This
will be worse than anything seen during the last 2,000 years," says the
lead author of the paper. Also: "Megadrought" is a real term.
A
new study published as a joint effort by scientists at Cornell University, the
University of Arizona, and the U.S. Geological Survey finds that the chances of
the Southwest facing a “megadrought” are much higher than previously suspected.
According
to the new study, “the chances of the southwestern United States experiencing a
decade-long 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.” Not so crazy, according to Richard Seager, a climate scientist at
Columbia University who has helped pen many studies of historical megadroughts:
“By some measures the west has been in drought since 1998 so we might be
approaching a megadrought classification!” he says. The study points to manmade
global climate change as a possible cause for the drought, which would affect
portions of California (where a drought is currently decimating farms), Arizona
and New Mexico.
“This will be worse than anything seen during
the last 2,000 years.”
“We know that megadroughts — droughts as
severe as the ones in past century, but lasting much longer, up to a few
decades – occurred over the past millennium in the southwest and the Great
Plains,” says Seager. Megadroughts are commonly called “decades-long droughts”
or “multi-decadal droughts,” and refer to length of time rather than severity.
Seager says that the region hasn’t had a megadrought in several centuries; the
Dust Bowl drought of The Grapes of Wrath, though incredibly severe, was not
long enough to qualify.
Jason
Smerdon, another climate scientist at Columbia University, spoke to us about
what this specific paper does differently. “What is novel about the paper,” he
says, “is that the authors use paleoclimate and observational evidence to
inform statistical models of drought variability, which are in turn used to
modify characterizations of future drought risks from climate model
simulations.” The combination of traditional climate models as well as
historical data and current observational data could give them much more
insight into the future in the American Southwest — and their evidence points
to a dry future indeed.
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