The extremely dry conditions in the western United States over the past 22 years have created a "megadrought" and can now be considered the driest period of time in over 1,200 years, according to a new study published on Monday.
The study was done by the peer-reviewed British journal Nature Climate Change, and said the main reason for the worst drought since the year 800 was 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," study lead author Park Williams, a climate hydrologist at UCLA, said.
"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."
The authors attribute 19% of the 2021 drought, and 42% of the drought dating back to 2000, to human-caused climate change.
The period of time from 2000 through 2018 was identified as the second-worst megadrought in 1,200 years, according to previous work by authors of the new study, per The Washington Post.
The last comparable megadrought in the western United States occurred in the 1500s.
"Without climate change, this would not be even close to as bad as one of those historical megadroughts," Williams said. "The thing that is really remarkable about this drought period is that temperatures have been warmer than average in all of the years but one."
95% of the western United States was experiencing drought as of Feb. 8, according to the U.S. Drought Monitor.
The study showed that the 21st century has had 8.3% less precipitation than the previous five decades. It was also an average of 1.8 degrees Fahrenheit warmer than the period from 1950 to 1999.
"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," Jonathan Overpeck, dean of environment at the University of Michigan, who wasn’t part of the study, said.
Extremely dry conditions have continued in the western United States early on in 2022, and are likely to continue. California has already been dealing with record temperatures last week, as the National Weather Service in Los Angeles issued a heat advisory for the first time during the winter months.
The UC Berkeley Central Sierra Snow Lab said that following the snowiest December on record there has been another record -- 37 straight days without precipitation. California's snowpack is down from 160% of normal in December to just 73% of normal as of Feb. 14.
"This drought will very likely persist through 2022," the study said, "matching the duration of the late-1500s megadrought."
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