Severely low snow conditions in the Western U.S. this past winter were made much more likely by human-caused climate change, a new study has found.
Warmer temperatures meant more precipitation fell as rain instead of snow, and that snow melted earlier than is typical. Researchers found the low amount of snow on the ground in mid-March was 4.4 times as likely in today’s climate as it would have been between 1850 and 1900, before widespread warming.
“We could have had bad snow years without climate change,” said Adrienne Marshall, an assistant professor of geology and geological engineering at Colorado School of Mines, who led the study. “But this study gives us evidence that a bad snow year in the climate we're living in now is substantially worse than what we would have had in the absence of climate change.”
The study, published in the journal Proceedings of the National Academy of Sciences, is among the first to use attribution science — a field that examines how much climate change influences particular weather events — to assess a snow drought.
The effects were especially pronounced in the Upper Colorado River Basin. There, researchers found this past winter’s low snow levels were 14 times more likely because of climate change.
The stakes go beyond ski conditions. Researchers estimated that warming reduced the amount of water stored in this year’s snowpack by an amount comparable to the capacity of Lake Mead, a key water source for communities across the Southwest.
Looking ahead, the study found that in a future with moderately high greenhouse gas emissions, snow droughts like this one could occur as often as onceevery three years by midcentury and about 87% of years by the 2090s.
“That suggests that snow conditions as bad would become more common than not,” Marshall said.
But she said that that future is not inevitable: “I hope that it helps us think critically about how we can avoid more of these low snow conditions by reducing greenhouse gas emissions.”
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
