High-Resolution Image

GISS Model-E is being readied for climate change simulation exercises similar to the ones conducted by the Hadley Center in the United Kingdom (see ClimatePrediction.Net). In a preliminary evaluation, the model was used to estimate the influence of doubled atmospheric CO2 on precipitation, maintaining the same sea-surface temperatures (SSTs). A twin ensemble of twenty-one cases for doubled and present-day CO2 produced a statistically significant influence on global precipitation almost everywhere. Figure shows 10-year ensemble-mean precipitation differences (centimeters per year). The shading indicates regions of statistical significance at the level of 99% or better. Brazil and parts of Amazonia simulate reductions, while some parts of tropical Africa, Arabia, and large areas of northern India simulate increases in rainfall. The changes are likely to be far stronger if SSTs were also allowed to evolve like in the real world.

(submitted by Yogesh Sud).