Working Group II: Impacts, Adaptation and Vulnerability

Other reports in this collection Use of Climate Model Outputs

The most common method of developing climate scenarios for quantitative impact assessments is to use results from GCM experiments. Most estimates of impacts described in this report rely on this type of scenario. GCMs are three-dimensional mathematical models that represent physical and dynamical processes that are responsible for climate. All models are first run for a control simulation that is representative of the present-day or preindustrial times. They have been used to conduct two types of "experiment" for estimating future climate: equilibrium and transient-response experiments. In the former, the equilibrium response (new stable state) of the global climate following an instantaneous increase (e.g., doubling) of atmospheric CO2 concentration or its radiative equivalent, including all GHGs, is evaluated (Schlesinger and Mitchell, 1987; Mitchell et al., 1990). Transient experiments are conducted with coupled atmosphere-ocean models (AOGCMs), which link, dynamically, detailed models of the ocean with those of the atmosphere. AOGCMs are able to simulate time lags between a given change in atmospheric composition and the response of climate (see TAR WGI Chapter 8). Most recent evaluations of impacts, as reflected in this report, are based on scenarios formed from results of transient experiments as opposed to equilibrium experiments.

Table 3-5: Catalog of GCM experiments used to develop scenarios applied by impact studies referenced in this report. Columns show the acronym of the modeling center; the common model acronym found in the impacts literature; a code for the model experiment; reference number for the experiment from Chapter 8, WGI TAR; main reference sources; type of experiment (EQ = equilibrium; TRS = transient with simple ocean; TRC = transient cold start with dynamic ocean; TRW = transient warm start with dynamic ocean); increase in CO2-equivalent concentration; effective climate sensitivity [equilibrium warming at CO2-doubling from AOGCM experiments (see Chapter 9, WG I TAR); in some cases this differs from climate sensitivities cited elsewhere derived from atmosphere-only GCMs]; and availability from IPCC Data Distribution Centre.
Center Model Expt WG I Reference Type Forcing dT2xCO2(°C) DDC
CCCma CCC a McFarlane et al. (1992) EQ 2 x CO2 3.5
  CGCM1 b 6 Boer et al. (2000) TRW 1% a-1 3.6 X
CCSR/NIES CCSR-98 c 5 Emori et al. (1999) TRW 1% a-1 3.5 X
CSIRO CSIRO d Watterson et al. (1997) EQ 2 x CO2 4.3
  CSIRO-Mk2 e 10 Gordon and O'Farrell (1997) TRW 1% a-1 3.7 X










Cubasch et al. (1992)








Cubasch et al. (1996)









Roeckner et al. (1996)





GFDL GFDL i -- Wetherald and Manabe (1986) EQ 2 x CO2 4.0
  GFDLTR j -- Manabe et al. (1991) TRC 1% a-1 4.0
  GFDL-R15 k 16 Haywood et al. (1997) TRW 1% a-1 4.2 X
GISS GISS l Hansen et al. (1983) EQ 2 x CO2 4.2
  GISSTR m Hansen et al. (1988) TRS 1.5% a-1 4.2
NCAR NCAR n Washington and Meehl (1984) EQ 2 x CO2 4.0
  NCAR1 o 28 Washington and Meehl (1996) TRW 1% a-1 4.6 X
OSU OSU p Schlesinger and Zhao (1989) EQ 2 x CO2 2.8
UKMO UKMO q -- Wilson and Mitchell (1987) EQ 2 x CO2 5.2 --
  UKHI r -- Haarsma et al. (1993) EQ 2 x CO2 3.5 --
  UKTR s -- Murphy (1995) TRC 1% a-1 2.7 --
  HadCM2 t 22 Mitchell and Johns (1997) TRW 1% a-1 2.5 X
  HadCM3 u 23 Gordon et al. (2000) TRW 1% a-1 3.0 X

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