Climate Change is Driving the Worst Western Drought in 1,200 Years
New research shows that the Western US and northern Mexico are undergoing their driest period in at least 1,200 years. The past 22 years constitute a megadrought, defined as a decades-long period of extreme dryness. Researchers estimate that 42% of this drought's severity is due to higher temperatures from climate change. Currently, 96% of the Western US is now abnormally dry or worse, and 88% of the region is in drought.
PBS: Western states face a bleak future amid the worst drought in more than 1,000 years, February 15, 2022.
Why This Matters
It's no secret that this past year has been the West's driest and hottest on record -- December 2021 was the US's hottest December ever recorded -- but this new research shows just how unprecedented this weather is. Because of this dry spell, fire season has gotten much longer; Colorado was hit with the state's most severe wildfire in December, which is usually a cold, wet month. Worse yet, the heat may not be letting up as another year of La Niña in 2022 could further exacerbate the Western drought.
Guardian: The climate science behind wildfires - why are they getting worse?, August 20, 2021.
CBS: What the megadrought means to the American West, July 18, 2021.
An Impending Water Crisis
Prolonged droughts are quickly depleting the West's water supply. The flow of the Colorado River during the 2020 and 2021 water years shrank to the lowest two-year average in more than a century of recordkeeping. The river's two largest reservoirs, Lake Mead and Lake Powell, declined to their lowest levels on record.
Important water sources like California's Sierra Nevada snowpack could disappear within 25 years if this trend continues. The Sierra Nevada snowpack typically accounts for around 30% of California's fresh water supply, and the region as a whole counts on snow for 75% of its fresh water supply.
While groundwaters and large reservoirs are buffering the West from the worst of the megadrought, these resources may not last long.
UCLA climate scientist Park Williams told the LA Times: "…We are utilizing those backstops so rapidly right now that we’re at real risk of those backstops not being there for us in 10 or 20 years when either this event still hasn’t ended, or when the next megadrought has already begun."
YaleClimateConnections: Is Western US experiencing a 'megadrought'?, August 15, 2021.
WW0: Newsmaker of the Week - Jacob Morrison, director of River's End, October 28, 2021.