The megadrought gripping the American West has generated the driest two decades in the region in at least 1,200 years, and human-caused climate change has fueled the problem, scientists said on Monday.
In their research, published in the journal Nature Climate Change, scientists analyzed droughts in southwestern North America dating back to the year 800 and found that conditions during this century are more severe than the megadrought in the late 1500s.
Researchers also warned that drought conditions will likely continue through 2022 and persist for years. A megadrought is defined as a prolonged severe and intense drought spanning two decades or longer, according to the National Oceanic and Atmospheric Administration.
“Rather than starting to die away after wet years in 2017 and 2019, the 2000s drought has ramped up with authority in 2020-2021, making clear that it’s now as strong as it ever was,” said A. Park Williams, a climate scientist at UCLA.
“There is no evidence that the 2000s drought is starting to relent,” added Williams, who led the analysis using tree ring data to study ancient records of droughts.
While the U.S. West would be in drought regardless of climate change, researchers calculated that 42% of the drought’s severity can be attributed to higher temperatures due to greenhouse gas emissions trapping heat in the atmosphere.
According to the U.S. drought monitor, nearly 95% of the Western U.S. is experiencing drought conditions. The drought has already triggered more intense wildfires across the region and declining water supplies as reservoir levels drop.
Water shortages on the Colorado River have caused the two largest reservoirs in the country, Lake Mead and Lake Powell, to drop to their lowest levels ever recorded. And in 2020, the worst wildfire season on record burned more than 10 million acres in the U.S.
Federal officials last year ordered the first-ever water cuts for the Colorado River Basin, affecting supplies water and power for more than 40 million people across the West.
In California, Gov. Gavin Newsom asked residents last year to curb household water consumption by 15% amid record-breaking temperatures. And water officials recently warned that California could face its third consecutive dry year due to a significant lack of snow this year.