but, for example, very different monsoon circulations, positions, and intensities of the semipermanent centers of action and quite different rainfall patterns. It is for this reason that we do not consider the existing models to be at all reliable in their predictions of regional climatic changes due to changes in CO2 concentration.

We conclude that the predictions of CO2-induced climate changes made with the various models examined are basically consistent and mutually supporting. The differences in model results are relatively small and may be accounted for by differences in model characteristics and simplifying assumptions. Of course, we can never be sure that some badly estimated or totally overlooked effect may not vitiate our conclusions. We can only say that we have not been able to find such effects. If the CO2 concentration of the atmosphere is indeed doubled and remains so long enough for the atmosphere and the intermediate layers of the ocean to attain approximate thermal equilibrium, our best estimate is that changes in global temperature of the order of 3°C will occur and that these will be accompanied by significant changes in regional climatic patterns.



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