A. Park Williams, Benjamin I. Cook & Jason E. Smerdon

Nature Climate Change

Published date February 14, 2022

Rapid intensification of the emerging southwestern North American megadrought in 2020–2021

Study key findings & significance

  • The Western U.S. and northern Mexico are experiencing their driest period in at least 1,200 years

Author quotes

"We have a society that's relying on there being the amount of water there was in the 1900s," said the study's lead author, Park Williams, a bioclimatologist at the University of California, Los Angeles. "But now with the number of water molecules available to us declining, it really is time for us to get real about how much water there is for us to use."


A previous reconstruction back to 800 CE indicated that the 2000–2018 soil moisture deficit in southwestern North America was exceeded during one megadrought in the late-1500s. Here, we show that after exceptional drought severity in 2021, ~19% of which is attributable to anthropogenic climate trends, 2000–2021 was the driest 22-yr period since at least 800. This drought will very likely persist through 2022, matching the duration of the late-1500s megadrought.