Ancient megadroughts preview warmer climate: study





WASHINGTON (Reuters) – Ancient megadroughts that lasted thousands of years in what is now the American Southwest could offer a preview of a climate changed by modern greenhouse gas emissions, researchers reported on Wednesday.

The scientists found these persistent dry periods were different from even the most severe decades-long modern droughts, including the 1930s "Dust Bowl." And they determined that these millennial droughts occurred at times when Earth's mean annual temperature was similar to or slightly higher than what it is now.

These findings tally with projections by the U.N. Intergovernmental Panel on Climate Change and others, according to study author Peter Fawcett of the University of New Mexico. The results were published in the current edition of Nature.

"The IPCC model suggests that when you warm the climate, you'll see extended droughts in this part of the world and this is what the paleo record seems to be telling us," Fawcett said in a telephone interview. "When you've got past temperatures that were at or above today's conditions, conditions got drier."

The U.S. Southwest has seen steep population growth over the last century, with population increasing by 1,500 percent from 1900 to 1990, according to the U.S. Geological Survey. The total U.S. population grew 225 percent over the same period....


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