnas.1216174110},
volume = {110},
year = {2013}
}
@article{Tsushima2014a,
author = {Tsushima, Yoko and Iga, Shin-ichi and Tomita, Hirofumi and Satoh, Masaki and Noda, Akira T. and Webb, Mark J.},
doi = {10.1002/2013MS000301},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
month = {sep},
number = {3},
pages = {571--585},
title = {{High cloud increase in a perturbed SST experiment with a global nonhydrostatic model including explicit convective processes}},
url = {http://doi.wiley.com/10.1002/2013MS000301},
volume = {6},
year = {2014}
}
@article{2020ClDy...55.1159T,
author = {Tsushima, Yoko and Ringer, Mark A and Martin, Gill M and Rostron, John W and Sexton, David M.H.},
doi = {10.1007/s00382-020-05318-y},
journal = {Climate Dynamics},
keywords = {Circulation weakening,Climate feedbacks,Perturbed parameter ensembles,Process based constraints,Sensitivity analysis},
number = {5-6},
pages = {1159--1185},
title = {{Investigating physical constraints on climate feedbacks using a perturbed parameter ensemble}},
volume = {55},
year = {2020}
}
@article{Tsutsui2020,
abstract = {A climate model emulator that mimics an ensemble of state-of-the-art coupled climate models has been used for probabilistic climate projections. To emulate and compare the latest and previous multimodel ensembles, this study establishes a new method to diagnose a set of parameters of effective radiative forcing, feedback, and impulse response functions by fitting a minimal emulator to time series of individual models in response to step- and ramp-shaped CO2 forcing up to a quadrupling concentration level. The diagnosed CO2 forcing is scaled down to a doubling level, leading to an unbiased estimate of equilibrium climate sensitivity. The average climate sensitivity of the latest ensemble is 18{\%} and 13{\%} greater than that of the previous ensemble for equilibrium and transient states. Although these increases are subject to data availability, the latter smaller rate is significant and is consistent with the relationship between feedback strength and response timescales.},
author = {Tsutsui, Junichi},
doi = {10.1029/2019GL085844},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {CO2 forcing,climate feedback,coupled climate model,equilibrium climate sensitivity,ocean mixing,transient climate response},
number = {7},
pages = {1--12},
title = {{Diagnosing Transient Response to CO2 Forcing in Coupled Atmosphere–Ocean Model Experiments Using a Climate Model Emulator}},
volume = {47},
year = {2020}
}
@article{ISI:000360646500023,
abstract = {Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry-climate models. Here we compare the HadGEM3-UKCA (Hadley Centre Global Environment Model-United Kingdom Chemistry and Aerosols) coupled chemistry-climate model for the period 1960-2009 against extensive ground-based observations of sulfate aerosol mass (1978-2009), total suspended particle matter (SPM, 1978-1998), PM10 (1997-2009), aerosol optical depth (AOD, 2000-2009), aerosol size distributions (2008-2009) and surface solar radiation (SSR, 1960-2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = -0.4), SPM (NMBF = -0.9), PM10 (NMBF = -0.2), aerosol number concentrations (N30 NMBF = -0.85; N50 NMBF = -0.65; and N100 NMBF = -0.96) and AOD (NMBF = -0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of -68{\%} (-78{\%}), SPM of -42{\%} (-20 {\%}), PM10 of -9{\%} (-8{\%}) and AOD of -11{\%} (-14 {\%}). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5 {\%}) during 1990-2009 ({\{}''{\}}brightening{\{}''{\}}) is better reproduced by the model when aerosol radiative effects (ARE) are included (3 {\%}), compared to simulations where ARE are excluded (0.2 {\%}). The simulated top-of-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by {\textgreater} 3.0 W m(-2) during the period 1970-2009 in response to changes in anthropogenic emissions and aerosol concentrations.},
address = {BAHNHOFSALLEE 1E, GOTTINGEN, 37081, GERMANY},
author = {Turnock, S T and Spracklen, D V and Carslaw, K S and Mann, G W and Woodhouse, M T and Forster, P M and Haywood, J and Johnson, C E and Dalvi, M and Bellouin, N and Sanchez-Lorenzo, A},
doi = {10.5194/acp-15-9477-2015},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
number = {16},
pages = {9477--9500},
publisher = {COPERNICUS GESELLSCHAFT MBH},
title = {{Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009}},
type = {Article},
volume = {15},
year = {2015}
}
@article{Tuzet17,
author = {Tuzet, F and Dumont, M and Lafaysse, M and Picard, G and Arnaud, L and Voisin, D and Lejeune, Y and Charrois, L and Nabat, P and Morin, S},
doi = {10.5194/tc-11-2633-2017},
journal = {The Cryosphere},
number = {6},
pages = {2633--2653},
title = {{A multilayer physically based snowpack model simulating direct and indirect radiative impacts of light-absorbing impurities in snow}},
url = {https://www.the-cryosphere.net/11/2633/2017/},
volume = {11},
year = {2017}
}
@article{Twomey1959,
author = {Twomey, S.},
doi = {10.1007/BF01993560},
issn = {0033-4553},
journal = {Geofisica Pura e Applicata},
month = {may},
number = {1},
pages = {243--249},
publisher = {Birkh{\"{a}}user-Verlag},
title = {{The nuclei of natural cloud formation part II: The supersaturation in natural clouds and the variation of cloud droplet concentration}},
volume = {43},
year = {1959}
}
@article{Ullrich2017,
abstract = {{\textless}p{\textgreater}Based on results of 11 yr of heterogeneous ice nucleation experiments at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) chamber in Karlsruhe, Germany, a new empirical parameterization framework for heterogeneous ice nucleation was developed. The framework currently includes desert dust and soot aerosol and quantifies the ice nucleation efficiency in terms of the ice nucleation active surface site (INAS) approach.{\textless}/p{\textgreater}},
author = {Ullrich, Romy and Hoose, Corinna and M{\"{o}}hler, Ottmar and Niemand, Monika and Wagner, Robert and H{\"{o}}hler, Kristina and Hiranuma, Naruki and Saathoff, Harald and Leisner, Thomas},
doi = {10.1175/JAS-D-16-0074.1},
issn = {0022-4928},
journal = {Journal of the Atmospheric Sciences},
month = {mar},
number = {3},
pages = {699--717},
title = {{A New Ice Nucleation Active Site Parameterization for Desert Dust and Soot}},
url = {http://journals.ametsoc.org/doi/10.1175/JAS-D-16-0074.1},
volume = {74},
year = {2017}
}
@article{Unger2014b,
abstract = {Human conversion of forest ecosystems to agriculture is a major driver of global change. Conventionally, the impacts of the historical cropland expansion on Earth's radiation balance have been quantified through two opposing effects: the release of stored carbon to the atmosphere as CO2 (warming) versus the increase in surface albedo (cooling)1 . Changing forest cover has a third effect on the global radiation balance by altering emissions of biogenic volatile organic compounds (BVOCs) that control the loadings of multiple warming and cooling climate pollutants: tropospheric ozone (O3 ), methane (CH4 ) and aerosols. Although human land cover change has dominated BVOC emission variability over the past century2–4 , the net effect on global climate has not been quantified. Here, I showthat the effects of the global cropland expansion between the 1850s and 2000s on BVOC emissions and atmospheric chemistry have imposed an additional net global radiative impact of −0.11 ± 0.17Wm−2 (cooling). This magnitude is comparable to that of the surface albedo and land carbon release effects. I conclude that atmospheric chemistry must be considered in climate impact assessments of anthropogenic land cover change and in forestry for climate protection strategies.},
author = {Unger, Nadine},
doi = {10.1038/nclimate2347},
isbn = {1758-678X},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {oct},
number = {10},
pages = {907--910},
title = {{Human land-use-driven reduction of forest volatiles cools global climate}},
url = {http://www.nature.com/articles/nclimate2347},
volume = {4},
year = {2014}
}
@article{Usoskin2015,
author = {Usoskin, Ilya G. and Arlt, Rainer and Asvestari, Eleanna and Hawkins, Ed and K{\"{a}}pyl{\"{a}}, Maarit and Kovaltsov, Gennady A. and Krivova, Natalie and Lockwood, Michael and Mursula, Kalevi and O'Reilly, Jezebel and Owens, Matthew and Scott, Chris J. and Sokoloff, Dmitry D. and Solanki, Sami K. and Soon, Willie and Vaquero, Jos{\'{e}} M.},
doi = {10.1051/0004-6361/201526652},
issn = {0004-6361},
journal = {Astronomy {\&} Astrophysics},
month = {sep},
pages = {A95},
title = {{The Maunder minimum (1645–1715) was indeed a grand minimum: A reassessment of multiple datasets}},
url = {http://www.aanda.org/10.1051/0004-6361/201526652},
volume = {581},
year = {2015}
}
@article{Varnai2015,
abstract = {Characterizing the way satellite-based aerosol statistics change near clouds is important for better understanding both aerosol-cloud interactions and aerosol direct radiative forcing. This study focuses on the question of whether the observed near-cloud increases in aerosol optical thickness and particle size may be explained by a combination of two factors: (i) Near-cloud data coming from areas with higher cloud fractions than far-from-cloud data and (ii) Cloud fraction being correlated with aerosol optical thickness and particle size. This question is addressed through a statistical analysis of aerosol parameters included in the MODIS (MODerate resolution Imaging Spectroradiometer) ocean color product. Results from ten Septembers (2002–2011) over part of the northeast Atlantic Ocean confirm that the combination of these two factors working together explains a significant but not dominant part (in our case, 15{\%}–30{\%}) of mean optical thickness changes near clouds. Overall, the findings show that cloud fraction plays a large role in shaping the way aerosol statistics change with distance to clouds. This implies that both cloud fraction and distance to clouds are important to consider when aerosol-cloud interactions or aerosol direct radiative effects are examined in satellite or modeling studies.},
author = {V{\'{a}}rnai, Tam{\'{a}}s and Marshak, Alexander},
doi = {10.3390/rs70505283},
issn = {2072-4292},
journal = {Remote Sensing},
keywords = {MODIS,aerosol,cloud,remote sensing,satellite},
month = {apr},
number = {5},
pages = {5283--5299},
publisher = {Multidisciplinary Digital Publishing Institute},
title = {{Effect of Cloud Fraction on Near-Cloud Aerosol Behavior in the MODIS Atmospheric Correction Ocean Color Product}},
url = {http://www.mdpi.com/2072-4292/7/5/5283},
volume = {7},
year = {2015}
}
@article{VaillantdeGuelis2018,
abstract = {Some of the most challenging questions in atmospheric science relate to how clouds will respond as the climate warms. On centennial scales, the response of clouds could either weaken or enhance the warming due to greenhouse gas emissions. Here we use space lidar observations to quantify changes in cloud altitude, cover, and opacity over the oceans between 2008 and 2014, together with a climate model with a lidar simulator to also simulate these changes in the present-day climate and in a future, warmer climate. We find that the longwave cloud altitude feedback, found to be robustly positive in simulations since the early climate models and backed up by physical explanations, is not the dominant longwave feedback term in the observations, although it is in the model we have used. These results suggest that the enhanced longwave warming due to clouds might be overestimated in climate models. These results highlight the importance of developing a long-term active sensor satellite record to reduce uncertainties in cloud feedbacks and prediction of future climate.},
author = {{Vaillant de Gu{\'{e}}lis}, Thibault and Chepfer, H{\'{e}}l{\`{e}}ne and Guzman, Rodrigo and Bonazzola, Marine and Winker, David M and Noel, Vincent},
doi = {10.1038/s41598-018-34943-1},
issn = {2045-2322},
journal = {Scientific Reports},
number = {1},
pages = {16570},
title = {{Space lidar observations constrain longwave cloud feedback}},
url = {https://doi.org/10.1038/s41598-018-34943-1},
volume = {8},
year = {2018}
}
@article{Vanderkelen2020,
abstract = {Heat uptake is a key variable for understanding the Earth system response to greenhouse gas forcing. Despite the importance of this heat budget, heat uptake by inland waters has so far not been quantified. Here we use a unique combination of global-scale lake models, global hydrological models and Earth system models to quantify global heat uptake by natural lakes, reservoirs, and rivers. The total net heat uptake by inland waters amounts to 2.6 ± 3.2 ×1020 J over the period 1900–2020, corresponding to 3.6{\%} of the energy stored on land. The overall uptake is dominated by natural lakes (111.7{\%}), followed by reservoir warming (2.3{\%}). Rivers contribute negatively (-14{\%}) due to a decreasing water volume. The thermal energy of water stored in artificial reservoirs exceeds inland water heat uptake by a factor ∼10.4. This first quantification underlines that the heat uptake by inland waters is relatively small, but non-negligible.},
author = {Vanderkelen, I. and Lipzig, N. P. M. and Lawrence, D. M. and Droppers, B. and Golub, M. and Gosling, S. N. and Janssen, A. B. G. and Marc{\'{e}}, R. and Schmied, H. M{\"{u}}ller and Perroud, M. and Pierson, D. and Pokhrel, Y. and Satoh, Y. and Schewe, J. and Seneviratne, S. I. and Stepanenko, V. M. and Tan, Z. and Woolway, R. I. and Thiery, W.},
doi = {10.1029/2020GL087867},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {heat uptake,inland waters,lakes,reservoirs,rivers},
month = {jun},
number = {12},
pages = {e2020GL087867},
publisher = {Blackwell Publishing Ltd},
title = {{Global Heat Uptake by Inland Waters}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL087867},
volume = {47},
year = {2020}
}
@article{VargasZeppetello2019,
abstract = {Downward longwave radiation (DLR) is often assumed to be an independent forcing on the surface energy budget in analyses of Arctic warming and land-atmosphere interaction. We use radiative kernels to show that the DLR response to forcing is largely determined by surface temperature perturbations. We develop a method by which vertically integrated versions of the radiative kernels are combined with surface temperature and specific humidity to estimate the surface DLR response to greenhouse forcing. Through a decomposition of the DLR response, we estimate that changes in surface temperature produce at least 63{\%} of the clear-sky DLR response in greenhouse forcing, while the changes associated with clouds account for only 11{\%} of the full-sky DLR response. Our results suggest that surface DLR is tightly coupled to surface temperature; therefore, it cannot be considered an independent component of the surface energy budget.},
author = {{Vargas Zeppetello}, L. R. and Donohoe, A. and Battisti, D. S.},
doi = {10.1029/2019GL082220},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {climate change,climate feedbacks,radiation,surface-atmosphere interaction},
month = {mar},
number = {5},
pages = {2781--2789},
publisher = {Blackwell Publishing Ltd},
title = {{Does Surface Temperature Respond to or Determine Downwelling Longwave Radiation?}},
volume = {46},
year = {2019}
}
@incollection{Vaughan2013b,
address = {Cambridge, United Kingdom and New York, NY, USA},
author = {Vaughan, D G and Comiso, J C and Allison, I and Carrasco, J and Kaser, G and Kwok, R and Mote, P and Murray, T and Paul, F and Ren, J and Rignot, E and Solomina, O and Steffen, K and Zhang, T},
booktitle = {Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change},
doi = {10.1017/CBO9781107415324.012},
editor = {Stocker, T.F. and Qin, D. and Plattner, G. K. and Tignor, M. and Allen, S. K. and Boschung, J. and Nauels, A. and Xia, Y. and Bex, V. and Midgley, P.M.},
isbn = {9781107661820},
pages = {317--382},
publisher = {Cambridge University Press},
title = {{Observations: Cryosphere}},
url = {https://www.ipcc.ch/report/ar5/wg1},
year = {2013}
}
@article{Vecchi2008a,
author = {Vecchi, Gabriel A. and Clement, Amy and Soden, Brian J.},
doi = {10.1029/2008EO090002},
issn = {00963941},
journal = {Eos},
number = {9},
pages = {81--83},
title = {{Examining the tropical Pacific's response to global warming}},
volume = {89},
year = {2008}
}
@article{Vecchi2006,
abstract = {Since the mid-nineteenth century the Earth's surface has warmed, and models indicate that human activities have caused part of the warming by altering the radiative balance of the atmosphere. Simple theories suggest that global warming will reduce the strength of the mean tropical atmospheric circulation. An important aspect of this tropical circulation is a large-scale zonal (east-west) overturning of air across the equatorial Pacific Ocean--driven by convection to the west and subsidence to the east--known as the Walker circulation. Here we explore changes in tropical Pacific circulation since the mid-nineteenth century using observations and a suite of global climate model experiments. Observed Indo-Pacific sea level pressure reveals a weakening of the Walker circulation. The size of this trend is consistent with theoretical predictions, is accurately reproduced by climate model simulations and, within the climate models, is largely due to anthropogenic forcing. The climate model indicates that the weakened surface winds have altered the thermal structure and circulation of the tropical Pacific Ocean. These results support model projections of further weakening of tropical atmospheric circulation during the twenty-first century.},
author = {Vecchi, Gabriel A. and Soden, Brian J. and Wittenberg, Andrew T. and Held, Isaac M. and Leetmaa, Ants and Harrison, Matthew J.},
doi = {10.1038/nature04744},
isbn = {0028-0836},
issn = {14764687},
journal = {Nature},
month = {may},
number = {1},
pages = {73--76},
pmid = {16672967},
publisher = {Nature Publishing Group},
title = {{Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing}},
volume = {441},
year = {2006}
}
@article{Vergara-Temprado2018,
abstract = {{\textcopyright}2018. The Authors. It has been hypothesized that black carbon (BC) influences mixed-phase clouds by acting as an ice-nucleating particle (INP). However, the literature data for ice nucleation by BC immersed in supercooled water are extremely varied, with some studies reporting that BC is very effective at nucleating ice, whereas others report no ice-nucleating ability. Here we present new experimental results for immersion mode ice nucleation by BC from two contrasting fuels (n-decane and eugenol). We observe no significant heterogeneous nucleation by either sample. Using a global aerosol model, we quantify the maximum relative importance of BC for ice nucleation when compared with K-feldspar and marine organic aerosol acting as INP. Based on the upper limit from our laboratory data, we show that BC contributes at least several orders of magnitude less INP than feldspar and marine organic aerosol. Representations of its atmospheric ice-nucleating ability based on older laboratory data produce unrealistic results when compared against ambient observations of INP. Since BC is a complex material, it cannot be unambiguously ruled out as an important INP species in all locations at all times. Therefore, we use our model to estimate a range of values for the density of active sites that BC particles must have to be relevant for ice nucleation in the atmosphere. The estimated values will guide future work on BC, defining the required sensitivity of future experimental studies.},
author = {Vergara-Temprado, Jes{\'{u}}s and Holden, Mark A. and Orton, Thomas R. and O'Sullivan, Daniel and Umo, Nsikanabasi S. and Browse, Jo and Reddington, Carly and Baeza-Romero, Mar{\'{i}}a Teresa and Jones, Jenny M. and Lea-Langton, Amanda and Williams, Alan and Carslaw, Ken S. and Murray, Benjamin J.},
doi = {10.1002/2017JD027831},
isbn = {2169-897X},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {apr},
number = {8},
pages = {4273--4283},
title = {{Is Black Carbon an Unimportant Ice-Nucleating Particle in Mixed-Phase Clouds?}},
url = {http://doi.wiley.com/10.1002/2017JD027831},
volume = {123},
year = {2018}
}
@article{Vial2013a,
abstract = {This study diagnoses the climate sensitivity, radiative forcing and climate feedback estimates from eleven general circulation models participating in the Fifth Phase of the Coupled Model Intercomparison Project (CMIP5), and analyzes inter-model differences. This is done by taking into account the fact that the climate response to increased carbon dioxide (CO2) is not necessarily only mediated by surface temperature changes, but can also result from fast land warming and tropospheric adjustments to the CO2radiative forcing. By considering tropospheric adjustments to CO2as part of the forcing rather than as feedbacks, and by using the radiative kernels approach, we decompose climate sensitivity estimates in terms of feedbacks and adjustments associated with water vapor, temperature lapse rate, surface albedo and clouds. Cloud adjustment to CO2is, with one exception, generally positive, and is associated with a reduced strength of the cloud feedback; the multi-model mean cloud feedback is about 33 {\%} weaker. Non-cloud adjustments associated with temperature, water vapor and albedo seem, however, to be better understood as responses to land surface warming. Separating out the tropospheric adjustments does not significantly affect the spread in climate sensitivity estimates, which primarily results from differing climate feedbacks. About 70 {\%} of the spread stems from the cloud feedback, which remains the major source of inter-model spread in climate sensitivity, with a large contribution from the tropics. Differences in tropical cloud feedbacks between low-sensitivity and high-sensitivity models occur over a large range of dynamical regimes, but primarily arise from the regimes associated with a predominance of shallow cumulus and stratocumulus clouds. The combined water vapor plus lapse rate feedback also contributes to the spread of climate sensitivity estimates, with inter-model differences arising primarily from the relative humidity responses throughout the troposphere. Finally, this study points to a substantial role of nonlinearities in the calculation of adjustments and feedbacks for the interpretation of inter-model spread in climate sensitivity estimates. We show that in climate model simulations with large forcing (e.g., 4 × CO2), nonlinearities cannot be assumed minor nor neglected. Having said that, most results presented here are consistent with a number of previous feedback studies, despite the very different nature of the methodologies and all the uncertainties associated with them. {\textcopyright} 2013 Springer-Verlag Berlin Heidelberg.},
author = {Vial, J. and Dufresne, J.-L. and Bony, S.},
doi = {10.1007/s00382-013-1725-9},
journal = {Climate Dynamics},
number = {11-12},
pages = {3339--3362},
title = {{On the interpretation of inter-model spread in CMIP5 climate sensitivity estimates}},
volume = {41},
year = {2013}
}
@article{2011A&A...531A...6V,
author = {Vieira, L.E.A. and Solanki, S.K. and Krivova, N.A. and Usoskin, I.},
doi = {10.1051/0004-6361/201015843},
journal = {Astronomy {\&} Astrophysics},
keywords = {Astrophysics - Solar and Stellar Astrophysics,Physics - Atmospheric and Oceanic Physics,Physics - Space Physics,Sun: UV radiation,Sun: activity,Sun: faculae,Sun: surface magnetism,plages,solar-terrestrial relations,sunspots},
month = {jul},
pages = {A6},
title = {{Evolution of the solar irradiance during the Holocene}},
volume = {531},
year = {2011}
}
@article{Vieira2018,
abstract = {Using a revised chronology, a new palynological study on the late Pliocene (Piacenzian and earliest Gelasian) Rio Maior site of the Tagus Basin in western Portugal has been undertaken from the F98 core. Combining light microscopy and scanning electron microscopy, a total of 127 different pollen and spore taxa have been identified from the Piacenzian Lake and indicate the presence of a subtropical to warm-temperate mixed forest during the majority of the Piacenzian (3.6–2.8 Ma). It is only in the latest Piacenzian (after 2.8 Ma) that progressive extinctions of climate sensitive taxa and a drop in diversity indicate a cooling and drying climate trend that has also been recorded from high-latitude localities. By the earliest Gelasian (2.58 Ma), a low diversity Ericaceae and Pinus dominated vegetation remained. The Piacenzian flora of Rio Maior also shows fluctuations in the presence of climate sensitive taxa and pollen-spore diversity that may be related to Piacenzian glaciations.},
author = {Vieira, Manuel and Pound, Matthew James and Pereira, Diamantino I.},
doi = {10.1016/j.palaeo.2018.01.018},
issn = {00310182},
journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
keywords = {Climate change,Flora, vegetation,Piacenzian,Pollen and spores,Tagus Basin},
month = {apr},
pages = {245--258},
publisher = {Elsevier B.V.},
title = {{The late Pliocene palaeoenvironments and palaeoclimates of the western Iberian Atlantic margin from the Rio Maior flora}},
volume = {495},
year = {2018}
}
@article{Vizcaino2010,
abstract = {The future evolution of global ice sheets under anthropogenic greenhouse forcing and its impact on the climate system, including the regional climate of the ice sheets, are investigated with a comprehensive earth system model consisting of a coupled AtmosphereOcean General Circulation Model, a dynamic vegetation model and an ice sheet model. The simulated control climate is realistic enough to permit a direct coupling of the atmosphere and ice sheet components, avoiding the use of anomaly coupling, which represents a strong improvement with respect to previous modelling studies. Glacier ablation is calculated with an energy-balance scheme, a more physical approach than the commonly used degree-day method. Modifications of glacier mask, topographic height and freshwater fluxes by the ice sheets influence the atmosphere and ocean via dynamical and thermodynamical processes. Several simulations under idealized scenarios of greenhouse forcing have been performed, where the atmospheric carbon dioxide stabilizes at two and four times pre-industrial levels. The evolution of the climate system and the ice sheets in the simulations with interactive ice sheets is compared with the simulations with passively coupled ice sheets. For a four-times CO2 scenario forcing, a faster decay rate of the Greenland ice sheet is found in the non-interactive case, where melting rates are higher. This is caused by overestimation of the increase in near-surface temperature that follows the reduction in topographic height. In areas close to retreating margins, melting rates are stronger in the interactive case, due to changes in local albedo. Our results call for careful consideration of the feedbacks operating between ice sheets and climate after substantial decay of the ice sheets.},
author = {Vizca{\'{i}}no, M. and Mikolajewicz, U. and Jungclaus, J. and Schurgers, G.},
doi = {10.1007/s00382-009-0591-y},
isbn = {0930-7575},
issn = {09307575},
journal = {Climate Dynamics},
number = {2},
pages = {301--324},
title = {{Climate modification by future ice sheet changes and consequences for ice sheet mass balance}},
volume = {34},
year = {2010}
}
@article{Volodin2008,
abstract = {The paper considers a relation between equilibrium global warming at doubled carbon dioxide (climate sensitivity) and the distribution of clouds and relative humidity in 18 state-of-the-art climate models. There is a strong correlation among three indices: (1) model climate sensitivity, (2) mean cloud amount change due to global warming, and (3) the difference in cloud amount between the tropics and midlatitudes. In the simulation of the present-day current, models with high sensitivity produce smaller clouds amounts in the tropics and larger cloud amounts over midlatitude oceans than models with low sensitivity. The relative humidity in the tropics is smaller in models with high sensitivity than in models with low sensitivity. There is a similarity between vertical profiles of cloud amount and relative humidity under global warming and vertical profiles of the difference in these quantities averaged over the tropics and midlatitudes. Based on the correlations obtained and observations of cloud amount and relative humidity, an estimate is made of the sensitivity of a real climate system.},
author = {Volodin, E M},
doi = {10.1134/S0001433808030043},
issn = {1555-628X},
journal = {Izvestiya, Atmospheric and Oceanic Physics},
number = {3},
pages = {288--299},
title = {{Relation between temperature sensitivity to doubled carbon dioxide and the distribution of clouds in current climate models}},
url = {https://doi.org/10.1134/S0001433808030043},
volume = {44},
year = {2008}
}
@article{https://doi.org/10.1029/2006GL026484,
abstract = {We present a new approach to estimate the magnitude of global-mean cooling (dTLGM) at the Last Glacial Maximum (LGM) relative to the pre-industrial climate, by combining an ensemble of coupled climate model simulations with empirical constraints on regional cooling inferred from proxy data. We have generated a large ensemble of paired runs (∼100) for pre-industrial and LGM boundary conditions with different versions of the same climate model of intermediate complexity. The model ensemble covers a broad range of climate sensitivities and produces a similarly broad range of dTLGM (4.3–9.8°C). Using reconstructed tropical SST cooling, we constrain the range of dTLGM to 5.8 ± 1.4°C, which is corroborated by proxy data from other regions. This cooling is considerably larger than most estimates of previous LGM simulations. The reason is that most models did not account for the effect of atmospheric dust content and vegetation changes, which yield an additional 1.0–1.7°C global cooling.},
author = {von Deimling, Thomas and Ganopolski, Andrey and Held, Hermann and Rahmstorf, Stefan},
doi = {10.1029/2006GL026484},
journal = {Geophysical Research Letters},
number = {14},
pages = {L14709},
title = {{How cold was the Last Glacial Maximum?}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2006GL026484},
volume = {33},
year = {2006}
}
@article{VonderHeydt2016c,
author = {von der Heydt, Anna S. and Dijkstra, Henk A. and van de Wal, Roderik S.W. and Caballero, Rodrigo and Crucifix, Michel and Foster, Gavin L. and Huber, Matthew and K{\"{o}}hler, Peter and Rohling, Eelco and Valdes, Paul J. and Ashwin, Peter and Bathiany, Sebastian and Berends, Tijn and van Bree, Loes G.J. and Ditlevsen, Peter and Ghil, Michael and Haywood, Alan M. and Katzav, Joel and Lohmann, Gerrit and Lohmann, Johannes and Lucarini, Valerio and Marzocchi, Alice and P{\"{a}}like, Heiko and Baroni, Itzel Ruvalcaba and Simon, Dirk and Sluijs, Appy and Stap, Lennert B. and Tantet, Alexis and Viebahn, Jan and Ziegler, Martin},
doi = {10.1007/s40641-016-0049-3},
isbn = {2198-6061},
issn = {21986061},
journal = {Current Climate Change Reports},
keywords = {Climate sensitivity,Climate tipping points,Palaeoclimate},
number = {4},
pages = {148--158},
title = {{Lessons on Climate Sensitivity From Past Climate Changes}},
volume = {2},
year = {2016}
}
@article{VonderHeydt2016b,
abstract = {Equilibrium climate sensitivity (ECS) is a key predictor of climate change. However, it is not very well constrained, either by climate models or by observational data. The reasons for this include strong internal variability and forcing on many time scales. In practise this means that the 'equilibrium' will only be relative to fixing the slow feedback processes before comparing palaeoclimate sensitivity estimates with estimates from model simulations. In addition, information from the late Pleistocene ice age cycles indicates that the climate cycles between cold and warm regimes, and the climate sensitivity varies considerably between regime because of fast feedback processes changing relative strength and time scales over one cycle. In this paper we consider climate sensitivity for quite general climate dynamics. Using a conceptual Earth system model of Gildor and Tziperman (2001) (with Milankovich forcing and dynamical ocean biogeochemistry) we explore various ways of quantifying the state-dependence of climate sensitivity from unperturbed and perturbed model time series. Even without considering any perturbations, we suggest that climate sensitivity can be usefully thought of as a distribution that quantifies variability within the 'climate attractor' and where there is a strong dependence on climate state and more specificially on the 'climate regime' where fast processes are approximately in equilibrium. We also consider perturbations by instantaneous doubling of CO{\$}{\_}2{\$} and similarly find a strong dependence on the climate state using our approach.},
archivePrefix = {arXiv},
arxivId = {1604.03311},
author = {von der Heydt, Anna S and Ashwin, Peter},
doi = {10.1093/climsys/dzx001},
eprint = {1604.03311},
issn = {2059-6987},
journal = {Dynamics and Statistics of the Climate System},
keywords = {climate response to perturbations,climate sensitivity,conceptual climate models,cycles,glacial,interglacial,palaeoclimate},
number = {1},
pages = {1--21},
title = {{State dependence of climate sensitivity: attractor constraints and palaeoclimate regimes}},
url = {http://arxiv.org/abs/1604.03311{\%}0Ahttp://dx.doi.org/10.1093/climsys/dzx001},
volume = {1},
year = {2016}
}
@article{VonderHeydt2014b,
author = {von der Heydt, Anna S. and Dijkstra, Henk A. and K{\"{o}}hler, Peter and Wal, Roderik Van De},
doi = {10.1002/2014GL061121},
issn = {00948276},
journal = {Geophysical Research Letters},
number = {2},
pages = {6484--6492},
title = {{On the background state dependency of (palaeo) climate sensitivity}},
volume = {41},
year = {2014}
}
@article{VonSchuckmann2016a,
abstract = {The current Earth's energy imbalance (EEI) is mostly caused by human activity, and is driving global warming. The absolute value of EEI represents the most fundamental metric defining the status of global climate change, and will be more useful than using global surface temperature. EEI can best be estimated from changes in ocean heat content, complemented by radiation measurements from space. Sustained observations from the Argo array of autonomous profiling floats and further development of the ocean observing system to sample the deep ocean, marginal seas and sea ice regions are crucial to refining future estimates of EEI. Combining multiple measurements in an optimal way holds considerable promise for estimating EEI and thus assessing the status of global climate change, improving climate syntheses and models, and testing the effectiveness of mitigation actions. Progress can be achieved with a concerted international effort.},
author = {von Schuckmann, K. and Palmer, M. D. and Trenberth, K. E. and Cazenave, A. and Chambers, D. and Champollion, N. and Hansen, J. and Josey, S. A. and Loeb, N. and Mathieu, P. P. and Meyssignac, B. and Wild, M.},
doi = {10.1038/nclimate2876},
isbn = {1758-678X},
issn = {17586798},
journal = {Nature Climate Change},
month = {jan},
number = {2},
pages = {138--144},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{An imperative to monitor Earth's energy imbalance}},
url = {http://dx.doi.org/10.1038/nclimate2876 http://10.0.4.14/nclimate2876},
volume = {6},
year = {2016}
}
@article{essd-12-2013-2020,
author = {von Schuckmann, K and Cheng, L and Palmer, M D and Hansen, J and Tassone, C and Aich, V and Adusumilli, S and Beltrami, H and Boyer, T and Cuesta-Valero, F J and Desbruy{\`{e}}res, D and Domingues, C and Garc$\backslash$'$\backslash$ia-Garc$\backslash$'$\backslash$ia, A and Gentine, P and Gilson, J and Gorfer, M and Haimberger, L and Ishii, M and Johnson, G C and Killick, R and King, B A and Kirchengast, G and Kolodziejczyk, N and Lyman, J and Marzeion, B and Mayer, M and Monier, M and Monselesan, D P and Purkey, S and Roemmich, D and Schweiger, A and Seneviratne, S I and Shepherd, A and Slater, D A and Steiner, A K and Straneo, F and Timmermans, M.-L. and Wijffels, S E},
doi = {10.5194/essd-12-2013-2020},
journal = {Earth System Science Data},
number = {3},
pages = {2013--2041},
title = {{Heat stored in the Earth system: where does the energy go?}},
url = {https://essd.copernicus.org/articles/12/2013/2020/},
volume = {12},
year = {2020}
}
@article{Voss2001,
abstract = {Abstract   The long-term adjustment processes of atmosphere and ocean in response to gradually increased atmospheric CO2 concentration have been analysed in two 850-year integrations with a coupled atmosphere-ocean general circulation model (AOGCM). In these experiments the CO2 concentration has been increased to double and four times the initial concentration, respectively, and is kept fixed thereafter. Three characteristic time scales have been identified: a very fast response associated with processes dominated by the atmospheric adjustment, an intermediate time scale of a few decades connected with processes in the upper ocean, and adjustment processes with time scales of centuries and longer due to the inertia of the deep ocean. The latter in particular is responsible for a still ongoing adjustment of the atmosphere-ocean system at the end of the integrations after 850 years. After 60 years, at the time of CO2 doubling, the global mean near-surface air temperature rises by 1.4 K. In spite of the constant CO2 concentration during the following centuries the warming continues to 2.6 K after 850 years. The behaviour of the quadrupling run is similar: global mean near-surface air temperature increases by 3.8 K at the time of CO2 quadrupling and by 4.8 K at the end of the simulation. The thermohaline circulation undergoes remarkable changes. Temporarily, the North Atlantic overturning circulation weakens by up to 30{\%} in the CO2 doubling experiment and up to 50{\%} in the CO2 quadrupling experiment. After reaching the minimum the North Atlantic overturning slowly recovers in both experiments.},
author = {Voss, R and Mikolajewicz, U},
doi = {10.1007/pl00007925},
isbn = {0930-7575},
issn = {0930-7575},
journal = {Climate Dynamics},
number = {1},
pages = {45--60},
title = {{Long-term climate changes due to increased CO2 concentration in the coupled atmosphere–ocean general circulation model ECHAM3/LSG}},
url = {http://dx.doi.org/10.1007/PL00007925},
volume = {17},
year = {2001}
}
@article{Waelbroeck2009,
abstract = {A quantitative reconstruction of the global climate during the last glacial maximum was published in the early 1980s. A synthesis of global sea-surface temperature reconstructions shows global cooling of the tropical oceans and strong longitudinal temperature-gradients.},
author = {Waelbroeck, C and Paul, A and Kucera, M and Rosell-Mel{\'{e}}, A and Weinelt, M and Schneider, R and Mix, A C and Abelmann, A and Armand, L and Bard, E and Barker, S and Barrows, T T and Benway, H and Cacho, I and Chen, M.-T. and Cortijo, E and Crosta, X and de Vernal, A and Dokken, T and Duprat, J and Elderfield, H and Eynaud, F and Gersonde, R and Hayes, A and Henry, M and Hillaire-Marcel, C and Huang, C.-C. and Jansen, E and Juggins, S and Kallel, N and Kiefer, T and Kienast, M and Labeyrie, L and Leclaire, H and Londeix, L and Mangin, S and Matthiessen, J and Marret, F and Meland, M and Morey, A E and Mulitza, S and Pflaumann, U and Pisias, N G and Radi, T and Rochon, A and Rohling, E J and Sbaffi, L and Sch{\"{a}}fer-Neth, C and Solignac, S and Spero, H and Tachikawa, K and Turon, J.-L. and Members, MARGO Project},
doi = {10.1038/ngeo411},
issn = {1752-0908},
journal = {Nature Geoscience},
number = {2},
pages = {127--132},
title = {{Constraints on the magnitude and patterns of ocean cooling at the Last Glacial Maximum}},
url = {https://doi.org/10.1038/ngeo411},
volume = {2},
year = {2009}
}
@article{ISI:000393208100035,
abstract = {Published estimates on the magnitude of solar dimming and brightening in China show large discrepancies and inconsistencies in its seasonal variations. A nationwide reorganization of the surface solar radiation (SSR) network during 1990-1993 contributed to these uncertainties, which is reflected in a sudden upward jump in the published composite SSR time series. This jump is found to be prevalent in 23 out of 130 stations due to both natural (7 stations) and operational factors (16 stations). After eliminating the stations containing artifacts and discontinuous records, a new magnitude of solar dimming and brightening was estimated for China, and seasonal trends were determined. A transition from dimming to brightening remains in the SSR trend in China after excluding the affected stations and associated jump, in line with the global SSR trend.},
address = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
author = {Wang, Yawen and Wild, Martin},
doi = {10.1002/2016GL071009},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {nov},
number = {22},
pages = {11777--11785},
publisher = {AMER GEOPHYSICAL UNION},
title = {{A new look at solar dimming and brightening in China}},
type = {Article},
volume = {43},
year = {2016}
}
@article{Wang2018l,
author = {Wang, Rong and Andrews, Elisabeth and Balkanski, Yves and Boucher, Olivier and Myhre, Gunnar and Samset, Bj{\o}rn Hallvard and Schulz, Michael and Schuster, Gregory L. and Valari, Myrto and Tao, Shu},
doi = {10.1002/2017GL076817},
issn = {00948276},
journal = {Geophysical Research Letters},
keywords = {AERONET,GAW,black carbon,model resolution,representativeness error},
month = {feb},
number = {4},
pages = {2106--2114},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Spatial Representativeness Error in the Ground-Level Observation Networks for Black Carbon Radiation Absorption}},
url = {http://doi.wiley.com/10.1002/2017GL076817},
volume = {45},
year = {2018}
}
@article{Wang2016c,
author = {Wang, Rong and Balkanski, Yves and Boucher, Olivier and Ciais, Philippe and Schuster, Gregory L. and Chevallier, Fr{\'{e}}d{\'{e}}ric and Samset, Bj{\o}rn H. and Liu, Junfeng and Piao, Shilong and Valari, Myrto and Tao, Shu},
doi = {10.1002/2015JD024326},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {black carbon,data assimilation,emission inventory,radiative forcing,remote sensing,transport model},
month = {may},
number = {10},
pages = {5948--5971},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Estimation of global black carbon direct radiative forcing and its uncertainty constrained by observations}},
url = {http://doi.wiley.com/10.1002/2015JD024326},
volume = {121},
year = {2016}
}
@article{ISI:000358695200013,
abstract = {Existing studies have shown that observed surface incident solar radiation (R-s) over China may have important inhomogeneity issues. This study provides metadata and reference data to homogenize observed R-s, from which the decadal variability of R-s over China can be accurately derived. From 1958 to 1990, diffuse solar radiation (R-sdif) and direct solar radiation (R-sdir) were measured separately, and R-s was calculated as their sum. The pyranometers used to measure R-sdif had a strong sensitivity drift problem, which introduced a spurious decreasing trend into the observed R-sdif and R-s data, whereas the observed R-sdir did not suffer from this sensitivity drift problem. From 1990 to 1993, instruments and measurement methods were replaced and measuring stations were restructured in China, which introduced an abrupt increase in the observed R-s. Intercomparisons between observation-based and model-based R-s performed in this research show that sunshine duration (SunDu)-derived R-s is of high quality and can be used as reference data to homogenize observed R-s data. The homogenized and adjusted data of observed R-s combines the advantages of observed R-s in quantifying hourly to monthly variability and SunDu-derived R-s in depicting decadal variability and trend. R-s averaged over 105 stations in China decreased at -2.9 W m(-2) per decade from 1961 to 1990 and remained stable afterward. This decadal variability is confirmed by the observed R-sdir and diurnal temperature ranges, and can be reproduced by high-quality Earth System Models. However, neither satellite retrievals nor reanalyses can accurately reproduce such decadal variability over China.},
author = {Wang, Kaicun and Ma, Qian and Li, Zhijun and Wang, Jiankai},
doi = {10.1002/2015JD023420},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {jul},
number = {13},
pages = {6500--6514},
title = {{Decadal variability of surface incident solar radiation over China: Observations, satellite retrievals, and reanalyses}},
volume = {120},
year = {2015}
}
@article{ISI:000331199200004,
abstract = {There is growing evidence that, corresponding to global dimming and brightening, surface solar radiation and sunshine hours over China have undergone decadal fluctuations during the 1960s-2000s. The results of a number of these analyses are, however, very different. In this study, we synthesize reliable results and conclusively address recent advances and insufficiencies in studies on dimming and brightening in China. A temporally and spatially prevalent dimming trend is noted in surface solar radiation, direct solar radiation and sunshine hours since the 1960s. Meanwhile, the changing trend in diffuse solar radiation is less pronounced. Increasing anthropogenic aerosol loading is regarded as the most plausible explanation for China's dimming. The brightening trend since 1990, which mainly occurs in southeastern China and in the spring season, is weak and insignificant. The reverse in the solar radiation trend is associated with climate change by cloud suppression and slowdown in anthropogenic emissions. The future solar radiation trend in China could largely depend on the development of air quality control. Other potential driving factors such as wind speed, water vapor and surface albedo are also non-negligible in specific regions of China. Hydrological implications of dimming and brightening in China lack systematic investigation. However, the fact that solar radiation and pan evaporation trends in China track a similar curve in 1990 further suggests that the pan evaporation paradox could be partly resolved by changes in solar radiation.},
author = {Wang, Y W and Yang, Y H},
doi = {10.5194/angeo-32-41-2014},
issn = {0992-7689},
journal = {Annales Geophysicae},
number = {1},
pages = {41--55},
title = {{China's dimming and brightening: evidence, causes and hydrological implications}},
volume = {32},
year = {2014}
}
@article{Wang2020,
abstract = {Stratospheric water vapor (SWV) is recognized as a potentially important positive feedback in global warming. The SWV change induces significant downward radiative flux perturbation at the tropopause and therefore is hypothesized to substantially amplify the surface warming. To test this hypothesis, we use a global climate model to quantify the surface warming contributed by the SWV change in the context of the quadrupled CO2. By prescribing the SWV increase as an external forcing, we find that SWV only accounts for 0.42 K surface warming, making up merely 5.4{\%} of the total CO2-caused surface warming (7.7 K). The efficacy of the stratosphere-adjusted SWV forcing is small (38{\%}), where the efficacy is defined as the ratio of the global temperature response per unit radiative forcing relative to that of the CO2 forcing. With the aid of a series of auxiliary experiments, we find that although the stratosphere-adjusted SWV forcing at the top of atmosphere (TOA) is significant (1.13 W m−2), more than half of the forcing is offset by a high-cloud decrease and an upper tropospheric warming in the tropospheric adjustment. The direct radiative impact of the SWV increase on surface temperature is negligible, and the SWV-induced surface temperature change is a result of interactions between the radiative and nonradiative processes.},
author = {Wang, Yuwei and Huang, Yi},
doi = {10.1029/2020JD032752},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {global warming,radiative forcing,stratospheric water vapor,surface temperature},
month = {sep},
number = {17},
pages = {e2020JD032752},
title = {{The Surface Warming Attributable to Stratospheric Water Vapor in CO2-Caused Global Warming}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020JD032752},
volume = {125},
year = {2020}
}
@article{Wang2021,
author = {Wang, Chenggong and Soden, Brian J. and Yang, Wenchang and Vecchi, Gabriel A.},
doi = {10.1029/2020GL091024},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {feb},
number = {4},
pages = {e2020GL091024},
title = {{Compensation Between Cloud Feedback and Aerosol–Cloud Interaction in CMIP6 Models}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL091024},
volume = {48},
year = {2021}
}
@article{Wang2014e,
abstract = {Anthropogenic aerosols over urban areas may have important effects on surface incident solar radiation (R-s). Studies have claimed that R-s decreased significantly more in urban areas than in rural areas from 1964 to 1989. However, these estimates have substantial biases because they ignored the spatial inhomogeneity of R-s measurements. To address this issue, we selected urban-rural station pairs collocated within 2 degrees x 2 degrees and found 105 such pairs based on the Global Energy Balance Archive (GEBA). On average, the impact of urban aerosols on mean and trend of R-s is 0.2(0.7, median)+/-11.2W m(-2) and 0.1(-0.7, median)+/-6.6 W m(-2) per decade from 1961 to 1990, respectively. Hence, the averaged urban impacts on the mean and trend of R-s over Europe, China and Japan from 1961 to 1990 are small although they may be significant at specific sites.},
address = {Wang, Kc Beijing Normal Univ, Coll Global Change {\&} Earth Syst Sci, State Key Lab Earth Surface Proc {\&} Resource Ecol, Beijing 100875, Peoples R China Beijing Normal Univ, Coll Global Change {\&} Earth Syst Sci, State Key Lab Earth Surface Proc {\&} Resource Ecol},
annote = {An0sw
Times Cited:0
Cited References Count:20},
author = {Wang, K and Ma, Q and Wang, X Y and Wild, M},
doi = {10.1002/2014gl060201},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {clouds},
language = {English},
number = {13},
pages = {4664--4668},
title = {{Urban impacts on mean and trend of surface incident solar radiation}},
volume = {41},
year = {2014}
}
@article{Wara2005,
abstract = {During the warm early Pliocene (∼4.5 to 3.0 million years ago), the most recent interval with a climate warmer than today, the eastern Pacific thermocline was deep and the average west-to-east sea surface temperature difference across the equatorial Pacific was only 1.5 ± 0.9deg;C, much like it is during a modern El Ni{\~{n}}o event. Thus, the modern strong sea surface temperature gradient across the equatorial Pacific is not a stable and permanent feature. Sustained El Ni{\~{n}}o-like conditions, including relatively weak zonal atmospheric (Walker) circulation, could be a consequence of, and play an important role in determining, global warmth.},
author = {Wara, Michael W. and Ravelo, Ana Christina and Delaney, Margaret L.},
doi = {10.1126/science.1112596},
issn = {00368075},
journal = {Science},
month = {jul},
number = {5735},
pages = {758--761},
title = {{Climate change: Permanent El Ni{\~{n}}o-like conditions during the Pliocene warm period}},
url = {http://science.sciencemag.org/content/309/5735/758.abstract},
volume = {309},
year = {2005}
}
@article{Ward2014,
abstract = {Abstract. Pressure on land resources is expected to increase as global population continues to climb and the world becomes more affluent, swelling the demand for food. Changing climate may exert additional pressures on natural lands as present-day productive regions may shift, or soil quality may degrade, and the recent rise in demand for biofuels increases competition with edible crops for arable land. Given these projected trends there is a need to understand the global climate impacts of land use and land cover change (LULCC). Here we quantify the climate impacts of global LULCC in terms of modifications to the balance between incoming and outgoing radiation at the top of the atmosphere (radiative forcing, RF) that are caused by changes in long-lived and short-lived greenhouse gas concentrations, aerosol effects, and land surface albedo. We attribute historical changes in terrestrial carbon storage, global fire emissions, secondary organic aerosol emissions, and surface albedo to LULCC using simulations with the Community Land Model version 3.5. These LULCC emissions are combined with estimates of agricultural emissions of important trace gases and mineral dust in two sets of Community Atmosphere Model simulations to calculate the RF of changes in atmospheric chemistry and aerosol concentrations attributed to LULCC. With all forcing agents considered together, we show that 40{\%} (±16{\%}) of the present-day anthropogenic RF can be attributed to LULCC. Changes in the emission of non-CO2 greenhouse gases and aerosols from LULCC enhance the total LULCC RF by a factor of 2 to 3 with respect to the LULCC RF from CO2 alone. This enhancement factor also applies to projected LULCC RF, which we compute for four future scenarios associated with the Representative Concentration Pathways. We attribute total RFs between 0.9 and 1.9 W m−2 to LULCC for the year 2100 (relative to a pre-industrial state). To place an upper bound on the potential of LULCC to alter the global radiation budget, we include a fifth scenario in which all arable land is cultivated by 2100. This theoretical extreme case leads to a LULCC RF of 3.9 W m−2 (±0.9 W m−2), suggesting that not only energy policy but also land policy is necessary to minimize future increases in RF and associated climate changes.},
author = {Ward, D. S. and Mahowald, N. M. and Kloster, S.},
doi = {10.5194/acp-14-12701-2014},
isbn = {1412701201},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {dec},
number = {23},
pages = {12701--12724},
title = {{Potential climate forcing of land use and land cover change}},
url = {https://acp.copernicus.org/articles/14/12701/2014/},
volume = {14},
year = {2014}
}
@article{Watanabe2018,
abstract = {Equilibrium climate sensitivity (ECS) and hydrological sensitivity describe the global mean surface temperature and precipitation responses to a doubling of atmospheric CO2. Despite their connection via the Earth's energy budget, the physical linkage between these two metrics remains controversial. Here, using a global climate model with a perturbed mean hydrological cycle, we show that ECS and hydrological sensitivity per unit warming are anti-correlated owing to the low-cloud response to surface warming. When the amount of low clouds decreases, ECS is enhanced through reductions in the reflection of shortwave radiation. In contrast, hydrological sensitivity is suppressed through weakening of atmospheric longwave cooling, necessitating weakened condensational heating by precipitation. These compensating cloud effects are also robustly found in a multi-model ensemble, and further constrained using satellite observations. Our estimates, combined with an existing constraint to clear-sky shortwave absorption, suggest that hydrological sensitivity could be lower by 30{\%} than raw estimates from global climate models.},
author = {Watanabe, Masahiro and Kamae, Youichi and Shiogama, Hideo and DeAngelis, Anthony M and Suzuki, Kentaroh},
doi = {10.1038/s41558-018-0272-0},
issn = {1758-6798},
journal = {Nature Climate Change},
number = {10},
pages = {901--906},
title = {{Low clouds link equilibrium climate sensitivity to hydrological sensitivity}},
url = {https://doi.org/10.1038/s41558-018-0272-0},
volume = {8},
year = {2018}
}
@article{Watanabe2020b,
abstract = {The increasing technological control of two-dimensional (2D) materials has allowed the demonstration of 2D lateral junctions exhibiting unique properties that might serve as the basis for a new generation of 2D electronic and optoelectronic devices. Notably, the chemically doped MoS2 homojunction, the WSe2-MoS2 monolayer and MoS2 monolayer/multilayer heterojunctions, have been demonstrated. Here we report the investigation of 2D lateral junction electrostatics, which differs from the bulk case because of the weaker screening, producing a much longer transition region between the space-charge region and the quasi-neutral region, making inappropriate the use of the complete-depletion region approximation. For such a purpose we have developed a method based on the conformal mapping technique to solve the 2D electrostatics, widely applicable to every kind of junctions, giving accurate results for even large asymmetric charge distribution scenarios.},
author = {Watanabe, Michio and Tatebe, Hiroaki and Suzuki, Tatsuo and Tachiiri, Kaoru},
doi = {10.1088/1748-9326/ab8ca7},
issn = {1748-9326},
journal = {Environmental Research Letters},
keywords = {article is available online,ocean heat uptake,sea level rise,supplementary material for this,transient climate response,turbulent mixing,vertical diffusivity},
number = {9},
pages = {094001},
title = {{Control of transient climate response and associated sea level rise by deep-ocean mixing}},
volume = {15},
year = {2020}
}
@article{Watanabe2020c,
abstract = {The equatorial Pacific zonal sea surface temperature (SST) gradient, known to be a pacemaker of global warming, has strengthened since the mid-twentieth century. However, the cause is controversial because a majority of Coupled Model Intercomparison Project Phase 5 (CMIP5) models suggest weakening of the zonal SST gradient from the past to the future. Reconciling this discrepancy is important for the climate change attribution and climate sensitivity assessment. Here we use the CMIP5 ensemble and large ensemble simulations by four climate models to show that the intensifying SST gradient observed during 1951–2010 could arise from internal climate variability. Models and members that simulate historical strengthening of the SST gradient commonly exhibit reversed future trends. Using these models as a constraint, the rate of global-mean temperature rise is amplified by 9–30{\%}, with higher values occurring in low-emission scenarios, because internal variability has a greater impact when the externally forced response is smaller.},
author = {Watanabe, Masahiro and Dufresne, Jean-Louis and Kosaka, Yu and Mauritsen, Thorsten and Tatebe, Hiroaki},
doi = {10.1038/s41558-020-00933-3},
issn = {1758-678X},
journal = {Nature Climate Change},
month = {jan},
number = {1},
pages = {33--37},
title = {{Enhanced warming constrained by past trends in equatorial Pacific sea surface temperature gradient}},
url = {https://doi.org/10.1038/s41558-020-00933-3 https://www.nature.com/articles/s41558-020-00933-3},
volume = {11},
year = {2021}
}
@article{Webb2015a,
abstract = {We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff' models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud feedback is discussed.},
author = {Webb, Mark J. and Lock, Adrian P. and Bretherton, Christopher S. and Bony, Sandrine and Cole, Jason N. S. and Idelkadi, Abderrahmane and Kang, Sarah M. and Koshiro, Tsuyoshi and Kawai, Hideaki and Ogura, Tomoo and Roehrig, Romain and Shin, Yechul and Mauritsen, Thorsten and Sherwood, Steven C. and Vial, Jessica and Watanabe, Masahiro and Woelfle, Matthew D. and Zhao, Ming},
doi = {10.1098/rsta.2014.0414},
issn = {1364-503X},
journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
keywords = {Climate,Cloud,Convection,Feedback,Parametrization},
month = {nov},
number = {2054},
pages = {20140414},
pmid = {26438278},
title = {{The impact of parametrized convection on cloud feedback}},
url = {https://royalsocietypublishing.org/doi/10.1098/rsta.2014.0414},
volume = {373},
year = {2015}
}
@article{Webb2013a,
abstract = {We diagnose climate feedback parameters and CO2 forcing including rapid adjustment in twelve atmosphere/mixed-layer-ocean (“slab”) climate models from the CMIP3/CFMIP-1 project (the AR4 ensemble) and fifteen parameter-perturbed versions of the HadSM3 slab model (the PPE). In both ensembles, differences in climate feedbacks can account for approximately twice as much of the range in climate sensitivity as differences in CO2 forcing. In the AR4 ensemble, cloud effects can explain the full range of climate sensitivities, and cloud feedback components contribute four times as much as cloud components of CO2 forcing to the range. Non-cloud feedbacks are required to fully account for the high sensitivities of some models however. The largest contribution to the high sensitivity of HadGEM1 is from a high latitude clear-sky shortwave feedback, and clear-sky longwave feedbacks contribute substantially to the highest sensitivity members of the PPE. Differences in low latitude ocean regions (30°N/S) contribute more to the range than those in mid-latitude oceans (30–55°N/S), low/mid latitude land (55°N/S) or high latitude ocean/land (55–90°N/S), but contributions from these other regions are required to account fully for the higher model sensitivities, for example from land areas in IPSL CM4. Net cloud feedback components over the low latitude oceans sorted into percentile ranges of lower tropospheric stability (LTS) show largest differences among models in stable regions, mainly due to their shortwave components, most of which are positive in spite of increasing LTS. Differences in the mid-stability range are smaller, but cover a larger area, contributing a comparable amount to the range in climate sensitivity. These are strongly anti-correlated with changes in subsidence. Cloud components of CO2 forcing also show the largest differences in stable regions, and are strongly anticorrelated with changes in estimated inversion strength (EIS). This is qualitatively consistent with what would be expected from observed relationships between EIS and low-level cloud fraction. We identify a number of cases where individual models show unusually strong forcings and feedbacks compared to other members of the ensemble. We encourage modelling groups to investigate unusual model behaviours further with sensitivity experiments. Most of the models fail to correctly reproduce the observed relationships between stability and cloud radiative effect in the subtropics, indicating that there remains considerable room for model improvements in the future.},
author = {Webb, Mark J and Lambert, F Hugo and Gregory, Jonathan M},
doi = {10.1007/s00382-012-1336-x},
issn = {1432-0894},
journal = {Climate Dynamics},
number = {3},
pages = {677--707},
title = {{Origins of differences in climate sensitivity, forcing and feedback in climate models}},
url = {https://doi.org/10.1007/s00382-012-1336-x},
volume = {40},
year = {2013}
}
@article{Webb2020,
author = {Webb, Mark J. and Lock, Adrian P.},
doi = {10.1029/2019MS001999},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
month = {sep},
number = {9},
pages = {e2019MS001999},
title = {{Testing a Physical Hypothesis for the Relationship Between Climate Sensitivity and Double‐ITCZ Bias in Climate Models}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2019MS001999},
volume = {12},
year = {2020}
}
@article{Wen2018,
abstract = {The global temperature changes under global warming result from two effects: one is the pure radiative heating effect caused by a change in greenhouse gases, and the other is the freshwater effect related to changes in precipitation, evaporation, and sea ice. The two effects are separated in a coupled climate model through sensitivity experiments in this study. It is indicated that freshwater change has a significant cooling effect that can mitigate the global surface warming by as much as {\~{}}30{\%}. Two significant regional cooling centers occur: one in the subpolar Atlantic and one in the Southern Ocean. The subpolar Atlantic cooling, also known as the “warming hole,” is triggered by sea ice melting and the southward cold-water advection from the Arctic Ocean, and is sustained by the weakened Atlantic meridional overturning circulation. The Southern Ocean surface cooling is triggered by sea ice melting along the Antarctic and is maintained by the enhanced northward Ekman flow. In these two regions, the effect of freshwater flux change dominates over that of radiation flux change, controlling the sea surface temperature change in the warming climate. The freshwater flux change also results in the Bjerknes compensation, with the atmosphere heat transport change compensating the ocean heat transport change by about 80{\%} during the transient stage of global warming. In terms of global temperature and Earth's energy balance, the freshwater change plays a stabilizing role in a warming climate.},
author = {Wen, Qin and Yao, Jie and D{\"{o}}{\"{o}}s, Kristofer and Yang, Haijun},
doi = {10.1175/JCLI-D-18-0297.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Atmosphere-ocean interaction,Dynamics,Heating,Hydrologic cycle},
month = {dec},
number = {23},
pages = {9605--9623},
title = {{Decoding Hosing and Heating Effects on Global Temperature and Meridional Circulations in a Warming Climate}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-18-0297.1},
volume = {31},
year = {2018}
}
@article{Westerhold2020,
abstract = {Much of our understanding of Earth's past climate comes from the measurement of oxygen and carbon isotope variations in deep-sea benthic foraminifera. Yet, long intervals in existing records lack the temporal resolution and age control needed to thoroughly categorize climate states of the Cenozoic era and to study their dynamics. Here, we present a new, highly resolved, astronomically dated, continuous composite of benthic foraminifer isotope records developed in our laboratories. Four climate states-Hothouse, Warmhouse, Coolhouse, Icehouse-are identified on the basis of their distinctive response to astronomical forcing depending on greenhouse gas concentrations and polar ice sheet volume. Statistical analysis of the nonlinear behavior encoded in our record reveals the key role that polar ice volume plays in the predictability of Cenozoic climate dynamics.},
author = {Westerhold, Thomas and Marwan, Norbert and Drury, Anna Joy and Liebrand, Diederik and Agnini, Claudia and Anagnostou, Eleni and Barnet, James S.K. and Bohaty, Steven M. and {De Vleeschouwer}, David and Florindo, Fabio and Frederichs, Thomas and Hodell, David A. and Holbourn, Ann E. and Kroon, Dick and Lauretano, Vittoria and Littler, Kate and Lourens, Lucas J. and Lyle, Mitchell and P{\"{a}}like, Heiko and R{\"{o}}hl, Ursula and Tian, Jun and Wilkens, Roy H. and Wilson, Paul A. and Zachos, James C.},
doi = {10.1126/SCIENCE.ABA6853},
issn = {10959203},
journal = {Science},
number = {6509},
pages = {1383--1388},
pmid = {32913105},
title = {{An astronomically dated record of Earth's climate and its predictability over the last 66 million years}},
volume = {369},
year = {2020}
}
@article{Wigley2005,
author = {Wigley, T. M. L. and Ammann, C. M. and Santer, B. D. and Raper, S. C. B.},
doi = {10.1029/2004JD005557},
isbn = {0148-0227},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
number = {D9},
pages = {D09107},
title = {{Effect of climate sensitivity on the response to volcanic forcing}},
url = {http://doi.wiley.com/10.1029/2004JD005557},
volume = {110},
year = {2005}
}
@article{Wigley1998,
abstract = {Kyoto Protocol implications for CO2, temperature and sea level are examined. Three scenarios for post-Kyoto emissions reductions are considered. In all cases, the long-term consequences are small. The limitations specified under the Protocol are interpreted in terms of both CO2 and CH4 emissions reductions and a new emissions comparison index, the Forcing Equivalence Index (FEI), is introduced. The use of GWPs to assess CO2-equivalence is assessed.},
author = {Wigley, T. M. L.},
doi = {10.1029/98GL01855},
issn = {00948276},
journal = {Geophysical Research Letters},
month = {jul},
number = {13},
pages = {2285--2288},
title = {{The Kyoto Protocol: CO2, CH4 and climate implications}},
url = {http://doi.wiley.com/10.1029/98GL01855},
volume = {25},
year = {1998}
}
@article{Wigley2018,
abstract = {The Paris Agreement states that, relative to pre-industrial times, the increase in global average temperature should be kept to well below 2 °C and efforts should be made to limit the temperature increase to 1.5 °C. Emissions scenarios consistent with these targets are derived. For an eventual 2 °C warming target, this could be achieved even if CO2 emissions remained positive. For a 1.5 °C target, CO2 emissions could remain positive, but only if a substantial and long-lasting temperature overshoot is accepted. In both cases, a warming overshoot of 0.2 to 0.4 °C appears unavoidable. If the allowable (or unavoidable) overshoot is small, then negative emissions are almost certainly required for the 1.5 °C target, peaking at negative 1.3 GtC/year. In this scenario, temperature stabilization occurs, but cumulative emissions continue to increase, contrary to a common belief regarding the relationship between temperature and cumulative emissions. Changes to the Paris Agreement to accommodate the overshoot possibility are suggested. For sea level rise, tipping points that might lead to inevitable collapse of Antarctic ice sheets or shelves might be avoided for the 2 °C target (for major ice shelves) or for the 1.5 °C target for the West Antarctic Ice Sheet. Even with the 1.5 °C target, however, sea level will continue to rise at a substantial rate for centuries.},
author = {Wigley, T. M. L.},
doi = {10.1007/s10584-017-2119-5},
issn = {15731480},
journal = {Climatic Change},
keywords = {Atmospheric Sciences,Climate Change/Climate Change Impacts},
month = {mar},
number = {1-2},
pages = {31--45},
publisher = {Springer Netherlands},
title = {{The Paris warming targets: emissions requirements and sea level consequences}},
url = {https://doi.org/10.1007/s10584-017-2119-5},
volume = {147},
year = {2018}
}
@article{Wijffels2016,
abstract = {Not Available},
author = {Wijffels, Susan and Roemmich, Dean and Monselesan, Didier and Church, John and Gilson, John},
doi = {10.1038/nclimate2924},
issn = {17586798},
journal = {Nature Climate Change},
month = {jan},
number = {2},
pages = {116--118},
publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
title = {{Ocean temperatures chronicle the ongoing warming of Earth}},
volume = {6},
year = {2016}
}
@article{Wilcox2016,
abstract = {The introduction of cloud condensation nuclei and radiative heating by sunlight-absorbing aerosols can modify the thickness and coverage of low clouds, yielding significant radiative forcing of climate. The magnitude and sign of changes in cloud coverage and depth in response to changing aerosols are impacted by turbulent dynamics of the cloudy atmosphere, but integrated measurements of aerosol solar absorption and turbulent fluxes have not been reported thus far. Here we report such integrated measurements made from unmanned aerial vehicles (UAVs) during the CARDEX (Cloud Aerosol Radiative Forcing and Dynamics Experiment) investigation conducted over the northern Indian Ocean. The UAV and surface data reveal a reduction in turbulent kinetic energy in the surface mixed layer at the base of the atmosphere concurrent with an increase in absorbing black carbon aerosols. Polluted conditions coincide with a warmer and shallower surface mixed layer because of aerosol radiative heating and reduced turbulence. The polluted surface mixed layer was also observed to be more humid with higher relative humidity. Greater humidity enhances cloud development, as evidenced by polluted clouds that penetrate higher above the top of the surface mixed layer. Reduced entrainment of dry air into the surface layer from above the inversion capping the surface mixed layer, due to weaker turbulence, may contribute to higher relative humidity in the surface layer during polluted conditions. Measurements of turbulence are important for studies of aerosol effects on clouds. Moreover, reduced turbulence can exacerbate both the human health impacts of high concentrations of fine particles and conditions favorable for low-visibility fog events.},
author = {Wilcox, Eric M. and Thomas, Rick M. and Praveen, Puppala S. and Pistone, Kristina and Bender, Frida A.M. and Ramanathan, Veerabhadran},
doi = {10.1073/pnas.1525746113},
issn = {10916490},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Aerosols,Atmospheric turbulence,Autonomous unmanned aerial vehicles,Cloud cover,Radiative forcing},
month = {oct},
number = {42},
pages = {11794--11799},
publisher = {National Academy of Sciences},
title = {{Black carbon solar absorption suppresses turbulence in the atmospheric boundary layer}},
volume = {113},
year = {2016}
}
@article{Wild2013a,
abstract = {In the framework of the global energy balance, the radiative energy exchanges between Sun, Earth and space are now accurately quantified from new satellite missions. Much less is known about the magnitude of the energy flows within the climate system and at the Earth surface, which cannot be directly measured by satellites. In addition to satellite observations, here we make extensive use of the growing number of surface observations to constrain the global energy balance not only from space, but also from the surface. We combine these observations with the latest modeling efforts performed for the 5th IPCC assessment report to infer best estimates for the global mean surface radiative components. Our analyses favor global mean downward surface solar and thermal radiation values near 185 and 342 Wm(-2), respectively, which are most compatible with surface observations. Combined with an estimated surface absorbed solar radiation and thermal emission of 161 and 397 Wm(-2), respectively, this leaves 106 Wm(-2) of surface net radiation available globally for distribution amongst the non-radiative surface energy balance components. The climate models overestimate the downward solar and underestimate the downward thermal radiation, thereby simulating nevertheless an adequate global mean surface net radiation by error compensation. This also suggests that, globally, the simulated surface sensible and latent heat fluxes, around 20 and 85 Wm(-2) on average, state realistic values. The findings of this study are compiled into a new global energy balance diagram, which may be able to reconcile currently disputed inconsistencies between energy and water cycle estimates.},
address = {Wild, M ETH, Inst Atmospher {\&} Climate Sci, Univ Str 16, CH-8092 Zurich, Switzerland ETH, Inst Atmospher {\&} Climate Sci, Univ Str 16, CH-8092 Zurich, Switzerland ETH, Inst Atmospher {\&} Climate Sci, CH-8092 Zurich, Switzerland NASA, Langley Res Ctr, Hampton, },
author = {Wild, M and Folini, D and Schar, C and Loeb, N and Dutton, E G and K{\"{o}}nig-Langlo, G},
doi = {10.1007/S00382-012-1569-8},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {earth radiation budget surface energy balance glob},
language = {English},
number = {11-12},
pages = {3107--3134},
title = {{The global energy balance from a surface perspective}},
volume = {40},
year = {2013}
}
@article{Wild2017,
abstract = {While global observational estimates of energy fluxes in and out of the climate system at the top of atmosphere (TOA) are now available with considerable accuracy from recent satellite programs, similar reference values are more difficult to establish for the surface energy fluxes, which cannot be directly measured from space. This is reflected in greatly diverging global estimates of the surface energy balance components that have been published over the years, or simulated in global climate models. Since the mid-1990s, accurate direct measurements become increasingly available from the networks of surface radiation stations, which allow to better constrain the energy fluxes at the Earth's surface. In parallel, satellite-derived products of surface fluxes profit from the great advancement in space-born observation systems that became operational since the turn of the millennium. As a consequence, recent independent global estimates of the surface radiation components based on surface and satellite data sources have converged to within a few watts per square meter. This suggests that we are approaching a stage where we are not only confident in the magnitudes of the global energy balance components at the TOA but also increasingly so at the surface. These recent estimates may also be able to reconcile formerly disputed inconsistencies between global energy and water cycle estimates. Remaining challenges include the accurate determination of representative surface albedos and skin temperatures in the calculation of surface shortwave absorption and upward longwave emission, respectively, as well as the partitioning of surface net radiation into the nonradiative fluxes of sensible and latent heat.},
author = {Wild, Martin},
doi = {10.1007/s40641-017-0058-x},
issn = {2198-6061},
journal = {Current Climate Change Reports},
month = {mar},
number = {1},
pages = {87--97},
title = {{Towards Global Estimates of the Surface Energy Budget}},
url = {https://doi.org/10.1007/s40641-017-0058-x},
volume = {3},
year = {2017}
}
@article{Wild2019,
author = {Wild, Martin and Hakuba, Maria Z. and Folini, Doris and D{\"{o}}rig-Ott, Patricia and Sch{\"{a}}r, Christoph and Kato, Seiji and Long, Charles N.},
doi = {10.1007/s00382-018-4413-y},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {apr},
number = {7-8},
pages = {4787--4812},
title = {{The cloud-free global energy balance and inferred cloud radiative effects: an assessment based on direct observations and climate models}},
url = {http://link.springer.com/10.1007/s00382-018-4413-y},
volume = {52},
year = {2019}
}
@article{Wild2015a,
abstract = {surface albedo and emissivity, we infer a surface absorbed solar and net thermal radiation of 136 and −66 Wm −2 over land, and 170 and −53 Wm −2 over oceans, respectively. The surface net radiation is thus estimated at 70 Wm −2 over land and 117 Wm −2 over oceans, which may impose addi-tional constraints on the poorly known sensible/latent heat flux magnitudes, estimated here near 32/38 Wm −2 over land, and 16/100 Wm −2 over oceans. Estimated uncertain-ties are on the order of 10 and 5 Wm −2 for most surface and TOA fluxes, respectively. By combining these surface budgets with satellite-determined TOA budgets we quan-tify the atmospheric energy budgets as residuals (includ-ing ocean to land transports), and revisit the global mean energy balance.},
author = {Wild, Martin and Folini, Doris and Hakuba, Maria Z and Sch{\"{a}}r, Christoph and Seneviratne, Sonia I and Kato, Seiji and Rutan, David and Ammann, Christof and Wood, Eric F and K{\"{o}}nig-Langlo, Gert},
doi = {10.1007/s00382-014-2430-z},
isbn = {0930-7575$\backslash$r1432-0894},
issn = {14320894},
journal = {Climate Dynamics},
keywords = {CMIP5,Global climate models,Global energy balance,Radiation budget,Surface and satellite observations},
number = {11-12},
pages = {3393--3429},
title = {{The energy balance over land and oceans: an assessment based on direct observations and CMIP5 climate models}},
url = {https://link.springer.com/content/pdf/10.1007{\%}2Fs00382-014-2430-z.pdf},
volume = {44},
year = {2015}
}
@article{ISI:000299655300005,
author = {Wild, Martin},
doi = {10.1175/BAMS-D-11-00074.1},
issn = {0003-0007},
journal = {Bulletin of the American Meteorological Society},
month = {jan},
number = {1},
pages = {27--37},
title = {{Enlightening global dimming and brightening}},
volume = {93},
year = {2012}
}
@article{Wild2020,
author = {Wild, Martin},
doi = {10.3929/ETHZ-B-000418579},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {may},
number = {3},
pages = {553--577},
publisher = {Springer},
title = {{The global energy balance as represented in CMIP6 climate models}},
url = {https://www.research-collection.ethz.ch:443/handle/20.500.11850/418579},
volume = {55},
year = {2020}
}
@article{ISI:000267490200004,
abstract = {There is increasing evidence that the amount of solar radiation incident at the Earth's surface is not stable over the years but undergoes significant decadal variations. Here I review the evidence for these changes, their magnitude, their possible causes, their representation in climate models, and their potential implications for climate change. The various studies analyzing long-term records of surface radiation measurements suggest a widespread decrease in surface solar radiation between the 1950s and 1980s ({\{}''{\}}global dimming''), with a partial recovery more recently at many locations ({\{}''{\}}brightening''). There are also some indications for an ``early brightening'' in the first part of the 20th century. These variations are in line with independent long-term observations of sunshine duration, diurnal temperature range, pan evaporation, and, more recently, satellite-derived estimates, which add credibility to the existence of these changes and their larger-scale significance. Current climate models, in general, tend to simulate these decadal variations to a much lesser degree. The origins of these variations are internal to the Earth's atmosphere and not externally forced by the Sun. Variations are not only found under cloudy but also under cloud-free atmospheres, indicative of an anthropogenic contribution through changes in aerosol emissions governed by economic developments and air pollution regulations. The relative importance of aerosols, clouds, and aerosol-cloud interactions may differ depending on region and pollution level. Highlighted are further potential implications of dimming and brightening for climate change, which may affect global warming, the components and intensity of the hydrological cycle, the carbon cycle, and the cryosphere among other climate elements.},
author = {Wild, Martin},
doi = {10.1029/2008JD011470},
issn = {0148-0227},
journal = {Journal of Geophysical Research: Atmospheres},
month = {jun},
number = {D10},
pages = {D00D16},
title = {{Global dimming and brightening: A review}},
url = {http://doi.wiley.com/10.1029/2008JD011470},
volume = {114},
year = {2009}
}
@article{Wild2021,
author = {Wild, Martin and Wacker, Stephan and Yang, Su and Sanchez‐Lorenzo, Arturo},
doi = {10.1029/2020GL092216},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {global dimming and brightening,surface radiation},
month = {mar},
number = {6},
pages = {e2020GL092216},
publisher = {American Geophysical Union (AGU)},
title = {{Evidence for Clear‐Sky Dimming and Brightening in Central Europe}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL092216},
volume = {48},
year = {2021}
}
@article{Wild2016a,
abstract = {Anthropogenic interference with climate occurs primarily through modification of radiative fluxes in the climate system. Increasing releases of greenhouse gases into the atmosphere lead to an enhancement of thermal radiation from the atmosphere to the surface by presently about 2 W m(-2) per decade, thereby causing global warming. Yet not only thermal radiation undergoes substantial decadal changes at the Earth surface, but also incident solar radiation (SSR), often in line with changes in aerosol emissions. Land-based observations suggest widespread declines in SSR from 1950s to 1980s (global dimming'), a partial recovery (brightening') since mid-1980s, and indication for an early' brightening in 1930s and 1940s. No similar extended observational records are available over oceans. However, modeling studies, conceptual frameworks and available satellite-derived records point to the existence of decadal SSR variations also over oceans. SSR changes overall match with decadal variations in observed warming rates, suggesting that SSR variations may effectively modulate greenhouse gas-induced warming. Specifically, on the Northern Hemisphere, the lack of warming from 1950s to 1980s and its subsequent acceleration in the 1990s fits to the trend reversal from dimming to brightening and associated changes in air pollution levels. From the 1950s to 1980s no warming was also observed over Northern Hemispheric Oceans, in line with conceptual ideas that subtle aerosol changes in pristine ocean areas, effectively amplified by aerosol-cloud interactions, can substantially alter SSR, thereby modulating Sea Surface Temperatures. On the Southern Hemisphere, the absence of significant aerosol levels fits to the observed stable (greenhouse gas-induced) warming rates since the 1950s. (C) 2015 Wiley Periodicals, Inc.},
address = {ETH, Inst Atmospher {\&} Climate Sci, Zurich, Switzerland},
annote = {Da1ir
Times Cited:0
Cited References Count:121},
author = {Wild, M},
doi = {10.1002/wcc.372},
issn = {1757-7780},
journal = {WIREs Climate Change},
keywords = {sunshine duration records diurnal temperature-rang},
language = {English},
number = {1},
pages = {91--107},
title = {{Decadal changes in radiative fluxes at land and ocean surfaces and their relevance for global warming}},
volume = {7},
year = {2016}
}
@article{Wild2011a,
abstract = {Observations indicate that solar radiation incident at the Earth surface underwent substantial decadal variations in the second half of the twentieth century, with a tendency towards reduction from the 1950s to the 1980s ("global dimming") and a partial recovery thereafter ("brightening") at widespread locations. The most reliable observational records from the Global Energy Balance Archive (GEBA) are used to evaluate the ability of the climate models participating in CMIP3/IPCC-AR4 as well as the ERA40 reanalysis to reproduce these decadal variations. The results from 23 models and reanalysis are analyzed in five different climatic regions where strong decadal variations in surface solar radiation (SSR) have been observed. Only about half of the models are capable of reproducing the observed decadal variations in a qualitative way, and all models show much smaller amplitudes in these variations than seen in the observations. Largely differing tendencies between the models are not only found under all-sky conditions, but also in cloud-free conditions and in the representation of cloud effects. The ERA40 reanalysis neither reproduces the major decadal variations in SSR, despite strong observational constraints on the temporal evolution of the state of the atmosphere, since time varying aerosol loadings are missing. Climate models and reanalyses are therefore not yet at a stage to provide regionally consistent estimates of decadal changes in SSR. Reproduction of these changes would be essential for an adequate representation of regional scale climate variations and impacts, and short-term (decadal) climate projections.},
address = {Wild, M ETH, Inst Atmospher {\&} Climate Sci, Univ Str 16, CH-8092 Zurich, Switzerland ETH, Inst Atmospher {\&} Climate Sci, Univ Str 16, CH-8092 Zurich, Switzerland ETH, Inst Atmospher {\&} Climate Sci, CH-8092 Zurich, Switzerland},
annote = {828SI
Times Cited:3
Cited References Count:40},
author = {Wild, M and Schmucki, E},
doi = {10.1007/S00382-010-0939-3},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {climate change global climate modeling solar radia},
language = {English},
number = {7-8},
pages = {1671--1688},
title = {{Assessment of global dimming and brightening in IPCC-AR4/CMIP3 models and ERA40}},
volume = {37},
year = {2011}
}
@article{Willeit2014,
abstract = {Abstract. Climate–vegetation feedback has the potential to significantly contribute to climate change, but little is known about its range of uncertainties. Here, using an Earth system model of intermediate complexity we address possible uncertainties in the strength of the biogeophysical climate–vegetation feedback using a single-model multi-physics ensemble. Equilibrium experiments with halving (140 ppm) and doubling (560 ppm) of CO2 give a contribution of the vegetation–climate feedback to global temperature change in the range −0.3 to −0.1 °C and −0.1 to 0.2 °C, respectively. There is an asymmetry between warming and cooling, with a larger, positive vegetation–climate feedback in the lower CO2 climate. Hotspots of climate–vegetation feedback are the boreal zone, the Amazon rainforest and the Sahara. Albedo parameterization is the dominant source of uncertainty in the subtropics and at high northern latitudes, while uncertainties in evapotranspiration are more relevant in the tropics. We analyse the separate impact of changes in stomatal conductance, leaf area index and vegetation dynamics on climate and we find that different processes are dominant in lower and higher CO2 worlds. The reduction in stomatal conductance gives the main contribution to temperature increase for a doubling of CO2, while dynamic vegetation is the dominant process in the CO2 halving experiments. Globally the climate–vegetation feedback is rather small compared to the sum of the fast climate feedbacks. However, it is comparable to the amplitude of the fast feedbacks at high northern latitudes where it can contribute considerably to polar amplification. The uncertainties in the climate–vegetation feedback are comparable to the multi-model spread of the fast climate feedbacks.},
author = {Willeit, M. and Ganopolski, A. and Feulner, G.},
doi = {10.5194/bg-11-17-2014},
issn = {17264170},
journal = {Biogeosciences},
number = {1},
pages = {17--32},
title = {{Asymmetry and uncertainties in biogeophysical climate–vegetation feedback over a range of CO2 forcings}},
volume = {11},
year = {2014}
}
@article{Williams2017a,
abstract = {We present a method to attribute cloud radiative feedbacks to convective processes, using sub-cloud layer buoyancy as a diagnostic of stable and deep convective regimes. Applying this approach to tropical remote-sensing measurements over years 2000-2016 shows that an inferred negative short-term cloud feedback from deep convection was nearly offset by a positive cloud feedback from stable regimes. The net cloud feedback was within statistical uncertainty of the NCAR Community Atmosphere Model (CAM5) with historical forcings, with discrepancies in the partitioning of the cloud feedback into convective regimes. Compensation between high-cloud responses to tropics-wide warming in stable and unstable regimes resulted in smaller net changes in high-cloud fraction with warming. In addition, deep convection and associated high clouds set in at warmer temperatures in response to warming, as a consequence of nearly invariant sub-cloud buoyancy. This invariance further constrained the magnitude of cloud radiative feedbacks, and is consistent with climate model projections.},
author = {Williams, Ian N. and Pierrehumbert, Raymond T.},
doi = {10.1002/2016GL072202},
issn = {19448007},
journal = {Geophysical Research Letters},
keywords = {cloud,deep convection,feedback,remote sensing,tropical,tropical circulation},
number = {3},
pages = {1503--1510},
title = {{Observational evidence against strongly stabilizing tropical cloud feedbacks}},
volume = {44},
year = {2017}
}
@article{Williams2008,
abstract = {Effective climate sensitivity is often assumed to be constant (if uncertain), but some previous studies of general circulation model (GCM) simulations have found it varying as the simulation progresses. This complicates the fitting of simple models to such simulations, as well as having implications for the estimation of climate sensitivity from observations. This study examines the evolution of the feedbacks determining the climate sensitivity in GCMs submitted to the Coupled Model Intercomparison Project. Apparent centennial-time-scale variations of effective climate sensitivity during stabilization to a forcing can be considered an artifact of using conventional forcings, which only allow for instantaneous effects and stratospheric adjustment. If the forcing is adjusted for processes occurring on time scales that are short compared to the climate stabilization time scale, then there is little centennial-time-scale evolution of effective climate sensitivity in any of the GCMs. Here it is suggested that much of the apparent variation in effective climate sensitivity identified in previous studies is actually due to the comparatively fast forcing adjustment.},
author = {Williams, Keith D. and Ingram, W. J. and Gregory, J. M.},
doi = {10.1175/2008JCLI2371.1},
isbn = {0894-8755},
issn = {1520-0442},
journal = {Journal of Climate},
month = {oct},
number = {19},
pages = {5076--5090},
title = {{Time Variation of Effective Climate Sensitivity in GCMs}},
url = {http://journals.ametsoc.org/doi/10.1175/2008JCLI2371.1},
volume = {21},
year = {2008}
}
@article{Williams2020a,
abstract = {The surface warming response to carbon emissions is diagnosed using a suite of Earth system models, 9 CMIP6 and 7 CMIP5, following an annual 1{\%} rise in atmospheric CO2 over 140 years. This surface warming response defines a climate metric, the Transient Climate Response to cumulative carbon Emissions (TCRE), which is important in estimating how much carbon may be emitted to avoid dangerous climate. The processes controlling these intermodel differences in the TCRE are revealed by defining the TCRE in terms of a product of three dependences: the surface warming dependence on radiative forcing (including the effects of physical climate feedbacks and planetary heat uptake), the radiative forcing dependence on changes in atmospheric carbon and the airborne fraction. Intermodel differences in the TCRE are mainly controlled by the thermal response involving the surface warming dependence on radiative forcing, which arise through large differences in physical climate feedbacks that are only partly compensated by smaller differences in ocean heat uptake. The other contributions to the TCRE from the radiative forcing and carbon responses are of comparable importance to the contribution from the thermal response on timescales of 50 years and longer for our subset of CMIP5 models and 100 years and longer for our subset of CMIP6 models. Hence, providing tighter constraints on how much carbon may be emitted based on the TCRE requires providing tighter bounds for estimates of the physical climate feedbacks, particularly from clouds, as well as to a lesser extent for the other contributions from the rate of ocean heat uptake, and the terrestrial and ocean cycling of carbon.},
author = {Williams, Richard G and Ceppi, Paulo and Katavouta, Anna},
doi = {10.1088/1748-9326/ab97c9},
issn = {1748-9326},
journal = {Environmental Research Letters},
number = {9},
pages = {0940c1},
publisher = {IOP Publishing},
title = {{Controls of the transient climate response to emissions by physical feedbacks, heat uptake and carbon cycling}},
url = {http://dx.doi.org/10.1088/1748-9326/ab97c9},
volume = {15},
year = {2020}
}
@article{Wing2014a,
abstract = {We elucidate the physics of self-aggregation by applying a new diagnostic technique to the output of a cloud resolving model. Specifically, the System for Atmospheric Modeling is used to perform 3- D cloud system resolving simulations of radiative-convective equilibrium in a nonrotating framework, with interactive radiation and surface fluxes and fixed sea surface temperature (SST). We note that self-aggregation begins as a dry patch that expands, eventually forcing all the convection into a single clump. Thus, when examining the initiation of self-aggregation, we focus on processes that can amplify this initial dry patch. We introduce a novel method to quantify the magnitudes of the various feedbacks that control self-aggregation within the framework of the budget for the spatial variance of column-integrated frozen moist static energy. The absorption of shortwave radiation by atmospheric water vapor is found to be a key positive feedback in the evolution of aggregation. In addition, we find a positive wind speed-surface flux feedback whose role is to counteract a negative feedback due to the effect of air-sea enthalpy disequilibrium on surface fluxes. The longwave radiation feedback can be either positive or negative in the early and intermediate stages of aggregation; however, it is the dominant positive feedback that maintains the aggregated state once it develops. Importantly, the mechanisms that maintain the aggregate state are distinct from those that instigate the evolution of self-aggregation.},
author = {Wing, Allison A. and Emanuel, Kerry A.},
doi = {10.1002/2013MS000269},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {convection,self-aggregation},
number = {1},
pages = {59--74},
title = {{Physical mechanisms controlling self-aggregation of convection in idealized numerical modeling simulations}},
volume = {6},
year = {2014}
}
@article{Wing2020,
abstract = {Abstract The Radiative-Convective Equilibrium Model Intercomparison Project (RCEMIP) is an intercomparison of multiple types of numerical models configured in radiative-convective equilibrium (RCE). RCE is an idealization of the tropical atmosphere that has long been used to study basic questions in climate science. Here, we employ RCE to investigate the role that clouds and convective activity play in determining cloud feedbacks, climate sensitivity, the state of convective aggregation, and the equilibrium climate. RCEMIP is unique among intercomparisons in its inclusion of a wide range of model types, including atmospheric general circulation models (GCMs), single column models (SCMs), cloud-resolving models (CRMs), large eddy simulations (LES), and global cloud-resolving models (GCRMs). The first results are presented from the RCEMIP ensemble of more than 30 models. While there are large differences across the RCEMIP ensemble in the representation of mean profiles of temperature, humidity, and cloudiness, in a majority of models anvil clouds rise, warm, and decrease in area coverage in response to an increase in sea surface temperature (SST). Nearly all models exhibit self-aggregation in large domains and agree that self-aggregation acts to dry and warm the troposphere, reduce high cloudiness, and increase cooling to space. The degree of self-aggregation exhibits no clear tendency with warming. There is a wide range of climate sensitivities, but models with parameterized convection tend to have lower climate sensitivities than models with explicit convection. In models with parameterized convection, aggregated simulations have lower climate sensitivities than unaggregated simulations.},
annote = {doi: 10.1029/2020MS002138},
author = {Wing, Allison A and Stauffer, Catherine L and Becker, Tobias and Reed, Kevin A and Ahn, Min-Seop and Arnold, Nathan P and Bony, Sandrine and Branson, Mark and Bryan, George H and Chaboureau, Jean-Pierre and {De Roode}, Stephan R and Gayatri, Kulkarni and Hohenegger, Cathy and Hu, I-Kuan and Jansson, Fredrik and Jones, Todd R and Khairoutdinov, Marat and Kim, Daehyun and Martin, Zane K and Matsugishi, Shuhei and Medeiros, Brian and Miura, Hiroaki and Moon, Yumin and M{\"{u}}ller, Sebastian K and Ohno, Tomoki and Popp, Max and Prabhakaran, Thara and Randall, David and Rios-Berrios, Rosimar and Rochetin, Nicolas and Roehrig, Romain and Romps, David M and {Ruppert Jr.}, James H and Satoh, Masaki and Silvers, Levi G and Singh, Martin S and Stevens, Bjorn and Tomassini, Lorenzo and van Heerwaarden, Chiel C and Wang, Shuguang and Zhao, Ming},
doi = {10.1029/2020MS002138},
issn = {1942-2466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {climate sensitivity,cloud feedbacks,clouds,convection,radiative-convective equilibrium,self-aggregation},
month = {sep},
number = {9},
pages = {e2020MS002138},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Clouds and Convective Self-Aggregation in a Multimodel Ensemble of Radiative–Convective Equilibrium Simulations}},
url = {https://doi.org/10.1029/2020MS002138},
volume = {12},
year = {2020}
}
@article{doi:10.1175/2009JCLI3113.1,
abstract = {Abstract The Paleocene–Eocene Thermal Maximum (PETM; 55 Ma) is of particular interest since it is regarded as a suitable analog to future climate change. In this study, the PETM climate is investigated using the Community Climate System Model (CCSM3) with atmospheric CO2 concentrations of 4×, 8×, and 16× the preindustrial value. Simulated climate change from 4× to 8× atmospheric CO2 concentration, possibly corresponding to an environmental precursor of the PETM event, leads to a warming of the North Atlantic Ocean Intermediate-Water masses, thus lowering the critical depth for methane hydrate destabilization by ∼500 m. A further increase from 8× to 16×CO2, analogous to a possible massive methane hydrate release, results in global oceanic warming and stratification. The increase in the radiative surface warming, especially at high latitudes, is partially offset by a decrease in the ocean heat transport due to a reduced overturning circulation. Surface temperature values simulated in the 16×CO2 PETM run represent the closest match to surface temperature reconstructions from proxies for this period. Simulated PETM precipitation, characterized by a slight northward shift of the intertropical convergence zone, increases at higher CO2 concentrations, especially for the northern midlatitudes as well as the high latitudes in both hemispheres. Data-inferred precipitation values and gradients for North America and Spain, for instance, are in good agreement with the 16×CO2 simulation. Increasing atmospheric CO2 concentrations might also have favored the release of terrestrial methane through warmer and wetter conditions over land, thus reinforcing the greenhouse gas concentration increase.},
author = {Winguth, A and Shellito, C and Shields, C and Winguth, C},
doi = {10.1175/2009JCLI3113.1},
journal = {Journal of Climate},
number = {10},
pages = {2562--2584},
title = {{Climate Response at the Paleocene–Eocene Thermal Maximum to Greenhouse Gas Forcing – A Model Study with CCSM3}},
url = {https://doi.org/10.1175/2009JCLI3113.1},
volume = {23},
year = {2010}
}
@article{Winterstein2019,
author = {Winterstein, Franziska and Tanalski, Fabian and J{\"{o}}ckel, Patrick and Dameris, Martin and Ponater, Michael},
doi = {10.5194/acp-19-7151-2019},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {may},
number = {10},
pages = {7151--7163},
title = {{Implication of strongly increased atmospheric methane concentrations for chemistry–climate connections}},
url = {https://acp.copernicus.org/articles/19/7151/2019/},
volume = {19},
year = {2019}
}
@article{Winton2013a,
abstract = {The influence of alternative ocean and atmosphere subcomponents on climate model simulation of transient sensitivities is examined by comparing three GFDL climate models used for phase 5 of the Coupled Model Intercomparison Project (CMIP5). The base model ESM2M is closely related to GFDL's CMIP3 climate model version 2.1 (CM2.1), and makes use of a depth coordinate ocean component. The second model, ESM2G, is identical to ESM2M but makes use of an isopycnal coordinate ocean model. The authors compare the impact of this “ocean swap” with an “atmosphere swap” that produces the GFDL Climate Model version 3 (CM3) by replacing the AM2 atmospheric component with AM3 while retaining a depth coordinate ocean model. The atmosphere swap is found to have much larger influence on sensitivities of global surface temperature and Northern Hemisphere sea ice cover. The atmosphere swap also introduces a multidecadal response time scale through its indirect influence on heat uptake. Despite significant differences in their interior ocean mean states, the ESM2M and ESM2G simulations of these metrics of climate change are very similar, except for an enhanced high-latitude salinity response accompanied by temporarily advancing sea ice in ESM2G. In the ESM2G historical simulation this behavior results in the establishment of a strong halocline in the subpolar North Atlantic during the early twentieth century and an associated cooling, which are counter to observations in that region. The Atlantic meridional overturning declines comparably in all three models.},
author = {Winton, Michael and Adcroft, Alistair and Griffies, Stephen M. and Hallberg, Robert W. and Horowitz, Larry W. and Stouffer, Ronald J.},
doi = {10.1175/JCLI-D-12-00121.1},
journal = {Journal of Climate},
month = {jan},
number = {1},
pages = {231--245},
title = {{Influence of Ocean and Atmosphere Components on Simulated Climate Sensitivities}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-12-00121.1},
volume = {26},
year = {2013}
}
@article{Winton2009,
abstract = {Abstract This article proposes a modification to the standard forcing?feedback diagnostic energy balance model to account for 1) differences between effective and equilibrium climate sensitivities and 2) the variation of effective sensitivity over time in climate change experiments with coupled atmosphere?ocean climate models. In the spirit of Hansen et al. an efficacy factor is applied to the ocean heat uptake. Comparing the time evolution of the surface warming in high and low efficacy models demonstrates the role of this efficacy in the transient response to CO2 forcing. Abrupt CO2 increase experiments show that the large efficacy of the Geophysical Fluid Dynamics Laboratory?s Climate Model version 2.1 (CM2.1) sets up in the first two decades following the increase in forcing. The use of an efficacy is necessary to fit this model?s global mean temperature evolution in periods with both increasing and stable forcing. The intermodel correlation of transient climate response with ocean heat uptake efficacy is greater than its correlation with equilibrium climate sensitivity in an ensemble of climate models used for the third and fourth Intergovernmental Panel on Climate Change (IPCC) assessments. When computed at the time of doubling in the standard experiment with 1{\%} yr?1 increase in CO2, the efficacy is variable amongst the models but is generally greater than 1, averages between 1.3 and 1.4, and is as large as 1.75 in several models.},
author = {Winton, Michael and Takahashi, Ken and Held, Isaac M.},
doi = {10.1175/2009JCLI3139.1},
isbn = {0894-8755},
issn = {0894-8755},
journal = {Journal of Climate},
month = {dec},
number = {9},
pages = {2333--2344},
publisher = {American Meteorological Society},
title = {{Importance of Ocean Heat Uptake Efficacy to Transient Climate Change}},
url = {https://doi.org/10.1175/2009JCLI3139.1},
volume = {23},
year = {2010}
}
@article{Winton2020,
abstract = {GFDL's new CM4.0 climate model has high transient and equilibrium climate sensitivities near the middle of the upper half of CMIP5 models. The CMIP5 models have been criticized for excessive sensitivity based on observations of present-day warming and heat uptake and estimates of radiative forcing. An ensemble of historical simulations with CM4.0 produces warming and heat uptake that are consistent with these observations under forcing that is at the middle of the assessed distribution. Energy budget-based methods for estimating sensitivities based on these quantities underestimate CM4.0's sensitivities when applied to its historical simulations. However, we argue using a simple attribution procedure that CM4.0's warming evolution indicates excessive transient sensitivity to greenhouse gases. This excessive sensitivity is offset prior to recent decades by excessive response to aerosol and land use changes.},
author = {Winton, M. and Adcroft, A. and Dunne, J. P. and Held, I. M. and Shevliakova, E. and Zhao, M. and Guo, H. and Hurlin, W. and Krasting, J. and Knutson, T. and Paynter, D. and Silvers, L. G. and Zhang, R.},
doi = {10.1029/2019MS001838},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
number = {1},
pages = {1--17},
title = {{Climate Sensitivity of GFDL's CM4.0}},
volume = {12},
year = {2020}
}
@article{Witkowskieaat4556,
abstract = {Past changes in the atmospheric concentration of carbon dioxide (Pco2) have had a major impact on earth system dynamics; yet, reconstructing secular trends of past Pco2 remains a prevalent challenge in paleoclimate studies. The current long-term Pco2 reconstructions rely largely on the compilation of many different proxies, often with discrepancies among proxies, particularly for periods older than 100 million years (Ma). Here, we reconstructed Phanerozoic Pco2 from a single proxy: the stable carbon isotopic fractionation associated with photosynthesis (Ɛp) that increases as Pco2 increases. This concept has been widely applied to alkenones, but here, we expand this concept both spatially and temporally by applying it to all marine phytoplankton via a diagenetic product of chlorophyll, phytane. We obtained data from 306 marine sediments and oils, which showed that Ɛp ranges from 11 to 24{\{}$\backslash$textperthousand{\}}, agreeing with the observed range of maximum fractionation of Rubisco (i.e., 25 to 28{\{}$\backslash$textperthousand{\}}). The observed secular Pco2 trend derived from phytane-based Ɛp mirrors the available compilations of Pco2 over the past 420 Ma, except for two periods in which our higher estimates agree with the warm climate during those time periods. Our record currently provides the longest secular trend in Pco2 based on a single marine proxy, covering the past 500 Ma of Earth history.},
author = {Witkowski, Caitlyn R and Weijers, Johan W H and Blais, Brian and Schouten, Stefan and {Sinninghe Damst{\'{e}}}, Jaap S},
doi = {10.1126/sciadv.aat4556},
issn = {2375-2548},
journal = {Science Advances},
month = {nov},
number = {11},
pages = {eaat4556},
publisher = {American Association for the Advancement of Science},
title = {{Molecular fossils from phytoplankton reveal secular PCO2 trend over the Phanerozoic}},
url = {https://advances.sciencemag.org/content/4/11/eaat4556 https://www.science.org/doi/10.1126/sciadv.aat4556},
volume = {4},
year = {2018}
}
@techreport{WMOWorldMeteorologicalOrganization2018,
address = {Geneva, Switzerland},
author = {WMO},
isbn = {978-1-7329317-1-8},
pages = {588},
publisher = {World Meteorological Organization (WMO)},
series = {Global Ozone Research and Monitoring Project – Report No. 58},
title = {{Scientific Assessment of Ozone Depletion: 2018}},
url = {https://csl.noaa.gov/assessments/ozone/2018/downloads/},
year = {2018}
}
@article{Wohland2020,
author = {Wohland, Jan and Brayshaw, David and Bloomfield, Hannah and Wild, Martin},
doi = {10.1088/1748-9326/aba7e6},
issn = {1748-9326},
journal = {Environmental Research Letters},
month = {sep},
number = {10},
pages = {104021},
title = {{European multidecadal solar variability badly captured in all centennial reanalyses except CERA20C}},
url = {https://iopscience.iop.org/article/10.1088/1748-9326/aba7e6},
volume = {15},
year = {2020}
}
@article{Wood2006,
abstract = {Observations in subtropical regions show that stratiform low cloud cover is well correlated with the lower-troposphere stability (LTS), defined as the difference in potential temperature $\theta$ between the 700-hPa level and the surface. The LTS can be regarded as a measure of the strength of the inversion that caps the planetary boundary layer (PBL). A stronger inversion is more effective at trapping moisture within the marine boundary layer (MBL), permitting greater cloud cover. This paper presents a new formulation, called the estimated inversion strength (EIS), to estimate the strength of the PBL inversion given the temperatures at 700 hPa and at the surface. The EIS accounts for the general observation that the free-tropospheric temperature profile is often close to a moist adiabat and its lapse rate is strongly temperature dependent. Therefore, for a given LTS, the EIS is greater at colder temperatures. It is demonstrated that while the seasonal cycles of LTS and low cloud cover fraction (CF) are strongly correlated in many regions, no single relationship between LTS and CF can be found that encompasses the wide range of temperatures occurring in the Tropics, subtropics, and midlatitudes. However, a single linear relationship between CF and EIS explains 83{\%} of the regional/seasonal variance in stratus cloud amount, suggesting that EIS is a more regime-independent predictor of stratus cloud amount than is LTS under a wide range of climatological conditions.},
author = {Wood, Robert and Bretherton, Christopher S.},
doi = {10.1175/JCLI3988.1},
isbn = {0894-8755},
issn = {1520-0442},
journal = {Journal of Climate},
month = {dec},
number = {24},
pages = {6425--6432},
title = {{On the Relationship between Stratiform Low Cloud Cover and Lower-Tropospheric Stability}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI3988.1},
volume = {19},
year = {2006}
}
@article{Woods2016,
abstract = {This paper examines the trajectories followed by intense intrusions of moist air into the Arctic polar region during autumn and winter and their impact on local temperature and sea ice concentration. It is found that the vertical structure of the warming associated with moist intrusions is bottom amplified, corresponding to a transition of local conditions from a “cold clear” state with a strong inversion to a “warm opaque” state with a weaker inversion. In the marginal sea ice zone of the Barents Sea, the passage of an intrusion also causes a retreat of the ice margin, which persists for many days after the intrusion has passed. The authors find that there is a positive trend in the number of intrusion events crossing 70°N during December and January that can explain roughly 45{\%} of the surface air temperature and 30{\%} of the sea ice concentration trends observed in the Barents Sea during the past two decades.},
author = {Woods, Cian and Caballero, Rodrigo},
doi = {10.1175/JCLI-D-15-0773.1},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Circulation/Dynamics,Climate change,Energy budget/balance,Energy transport,Ice loss/growth,Ice thickness,Moisture/moisture budget,Physical meteorology and climatology},
month = {jun},
number = {12},
pages = {4473--4485},
title = {{The Role of Moist Intrusions in Winter Arctic Warming and Sea Ice Decline}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-15-0773.1},
volume = {29},
year = {2016}
}
@article{Wyant-2006,
author = {Wyant, Matthew C and Bretherton, Christopher S and Bacmeister, Julio T and Kiehl, Jeffrey T and Held, Isaac M and Zhao, Ming and Klein, Stephen A and Soden, Brian J},
doi = {10.1007/s00382-006-0138-4},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {aug},
number = {2-3},
pages = {261--279},
title = {{A comparison of low-latitude cloud properties and their response to climate change in three AGCMs sorted into regimes using mid-tropospheric vertical velocity}},
url = {http://link.springer.com/10.1007/s00382-006-0138-4},
volume = {27},
year = {2006}
}
@article{doi:10.1029/2019PA003685,
abstract = {Abstract A controversial aspect of the Pliocene climate system is a posited permanent sea surface temperature (SST) distribution resembling that during El Ni{\~{n}}o events, which is largely inferred from sea surface temperatures reconstructed from several sites in the equatorial Pacific. We utilize a reduced-dimension methodology on a compilation of previously published multiproxy (Mg/Ca, Uk′37, TEX86, and foraminifer assemblages) Pliocene SST records from the equatorial Pacific to reconstruct spatial and temporal snapshots of SST anomalies and a time series of Ni{\~{n}}o indices from 5 to 1 Ma. The use of multiple proxies increases the number of study sites and thereby improves the robustness of the reconstruction. We find that the early Pliocene equatorial Pacific was characterized by a reduced zonal SST difference due to minimal change in the west and extreme warmth in the east which peaked at 4.3 Ma. The intensity of this mean El Ni{\~{n}}o-like SST state then gradually diminished toward modern conditions. We also use the Pliocene Ni{\~{n}}o 4 time series to estimate the past strength of Indian Summer Monsoon given the modern correlation of it to the Ni{\~{n}}o 4 index. Results indicate the monsoon was weaker throughout the study interval with weakest conditions ({\~{}}37{\%} less rainfall than modern) occurring at 4.3 Ma, congruent with regional proxy records. In summation, this reduced-dimension approach spatially and temporally resolves the warm mean state of the Pliocene equatorial Pacific and has numerous applications to inferences of paleoclimate conditions in distal regions teleconnected to El Ni{\~{n}}o today.},
annote = {e2019PA003685 2019PA003685},
author = {Wycech, J B and Gill, E and Rajagopalan, B and {Marchitto Jr}, T M and Molnar, P H},
doi = {10.1029/2019PA003685},
journal = {Paleoceanography and Paleoclimatology},
keywords = {El Ni{\~{n}}o,Pliocene,Principal Component Analysis,multi-proxy,paleoceanography,sea surface temperature},
number = {1},
pages = {e2019PA003685},
title = {{Multiproxy Reduced-Dimension Reconstruction of Pliocene Equatorial Pacific Sea Surface Temperatures}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019PA003685},
volume = {35},
year = {2020}
}
@article{Xia2020,
abstract = {Recent studies demonstrate that the Antarctic Ozone Hole has important influences on Antarctic sea ice. While most of these works have focused on effects associated with atmospheric and oceanic dynamic processes caused by stratospheric ozone changes, here we show that stratospheric ozone-induced cloud radiative effects also play important roles in causing changes in Antarctic sea ice. Our simulations demonstrate that the recovery of the Antarctic Ozone Hole causes decreases in clouds over Southern Hemisphere (SH) high latitudes and increases in clouds over the SH extratropics. The decrease in clouds leads to a reduction in downward infrared radiation, especially in austral autumn. This results in cooling of the Southern Ocean surface and increasing Antarctic sea ice. Surface cooling also involves ice-albedo feedback. Increasing sea ice reflects solar radiation and causes further cooling and more increases in Antarctic sea ice.},
author = {Xia, Yan and Hu, Yongyun and Liu, Jiping and Huang, Yi and Xie, Fei and Lin, Jintai},
doi = {10.1007/s00376-019-8251-6},
issn = {0256-1530},
journal = {Advances in Atmospheric Sciences},
keywords = {Antarctic sea ice,climate change,cloud radiative effects,ice-albedo feedback,stratospheric ozone recovery},
month = {may},
number = {5},
pages = {505--514},
title = {{Stratospheric Ozone-induced Cloud Radiative Effects on Antarctic Sea Ice}},
url = {http://link.springer.com/10.1007/s00376-019-8251-6},
volume = {37},
year = {2020}
}
@article{Xia2016,
abstract = {Abstract. We investigate the climatic impact of stratospheric ozone recovery (SOR), with a focus on the surface temperature change in atmosphere–slab ocean coupled climate simulations. We find that although SOR would cause significant surface warming (global mean: 0.2 K) in a climate free of clouds and sea ice, it causes surface cooling (−0.06 K) in the real climate. The results here are especially interesting in that the stratosphere-adjusted radiative forcing is positive in both cases. Radiation diagnosis shows that the surface cooling is mainly due to a strong radiative effect resulting from significant reduction of global high clouds and, to a lesser extent, from an increase in high-latitude sea ice. Our simulation experiments suggest that clouds and sea ice are sensitive to stratospheric ozone perturbation, which constitutes a significant radiative adjustment that influences the sign and magnitude of the global surface temperature change.},
author = {Xia, Yan and Hu, Yongyun and Huang, Yi},
doi = {10.5194/acp-16-7559-2016},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jun},
number = {12},
pages = {7559--7567},
title = {{Strong modification of stratospheric ozone forcing by cloud and sea-ice adjustments}},
url = {https://acp.copernicus.org/articles/16/7559/2016/},
volume = {16},
year = {2016}
}
@article{Xie2010,
abstract = {Spatial variations in sea surface temperature (SST) and rainfall changes over the tropics are investigated based on ensemble simulations for the first half of the twenty-first century under the greenhouse gas (GHG) emission scenario A1B with coupled ocean–atmosphere general circulation models of the Geophysical Fluid Dynamics Laboratory (GFDL) and National Center for Atmospheric Research (NCAR). Despite a GHG increase that is nearly uniform in space, pronounced patterns emerge in both SST and precipitation. Regional differences in SST warming can be as large as the tropical-mean warming. Specifically, the tropical Pacific warming features a conspicuous maximum along the equator and a minimum in the southeast subtropics. The former is associated with westerly wind anomalies whereas the latter is linked to intensified southeast trade winds, suggestive of wind–evaporation–SST feedback. There is a tendency for a greater warming in the northern subtropics than in the southern subtropics in accordance with asymmetries in trade wind changes. Over the equatorial Indian Ocean, surface wind anomalies are easterly, the thermocline shoals, and the warming is reduced in the east, indicative of Bjerknes feedback. In the midlatitudes, ocean circulation changes generate narrow banded structures in SST warming. The warming is negatively correlated with wind speed change over the tropics and positively correlated with ocean heat transport change in the northern extratropics. A diagnostic method based on the ocean mixed layer heat budget is developed to investigate mechanisms for SST pattern formation.},
author = {Xie, Shang-Ping and Deser, Clara and Vecchi, Gabriel A. and Ma, Jian and Teng, Haiyan and Wittenberg, Andrew T.},
doi = {10.1175/2009JCLI3329.1},
isbn = {0894-8755},
issn = {1520-0442},
journal = {Journal of Climate},
month = {feb},
number = {4},
pages = {966--986},
pmid = {11182606},
title = {{Global Warming Pattern Formation: Sea Surface Temperature and Rainfall}},
url = {http://journals.ametsoc.org/doi/10.1175/2009JCLI3329.1},
volume = {23},
year = {2010}
}
@article{Xie2016b,
author = {Xie, Bing and Zhang, Hua and Wang, Zhili and Zhao, Shuyun and Fu, Qiang},
doi = {10.1007/s00376-016-5193-0},
issn = {0256-1530},
journal = {Advances in Atmospheric Sciences},
month = {jul},
number = {7},
pages = {819--828},
title = {{A modeling study of effective radiative forcing and climate response due to tropospheric ozone}},
url = {http://link.springer.com/10.1007/s00376-016-5193-0},
volume = {33},
year = {2016}
}
@article{ISI:000289548200016,
abstract = {This study investigated the decadal variation of the direct surface solar radiation (DiSR) and the diffuse surface solar radiation (DfSR) during 1961-2008 in the Shanghai megacity as well as their relationships to Aerosol Optical Depth (AOD) under clear-sky conditions. Three successive periods with unique features of long term variation of DiSR were identified for both clear-sky and all-sky conditions: a ``dimming{\{}''{\}} period from the late 1960s to the mid 1980s, a ``stabilization{\{}''{\}}/{\{}''{\}}slight brightening{\{}''{\}} period from the mid 1980s to the mid 1990s, and a ``renewed dimming{\{}''{\}} period thereafter. During the two dimming periods of DiSR, DfSR brightened significantly under clear-sky conditions, indicating that change in atmospheric transparency resulting from aerosol emission has an important role on decadal variation of surface solar radiation (SSR) over this area. The analysis on the relationship between the Moderate-resolution Imaging Spectroradiometer (MODIS) retrieved AOD and the corresponding hourly measurements of DiSR and DfSR under clear-sky conditions clearly revealed that AOD is significantly correlated and anti-correlated with DfSR and DiSR, respectively, both above 99{\%} confidence in all seasons, indicating the great impact of aerosols on SSR through absorption and/or scattering in the atmosphere. In addition, both AOD and the corresponding DiSR and DfSR measured during the satellite passage over Shanghai show obvious weekly cycles. On weekends, AOD is lower than the weekly average, corresponding to higher DiSR and lower DfSR, while the opposite pattern was true for weekdays. Less AOD on weekends due to the reduction of transportation and industrial activities results in enhancement of atmospheric transparency under cloud free conditions so as to increase DiSR and decrease DfSR simultaneously. Results show that aerosol loading from the anthropogenic emissions is an important modulator for the long term variation of SSR in Shanghai.},
author = {Xu, J and Li, C and Shi, H and He, Q and Pan, L},
doi = {10.5194/acp-11-3281-2011},
issn = {1680-7316},
journal = {Atmospheric Chemistry and Physics},
number = {7},
pages = {3281--3289},
title = {{Analysis on the impact of aerosol optical depth on surface solar radiation in the Shanghai megacity, China}},
volume = {11},
year = {2011}
}
@article{doi:10.1002/2016EF000417,
abstract = {Abstract Global mean surface temperatures (GMST) exhibited a smaller rate of warming during 1998–2013, compared to the warming in the latter half of the 20th Century. Although, not a “true” hiatus in the strict definition of the word, this has been termed the “global warming hiatus” by IPCC (2013). There have been other periods that have also been defined as the “hiatus” depending on the analysis. There are a number of uncertainties and knowledge gaps regarding the “hiatus.” This report reviews these issues and also posits insights from a collective set of diverse information that helps us understand what we do and do not know. One salient insight is that the GMST phenomenon is a surface characteristic that does not represent a slowdown in warming of the climate system but rather is an energy redistribution within the oceans. Improved understanding of the ocean distribution and redistribution of heat will help better monitor Earth's energy budget and its consequences. A review of recent scientific publications on the “hiatus” shows the difficulty and complexities in pinpointing the oceanic sink of the “missing heat” from the atmosphere and the upper layer of the oceans, which defines the “hiatus.” Advances in “hiatus” research and outlooks (recommendations) are given in this report.},
author = {Yan, Xiao-Hai and Boyer, Tim and Trenberth, Kevin and Karl, Thomas R and Xie, Shang-Ping and Nieves, Veronica and Tung, Ka-Kit and Roemmich, Dean},
doi = {10.1002/2016EF000417},
journal = {Earth's Future},
keywords = {Global warming hiatus,Heat energy,Ocean monitoring},
number = {11},
pages = {472--482},
title = {{The global warming hiatus: Slowdown or redistribution?}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016EF000417},
volume = {4},
year = {2016}
}
@article{ISI:000432465200007,
abstract = {This paper presents a method to homogenize China's surface solar radiation (SSR) data and uses the resulting homogenized SSR data to assess the SSR trend over the period 1958–2016. Neighboring surface sunshine duration (SSD) data are used as reference data to assess the SSR data homogeneity. A principal component analysis is applied to build a reference series, which is proven to be less sensitive to occasional data issues than using the arithmetic mean of data from adjacent stations. A relative or absolute test is applied to detect changepoints, depending on whether or not a suitable reference series is available. A quantile-matching method is used to adjust the data to diminish the inhomogeneities. As a result, 60 out of the 119 SSR stations were found to have inhomogeneity issues. These were mainly caused by changes in instrument and observation schedule. The nonclimatic changes exaggerated the SSR change rates in 1991–93 and resulted in a sudden rise in the national average SSR series, causing an unrealistically drastic trend reversal in the 1990s. This was diminished by the data homogenization. The homogenized data show that the national average SSR has been declining significantly over the period 1958–90; this dimming trend mostly diminished over the period 1991–2005 and was replaced by a brightening trend in the recent decade. From the homogenized SSR data, the 1958–90 and 1958–2005 dimming rate is estimated to be −6.13 ± 0.47 and −5.08 ± 0.27 W m−2 decade−1, respectively, and the 2005–16 brightening rate is 6.13 ± 1.77 W m−2 decade−1.},
address = {45 BEACON ST, BOSTON, MA 02108-3693 USA},
author = {Yang, Su and Wang, Xiaolan L and Wild, Martin},
doi = {10.1175/JCLI-D-17-0891.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jun},
number = {11},
pages = {4529--4541},
publisher = {AMER METEOROLOGICAL SOC},
title = {{Homogenization and Trend Analysis of the 1958–2016 In Situ Surface Solar Radiation Records in China}},
type = {Article},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-17-0891.1},
volume = {31},
year = {2018}
}
@article{ISI:000481476900001,
abstract = {This paper presents a study on long-term surface solar radiation (SSR) changes over China under clear- and all-sky conditions and analyzes the causes of the ``dimming{\{}''{\}} and ``brightening.{\{}''{\}} To eliminate the nonclimatic signals in the historical records, the daily SSR dataset was first homogenized using quantile-matching (QM) adjustment. The results reveal rapid dimming before 2000 not only under all-sky conditions, but also under clear-sky conditions, at a decline rate of -9.7 +/- 0.4 W m(-2) decade(-1) (1958-99). This is slightly stronger than that under all-sky conditions at -7.4 +/- 0.4 W m(-2) decade(-1), since the clear-sky dimming stopped 15 years later. A rapid ``wettening{\{}''{\}} of about 40-Pa surface water vapor pressure (SWVP) from 1985 to 2000 was found over China. It contributed 2.2{\%} to the SSR decline under clear-sky conditions during the whole dimming period (1958-99). Therefore, water vapor cannot be the main cause of the long-term dimming in China. After a stable decade (1999-2008), an intensive brightening appeared under the clear-sky conditions at a rate of 10.6 +/- 2.0 W m(-2) decade(-1), whereas a much weaker brightening (-0.8 +/- 3.1 W m(-2) decade(-1)) has been observed under all-sky conditions between 2008 and 2016. The remarkable divergence between clear- and all-sky trends in recent decades indicates that the clouds played two opposite roles in the SSR changes during the past 30 years, by compensating for the declining SSR under the cloud-free conditions in 1985-99 and by counteracting the increasing SSR under cloud-free conditions in 2008-16. Aerosols remain as the main cause of dimming and brightening over China in the last 60 years, although the clouds counteract the effects of aerosols after 2000.},
author = {Yang, Su and Wang, Xiaolan L and Wild, Martin},
doi = {10.1175/JCLI-D-18-0666.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {18},
pages = {5901--5913},
title = {{Causes of Dimming and Brightening in China Inferred from Homogenized Daily Clear-Sky and All-Sky in situ Surface Solar Radiation Records (1958–2016)}},
volume = {32},
year = {2019}
}
@article{doi:10.1002/2014JD022977,
abstract = {AbstractDust, black carbon (BC), and organic carbon (OC) aerosols, when deposited onto snow, are known to reduce the albedo of the snow (i.e., snow darkening effect (SDE)). Here using the NASA Goddard Earth Observing System Model, Version 5 (GEOS-5) with aerosol tracers and a state-of-the-art snow darkening module (GOddard SnoW Impurity Module: GOSWIM) for the land surface, we examine the role of SDE on climate in the boreal spring snowmelt season. SDE is found to produce significant surface warming (over 15 W m−2) over broad areas in midlatitudes, with dust being the most important contributor to the warming in central Asia and the western Himalayas and with BC having larger impact in the Europe, eastern Himalayas, East Asia, and North America. The contribution of OC to the warming is generally low but still significant mainly over southeastern Siberia, northeastern East Asia, and western Canada ({\~{}}19{\%} of the total solar visible absorption by these snow impurities). The simulations suggest that SDE strengthens the boreal spring water cycle in East Asia through water recycling and moisture advection from the ocean and contributes to the maintenance of dry conditions in parts of a region spanning Europe to central Asia, partially through feedback on the model's background climatology. Overall, our study suggests that the existence of SDE in the Earth system associated with dust, BC, and OC contributes significantly to enhanced surface warming over continents in northern hemisphere midlatitudes during boreal spring, raising the surface skin temperature by approximately 3–6 K near the snowline.},
author = {Yasunari, Teppei J and Koster, Randal D and Lau, William K M and Kim, Kyu-Myong},
doi = {10.1002/2014JD022977},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {black carbon,climate,dust,global model,organic carbon,snow darkening},
month = {jun},
number = {11},
pages = {5485--5503},
title = {{Impact of snow darkening via dust, black carbon, and organic carbon on boreal spring climate in the Earth system}},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2014JD022977 https://onlinelibrary.wiley.com/doi/abs/10.1002/2014JD022977},
volume = {120},
year = {2015}
}
@article{Yeo2020,
abstract = {How the solar electromagnetic energy entering the Earth's atmosphere varied since preindustrial times is an important consideration in the climate change debate. Detrimental to this debate, estimates of the change in total solar irradiance (TSI) since the Maunder minimum, an extended period of weak solar activity preceding the industrial revolution, differ markedly, ranging from a drop of 0.75 W m−2 to a rise of 6.3 W m−2. Consequently, the exact contribution by solar forcing to the rise in global temperatures over the past centuries remains inconclusive. Adopting a novel approach based on state-of-the-art solar imagery and numerical simulations, we establish the TSI level of the Sun when it is in its least-active state to be 2.0 ± 0.7 W m−2 below the 2019 level. This means TSI could not have risen since the Maunder minimum by more than this amount, thus restricting the possible role of solar forcing in global warming.},
author = {Yeo, K. L. and Solanki, S. K. and Krivova, N. A. and Rempel, M. and Anusha, L. S. and Shapiro, A. I. and Tagirov, R. V. and Witzke, V.},
doi = {10.1029/2020GL090243},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {oct},
number = {19},
pages = {e2020GL090243},
publisher = {Blackwell Publishing Ltd},
title = {{The Dimmest State of the Sun}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL090243},
volume = {47},
year = {2020}
}
@article{Yoshimori2011,
abstract = {Climate sensitivity is one of the most important metrics for future climate projections. In previous studies the climate of the last glacial maximum has been used to constrain the range of climate sensitivity, and similarities and differences of temperature response to the forcing of the last glacial maximum and to idealized future forcing have been investigated. The feedback processes behind the response have not, however, been fully explored in a large model parameter space. In this study, the authors first examine the performance of various feedback analysis methods that identify important feedbacks for a physics parameter ensemble in experiments simulating both past and future climates. The selected methods are then used to reveal the relationship between the different ensemble experiments in terms of individual feedback processes. For the first time, all of the major feedback processes for an ensemble of paleoclimate simulations are evaluated. It is shown that the feedback and climate sensitivity parameters depend on the nature of the forcing and background climate state. The forcing dependency arises through the shortwave cloud feedback while the state dependency arises through the combined water vapor and lapse-rate feedback. The forcing dependency is, however, weakened when the feedback is estimated from the forcing that includes tropospheric adjustments. Despite these dependencies, past climate can still be used to provide a useful constraint on climate sensitivity as long as the limitation is properly taken into account because the strength of each feedback correlates reasonably well between the ensembles. It is, however, shown that the physics parameter ensemble does not cover the range of results simulated by structurally different models, which suggests the need for further study exploring both structural and parameter uncertainties.},
author = {Yoshimori, Masakazu and Hargreaves, Julia C. and Annan, James D. and Yokohata, Tokuta and Abe-Ouchi, Ayako},
doi = {10.1175/2011JCLI3954.1},
isbn = {0894-8755},
issn = {08948755},
journal = {Journal of Climate},
keywords = {Climate sensitivity,Cloud radiative effects,Feedback,Forcing,Temperature},
number = {24},
pages = {6440--6455},
title = {{Dependency of feedbacks on forcing and climate state in physics parameter ensembles}},
volume = {24},
year = {2011}
}
@article{Yoshimori2017,
abstract = {It is well known that the Arctic warms much more than the rest of the world even under spatially quasi-uniform radiative forcing such as that due to an increase in atmospheric CO2 concentration. While the surface albedo feedback is often referred to as the explanation of the enhanced Arctic warming, the importance of atmospheric heat transport from the lower latitudes has also been reported in previous studies. In the current study, an attempt is made to understand how the regional feedbacks in the Arctic are induced by the change in atmospheric heat transport and vice versa. Equilibrium sensitivity experiments that enable us to separate the contributions of the Northern Hemisphere mid-high latitude response to the CO2 increase and the remote influence of surface warming in other regions are carried out. The result shows that the effect of remote forcing is predominant in the Arctic warming. The dry-static energy transport to the Arctic is reduced once the Arctic surface warms in response to the local or remote forcing. The feedback analysis based on the energy budget reveals that the increased moisture transport from lower latitudes, on the other hand, warms the Arctic in winter more effectively not only via latent heat release but also via greenhouse effect of water vapor and clouds. The change in total atmospheric heat transport determined as a result of counteracting dry-static and latent heat components, therefore, is not a reliable measure for the net effect of atmospheric dynamics on the Arctic warming. The current numerical experiments support a recent interpretation based on the regression analysis: the concurrent reduction in the atmospheric poleward heat transport and future Arctic warming predicted in some models does not imply a minor role of the atmospheric dynamics. Despite the similar magnitude of poleward heat transport change, the Arctic warms more than the Southern Ocean even in the equilibrium response without ocean dynamics. It is shown that a large negative shortwave cloud feedback over the Southern Ocean, greatly influenced by low-latitude surface warming, is responsible for this asymmetric polar warming.},
author = {Yoshimori, Masakazu and Abe-Ouchi, Ayako and La{\^{i}}n{\'{e}}, Alexandre},
doi = {10.1007/s00382-017-3523-2},
isbn = {0123456789},
issn = {0930-7575},
journal = {Climate Dynamics},
month = {nov},
number = {9-10},
pages = {3457--3472},
title = {{The role of atmospheric heat transport and regional feedbacks in the Arctic warming at equilibrium}},
url = {http://link.springer.com/10.1007/s00382-017-3523-2},
volume = {49},
year = {2017}
}
@article{Yoshimori2020,
abstract = {The fixed anvil temperature (FAT) theory describes a mechanism for how tropical anvil clouds respond to global warming and has been used to argue for a robust positive longwave cloud feedback. A constant cloud anvil temperature, due to increased anvil altitude, has been argued to lead to a “zero cloud emission change” feedback, which can be considered positive relative to the negative feedback associated with cloud anvil warming when cloud altitude is unchanged. Here, partial radiative perturbation (PRP) analysis is used to quantify the radiative feedback caused by clouds that follow the FAT theory (FAT–cloud feedback) and to set this in the context of other feedback components in two atmospheric general circulation models. The FAT–cloud feedback is positive in the PRP framework due to increasing anvil altitude, but because the cloud emission does not change, this positive feedback is cancelled by an equal and opposite component of the temperature feedback due to increasing emission from the cloud. To incorporate this cancellation, the thermal radiative damping with fixed relative humidity and anvil temperature (T-FRAT) decomposition framework is proposed for longwave feedbacks, in which temperature, fixed relative humidity, and FAT–cloud feedbacks are combined. In T-FRAT, the cloud feedback under the FAT constraint is zero, while that under the proportionately higher anvil temperature (PHAT) constraint is negative. The change in the observable cloud radiative effect with FAT–cloud response is also evaluated and shown to be negative due to so-called cloud masking effects. It is shown that “cloud masking” is a misleading term in this context, and these effects are interpreted more generally as “cloud climatology effects.”},
author = {Yoshimori, Masakazu and Lambert, F Hugo and Webb, Mark J and Andrews, Timothy},
doi = {10.1175/JCLI-D-19-0108.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {mar},
number = {7},
pages = {2719--2739},
title = {{Fixed Anvil Temperature Feedback: Positive, Zero, or Negative?}},
url = {https://doi.org/10.1175/JCLI-D-19-0108.1},
volume = {33},
year = {2020}
}
@article{10.1175/2009JCLI2801.1,
abstract = {Studies of the climate in the past potentially provide a constraint on the uncertainty of climate sensitivity, but previous studies warn against a simple scaling to the future. Climate sensitivity is determined by a number of feedback processes, and they may vary according to climate states and forcings. In this study, the similarities and differences in feedbacks for CO2 doubling, a Last Glacial Maximum (LGM), and LGM greenhouse gas (GHG) forcing experiments are investigated using an atmospheric general circulation model coupled to a slab ocean model. After computing the radiative forcing, the individual feedback strengths of water vapor, lapse-rate, albedo, and cloud feedbacks are evaluated explicitly. For this particular model, the difference in the climate sensitivity between the experiments is attributed to the shortwave cloud feedback, in which there is a tendency for it to become weaker or even negative in cooling experiments. No significant difference is found in the water vapor feedback between warming and cooling experiments by GHGs. The weaker positive water vapor feedback in the LGM experiment resulting from a relatively weaker tropical forcing is compensated for by the stronger positive lapse-rate feedback resulting from a relatively stronger extratropical forcing. A hypothesis is proposed that explains the asymmetric cloud response between the warming and cooling experiments associated with a displacement of the region of mixed-phase clouds. The difference in the total feedback strength between the experiments is, however, relatively small compared to the current intermodel spread, and does not necessarily preclude the use of LGM climate as a future constraint.},
author = {Yoshimori, Masakazu and Yokohata, Tokuta and Abe-Ouchi, Ayako},
doi = {10.1175/2009JCLI2801.1},
issn = {0894-8755},
journal = {Journal of Climate},
number = {12},
pages = {3374--3395},
title = {{A Comparison of Climate Feedback Strength between CO2 Doubling and LGM Experiments}},
url = {https://doi.org/10.1175/2009JCLI2801.1},
volume = {22},
year = {2009}
}
@article{You2013a,
abstract = {In this study, the annual and seasonal variations of all-sky and clear-sky surface solar radiation (SSR) in the eastern and central Tibetan Plateau (TP) during the period 1960-2009 are investigated, based on surface observational data, reanalyses and ensemble simulations with the global climate model ECHAM5-HAM. The mean annual all-sky SSR series shows a decreasing trend with a rate of -1.00 Wm(-2) decade(-1), which is mainly seen in autumn and secondly in summer and winter. A stronger decrease of -2.80 Wm(-2) decade(-1) is found in the mean annual clear-sky SSR series, especially during winter and autumn. Overall, these results confirm a tendency towards a decrease of SSR in the TP during the last five decades. The comparisons with reanalysis show that both NCEP/NCAR and ERA-40 reanalyses do not capture the decadal variations of the all-sky and clear-sky SSR. This is probably due to a missing consideration of aerosols in the reanalysis assimilation model. The SSR simulated with the ECHAM5-HAM global climate model under both all-sky and clear-sky conditions reproduce the decrease seen in the surface observations, especially after 1980. The steadily increasing aerosol optical depth (AOD) at 550 nm over the TP in the ECHAM5-HAM results suggests transient aerosol emissions as a plausible cause.},
address = {You, Ql Chinese Acad Sci, Inst Tibetan Plateau Res, Lab Tibetan Environm Changes {\&} Land Surface Proc, Beijing 100085, Peoples R China Chinese Acad Sci, Inst Tibetan Plateau Res, Lab Tibetan Environm Changes {\&} Land Surface Proc, Beijing 100085, Peoples R C},
annote = {119CV
Times Cited:5
Cited References Count:59},
author = {You, Q L and Sanchez-Lorenzo, A and Wild, M and Folini, D and Fraedrich, K and Ren, G Y and Kang, S C},
doi = {10.1007/S00382-012-1383-3},
issn = {0930-7575},
journal = {Climate Dynamics},
keywords = {surface solar radiation ncep/ncar era-40 echam5-ha},
language = {English},
number = {7-8},
pages = {2073--2086},
title = {{Decadal variation of surface solar radiation in the Tibetan Plateau from observations, reanalysis and model simulations}},
volume = {40},
year = {2013}
}
@article{ISI:000456386600011,
abstract = {The ocean interacts with the atmosphere via interfacial exchanges of momentum, heat (via radiation and convection), and fresh water (via evaporation and precipitation). These fluxes, or exchanges, constitute the ocean-surface energy and water budgets and define the ocean's role in Earth's climate and its variability on both short and long timescales. However, direct flux measurements are available only at limited locations. Air-sea fluxes are commonly estimated from bulk flux parameterization using flux-related near-surface meteorological variables (winds, sea and air temperatures, and humidity) that are available from buoys, ships, satellite remote sensing, numerical weather prediction models, and/or a combination of any of these sources. Uncertainties in parameterization-based flux estimates are large, and when they are integrated over the ocean basins, they cause a large imbalance in the global-ocean budgets. Despite the significant progress that has been made in quantifying surface fluxes in the past 30 years, achieving a global closure of ocean-surface energy and water budgets remains a challenge for flux products constructed from all data sources. This review provides a personal perspective on three questions: First, to what extent can time-series measurements from air-sea buoys be used as benchmarks for accuracy and reliability in the context of the budget closures? Second, what is the dominant source of uncertainties for surface flux products, the flux-related variables or the bulk flux algorithms? And third, given the coupling between the energy and water cycles, precipitation and surface radiation can act as twin budget constraints-are the community-standard precipitation and surface radiation products pairwise compatible?},
author = {Yu, Lisan},
doi = {10.1146/annurev-marine-010816-060704},
editor = {{Carlson, CA and Giovannoni}, SJ},
issn = {1941-1405},
journal = {Annual Review of Marine Science},
keywords = {global-ocean energy budget,global-ocean freshwate},
pages = {227--248},
publisher = {ANNUAL REVIEWS},
series = {Annual Review of Marine Science},
title = {{Global Air–Sea Fluxes of Heat, Fresh Water, and Momentum: Energy Budget Closure and Unanswered Questions}},
volume = {11},
year = {2019}
}
@article{Yu2014,
abstract = {The impact of solar variations on particle formation and cloud condensation nuclei (CCN), a critical step for one of the possible solar indirect climate forcing pathways, is studied here with a global aerosol model optimized for simulating detailed particle formation and growth processes. The effect of temperature change in enhancing the solar cycle CCN signal is investigated for the first time. Our global simulations indicate that a decrease in ionization rate associated with galactic cosmic ray flux change from solar minimum to solar maximum reduces annual mean nucleation rates, number concentration of condensation nuclei larger than 10nm (CN10), and number concentrations of CCN at water supersaturation ratio of 0.8{\%} (CCN0.8) and 0.2{\%} (CCN0.2) in the lower troposphere by 6.8{\%}, 1.36{\%}, 0.74{\%}, and 0.43{\%}, respectively. The inclusion of 0.2 C temperature increase enhances the CCN solar cycle signals by around 50{\%}. The annual mean solar cycle CCN signals have large spatial and seasonal variations: (1) stronger in the lower troposphere where warm clouds are formed, (2) about 50{\%} larger in the northern hemisphere than in the southern hemisphere, and (3) about a factor of two larger during the corresponding hemispheric summer seasons. The effect of solar cycle perturbation on CCN0.2 based on present study is generally higher than those reported in several previous studies, up to around one order of magnitude. {\textcopyright} 2014 IOP Publishing Ltd.},
author = {Yu, Fangqun and Luo, Gan},
doi = {10.1088/1748-9326/9/4/045004},
issn = {17489326},
journal = {Environmental Research Letters},
keywords = {cloud condensation nuclei,effect of temperature change,galactic cosmic ray,ionmediated nucleation,particle formation,solar cycle,solar variations},
number = {4},
pages = {045004},
publisher = {Institute of Physics Publishing},
title = {{Effect of solar variations on particle formation and cloud condensation nuclei}},
volume = {9},
year = {2014}
}
@article{Yuan2011,
abstract = {{\textless}p{\textgreater}{\textless}p{\textgreater}{\textless}strong{\textgreater}Abstract.{\textless}/strong{\textgreater} Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-term degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount, is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.{\textless}/p{\textgreater}{\textless}/p{\textgreater}},
author = {Yuan, T. and Remer, L. A. and Yu, H.},
doi = {10.5194/acp-11-7119-2011},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jul},
number = {14},
pages = {7119--7132},
title = {{Microphysical, macrophysical and radiative signatures of volcanic aerosols in trade wind cumulus observed by the A-Train}},
url = {https://www.atmos-chem-phys.net/11/7119/2011/},
volume = {11},
year = {2011}
}
@article{Zaehle2015,
abstract = {Coupled carbon cycle–climate models in the Coupled Model Intercomparison Project, phase 5 (CMIP5), Earth system model ensemble simulate the effects of changes in anthropogenic fossil-fuel emissions and ensuing climatic changes on the global carbon (C) balance but largely ignore the consequences of widespread terrestrial nitrogen (N) limitation. Based on plausible ranges of terrestrial C:N stoichiometry, this study investigates whether the terrestrial C sequestration projections of nine CMIP5 models for four representative concentration pathways (RCPs) are consistent with estimates of N supply from increased biological fixation, atmospheric deposition, and reduced ecosystem N losses. Discrepancies between the timing and places of N demand and supply indicated increases in terrestrial N implicit to the projections of all nine CMIP5 models under all scenarios that are larger than the estimated N supply. Omitting N constraints leads to an overestimation of land C sequestration in these models between the years 1860 and 2100 by between 97 Pg C (69–252 Pg C; RCP 2.6) and 150 Pg C (57–323 Pg C; RCP 8.5), with a large spread across models. The CMIP5 models overestimated the average 2006–2100 fossil-fuel emissions required to keep atmospheric CO2 levels on the trajectories described in the RCP scenarios by between 0.6 Pg C yr−1 (0.4–2.2 Pg C yr−1; RCP 2.6) and 1.2 Pg C yr−1 (0.5–3.3 Pg C yr−1; RCP 8.5). If unabated, reduced land C sequestration would enhance CO2 accumulation in the ocean and atmosphere, increasing atmospheric CO2 burden by 26 ppm (16–88 ppm; RCP 2.6) to 61 ppm (29–147 ppm; RCP 8.5) by the year 2100.},
author = {Zaehle, S{\"{o}}nke and Jones, Chris D. and Houlton, Benjamin and Lamarque, Jean-Francois and Robertson, Eddy},
doi = {10.1175/JCLI-D-13-00776.1},
isbn = {0894-8755},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Carbon dioxide,Climate change,Ecological models,Ecosystem effects,Land surface model,Vegetation-atmosphere interactions},
month = {mar},
number = {6},
pages = {2494--2511},
title = {{Nitrogen Availability Reduces CMIP5 Projections of Twenty-First-Century Land Carbon Uptake}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-13-00776.1},
volume = {28},
year = {2015}
}
@article{Zaliapin2010,
abstract = {Abstract. We revisit a recent claim that the Earth's climate system is characterized by sensitive dependence to parameters; in particular, that the system exhibits an asymmetric, large-amplitude response to normally distributed feedback forcing. Such a response would imply irreducible uncertainty in climate change predictions and thus have notable implications for climate science and climate-related policy making. We show that equilibrium climate sensitivity in all generality does not support such an intrinsic indeterminacy; the latter appears only in essentially linear systems. The main flaw in the analysis that led to this claim is inappropriate linearization of an intrinsically nonlinear model; there is no room for physical interpretations or policy conclusions based on this mathematical error. Sensitive dependence nonetheless does exist in the climate system, as well as in climate models – albeit in a very different sense from the one claimed in the linear work under scrutiny – and we illustrate it using a classical energy balance model (EBM) with nonlinear feedbacks. EBMs exhibit two saddle-node bifurcations, more recently called "tipping points," which give rise to three distinct steady-state climates, two of which are stable. Such bistable behavior is, furthermore, supported by results from more realistic, nonequilibrium climate models. In a truly nonlinear setting, indeterminacy in the size of the response is observed only in the vicinity of tipping points. We show, in fact, that small disturbances cannot result in a large-amplitude response, unless the system is at or near such a point. We discuss briefly how the distance to the bifurcation may be related to the strength of Earth's ice-albedo feedback.},
archivePrefix = {arXiv},
arxivId = {1003.0253},
author = {Zaliapin, I and Ghil, M},
doi = {10.5194/npg-17-113-2010},
eprint = {1003.0253},
issn = {1607-7946},
journal = {Nonlinear Processes in Geophysics},
month = {mar},
number = {2},
pages = {113--122},
title = {{Another look at climate sensitivity}},
url = {www.nonlin-processes-geophys.net/17/113/2010/ https://npg.copernicus.org/articles/17/113/2010/},
volume = {17},
year = {2010}
}
@article{Zanatta2016,
author = {Zanatta, M. and Gysel, M. and Bukowiecki, N. and M{\"{u}}ller, T. and Weingartner, E. and Areskoug, H. and Fiebig, M. and Yttri, K.E. and Mihalopoulos, N. and Kouvarakis, G. and Beddows, D. and Harrison, R.M. and Cavalli, F. and Putaud, J.P. and Spindler, G. and Wiedensohler, A. and Alastuey, A. and Pandolfi, M. and Sellegri, K. and Swietlicki, E. and Jaffrezo, J.L. and Baltensperger, U. and Laj, P.},
doi = {10.1016/J.ATMOSENV.2016.09.035},
issn = {1352-2310},
journal = {Atmospheric Environment},
month = {nov},
pages = {346--364},
publisher = {Pergamon},
title = {{A European aerosol phenomenology-5: Climatology of black carbon optical properties at 9 regional background sites across Europe}},
url = {https://www.sciencedirect.com/science/article/pii/S135223101630735X?via{\%}3Dihub},
volume = {145},
year = {2016}
}
@article{Zanna1126,
abstract = {Since the 19th century, rising greenhouse gas concentrations have caused the ocean to absorb most of the Earth{\{}$\backslash$textquoteright{\}}s excess heat and warm up. Before the 1990s, most ocean temperature measurements were above 700 m and therefore, insufficient for an accurate global estimate of ocean warming. We present a method to reconstruct ocean temperature changes with global, full-depth ocean coverage, revealing warming of 436 {\{}$\backslash$texttimes{\}}1021 J since 1871. Our reconstruction, which agrees with other estimates for the well-observed period, demonstrates that the ocean absorbed as much heat during 1921{\{}$\backslash$textendash{\}}1946 as during 1990{\{}$\backslash$textendash{\}}2015. Since the 1950s, up to one-half of excess heat in the Atlantic Ocean at midlatitudes has come from other regions via circulation-related changes in heat transport.Most of the excess energy stored in the climate system due to anthropogenic greenhouse gas emissions has been taken up by the oceans, leading to thermal expansion and sea-level rise. The oceans thus have an important role in the Earth{\{}$\backslash$textquoteright{\}}s energy imbalance. Observational constraints on future anthropogenic warming critically depend on accurate estimates of past ocean heat content (OHC) change. We present a reconstruction of OHC since 1871, with global coverage of the full ocean depth. Our estimates combine timeseries of observed sea surface temperatures with much longer historical coverage than those in the ocean interior together with a representation (a Green{\{}$\backslash$textquoteright{\}}s function) of time-independent ocean transport processes. For 1955{\{}$\backslash$textendash{\}}2017, our estimates are comparable with direct estimates made by infilling the available 3D time-dependent ocean temperature observations. We find that the global ocean absorbed heat during this period at a rate of 0.30 {\{}$\backslash$textpm{\}} 0.06 W/m2 in the upper 2,000 m and 0.028 {\{}$\backslash$textpm{\}} 0.026 W/m2 below 2,000 m, with large decadal fluctuations. The total OHC change since 1871 is estimated at 436 {\{}$\backslash$textpm{\}} 91 {\{}$\backslash$texttimes{\}}1021 J, with an increase during 1921{\{}$\backslash$textendash{\}}1946 (145 {\{}$\backslash$textpm{\}} 62 {\{}$\backslash$texttimes{\}}1021 J) that is as large as during 1990{\{}$\backslash$textendash{\}}2015. By comparing with direct estimates, we also infer that, during 1955{\{}$\backslash$textendash{\}}2017, up to one-half of the Atlantic Ocean warming and thermosteric sea-level rise at low latitudes to midlatitudes emerged due to heat convergence from changes in ocean transport.},
author = {Zanna, Laure and Khatiwala, Samar and Gregory, Jonathan M. and Ison, Jonathan and Heimbach, Patrick},
doi = {10.1073/pnas.1808838115},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
number = {4},
pages = {1126--1131},
pmid = {30617081},
publisher = {National Academy of Sciences},
title = {{Global reconstruction of historical ocean heat storage and transport}},
url = {https://www.pnas.org/content/116/4/1126},
volume = {116},
year = {2019}
}
@article{Zarakas2020,
abstract = {Increasing concentrations of CO 2 in the atmosphere influence climate both through CO 2 's role as a greenhouse gas and through its impact on plants. Plants respond to atmospheric CO 2 concentrations in several ways that can alter surface energy and water fluxes and thus surface climate, including changes in stomatal conductance, water use, and canopy leaf area. These plant physiological responses are already embedded in most Earth system models, and a robust literature demonstrates that they can affect global-scale temperature. However, the physiological contribution to transient warming has yet to be assessed systematically in Earth system models. Here this gap is addressed using carbon cycle simulations from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP) to isolate the radiative and physiological contributions to the transient climate response (TCR), which is defined as the change in globally averaged near-surface air temperature during the 20-yr window centered on the time of CO 2 doubling relative to preindustrial CO 2 concentrations. In CMIP6 models, the physiological effect contributes 0.12°C ( $\sigma$ : 0.09°C; range: 0.02°–0.29°C) of warming to the TCR, corresponding to 6.1{\%} of the full TCR ( $\sigma$ : 3.8{\%}; range: 1.4{\%}–13.9{\%}). Moreover, variation in the physiological contribution to the TCR across models contributes disproportionately more to the intermodel spread of TCR estimates than it does to the mean. The largest contribution of plant physiology to CO 2 -forced warming—and the intermodel spread in warming—occurs over land, especially in forested regions.},
author = {Zarakas, Claire M. and Swann, Abigail L. S. and Lagu{\"{e}}, Marysa M. and Armour, Kyle C. and Randerson, James T.},
doi = {10.1175/JCLI-D-20-0078.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {19},
pages = {8561--8578},
title = {{Plant Physiology Increases the Magnitude and Spread of the Transient Climate Response to CO2 in CMIP6 Earth System Models}},
url = {https://journals.ametsoc.org/doi/10.1175/JCLI-D-20-0078.1},
volume = {33},
year = {2020}
}
@article{Zelinka2012a,
abstract = {Feedbacks determine the efficiency with which the climate system comes back into equilibrium in response to a radiative perturbation. Although feedbacks are integrated quantities, the processes from which they arise have rich spatial structures that alter the distribution of top of atmosphere (TOA) net radiation. Here, the authors investigate the implications of the structure of climate feedbacks for the change in poleward energy transport as the planet warms over the twenty-first century in a suite of GCMs. Using radiative kernels that describe the TOA radiative response to small perturbations in temperature, water vapor, and surface albedo, the change in poleward energy flux is partitioned into the individual feedbacks that cause it.},
author = {Zelinka, Mark D. and Hartmann, Dennis L.},
doi = {10.1175/JCLI-D-11-00096.1},
isbn = {0894-8755$\backslash$r1520-0442},
issn = {0894-8755},
journal = {Journal of Climate},
keywords = {Climate change,Climate sensitivity,Energy transport,Feedback,Fluxes,Forcing,General circulation models,Heat budgets,Radiation budgets,Radiative forcing},
month = {jan},
number = {2},
pages = {608--624},
title = {{Climate Feedbacks and Their Implications for Poleward Energy Flux Changes in a Warming Climate}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-11-00096.1},
volume = {25},
year = {2012}
}
@article{Zelinka2014,
author = {Zelinka, Mark D. and Andrews, Timothy and Forster, Piers M. and Taylor, Karl E.},
doi = {10.1002/2014JD021710},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
number = {12},
pages = {7599--7615},
title = {{Quantifying components of aerosol–cloud–radiation interactions in climate models}},
volume = {119},
year = {2014}
}
@article{Zelinka2016a,
author = {Zelinka, M. D. and Zhou, C. and Klein, S. A.},
doi = {10.1002/2016GL069917},
journal = {Geophysical Research Letters},
pages = {9259--9269},
title = {{Insights from a refined decomposition of cloud feedbacks}},
volume = {43},
year = {2016}
}
@article{Zelinka2018,
abstract = {AbstractThe long-standing expectation that poleward shifts of the midlatitude jet under global warming will lead to poleward shifts of clouds and a positive radiative feedback on the climate system has been shown to be misguided by several recent studies. On interannual time scales, free-tropospheric clouds are observed to shift along with the jet, but low clouds increase across a broad expanse of the North Pacific Ocean basin, resulting in negligible changes in total cloud fraction and top-of-atmosphere radiation. Here it is shown that this low-cloud response is consistent across eight independent satellite-derived cloud products. Using multiple linear regression, it is demonstrated that the spatial pattern and magnitude of the low-cloud-coverage response is primarily driven by anomalous surface temperature advection. In the eastern North Pacific, anomalous cold advection by anomalous northerly surface winds enhances sensible and latent heat fluxes from the ocean into the boundary layer, resulting in large increases in low-cloud coverage. Local increases in low-level stability make a smaller contribution to this low-cloud increase. Despite closely capturing the observed response of large-scale meteorology to jet shifts, global climate models largely fail to capture the observed response of clouds and radiation to interannual jet shifts because they systematically underestimate how sensitive low clouds are to surface temperature advection, and to a lesser extent, low-level stability. More realistic model simulations of cloud?radiation?jet interactions require that parameterizations more accurately capture the sensitivity of low clouds to surface temperature advection.},
author = {Zelinka, Mark D and Grise, Kevin M and Klein, Stephen A and Zhou, Chen and DeAngelis, Anthony M and Christensen, Matthew W},
doi = {10.1175/JCLI-D-18-0114.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {jul},
number = {19},
pages = {7925--7947},
publisher = {American Meteorological Society},
title = {{Drivers of the Low-Cloud Response to Poleward Jet Shifts in the North Pacific in Observations and Models}},
url = {https://doi.org/10.1175/JCLI-D-18-0114.1},
volume = {31},
year = {2018}
}
@article{Zelinka-grl-smi-2019,
author = {Zelinka, Mark D. and Myers, Timothy A. and McCoy, Daniel T. and Po‐Chedley, Stephen and Caldwell, Peter M. and Ceppi, Paulo and Klein, Stephen A. and Taylor, Karl E.},
doi = {10.1029/2019GL085782},
issn = {0094-8276},
journal = {Geophysical Research Letters},
month = {jan},
pages = {2019GL085782},
title = {{Causes of higher climate sensitivity in CMIP6 models}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GL085782},
volume = {46},
year = {2020}
}
@article{Zhai2015a,
abstract = {Abstract The large spread of model equilibrium climate sensitivity (ECS) is mainly caused by the differences in the simulated marine boundary layer cloud (MBLC) radiative feedback. We examine the variations of MBLC fraction in response to the changes of sea surface temperature (SST) at seasonal and centennial time scales for 27 climate models that participated in the Coupled Model Intercomparison Project phase 3 and phase 5. We find that the intermodel spread in the seasonal variation of MBLC fraction with SST is strongly correlated with the intermodel spread in the centennial MBLC fraction change per degree of SST warming and that both are well correlated with ECS. Seven models that are consistent with the observed seasonal variation of MBLC fraction with SST at a rate ?1.28?±?0.56{\%}/K all have ECS higher than the multimodel mean of 3.3?K yielding an ensemble-mean ECS of 3.9?K and a standard deviation of 0.45?K.},
annote = {doi: 10.1002/2015GL065911},
author = {Zhai, Chengxing and Jiang, Jonathan H and Su, Hui},
doi = {10.1002/2015GL065911},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {boundary layer cloud feedback,climate sensitivity,global warming response,long-term climate change,marine boundary layer cloud,seasonal variation},
month = {oct},
number = {20},
pages = {8729--8737},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Long-term cloud change imprinted in seasonal cloud variation: More evidence of high climate sensitivity}},
url = {https://doi.org/10.1002/2015GL065911},
volume = {42},
year = {2015}
}
@article{Zhang2015b,
abstract = {Incident solar radiation (R-s) over the Earth's surface is important for studying our climate and environment Global observation networks have been established, but many land surfaces are under-represented. Satellite remote sensing is the only way to estimate R-s at both global and regional scales. Many efforts have been made to evaluate the accuracy of current R-s products generated from satellite observations, but only a limited amount of ground measurements was generally used and the individual satellite products were used for analyzing R-s variability. In this study, four satellite estimates of R-s, including the Global Energy and Water Cycle Experiment - Surface Radiation Budget (GEWEX-SRB V3.0), the International Satellite Cloud Climatology Project - Flux Data (ISCCP-FD), the University of Maryland (UMD)/Shortwave Radiation Budget (SRB) (UMD-SRB V3.33) product, and the Earth's Radiant Energy System (CERES) EBAF, were evaluated using comprehensive ground measurements at 1151 sites around the world from the Global Energy Balance Archive (GEBA) and the China Meteorological Administration (CMA). It was found that these satellite estimates of R-s agree better with surface measurements at monthly than at daily time scale and can capture the seasonal variation of R-s very well, but these satellite products overestimated R-s by approximately 10w m(-2). The mean bias and the root mean square error (RMSE) of the monthly mean estimates from these four data sets were 10.2 w m(-2) and 24.8 w m(-2) respectively. The global annual mean values of R-s were 186.7 w m(-2), 185.4 w m(-2), and 188.6 w m(-2) for CERES-EBAF, ISCCP-FD, and GEWEX-SRB V3.0 respectively. The averaged global annual mean R-s value from ground-measured-calibrated three satellite derived R-s products was 180.6 w m(-2), which is smaller than that estimated from individual satellite-derived products. The CERES-EBAF product shows the best accuracy among these four data sets, which indicates that including more accurate cloud information from active instruments can improve the accuracy of R-s. These satellite products show different temporal trends. Both GEWEX-SRB V3.0 and ISCCP-FD showed similar trends at the global scale but with different magnitudes. A significant dimming was found between 1984 and 1991, followed by brightening from 1992 to 2000, and then by a significant dimming over 2001-2007. The CERES-EBAF product showed a brightening trend, but not significantly since 2000. The variability from satellite estimates at pixel level was also analyzed. The results are comparable with previous studies based on observed R-s at the surface for specific regions, although some inconsistencies still exist and the magnitudes of the variations should be further quantified. We also found that clouds contribute more to the long-term variations of R-s derived from satellite observations than aerosols. (C) 2015 Elsevier Inc. All rights reserved.},
address = {Zhang, XT Beijing Normal Univ, Sch Geog, State Key Lab Remote Sensing Sci, Beijing 100875, Peoples R China Beijing Normal Univ, Sch Geog, State Key Lab Remote Sensing Sci, Beijing 100875, Peoples R China Beijing Normal Univ, Sch Geog, State Key Lab Remote},
annote = {Cm2xk
Times Cited:0
Cited References Count:95},
author = {Zhang, X T and Liang, S L and Wild, M and Jiang, B},
doi = {10.1016/j.rse2015.05.015},
issn = {0034-4257},
journal = {Remote Sensing of Environment},
keywords = {incident shortwave radiation remote sensing satell},
language = {English},
pages = {186--202},
title = {{Analysis of surface incident shortwave radiation from four satellite products}},
volume = {165},
year = {2015}
}
@article{Zhang2014,
abstract = {An analysis method proposed by Huang is improved and used to dissect the radiative forcing in the instantaneous quadrupling CO2 experiment from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Multiple validation tests show that the errors in the forcing estimates are generally within 10{\%}. The results show that quadrupling CO2, on average, induces a global-mean all-sky instantaneous top-of-the-atmosphere forcing of 5.4W m-2, which is amended by a stratospheric adjustment of 1.9W m-2 and a tropospheric adjustment of 20.1Wm-2. The resulting fully adjusted radiative forcing has an ensemble mean of 7.2W m-2 and a substantial intermodel spread (maximum-minimum) of 2.4W m-2, which results from all the forcing components, especially the instantaneous forcing and tropospheric adjustment. The fidelity of the linear decomposition of the overall radiation variation is improved when forcing is explicitly estimated for each model. A significant contribution by forcing uncertainty to the intermodel spread of the surface temperature projection is verified. The results reaffirm the importance of evaluating the radiative forcing components in climate feedback analyses. {\textcopyright} 2014 American Meteorological Society.},
author = {Zhang, M. and Huang, Y.},
doi = {10.1175/JCLI-D-13-00535.1},
journal = {Journal of Climate},
number = {7},
pages = {2496--2508},
title = {{Radiative Forcing of Quadrupling CO2}},
volume = {27},
year = {2014}
}
@article{Zhang2016,
abstract = {In hematopoietic cells, the signals initiated by activation of the phosphoinositide 3-kinase (PI3K) family have been implicated in cell proliferation and survival, membrane and cytoskeletal reorganization, chemotaxis, and the neutrophil respiratory burst. Of the four isoforms of human PI3K that phosphorylate phosphatidylinositol 4, 5-bisphosphate, only p110gamma (or PI3Kgamma) is associated with the regulatory subunit, p101, and is stimulated by G protein betagamma heterodimers. We performed immunolocalization of transfected p110gamma in HepG2 cells and found that, under resting conditions, p110gamma was present in a diffuse cytoplasmic pattern, but translocated to the cell nucleus after serum stimulation. Serum-stimulated p110gamma translocation was inhibited by pertussis toxin and could also be induced by overexpression of Gbetagamma in the absence of serum. In addition, we found that deletion of the amino-terminal 33 residues of p110gamma had no effect on association with p101 or on its agonist-regulated translocation, but truncation of the amino-terminal 82 residues yielded a p110gamma variant that did not associate with p101 and was constitutively localized in the nucleus. This finding implies that the intracellular localization of p110gamma is regulated by p101 as well as Gbetagamma. The effect of PI3Kgamma in the nucleus is an area of active investigation.},
author = {Zhang, Hua and Zhao, Shuyun and Wang, Zhili and Zhang, Xiaoye and Song, Lianchun},
doi = {10.1002/joc.4613},
issn = {10970088},
journal = {International Journal of Climatology},
number = {12},
pages = {4029--4044},
title = {{The updated effective radiative forcing of major anthropogenic aerosols and their effects on global climate at present and in the future}},
volume = {36},
year = {2016}
}
@article{ISI:000430108900002,
abstract = {All the weather and climate models participating in the Clouds Above the United States and Errors at the Surface project show a summertime surface air temperature (T2m) warm bias in the region of the central United States. To understand the warm bias in long-term climate simulations, we assess the Atmospheric Model Intercomparison Project simulations from the Coupled Model Intercomparison Project Phase 5, with long-term observations mainly from the Atmospheric Radiation Measurement program Southern Great Plains site. Quantities related to the surface energy and water budget, and large-scale circulation are analyzed to identify possible factors and plausible links involved in the warm bias. The systematic warm season bias is characterized by an overestimation of T2m and underestimation of surface humidity, precipitation, and precipitable water. Accompanying the warm bias is an overestimation of absorbed solar radiation at the surface, which is due to a combination of insufficient cloud reflection and clear-sky shortwave absorption by water vapor and an underestimation in surface albedo. The bias in cloud is shown to contribute most to the radiation bias. The surface layer soil moisture impacts T2m through its control on evaporative fraction. The error in evaporative fraction is another important contributor to T2m. Similar sources of error are found in hindcast from other Clouds Above the United States and Errors at the Surface studies. In Atmospheric Model Intercomparison Project simulations, biases in meridional wind velocity associated with the low-level jet and the 500hPa vertical velocity may also relate to T2m bias through their control on the surface energy and water budget.},
author = {Zhang, Chengzhu and Xie, Shaocheng and Klein, Stephen A and Ma, Hsi-yen and Tang, Shuaiqi and {Van Weverberg}, Kwinten and Morcrette, Cyril J and Petch, Jon},
doi = {10.1002/2017JD027200},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
month = {mar},
number = {6},
pages = {2968--2992},
title = {{CAUSES: Diagnosis of the Summertime Warm Bias in CMIP5 Climate Models at the ARM Southern Great Plains Site}},
volume = {123},
year = {2018}
}
@article{Zhang2014a,
abstract = {The surface ocean temperature gradient between the warmer Western Equatorial Pacific and the cooler Eastern Equatorial Pacific is smaller during El Ni{\~{n}}o episodes than during neutral periods or during La Ni{\~{n}}as. Some reconstructions of Pacific Ocean sea surface temperatures (SST) covering periods before ∼3 million years ago have suggested a permanent El Ni{\~{n}}o–like state. Zhang et al. (p. 84; see the Perspective by Lea) present data from a biomarker-derived proxy for SST that indicate a sizable east-west gradient has existed for the past 12 million years, contradicting the concept of a permanent El Ni{\~{n}}o–like state existed. The appearance of permanent El Ni{\~{n}}o–like conditions prior to 3 million years ago is founded on sea-surface temperature (SST) reconstructions that show invariant Pacific warm pool temperatures and negligible equatorial zonal temperature gradients. However, only a few SST records are available, and these are potentially compromised by changes in seawater chemistry, diagenesis, and calibration limitations. For this study, we establish new biomarker-SST records and show that the Pacific warm pool was {\~{}}4°C warmer 12 million years ago. Both the warm pool and cold tongue slowly cooled toward modern conditions while maintaining a zonal temperature gradient of {\~{}}3°C in the late Miocene, which increased during the Plio-Pleistocene. Our results contrast with previous temperature reconstructions that support the supposition of a permanent El Ni{\~{n}}o–like state.},
author = {Zhang, Yi Ge and Pagani, Mark and Liu, Zhonghui},
doi = {10.1126/science.1246172},
issn = {0036-8075},
journal = {Science},
month = {apr},
number = {6179},
pages = {84--87},
title = {{A 12-Million-Year Temperature History of the Tropical Pacific Ocean}},
url = {https://www.science.org/doi/10.1126/science.1246172},
volume = {344},
year = {2014}
}
@article{Zhang2018i,
abstract = {Purified cyanobacterial lipopolysaccharide (LPS) was not acutely toxic to three aquatic invertebrates (Artemia salina, Daphnia magna and Daphnia galeata) in immersion trials. However, pre-exposure (24 h) to 2 ngmL(-1) LPS increased the LC(50) of microcystin-LR significantly in all 3 species. Similar results were observed with A. salina pre-treated with the same concentration of cyanobacterial LPS and subsequently exposed to cylindrospermopsin, increasing the LC(50) by 8. The findings indicate the need to include exposures to defined combinations of cyanotoxins, and in defined sequences, to understand the contributions of individual cyanotoxins in accounting for cyanobacterial toxicity to invertebrates in natural aquatic environments.},
author = {Zhang, W. and Miller, P. A. and Jansson, C. and Samuelsson, P. and Mao, J. and Smith, B.},
doi = {10.1029/2018GL077830},
issn = {19448007},
journal = {Geophysical Research Letters},
number = {14},
pages = {7102--7111},
pmid = {16982077},
title = {{Self-Amplifying Feedbacks Accelerate Greening and Warming of the Arctic}},
volume = {45},
year = {2018}
}
@article{Zhang201915258,
abstract = {The Arctic has warmed significantly since the early 1980s and much of this warming can be attributed to the surface albedo feedback. In this study, satellite observations reveal a 1.25 to 1.51{\%} per decade absolute reduction in the Arctic mean surface albedo in spring and summer during 1982 to 2014. Results from a global model and reanalysis data are used to unravel the causes of this albedo reduction. We find that reductions of terrestrial snow cover, snow cover fraction over sea ice, and sea ice extent appear to contribute equally to the Arctic albedo decline. We show that the decrease in snow cover fraction is primarily driven by the increase in surface air temperature, followed by declining snowfall. Although the total precipitation has increased as the Arctic warms, Arctic snowfall is reduced substantially in all analyzed data sets. Light-absorbing soot in snow has been decreasing in past decades over the Arctic, indicating that soot heating has not been the driver of changes in the Arctic snow cover, ice cover, and surface albedo since the 1980s.},
author = {Zhang, Rudong and Wang, Hailong and Fu, Qiang and Rasch, Philip J and Wang, Xuanji},
doi = {10.1073/pnas.1915258116},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
month = {nov},
number = {48},
pages = {23947--23953},
publisher = {National Academy of Sciences},
title = {{Unraveling driving forces explaining significant reduction in satellite-inferred Arctic surface albedo since the 1980s}},
url = {https://www.pnas.org/content/early/2019/11/05/1915258116 http://www.pnas.org/lookup/doi/10.1073/pnas.1915258116},
volume = {116},
year = {2019}
}
@article{Zhang2018k,
abstract = {Abstract We compare various radiative feedbacks over the Arctic (60?90°N) estimated from short-term climate variations occurring in reanalysis, satellite, and global climate model data sets using the combined Kernel-Gregory approach. The lapse rate and surface albedo feedbacks are positive, and their magnitudes are comparable. Relative to the tropics (30°S?30°N), the lapse rate feedback is the largest contributor to Arctic amplification among all feedbacks, followed by surface albedo feedback and Planck feedback deviation from its global mean. Both shortwave and longwave water vapor feedbacks are positive, leading to a significant positive net water vapor feedback over the Arctic. The net cloud feedback has large uncertainties including its sign, which strongly depends on the data used for all-sky and clear-sky radiative fluxes at the top of the atmosphere, the time periods considered, and the methods used to estimate the cloud feedback.},
annote = {doi: 10.1029/2018GL077852},
author = {Zhang, Rudong and Wang, Hailong and Fu, Qiang and Pendergrass, Angeline G and Wang, Minghuai and Yang, Yang and Ma, Po-Lun and Rasch, Philip J},
doi = {10.1029/2018GL077852},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {Arctic amplification,climate modeling,radiative feedback,reanalysis data,satellite data,surface albedo},
month = {jun},
number = {11},
pages = {5761--5770},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Local Radiative Feedbacks Over the Arctic Based on Observed Short-Term Climate Variations}},
url = {https://doi.org/10.1029/2018GL077852},
volume = {45},
year = {2018}
}
@article{Zhang2021,
abstract = {{\textless}p{\textgreater}{\textless}![CDATA[Abstract. In the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), coupled climate models have been used to simulate an interglacial climate during the mid-Piacenzian warm period (mPWP; 3.264 to 3.025 Ma). Here, we compare the Atlantic Meridional Overturning Circulation (AMOC), poleward ocean heat transport and sea surface warming in the Atlantic simulated with these models. In PlioMIP2, all models simulate an intensified mid-Pliocene AMOC. However, there is no consistent response in the simulated Atlantic ocean heat transport nor in the depth of the Atlantic overturning cell. The models show a large spread in the simulated AMOC maximum, the Atlantic ocean heat transport and the surface warming in the North Atlantic. Although a few models simulate a surface warming of ∼ 8–12 ∘C in the North Atlantic, similar to the reconstruction from Pliocene Research, Interpretation and Synoptic Mapping (PRISM) version 4, most models appear to underestimate this warming. The large model spread and model–data discrepancies in the PlioMIP2 ensemble do not support the hypothesis that an intensification of the AMOC, together with an increase in northward ocean heat transport, is the dominant mechanism for the mid-Pliocene warm climate over the North Atlantic.]]{\textgreater}{\textless}/p{\textgreater}},
author = {Zhang, Zhongshi and Li, Xiangyu and Guo, Chuncheng and Otter{\aa}, Odd Helge and Nisancioglu, Kerim H. and Tan, Ning and Contoux, Camille and Ramstein, Gilles and Feng, Ran and Otto-Bliesner, Bette L. and Brady, Esther and Chandan, Deepak and Peltier, W. Richard and Baatsen, Michiel L. J. and von der Heydt, Anna S. and Weiffenbach, Julia E. and Stepanek, Christian and Lohmann, Gerrit and Zhang, Qiong and Li, Qiang and Chandler, Mark A. and Sohl, Linda E. and Haywood, Alan M. and Hunter, Stephen J. and Tindall, Julia C. and Williams, Charles and Lunt, Daniel J. and Chan, Wing-Le and Abe-Ouchi, Ayako},
doi = {10.5194/cp-17-529-2021},
issn = {1814-9332},
journal = {Climate of the Past},
month = {feb},
number = {1},
pages = {529--543},
title = {{Mid-Pliocene Atlantic Meridional Overturning Circulation simulated in PlioMIP2}},
url = {https://cp.copernicus.org/articles/17/529/2021/},
volume = {17},
year = {2021}
}
@article{Zhao2018c,
abstract = {Abstract. The interactions between aerosols and ice clouds represent one of the largest uncertainties in global radiative forcing from pre-industrial time to the present. In particular, the impact of aerosols on ice crystal effective radius (Rei), which is a key parameter determining ice clouds' net radiative effect, is highly uncertain due to limited and conflicting observational evidence. Here we investigate the effects of aerosols on Rei under different meteorological conditions using 9-year satellite observations. We find that the responses of Rei to aerosol loadings are modulated by water vapor amount in conjunction with several other meteorological parameters. While there is a significant negative correlation between Rei and aerosol loading in moist conditions, consistent with the “Twomey effect” for liquid clouds, a strong positive correlation between the two occurs in dry conditions. Simulations based on a cloud parcel model suggest that water vapor modulates the relative importance of different ice nucleation modes, leading to the opposite aerosol impacts between moist and dry conditions. When ice clouds are decomposed into those generated from deep convection and formed in situ, the water vapor modulation remains in effect for both ice cloud types, although the sensitivities of Rei to aerosols differ noticeably between them due to distinct formation mechanisms. The water vapor modulation can largely explain the difference in the responses of Rei to aerosol loadings in various seasons. A proper representation of the water vapor modulation is essential for an accurate estimate of aerosol–cloud radiative forcing produced by ice clouds. ]]{\textgreater}},
author = {Zhao, Bin and Liou, Kuo-Nan and Gu, Yu and Jiang, Jonathan H. and Li, Qinbin and Fu, Rong and Huang, Lei and Liu, Xiaohong and Shi, Xiangjun and Su, Hui and He, Cenlin},
doi = {10.5194/acp-18-1065-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jan},
number = {2},
pages = {1065--1078},
title = {{Impact of aerosols on ice crystal size}},
url = {https://www.atmos-chem-phys.net/18/1065/2018/},
volume = {18},
year = {2018}
}
@article{Zhao,
abstract = {This study explores the effects of black carbon (BC) and sulfate (SO 4 ) on global and tropical precipitation with a climate model. Results show that BC causes a decrease in global annual mean precipitation, consisting of a large negative tendency of a fast precipitation response scaling with instantaneous atmospheric absorption and a small positive tendency of a slow precipitation response scaling with the BC-caused global warming. SO 4 also causes a decrease in global annual mean precipitation, which is dominated by a slow precipitation response corresponding to the surface cooling caused by SO 4 . BC causes a northward shift of the intertropical convergence zone (ITCZ), mainly through a fast precipitation response, whereas SO 4 causes a southward shift of the ITCZ through a slow precipitation response. The displacements of the ITCZ caused by BC and SO 4 are found to linearly correlate with the corresponding changes in cross-equatorial heat transport in the atmosphere, with a regression coefficient of about −3° PW −1 , implying that the ITCZ shifts occur as manifestations of the atmospheric cross-equatorial heat transport changes in response to the BC and SO 4 forcings. The atmospheric cross-equatorial heat transport anomaly caused by BC is basically driven by the BC-induced interhemispheric contrast in instantaneous atmospheric absorption, whereas the atmospheric cross-equatorial heat transport anomaly caused by SO 4 is mostly attributable to the response of evaporation. It is found that a slab-ocean model exaggerates the cross-equatorial heat transport response in the atmosphere and the ITCZ shift both for BC and SO 4 , as compared with an ocean-coupled model. This underscores the importance of using an ocean-coupled model in modeling studies of the tropical climate response to aerosols.},
author = {Zhao, Shuyun and Suzuki, Kentaroh},
doi = {10.1175/JCLI-D-18-0616.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {sep},
number = {17},
pages = {5567--5582},
title = {{Differing Impacts of Black Carbon and Sulfate Aerosols on Global Precipitation and the ITCZ Location via Atmosphere and Ocean Energy Perturbations}},
url = {http://journals.ametsoc.org/doi/10.1175/JCLI-D-18-0616.1},
volume = {32},
year = {2019}
}
@article{Zhao2015,
abstract = {AbstractUncertainty in equilibrium climate sensitivity impedes accurate climate projections. While the intermodel spread is known to arise primarily from differences in cloud feedback, the exact processes responsible for the spread remain unclear. To help identify some key sources of uncertainty, the authors use a developmental version of the next-generation Geophysical Fluid Dynamics Laboratory global climate model (GCM) to construct a tightly controlled set of GCMs where only the formulation of convective precipitation is changed. The different models provide simulation of present-day climatology of comparable quality compared to the model ensemble from phase 5 of CMIP (CMIP5). The authors demonstrate that model estimates of climate sensitivity can be strongly affected by the manner through which cumulus cloud condensate is converted into precipitation in a model?s convection parameterization, processes that are only crudely accounted for in GCMs. In particular, two commonly used methods for converting cumulus condensate into precipitation can lead to drastically different climate sensitivity, as estimated here with an atmosphere?land model by increasing sea surface temperatures uniformly and examining the response in the top-of-atmosphere energy balance. The effect can be quantified through a bulk convective detrainment efficiency, which measures the ability of cumulus convection to generate condensate per unit precipitation. The model differences, dominated by shortwave feedbacks, come from broad regimes ranging from large-scale ascent to subsidence regions. Given current uncertainties in representing convective precipitation microphysics and the current inability to find a clear observational constraint that favors one version of the authors? model over the others, the implications of this ability to engineer climate sensitivity need to be considered when estimating the uncertainty in climate projections.},
author = {Zhao, Ming and Golaz, J.-C. and Held, I M and Ramaswamy, V and Lin, S.-J. and Ming, Y and Ginoux, P and Wyman, B and Donner, L J and Paynter, D and Guo, H},
doi = {10.1175/JCLI-D-15-0191.1},
issn = {0894-8755},
journal = {Journal of Climate},
month = {oct},
number = {2},
pages = {543--560},
publisher = {American Meteorological Society},
title = {{Uncertainty in Model Climate Sensitivity Traced to Representations of Cumulus Precipitation Microphysics}},
url = {https://doi.org/10.1175/JCLI-D-15-0191.1},
volume = {29},
year = {2015}
}
@article{Zhou2015,
abstract = {Analyses of CMIP5 simulations suggest that climate models with more positive cloud feedback in response to inter-annual climate fluctuations also have more positive cloud feedback in response to long-term global warming. Ensemble mean vertical profiles of cloud change in response to inter-annual and long-term surface warming are similar, and the ensemble mean cloud feedback is positive on both timescales. However, the average long-term cloud feedback is smaller than the inter-annual cloud feedback, likely due to differences in surface warming pattern on the two timescales. Low cloud cover (LCC) change in response to inter-annual and long-term global surface warming is found to be well correlated across models, and explains over half of the covariance between inter-annual and long-term cloud feedback. The inter-model correlation of LCC across timescales likely results from model-specific sensitivities of LCC to sea surface warming.},
author = {Zhou, Chen and Zelinka, Mark D. and Dessler, Andrew E. and Klein, Stephen A.},
doi = {10.1002/2015GL066698},
isbn = {1944-8007},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {climate change and variability,cloud feedback,low cloud cover},
month = {dec},
number = {23},
pages = {10463--10469},
pmid = {20944749},
title = {{The relationship between interannual and long-term cloud feedbacks}},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/2015GL066698},
volume = {42},
year = {2015}
}
@article{Zhou2017a,
author = {Zhou, Chen and Zelinka, Mark D. and Klein, Stephen A.},
doi = {10.1002/2017MS001096},
issn = {19422466},
journal = {Journal of Advances in Modeling Earth Systems},
keywords = {Green's function approach,cloud feedback,spatial pattern of warming},
number = {5},
pages = {2174--2189},
title = {{Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach}},
volume = {9},
year = {2017}
}
@article{Zhou2016a,
abstract = {Feedbacks of clouds on climate change strongly influence the magnitude of global warming1–3 . Cloud feedbacks, in turn, depend on the spatial patterns of surface warming4–9 , which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback4 . Here we present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. We find that cloud anomalies associated with these patterns significantly modify the Earth's energy budget. Specifically, the decadal cloud feedback between the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. These results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and oer a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low},
author = {Zhou, Chen and Zelinka, Mark D. and Klein, Stephen A.},
doi = {10.1038/ngeo2828},
isbn = {1752-0894},
issn = {17520908},
journal = {Nature Geoscience},
number = {12},
pages = {871--874},
title = {{Impact of decadal cloud variations on the Earth's energy budget}},
volume = {9},
year = {2016}
}
@article{Zhou2017e,
abstract = {ABSTRACT A partial internal mixing (PIM) treatment of black carbon (BC), organic carbon (OC), and sulphate was examined, and the core‐shell model was used to represent the internally mixed aerosols with BC as the core and sulphate or OC as the shell. The influences of PIM treatment on the effective radiative forcing due to aerosol–radiative interaction (ERFari) and global temperature were examined and compared to those of external mixing (EM) treatment using an aerosol‐climate online coupled model of BCC{\_}AGCM2.0{\_}CUACE/Aero. Radiative forcing due to aerosol–radiation interaction (RFari) of the anthropogenic aerosols since the preindustrial era was −0.34 W m−2 for EM and −0.23 W m−2 for PIM, respectively. The global annual mean ERFari of anthropogenic aerosols since the preindustrial era was −0.42 W m−2 for EM and −0.34 W m−2 for PIM, respectively. The change in global annual mean surface temperature increased accordingly from −0.18 K in the EM case to −0.125 K in the PIM case. Well geographic consistence between the change in low‐level cloud amount and the change in temperature can be found. The atmospheric temperature in the troposphere was markedly less reduced in the PIM case than in the EM case. The RFari/ERFari for 50{\%} and 100{\%} were −0.11/–0.07 and 0.13/0.14 W m−2, respectively. RFari, ERFari, and surface temperature changed approximately linearly with the internal mixing proportion.},
author = {Zhou, Chen and Zhang, Hua and Zhao, Shuyun and Li, Jiangnan},
doi = {10.1002/joc.5050},
issn = {10970088},
journal = {International Journal of Climatology},
pages = {972--986},
title = {{Simulated effects of internal mixing of anthropogenic aerosols on the aerosol–radiation interaction and global temperature}},
volume = {37},
year = {2017}
}
@article{Zhou2018b,
abstract = {{\textcopyright}2017. American Geophysical Union. All Rights Reserved. The total effective radiative forcing (ERF) due to partial internally mixed (PIM) and externally mixed (EM) anthropogenic aerosols, as well as their climatic effects since the year of 1850, was evaluated and compared using the aerosol-climate online coupled model of BCC{\_}AGCM2.0{\_}CUACE/Aero. The influences of internal mixing (IM) on aerosol hygroscopicity parameter, optical properties, and concentration were considered. Generally, IM could markedly weaken the negative ERF and cooling effects of anthropogenic aerosols. The global annual mean ERF of EM anthropogenic aerosols from 1850 to 2010 was −1.87 W m −2 , of which the aerosol-radiation interactive ERF (ERF ari ) and aerosol-cloud interactive ERF (ERF aci ) were −0.49 and −1.38 W m −2 , respectively. The global annual mean ERF due to PIM anthropogenic aerosols from 1850 to 2010 was −1.23 W m −2 , with ERF ari and ERF aci of −0.23 and −1.01 W m −2 , respectively. The global annual mean surface temperature and water evaporation and precipitation were reduced by 1.74 K and 0.14 mm d −1 for EM scheme and 1.28 K and 0.11 mm d −1 for PIM scheme, respectively. However, the relative humidity near the surface was slightly increased for both mixing cases. The Intertropical Convergence Zone was southwardly shifted for both EM and PIM cases but was less southwardly shifted in PIM scheme due to the less reduction in atmospheric temperature in the midlatitude and low latitude of the Northern Hemisphere.},
author = {Zhou, Chen and Zhang, Hua and Zhao, Shuyun and Li, Jiangnan},
doi = {10.1002/2017JD027603},
issn = {21698996},
journal = {Journal of Geophysical Research: Atmospheres},
number = {1},
pages = {401--423},
title = {{On Effective Radiative Forcing of Partial Internally and Externally Mixed Aerosols and Their Effects on Global Climate}},
volume = {123},
year = {2018}
}
@article{doi:10.1175/JCLI-D-16-0903.1,
abstract = { AbstractLand surface temperature Ts provides essential supplementary information to surface air temperature, the most widely used metric in global warming studies. A lack of reliable observational Ts data makes assessing model simulations difficult. Here, the authors first examined the simulated Ts of eight current reanalyses based on homogenized Ts data collected at {\~{}}2200 weather stations from 1979 to 2003 in China. The results show that the reanalyses are skillful in simulating the interannual variance of Ts in China (r = 0.95) except over the Tibetan Plateau. ERA-Interim and MERRA land versions perform better in this respect than ERA-Interim and MERRA. Observations show that the interannual variance of Ts over the north China plain and south China is mostly influenced by surface incident solar radiation Rs, followed by precipitation frequency, whereas the opposite is true over the northwest China, northeast China, and the Tibetan Plateau. This variable relationship is well captured by ERA-Interim, ERA-Interim land, MERRA, and JRA-55. The homogenized Ts data show a warming of 0.34°C decade−1 from 1979 to 2003 in China, varying between 0.25° and 0.42°C decade−1 for the eight reanalyses. However, the reanalyses substantially underestimate the warming trend of Ts over northwest China, northeast China, and the Tibetan Plateau and significantly overestimate the warming trend of Ts over the north China plain and south China owing to their biases in simulating the Rs and precipitation frequency trends. This study provides a diagnostic method for examining the capability of current atmospheric/land reanalysis data in regional climate change studies. },
author = {Zhou, Chunl{\"{u}}e and Wang, Kaicun and Ma, Qian},
doi = {10.1175/JCLI-D-16-0903.1},
journal = {Journal of Climate},
number = {18},
pages = {7379--7398},
title = {{Evaluation of Eight Current Reanalyses in Simulating Land Surface Temperature from 1979 to 2003 in China}},
url = {https://doi.org/10.1175/JCLI-D-16-0903.1},
volume = {30},
year = {2017}
}
@article{ISI:000434687100004,
abstract = {Abstract. Reanalyses are widely used because they add value to routine observations by generating physically or dynamically consistent and spatiotemporally complete atmospheric fields. Existing studies include extensive discussions of the temporal suitability of reanalyses in studies of global change. This study adds to this existing work by investigating the suitability of reanalyses in studies of regional climate change, in which land–atmosphere interactions play a comparatively important role. In this study, surface air temperatures (Ta) from 12 current reanalysis products are investigated; in particular, the spatial patterns of trends in Ta are examined using homogenized measurements of Ta made at ∼ 2200 meteorological stations in China from 1979 to 2010. The results show that ∼ 80 {\%} of the mean differences in Ta between the reanalyses and the in situ observations can be attributed to the differences in elevation between the stations and the model grids. Thus, the Ta climatologies display good skill, and these findings rebut previous reports of biases in Ta. However, the biases in theTa trends in the reanalyses diverge spatially (standard deviation = 0.15–0.30 °C decade−1 using 1° × 1° grid cells). The simulated biases in the trends in Ta correlate well with those of precipitation frequency, surface incident solar radiation (Rs) and atmospheric downward longwave radiation (Ld) among the reanalyses (r = −0.83, 0.80 and 0.77; p},
author = {Zhou, Chunl{\"{u}}e and He, Yanyi and Wang, Kaicun},
doi = {10.5194/acp-18-8113-2018},
issn = {1680-7324},
journal = {Atmospheric Chemistry and Physics},
month = {jun},
number = {11},
pages = {8113--8136},
title = {{On the suitability of current atmospheric reanalyses for regional warming studies over China}},
url = {https://acp.copernicus.org/articles/18/8113/2018/},
volume = {18},
year = {2018}
}
@article{Zhou2014,
abstract = {Abstract Cirrus clouds are not only important in determining the current climate but also play an important role in climate change and variability. Analysis of satellite observations shows that the amount and altitude of cirrus clouds (cloud optical depth?{\textless}?3.6, cloud top pressure?{\textless}?440?hPa) increase in response to interannual surface warming. Using cirrus cloud radiative kernels, the magnitude of the interannual cirrus feedback is estimated to be 0.20?±?0.21?W/m2/°C, which represents an important component of the cloud feedback. Thus, cirrus clouds are likely to act as a positive feedback on interannual climate fluctuations, by reducing the Earth's ability to radiate longwave radiation to space in response to planetary surface warming. Most of the cirrus feedback comes from increasing cloud amount in the tropical tropopause layer (TTL) and subtropical upper troposphere.},
annote = {doi: 10.1002/2014GL062095},
author = {Zhou, C and Dessler, A E and Zelinka, M D and Yang, P and Wang, T},
doi = {10.1002/2014GL062095},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {cirrus,climate change and variability,cloud feedback},
month = {dec},
number = {24},
pages = {9166--9173},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Cirrus feedback on interannual climate fluctuations}},
url = {https://doi.org/10.1002/2014GL062095},
volume = {41},
year = {2014}
}
@article{Zhu2018b,
author = {Zhu, Yannian and Rosenfeld, Daniel and Li, Zhanqing},
doi = {10.1029/2017JD028083},
issn = {2169897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {cloud drop concentrations,cloud physics,remote sensing},
month = {aug},
number = {16},
pages = {8754--8767},
publisher = {John Wiley {\&} Sons, Ltd},
title = {{Under What Conditions Can We Trust Retrieved Cloud Drop Concentrations in Broken Marine Stratocumulus?}},
url = {http://doi.wiley.com/10.1029/2017JD028083},
volume = {123},
year = {2018}
}
@article{Zhueaax1874,
abstract = {The Early Eocene, a period of elevated atmospheric CO2 ({\textgreater}1000 ppmv), is considered an analog for future climate. Previous modeling attempts have been unable to reproduce major features of Eocene climate indicated by proxy data without substantial modification to the model physics. Here, we present simulations using a state-of-the-art climate model forced by proxy-estimated CO2 levels that capture the extreme surface warmth and reduced latitudinal temperature gradient of the Early Eocene and the warming of the Paleocene-Eocene Thermal Maximum. Our simulations exhibit increasing equilibrium climate sensitivity with warming and suggest an Eocene sensitivity of more than 6.6{\{}$\backslash$textdegree{\}}C, much greater than the present-day value (4.2{\{}$\backslash$textdegree{\}}C). This higher climate sensitivity is mainly attributable to the shortwave cloud feedback, which is linked primarily to cloud microphysical processes. Our findings highlight the role of small-scale cloud processes in determining large-scale climate changes and suggest a potential increase in climate sensitivity with future warming.},
author = {Zhu, Jiang and Poulsen, Christopher J and Tierney, Jessica E},
doi = {10.1126/sciadv.aax1874},
journal = {Science Advances},
number = {9},
pages = {eaax1874},
publisher = {American Association for the Advancement of Science},
title = {{Simulation of Eocene extreme warmth and high climate sensitivity through cloud feedbacks}},
url = {https://advances.sciencemag.org/content/5/9/eaax1874},
volume = {5},
year = {2019}
}
@article{Zhu2020b,
author = {Zhu, Jiang and Poulsen, Christopher J. and Otto-Bliesner, Bette L.},
doi = {10.1038/s41558-020-0764-6},
isbn = {4155802007},
issn = {17586798},
journal = {Nature Climate Change},
number = {5},
pages = {378--379},
publisher = {Springer US},
title = {{High climate sensitivity in CMIP6 model not supported by paleoclimate}},
url = {http://dx.doi.org/10.1038/s41558-020-0764-6},
volume = {10},
year = {2020}
}
@article{Zhu2020a,
abstract = {Secondary organic aerosols (SOA) have been identified as a potential source of depositional ice nucleating particles and thus may have a radiative effect on cirrus clouds. This study develops a global model to examine the radiative effect of SOA on cirrus clouds using different treatments for the size distribution of SOA. The SOA from new particle formation by organics and their subsequent growth has a radiative effect of 0.35 ± 0.06 W m−2, while the radiative effect of SOA calculated by assuming a fixed size distribution is 0.31 ± 0.08 W m−2. This positive radiative effect on cirrus clouds opposes the negative effect of anthropogenic soot on cirrus clouds. In addition, the inclusion of SOA as an ice nucleating particle changes the background ice crystal number concentration, which impacts the calculation of radiative forcing from other aerosols. The radiative forcing of aircraft soot is estimated to be −0.11 ± 0.03 W m−2 when including SOA formed from new particle formation by organics and growth. This is less negative than simulations that do not include ice nucleation from SOA. The change in SOA formed from organic nucleation from the preindustrial period to the present day causes a positive forcing of 0.02 ± 0.04 W m−2. It is important to use a size distribution based on the explicit formation mechanism for SOA to calculate their radiative effects. The simulation using an assumed fixed size distribution incorrectly results in a negative forcing of SOA between the present day and preindustrial atmospheres because it does not correctly calculate the change of SOA in the accumulation mode.},
author = {Zhu, Jialei and Penner, Joyce E.},
doi = {10.1029/2019JD032233},
issn = {2169-897X},
journal = {Journal of Geophysical Research: Atmospheres},
keywords = {aircraft soot,cirrus clouds,global model,radiative effect,secondary organic aerosol},
month = {apr},
number = {7},
pages = {e2019JD032233},
title = {{Indirect Effects of Secondary Organic Aerosol on Cirrus Clouds}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2019JD032233},
volume = {125},
year = {2020}
}
@article{Zhu2019b,
abstract = {Organic nucleation is an important source of atmospheric aerosol number concentration, especially in pristine continental regions and during the preindustrial period. Here, we improve on previous simulations that overestimate boundary layer nucleation in the tropics and add changes to climate and land use to evaluate climate forcing. Our model includes both pure organic nucleation and heteromolecular nucleation of sulfuric acid and organics and reproduces the profile of aerosol number concentration measured in the Amazon. Organic nucleation decreases the sum of the total aerosol direct and indirect radiative forcing by 12.5{\%}. The addition of climate and land use change decreases the direct radiative forcing (−0.38 W m −2 ) by 6.3{\%} and the indirect radiative forcing (−1.68 W m −2 ) by 3.5{\%} due to the size distribution and number concentration change of secondary organic aerosol and sulfate. Overall, the total radiative forcing associated with anthropogenic aerosols is decreased by 16{\%}.},
author = {Zhu, Jialei and Penner, Joyce E. and Yu, Fangqun and Sillman, Sanford and Andreae, Meinrat O. and Coe, Hugh},
doi = {10.1038/s41467-019-08407-7},
issn = {2041-1723},
journal = {Nature Communications},
month = {dec},
number = {1},
pages = {423},
pmid = {30679429},
title = {{Decrease in radiative forcing by organic aerosol nucleation, climate, and land use change}},
url = {http://www.nature.com/articles/s41467-019-08407-7},
volume = {10},
year = {2019}
}
@article{Zhu2021,
abstract = {AbstractThe upper end of the equilibrium climate sensitivity (ECS) has increased substantially in the latest Coupled Model Intercomparison Projects phase 6 with eight models (as of this writing) reporting an ECS {\textgreater} 5°C. The Community Earth System Model version 2 (CESM2) is one such high-ECS model. Here we perform paleoclimate simulations of the Last Glacial Maximum (LGM) using CESM2 to examine whether its high ECS is realistic. We find that the simulated LGM global mean temperature decrease exceeds 11°C, greater than both the cooling estimated from proxies and simulated by an earlier model version (CESM1). The large LGM cooling in CESM2 is attributed to a strong shortwave cloud feedback in the newest atmosphere model. Our results indicate that the high ECS of CESM2 is incompatible with LGM constraints and that the projected future warming in CESM2, and models with a similarly high ECS, is thus likely too large.},
author = {Zhu, Jiang and Otto‐Bliesner, Bette L. and Brady, Esther C. and Poulsen, Christopher J. and Tierney, Jessica E. and Lofverstrom, Marcus and DiNezio, Pedro},
doi = {10.1029/2020GL091220},
issn = {0094-8276},
journal = {Geophysical Research Letters},
keywords = {cloud feedback,equilibrium climate sensitivity,last glacial maximum},
month = {feb},
number = {3},
pages = {e2020GL091220},
publisher = {American Geophysical Union (AGU)},
title = {{Assessment of Equilibrium Climate Sensitivity of the Community Earth System Model Version 2 Through Simulation of the Last Glacial Maximum}},
url = {https://onlinelibrary.wiley.com/doi/10.1029/2020GL091220},
volume = {48},
year = {2021}
}
@article{Zhu2021a,
abstract = {Equilibrium climate sensitivity (ECS) has been directly estimated using reconstructions of past climates that are different than today's. A challenge to this approach is that temperature proxies integrate over the timescales of the fast feedback processes (e.g., changes in water vapor, snow, and clouds) that are captured in ECS as well as the slower feedback processes (e.g., changes in ice sheets and ocean circulation) that are not. A way around this issue is to treat the slow feedbacks as climate forcings and independently account for their impact on global temperature. Here we conduct a suite of Last Glacial Maximum (LGM) simulations using the Community Earth System Model version 1.2 (CESM1.2) to quantify the forcing and efficacy of land ice sheets (LISs) and greenhouse gases (GHGs) in order to estimate ECS. Our forcing and efficacy quantification adopts the effective radiative forcing (ERF) and adjustment framework and provides a complete accounting for the radiative, topographic, and dynamical impacts of LIS on surface temperatures. ERF and efficacy of LGM LIS are {\textless}span classCombining double low line"inline-formula-3.2 W m{\textless}span classCombining double low line"inline-formula-2 and 1.1, respectively. The larger-than-unity efficacy is caused by the temperature changes over land and the Northern Hemisphere subtropical oceans which are relatively larger than those in response to a doubling of atmospheric {\textless}span classCombining double low line"inline-formulaCO2. The subtropical sea-surface temperature (SST) response is linked to LIS-induced wind changes and feedbacks in ocean-atmosphere coupling and clouds. ERF and efficacy of LGM GHG are {\textless}span classCombining double low line"inline-formula-2.8 W m{\textless}span classCombining double low line"inline-formula-2 and 0.9, respectively. The lower efficacy is primarily attributed to a smaller cloud feedback at colder temperatures. Our simulations further demonstrate that the direct ECS calculation using the forcing, efficacy, and temperature response in CESM1.2 overestimates the true value in the model by approximately 25 {\%} due to the neglect of slow ocean dynamical feedback. This is supported by the greater cooling (6.8 C) in a fully coupled LGM simulation than that (5.3 C) in a slab ocean model simulation with ocean dynamics disabled. The majority (67 {\%}) of the ocean dynamical feedback is attributed to dynamical changes in the Southern Ocean, where interactions between upper-ocean stratification, heat transport, and sea-ice cover are found to amplify the LGM cooling. Our study demonstrates the value of climate models in the quantification of climate forcings and the ocean dynamical feedback, which is necessary for an accurate direct ECS estimation.},
author = {Zhu, Jiang and Poulsen, Christopher J.},
doi = {10.5194/cp-17-253-2021},
issn = {18149332},
journal = {Climate of the Past},
month = {jan},
number = {1},
pages = {253--267},
publisher = {Copernicus GmbH},
title = {{Last Glacial Maximum (LGM) climate forcing and ocean dynamical feedback and their implications for estimating climate sensitivity}},
volume = {17},
year = {2021}
}
@article{Zickfeld2017,
abstract = {Mitigation of anthropogenic greenhouse gases with short lifetimes (order of a year to decades) can contribute to limiting warming, but less attention has been paid to their impacts on longer-term sea-level rise. We show that short-lived greenhouse gases contribute to sea-level rise through thermal expansion (TSLR) over much longer time scales than their atmospheric lifetimes. For example, at least half of the TSLR due to increases in methane is expected to remain present for more than 200 y, even if anthropogenic emissions cease altogether, despite the 10-y atmospheric lifetime of this gas. Chlorofluorocarbons and hydrochlorofluorocarbons have already been phased out under the Montreal Protocol due to concerns about ozone depletion and provide an illustration of how emission reductions avoid multiple centuries of future TSLR. We examine the “world avoided” by the Montreal Protocol by showing that if these gases had instead been eliminated in 2050, additional TSLR of up to about 14 cm would be expected in the 21st century, with continuing contributions lasting more than 500 y. Emissions of the hydrofluorocarbon substitutes in the next half-century would also contribute to centuries of future TSLR. Consideration of the time scales of reversibility of TSLR due to short-lived substances provides insights into physical processes: sea-level rise is often assumed to follow air temperature, but this assumption holds only for TSLR when temperatures are increasing. We present a more complete formulation that is accurate even when atmospheric temperatures are stable or decreasing due to reductions in short-lived gases or net radiative forcing.},
author = {Zickfeld, Kirsten and Solomon, Susan and Gilford, Daniel M},
doi = {10.1073/pnas.1612066114},
issn = {0027-8424},
journal = {Proceedings of the National Academy of Sciences},
keywords = {Montreal Protocol,climate change,greenhouse gases,reversibility,sea-level rise},
month = {jan},
number = {4},
pages = {657--662},
pmid = {28069937},
publisher = {National Academy of Sciences},
title = {{Centuries of thermal sea-level rise due to anthropogenic emissions of short-lived greenhouse gases}},
url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1612066114},
volume = {114},
year = {2017}
}