Global warming could mean dry tropics

PITTSBURGH, May 11 (UPI) -- As temperatures rise with global warming, densely populated tropical regions will likely become much drier, U.S. researchers say.

University of Pittsburgh researchers base their prediction on their examination of 2,300 years of climatological data gleaned from an Andes Mountains lake. They conclude as temperatures in the Northern Hemisphere rise, tropical regions will most likely experience much drier summer monsoon seasons, a university release issued Wednesday said.

The researchers found that equatorial regions of South America already are receiving less rainfall than at any point in the past millennium, the release said.

The 6-foot-long sediment core from Laguna Pumacocha in Peru shows rainfall during the South American summer monsoon has dropped sharply since 1900, the greatest shift in rainfall patterns since 300 B.C., while the Northern Hemisphere has experienced warmer temperatures.

"This model suggests that tropical regions are dry to a point we would not have predicted," Mark Abbott, a Pitt professor of geology and planetary science, said. "If the monsoons that are so critical to the water supply in tropical areas continue to diminish at this pace, it will have devastating implications for the water resources of a huge swath of the planet."