Longer, More Frequent Periods of Drought Plague Western United States

Tuesday, April 6, 2021
According to a new study from UArizona researchers, average temperatures have increased, annual rainfall has decreased, and dry periods have become longer and more variable across the American West over the last 50 years.

Periods of drought in the western United States have become longer over the past 50 years, according to a new study from researchers in the University of Arizona College of Agriculture and Life Sciences in partnership with the USDA Agricultural Research Service.

"The region that really stood out, in terms of combined detrimental changes, was the desert southwest, where daily temperatures have increased by 0.2 (degrees) Celsius per decade, total annual precipitation has decreased by 19 millimeters per decade, and mean dry intervals have jumped from 31 days to 48 days," said lead author Fangyue Zhang, a postdoctoral researcher in the School of Natural Resources and the Environment.

Against the backdrop of steadily warming temperatures and decreasing annual rainfall totals, extreme-duration drought is becoming more common – and what rain does fall comes in fewer and sometimes larger storms. Together, these changes will likely have long-lasting and significant consequences for social and ecological systems in the western U.S., according to researchers.

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