The brutal American Southwest megadrought responsible for conjuring up these horrific images of dried-up lakes and reservoirs is officially one of the worst prolonged droughts in recorded human history, one built largely on the backs of human-induced climate change.
That historic drought now ranks as the driest 22-year period dating back at least 1,200 years with the closest comparable drought taking place about half a millennia ago according to a new study published in Nature Climate Change this week. The findings pointed to an exceptionally dry 2021 as being primarily responsible for pushing this recent stretch of time up and above the next driest period, which occurred in the late 1500s.
The drought’s geographical boundaries reportedly stretch from Montana to northern Mexico and between the Pacific Ocean and the Rocky mountains. “This represents the largest SWNA [southwestern North America] area to experience a top-five 22-yr drought-severity ranking in at least 1,200 years,” the study reads.
The study’s lead researcher, University of California, Los Angeles bioclimatology Park Williams, reportedly looked at tree ring data dating back over a thousand years to 800 AD. Williams found just four other megadroughts within that time span. Meanwhile, 2002 marked the second driest year during that time span, according to the data, only trailing behind 1580. Though the 2002 findings were surprising on their own, William told the Associated Press he was shocked to find a “statistical tie” in drought level less than 20 years later in 2021.
The study’s authors reportedly created a hypothetical world with no human-induced warming based on 29 models to suss out just how large a role humans played in the recent drought. In the end, the study directly attributed 42% of drought conditions to human-caused warming.
Park had previously investigated the long-term data through 2018. At that time, the researchers had speculated the drought could have subsided by 2019 only to find dry conditions return and intensify over the course of the next two years. Unsettlingly, the researchers believe recent data suggests the drought may be far from over.
“From summer 2020 through all of 2021, it was just exceptionally dry across the West,” Williams told NPR. “Indicating that this drought is nowhere near done.”
The study comes on the heels of a year marked by record low water levels at both Lake Mead and Lake Powell, the two largest reservoirs in the U.S. Those are troubling realities for a region, now populated by millions of inhabitants, who are facing drought levels last seen hundreds of years prior to the industrial revolution.