Global Warming Not as Severe in Central U.S.

Newswise — Scientists at the Regional Climate Modeling Laboratory at Iowa State University have discovered global warming might not be as severe in the central United States as in other parts of the country. Using a detailed regional climate model, they estimate summertime daily maximum temperatures will warm less in a region centered on eastern Kansas than anywhere else in the United States.

The findings, in the current issue of Geophysical Research Letters, underscore the need to consider the impact of global warming on a region-by-region basis, said Gene Takle, professor of agronomy and geological and atmospheric sciences. "Modeling allows us to make projections of future scenario climates," he said.

Lead author Zaitao Pan is a former Iowa State graduate student and research associate. He joined the faculty at Saint Louis University last year.

"The modeling showed that warming in the United States will be stronger in winter than summer and stronger at night than during the day. But we found what looked to us like a 'hole' in the daytime warming in summer, which was a surprise," Pan said.

After discovering the 'hole' in climate projections for the 2040s, Pan went back to carefully examine the observed maximum daily temperatures from 1975-2000 in a region that centers in eastern Kansas and touches parts of Missouri, Oklahoma, Nebraska and Iowa. "We found that, in fact, this hole already has started to develop," he said.

Ray Arritt, agronomy professor, said the existence of this 'hole' in the warming, makes sense. "Our model tells us the future climate will have more rainfall and wetter soil, so more of the sun's energy goes into evaporating water than heating the air," he said. "Rainfall in the northern Great Plains already has increased by about 10 percent over the past few decades, which is consistent with our predictions."

Besides Pan, Takle and Arritt, other authors are Chris Anderson, doctoral student in agronomy, Bill Gutowski, professor of geological and atmospheric sciences and Moti Segal, research scientist in agronomy.

Team members caution that independent evaluations are needed to confirm this finding and to determine whether the 'hole' might be a temporary phenomenon that will disappear as global warming becomes more severe in the latter half of the 21st century.

The Iowa State University Regional Climate Modeling Lab has been doing climate studies using models for about 10 years. Arritt, Gutowski and Takle are members of the U.S. science team that is creating models of future scenario climates for the next major study of the impact of climate change in North America. That study is targeted for completion in 2006.