Southwestern US may face 'megadrought' within century

Blaine Friedlander in the Cornell Chronicle: Due to global warming, scientists say, the chances of the southwestern United States experiencing a decadelong drought is at least 50 percent, and the chances of a “megadrought” – one that lasts up to 35 years – ranges from 20 to 50 percent over the next century.

... “For the southwestern U.S., I’m not optimistic about avoiding real megadroughts,” said Toby Ault, Cornell assistant professor of earth and atmospheric sciences and lead author of the paper. “As we add greenhouse gases into the atmosphere – and we haven’t put the brakes on stopping this – we are weighting the dice for megadrought.”

As of Aug. 12, most of California sits in a D4 “exceptional drought,” which is in the most severe category. Oregon, Arizona, New Mexico, Oklahoma and Texas loiter in a substantially less severe D1 moderate drought. Ault says climatologists don’t know whether the severe western and southwestern drought will continue, but “with ongoing climate change, this is a glimpse of things to come. It’s a preview of our future,” he said.

While the 1930s Dust Bowl in the Midwest lasted four to eight years, depending upon location, a megadrought can last more than three decades, which could lead to mass population migration on a scale never before seen in this country.

Ault said that the West and Southwest must look for mitigation strategies to cope with looming long-drought scenarios. “This will be worse than anything seen during the last 2,000 years and would pose unprecedented challenges to water resources in the region,” he said....

Dried mud, shot by Frank Vincentz, Wikimedia Commons, under the Creative Commons 3.0 license