Nov 2, 2021 - Energy & Environment

Study: Climate change main cause of wildfire weather in U.S. West

A firefighter from San Diego, saves an American flag as flames consume a home during the Dixie fire in Greenville, California on August 4, 2021.
A firefighter saves an American flag as flames consume a home during the Dixie Fire in Greenville, California, on Aug. 4. Photo: Josh Edelson/AFP via Getty Images

Human-caused climate change is the main driver behind increased wildfire risk in the U.S. West, according to a study published Monday.

Why it matters: Researchers hadn't expected human-caused global warming to take over from natural climate variability as the main contributor to fire weather until much later this century, around 2080, per the Los Angeles Times.

By the numbers: Wildfires razed an average of 5,200 square miles of land per year in the Western U.S. from 2001 to 2018 — nearly double the area burned when compared with the period from 1984 to 2000, per the study, published in the Proceedings of the National Academy of Sciences.

  • Researchers found global warming was 68%-88% likely the driving factor for atmospheric conditions fueling increasingly destructive wildfires.

The big picture: The team from UCLA and the Lawrence Livermore National Laboratory analyzed factors behind the "vapor pressure deficit" (VPD), the leading climate variable predicting wildfire risk which indicates how dry the air is.

  • As part of the study, researchers analyzed the role of human-caused climate change in last year's August Complex Fire — California's biggest wildfire event on record, which saw some 1,600 square miles razed.
  • "In the case of the August Complex Gigafire in 2020, the results suggest that anthropogenic warming [originating from human activity] explains 50% of the anomalously high VPD observed during that month," per a statement accompanying the study.

Of note: A UN report published last August warned of the "unequivocal" connection between human-caused global warming and extreme weather and climate events.

The bottom line: The new findings, combined with previous research, show that further global warming will likely continue to intensify "conditions that create record or near-record fuel aridity conditions on the landscape," said Noah Diffenbaugh, a climate scientist at Stanford University to the L.A. Times.

  • "It means a higher risk of more severe fire conditions, simultaneously, in multiple areas of the region," added Diffenbaugh, who wasn't involved in the study.

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