Greenhouse-gas warming may raise summer temps 10 degrees in eastern U.S. by 2080

NASA's weather prediction model shows that extreme summertime surface temperatures develop when CO2 emissions are assumed to continue to increase about 2% a year, i.e., the "business as usual" scenario. The weather model used in this research assesses details about future climate at a smaller geographic scale than global models. It provides reliable simulations on summer precipitation and its frequency and timing, important for predicting summer temperatures.

NASA's computer model projection.

Daily temperatures are usually higher on rainless days or when precipitation falls less frequently than normal. By contrast to global models which simulate rainfall too frequently, NASA's model is considered to be more accurate by accounting for precipitation shortfalls.

This may be the first study documenting the impact of precipitation simulation imperfections on model predictions of surface air temperature. "Using high-resolution weather prediction models, we were able to show how greenhouse gases enhance feedbacks between precipitation, radiation, and atmospheric circulations that will likely lead to extreme temperatures in our not so distant future," said author Barry Lynn of NASA's Goddard Institute for Space Studies and Columbia University, New York.

The study is published in the April 2007 issue of the American Meteorological Society's Journal of Climate. See this summary at ScienceDaily.