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Drying Southwest

April 16, 2007

The American Southwest is pretty dry already. But a drier future may be in store.


The drying of the American Southwest. I’m Bob Hirshon and this is Science Update.

In the coming decades, the American Southwest may face a permanent drought, one as dry as the region’s worst drought in the 20th century. This according to climatologist Richard Seager of Columbia University’s Lamont Doherty Earth Observatory. Drawing on 19 different climate models, his team identified a global drying trend in subtropical areas like the Southwest.

RICHARD SEAGER (Lamont Doherty Earth Observatory):
It begins right at the junction of the 20th century and the 21st century. So the models say that yes, this should already be underway.

Seager says that unlike past droughts, this one appears to be caused by changes in air circulation due to global warming. If so, he says it’s too late to stop it, but restricting greenhouse gas emissions may limit how dry it ultimately gets.

I’m Bob Hirshon, for AAAS, the science society.