Climate Change 2001:
Working Group I: The Scientific Basis
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Figure 12.13: Global mean temperature in the decade 2036 to 2046 (relative to pre-industrial, in response to greenhouse gas and sulphate aerosol forcing following the IS92a (IPCC, 1992) scenario), based on original model simulations (squares) and after scaling to fit the observed signal as in Figure 12.12(a) (diamonds), with 5 to 95% confidence intervals. While the original projections vary (depending, for example, on each modelís climate sensitivity), the scale should be independent of errors in both sensitivity and rate of oceanic heat uptake, provided these errors are persistent over time. GS indicates combined greenhouse and sulphate forcing. G shows the impact of setting the sulphate forcing to zero but correcting the response to be consistent with observed 20th century climate change. G&S indicates greenhouse and sulphate responses estimated separately (in which case the result is also approximately independent, under this forcing scenario, to persistent errors in the sulphate forcing and response) and G&S&N indicates greenhouse, sulphate and natural responses estimated separately (showing the small impact of natural forcing on the diagnostic used for this analysis). (From Allen et al., 2000b.)

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