BER Scientists Test Cloud-Climate Interactions in Climate Models


Scientists funded by the Office of Science tested model representations of the interactions between clouds and radiation, an area that comprises one of the greatest uncertainties in simulating and predicting current and future climate and climatic changes. The focus of the investigation was to determine how well the models reproduce the observed present-day distribution of clouds and their effects on sunlight and heat moving through the atmosphere. One surprising result of the test of 19 atmospheric general circulation models was that 11 of the models significantly overestimate the cooling effect of clouds. In addition, the study found that when averaged over specific regions, the models produced reasonable agreement with satellite observations of radiation balance at the top of the atmosphere, but when analyzed in detail the regional agreement was an artifact, resulting, in part, from compensating errors in the models. Some of the models in the study also produced large errors even in the absence of clouds. The results indicate continued research is needed to improve our understanding of the effect of clouds on the climate on local, regional, and global scales.