80% Chance of 10-Year Drought in Southwest; 50% for a Megadrought

Tuesday, September 02, 2014

In what is shaping up as a spirited contest to predict the worst possible future climate for California, university researchers and the federal government have teamed up to project an 80% chance of a 10-year drought in the Southwest during the next century; 90% in some areas.

“This will be worse than anything seen during the last 2,000 years and would pose unprecedented challenges to water resources in the region,” lead researcher Toby Ault told the Cornell Chronicle.

Ault wasn’t just talking about the 10-year drought. The study also projected a 20%-50% chance of a 35-year-plus megadrought in the next 100 years. “The risk of an unprecedented 50-year megadrought is non-negligible under the most severe warming scenario (5-10%),” an abstract for the report says.

The 10-year projection of 80% was considerably higher than current state-of-the-art global climate models of less than 50%, which use short-term rainfall changes but not global patterns as they fluctuate across multidecades and multicenturies. These longer- term changes in climate usher in “mega” events, as in mega methane releases, mega heat waves and megadrought, Ault told writers for Motherboard.    

The study’s computer model found there was a greater risk of future drought in California, New Mexico and Arizona, but Washington, Idaho and Montana may actually experience a decrease. 

California is in the third year of savage drought and, according to the U.S. Drought Monitor, 58.4% of the state is in “exceptional” drought, the most severe level possible. Three months ago, 24.7% were at that level. No one was at the beginning of the year.

The report, “Assessing the Risk of Persistent Drought Using Climate Model Simulations and Paleoclimate Data,” was just published in the American Meteorological Society’s Journal of Climate by researchers at Cornell University, the University of Arizona and the U.S. Geological Survey (USGS).   

Ault told Motherboard he couldn’t say that the current drought is caused by climate change and, so far, doesn’t fit the definition of a mega event. But he said a mega event would kind of look like this, providing an ideal opportunity to plan for a drought-ravaged future.

Ault sounded much more optimistic about the chances of humans surviving the impending megadrought when he talked to The Huffington Post than he is about avoiding it. “Humans are incredibly adaptable creatures, and civilizations in the past have managed water with far fewer resources than we have available to us today.”

–Ken Broder


To Learn More:

There's a Good Chance the Southwest Will See a 35-Year Megadrought This Century (by Brian Merchant and Jordan Pearson, Motherboard)

Study: Southwest May Face "Megadrought" within Century (by Blaine Friedlander, Cornell Chronicler)

Chance of “Megadrought” in U.S. Southwest Now 50%, Study Concludes (by Veronica Rocha, Los Angeles Times)

Assessing the Risk of Persistent Drought Using Climate Model Simulations and Paleoclimate Data (by Toby R. Ault, Julia E. Cole, Jonathan T. Overpeck, Gregory T. Pederson and David M. Meko, Journal of Climate)

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