Intercomparison and interpretation of climate feedback processes in 19 atmospheric general circulation models

TLDR

Cloud feedback results from interacting physical and dynamical processes in a general circulation model, producing changes in temperature, moisture distribution, and clouds that are integrated into the radiative response. The study aims to intercompare and interpret climate feedback processes, especially cloud–climate interactions, across 19 atmospheric general circulation models to understand differences in CO₂‑induced climate change projections. The intercomparison uses sea surface temperature change as a surrogate for climate change to assess cloud–climate interactions. The models show a roughly threefold variation in global climate sensitivity, largely due to differences in cloud feedback representation, underscoring the need to improve cloud treatment for reliable predictions.

Abstract

The need to understand differences among general circulation model projections of CO 2 ‐induced climatic change has motivated the present study, which provides an intercomparison and interpretation of climate feedback processes in 19 atmospheric general circulation models. This intercomparison uses sea surface temperature change as a surrogate for climate change. The interpretation of cloud‐climate interactions is given special attention. A roughly threefold variation in one measure of global climate sensitivity is found among the 19 models. The important conclusion is that most of this variation is attributable to differences in the models' depiction of cloud feedback, a result that emphasizes the need for improvements in the treatment of clouds in these models if they are ultimately to be used as reliable climate predictors. It is further emphasized that cloud feedback is the consequence of all interacting physical and dynamical processes in a general circulation model. The result of these processes is to produce changes in temperature, moisture distribution, and clouds which are integrated into the radiative response termed cloud feedback.