Megadrought that has affected southwestern North America for two decades is the worst in 1,200 years

The megadrought that has hit southwestern North America for two decades is the worst in the last 1,200 years, according to a study that highlights that this episode, aggravated by climate change, will probably continue in 2022.

Since 2000, the western United States and northern Mexico have suffered an exceptional drought that has already exceeded two decades, which allows it to be classified as a “mega-drought”.

“Following an exceptionally severe drought in 2021, of which around 19% is attributable to human-induced climate change, the 2000-2021 period was the driest 22 years since at least the year 800,” the researchers write. researchers in the scientific journal Nature Climate Change.

Due to the very high temperatures and low rainfall between the summer of 2020 and 2021, this megadrought “exceeded the severity” of the one at the end of the 16th century, which until now was the worst recorded in the 1,200 years reviewed by scientists, notes a statement from the University of California at Los Angeles (UCLA).

And since 2000, the soil moisture deficit has been twice as large as during any drought in the 20th century.

In addition, this episode “is likely to persist until 2022, reaching the duration of the mega-drought at the end of the 16th century,” the study says.

Even if the rain does return, the impact is likely to last from southern Montana to northern Mexico and from the Pacific Ocean to the Rocky Mountains.

“It’s very unlikely that this drought could end a single wet year,” said study lead author Park Williams, a UCLA geographer.

“Without climate change, the last 22 years would probably still be the driest in the last 300 years,” but “not on a par with the megadroughts of the 1500s, 1200s and 1100s,” it said in a statement.

According to the study, climate change linked to human activities, which increases heat waves and alters the rainfall pattern, is responsible for 42% of the soil moisture deficit in the period 2000-2021 in this area, and 19 % in 2021.

Last August, this chronic drought in the western United States led the federal government to impose the first water restrictions on Lake Mead, the largest man-made reservoir in the country, fed by the Colorado River.