Public Release: 

Southwest & Central Plains face unprecedented drought risk in the 21st century

Study suggests both regions will likely experience droughts worse than any in the last millennium, and it may be difficult for humans to adapt to the change.

American Association for the Advancement of Science

When the results came in from computer model simulations of future climate in the Southwestern & Central Plains compared to climate reconstructions from an unusually warm period in the 12th and 13th centuries, scientist Toby Ault was startled.

"I was honestly surprised at just how dry the future is likely to be," said Ault, an assistant professor in the Department of Earth and Atmospheric Sciences at Cornell University and co-author of the research, which appears in the inaugural issue of the journal Science Advances.

Although it is well-established that global warming will exacerbate the ongoing drought situation in the American Southwest and Central Plains, the findings by Cook, Ault, and Jason Smerdon, a research professor at the Lamont-Doherty Earth Observatory of Columbia University, suggest that both regions will experience extended drought conditions in the future that will be more severe than even the hottest, driest megadroughts of the 12th and 13th centuries, an unusually warm period climatologists call the Medieval Climatic Anomaly.

It's believed that this extended period of severe drought may have contributed to the fall of the Ancient Pueblos, a prehistoric Native American civilization that once lived in the region that is now the American Southwest.

Using drought records of the Medieval Period documented in the growth rings of trees, the researchers compared past climate reconstructions to 17 different computer model projections of 21st century climate. The results showed robust and consistent drying in nearly all the models, caused by a combination of reduced precipitation and warmer temperatures drying out the model soils. Notably, the results pointed to an extremely parched Southwest and Central Plains that will likely be drier than any other period of the last one thousand years.

"Understanding climates of the past provides a strong benchmark of natural variability, allowing us to better contextualize the magnitude of modern and future human-driven climate change, including contributions to extreme event such as droughts," said Benjamin Cook, lead author of the study and research scientist at NASA's Goddard Institute for Space Studies.

The metrics used in the study could be useful for future water resource management and agricultural planning. In further studies, the researchers plan to study in detail individual drought events in the 21st century projections to glean insight into their future severity, persistence and geographical scope.

"I look at these future megadroughts like a slow moving natural disaster. We have to put megadroughts into the same category as other natural disasters that can be dealt with through risk management," said Ault.

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Live-Streaming Press Conference

A news briefing related to the forthcoming Science Advances paper, "Unprecedented 21st-Century Drought Risk in the American Southwest and Central Plains," will take place during the 2015 AAAS Annual Meeting. This event, open to credentialed Annual Meeting press registrants only, will take place at 10:00 a.m. U.S. Pacific Standard Time on Thursday, 12 February, in Salon V of the San Jose Marriott, 301 South Market Street in San Jose, California. The embargo on the paper by Cook et al. will lift at 2:00 p.m. U.S. Eastern Standard Time (or 11:00 a.m. Pacific Standard Time) Thursday, 12 February. Reporters, who are registered with EurekAlert!, may participate in the live video-conference by visiting the Virtual Newsroom for further information. (At that link, you also can see the schedule for all AAAS Annual Meeting news briefing webcasts, which will be archived.)

In San Jose, journalists can obtain an Annual Meeting press badge by bringing photographic identification and documentation of status to the AAAS Newsroom Headquarters, Salon II (meeting level) of the San Jose Marriott, 301 South Market Street. Speakers at this event will include Dr. Benjamin I. Cook from NASA, Dr. Toby Ault from Cornell University, and Dr. Jason Smerdon from Columbia University.

The press briefing and related webcast are being made possible through the generosity of the nonprofit American Association for the Advancement of Science (AAAS). Thanks for citing the journal Science Advances (@ScienceAdvances) as well as the AAAS Annual Meeting (#AAASmtg) in coverage of this story. Reporters interested in joining this briefing are asked to send an e-mail to scipak@aaas.org requesting pre-registration.

About AAAS

The American Association for the Advancement of Science (AAAS) is the world's largest general scientific society, and publisher of the journal Science as well as Science Translational Medicine , Science Signaling, and Science Advances, a new digital, open access journal. AAAS was founded in 1848, and includes more than 250 affiliated societies and academies of science, serving 10 million individuals. Science has the largest paid circulation of any peer-reviewed general science journal in the world, with an estimated total readership of 1 million. The nonprofit AAAS is open to all and fulfills its mission to "advance science and serve society" through initiatives in science policy, international programs, science education, and more. For the latest research news, log onto EurekAlert!, http://www.eurekalert.org, the premier science-news Web site, a service of AAAS.

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