DroughtsWarming pushes Western U.S. toward driest period in 1,000 years

Published 13 February 2015

Study warns of unprecedented risk of drought in twenty-first century. Today, eleven of the past fourteen years have been drought years in much of the American West, including California, Nevada, New Mexico, and Arizona and across the Southern Plains to Texas and Oklahoma. The current drought directly affects more than sixty-four million people in the Southwest and Southern Plains, and many more are indirectly affected because of the impacts on agricultural regions. A new study predicts that during the second half of the twenty-first century, the U.S. Southwest and Great Plains will face persistent drought worse than anything seen in times ancient or modern, with the drying conditions “driven primarily” by human-induced global warming.

During the second half of the twenty-first century, the U.S. Southwest and Great Plains will face persistent drought worse than anything seen in times ancient or modern, with the drying conditions “driven primarily” by human-induced global warming, a new study predicts.

The research says the drying would surpass in severity any of the decades-long “megadroughts” that occurred much earlier during the past 1,000 years — one of which has been tied by some researchers to the decline of the Anasazi or Ancient Pueblo Peoples in the Colorado Plateau in the late thirteenth century. Many studies have already predicted that the Southwest could dry due to global warming, but this is the first to say that such drying could exceed the worst conditions of the distant past. The impacts today would be devastating, given the region’s much larger population and use of resources.

“We are the first to do this kind of quantitative comparison between the projections and the distant past, and the story is a bit bleak,” said Jason E. Smerdon, a co-author and climate scientist at the Lamont-Doherty Earth Observatory, part of the Earth Institute at Columbia University. “Even when selecting for the worst megadrought-dominated period, the 21st century projections make the megadroughts seem like quaint walks through the Garden of Eden.”

“The surprising thing to us was really how consistent the response was over these regions, nearly regardless of what model we used or what soil moisture metric we looked at,” said lead author Benjamin I. Cook of the NASA Goddard Institute for Space Studies and the Lamont-Doherty Earth Observatory. “It all showed this really, really significant drying.”

A Columbia University release reports that the new study, “Unprecedented 21st-Century Drought Risk in the American Southwest and Central Plains,” is featured in the inaugural edition of the new online journal Science Advances, produced by the American Association for the Advancement of Science, which also publishes the leading journal Science.

Today, eleven of the past fourteen years have been drought years in much of the American West, including California, Nevada, New Mexico, and Arizona and across the Southern Plains to Texas and Oklahoma, according to the U.S. Drought Monitor, a collaboration of U.S. government agencies.

The current drought directly affects more than sixty-four million people in the Southwest and Southern Plains, according to NASA, and many more are indirectly affected because of the impacts on agricultural regions.