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Sean de Guzman takes a sample of the snowpack on Feb. 1 near Twin Bridges, Calif. Photo: Justin Sullivan\/Getty Images<\/p>\n
A "megadrought" that grips the Southwest has broken another record, according to a new study. The last 22 years now rank as the driest such period since at least 800 AD, with human emissions of greenhouse gases accounting for about 42% of the drought's severity. <\/p>\n
The big picture: <\/strong>The new study updates findings from research published in 2020 that found evidence for the first partially human-caused megadrought in the Southwest, but noted that a drought in the 1500s rivaled its intensity and duration. That is no longer the case, the new research shows. <\/p>\n Driving the news: <\/strong>The study looks closely at the 2000 to 2021 period and finds that across southwestern North America, this period was the hottest and driest stretch since at least 1901. <\/p>\n Between the lines: <\/strong>The study was published in 2000 and marked the first time human-induced climate change had been blamed for setting off a megadrought. It contained some hope that the drought was ending in 2019, thanks to more abundant rains. <\/p>\n Threat level: <\/strong>The ongoing drought is affecting water resources in the growing region. Last year, Lake Mead in Nevada hit a record low, which helped to trigger the first federal "water shortage" declaration for the Colorado River basin. This in turn set off water allocation reductions to several states.<\/p>\n What's next: <\/strong>The study cites previous work showing that human-caused climate change, largely due to the burning of fossil fuels, would raise the odds of long, widespread and severe region-wide megadroughts returning to the Southwest after a multi-century-long absence. <\/p>\n\n
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