A megadrought ailing the American West got even drier last year and is becoming the deepest dry spell in more than 1,200 years. A study out Monday said the megadrought is now the worst-case scenario officials and scientists worried about in the 1900s. The drought deepened so much in 2021 that it is 5% worse than the old record in the late 1500s.

Scientists compare this megadrought to what would happen in a hypothetical world without human-caused climate change. And they calculate that 42% of this drought is due to global warming from the burning of fossil fuels.

A study published in the journalNature Climate Changefound that the window of time between 2020-2021 was the driest for southwestern North America in 1,200 years.

In the study, researchers said, "Since the year 2000, southwestern North America has been unusually dry due to low precipitation totals and heat, punctuated most recently by exceptional drought in 2021."

As CNN reported, the burning of fossil fuels has been found to be directly related to water availability in the West. The National Oceanic and Atmospheric Administration reported that in December Los Angles experienced its second-wettest month on record, but then last month Los Angeles experienced its eight-driest January on record for the city.