Sep 23, 2021 - Energy & Environment

Southwest drought is worst on record, NOAA finds

In a stark new report, a team of NOAA and independent researchers found the 2020-2021 drought across the Southwest is the worst in the instrumental record, which dates to 1895.

Why it matters: They also concluded that global warming is making it far more severe, primarily by increasing average temperatures, which boosts evaporation.

State of play: The Southwest is facing historic water woes, with the first-ever federal water shortage declaration at Lake Mead, the nation's largest reservoir by surface volume.

  • This triggered cutbacks in Colorado River water allocations to Arizona and other states, a waterway that 40 million people rely on for irrigation and drinking water.
  • A dangerous wildfire scenario continues to play out, especially in California, where the Dixie Fire is now the state's second-largest on record, approaching the rare category of a "gigafire," by charring at least 1 million acres.
  • The report found that the 20-month period from January 2020 to August 2021 was the driest such period on record, as well as the third-warmest.

Threat level: The study ties the heat directly to climate change, and warns the severity of such drought events is sure to worsen barring reductions in greenhouse gas emissions.

  • Higher temperatures cause spring snowpack to disappear early and accelerates the drying of soils.

The big picture: The drought is occurring in the context of the first climate change-induced "megadrought," which research shows began in 2000 and is exceptional on millennial timescales, study co-author Justin S. Mankin of Dartmouth University, told Axios.

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