The intense dry spell in the West is worst 'megadrought' in 1,200 years, new study says
The intense dry spell that has parched the western U.S. the past 22 years is the region's worst "megadrought" since at least the year 800, a new study says.
Megadroughts, which are defined as intense droughts that last for decades or longer, once plagued western North America. Now, thanks in part to global warming, an especially fierce one is back.
The study, published Monday in the peer-reviewed British journal Nature Climate Change, said that more than 40% of the drought can be blamed on human-caused climate change.
“Climate change is changing the baseline conditions toward a drier, gradually drier state in the West, and that means the worst-case scenario keeps getting worse,” said study lead author Park Williams, a climate hydrologist at UCLA. “This is right in line with what people were thinking of in the 1900s as a worst-case scenario. But today I think we need to be even preparing for conditions in the future that are far worse than this.”
Climate change from the burning of fossil fuels is bringing hotter temperatures and increasing evaporation in the air, scientists say.
Thanks to the region’s high temperatures and low rain and snow levels from summer 2020 through summer 2021, the drought has exceeded the severity of a late-1500s megadrought that had been identified as the worst such drought in the 1,200 years the scientists studied.
The researchers calculated the intensity of past droughts by analyzing tree ring patterns, which provide insights about soil moisture levels each year over time.
As of Feb. 10, according to the U.S. Drought Monitor, 95% of the western U.S. was experiencing drought conditions. And in summer 2021, according to the U.S. Bureau of Reclamation, two of the largest reservoirs in North America – Lake Mead and Lake Powell, both on the Colorado River – reached their lowest recorded levels.
The study “is an important wake-up call,” said Jonathan Overpeck, dean of environment at the University of Michigan, who wasn’t part of the study. “Climate change is literally baking the water supply and forests of the Southwest, and it could get a whole lot worse if we don’t halt climate change soon.”
Contributing: The Associated Press
This article originally appeared on USA TODAY: Megadrought: Western U.S. dry spell is worst in 1,200 years, study says