Updated Dec 31, 2021 - Science

Climate changes linked to Colorado's fire disaster

Picture of a building burning in a Colorado wildfire on Dec. 30, 2021.

Fire takes over a business in Louisville, Colorado. on Dec. 30. Photo: Helen H. Richardson/MediaNews Group/The Denver Post via Getty Images

The Boulder, Colorado-area wildfires — the most destructive in state history — were likely made worse by the effects of climate change, including extremely dry conditions and long stretches of record warm weather in recent months.

Why it matters: The Marshall Fire that consumed at least 1,600 acres on Thursday destroyed nearly 600 homes, Boulder County Sheriff Joe Pelle said at a Thursday news conference.

  • Climate factors provided the fuel for the devastating fires, while an extreme weather event, in the form of powerful downslope winds coming off the Rocky Mountains, provided the spark and fanned the flames.
  • Wind gusts peaked as high as 110-115 miles per hour -- equivalent to a Category 2 or 3 hurricane.

Catch up fast: The rapidly-moving flames led to evacuation orders covering more than 30,000 people in Superior, Louisville and portions of other communities.

Threat level: The conditions that helped make the fire so devastating bear the imprint of climate change.

Context: Late December is downslope wind season along Colorado's Front Range, Boulder meteorologist Matthew Kelsch told Axios. However, this event was unusually intense, he said, and overlapped with the tinderbox dry conditions.

  • This enabled any spark to fuel an inferno, whereas in previous years, such winds came after snowstorms had already occurred.
  • This year, Denver had its least snowy September through November period on record and latest first snow on record. Fall finished without measurable snow for the first time since records began in 1882, the Weather Service stated.
  • Heavy snow finally arrived Friday, one day too late to prevent the disaster.
  • As is occurring in California and other western states, Colorado has seen an uptick in large wildfires and wildfire severity in recent years, which studies have tied to human-caused climate change.
  • Sixteen of the top 20 largest wildfires on record have occurred since 2008, according to the Colorado Division of Fire Prevention and Control.

What they're saying: With universities and government research labs located there, the Boulder region is home to some of the top authorities on climate change and extreme weather events.

  • University of Colorado ecologist Merritt R. Turetsky, an expert in wildfire behavior, said via Twitter that extremely dry conditions and high winds together create "hot, flashy, and very dangerous grass fires."
  • "This is the human and health cost of the #ClimateCrisis," she tweeted.
  • Daniel Swain, a climate scientist at UCLA and researcher at the National Center for Atmospheric Research in Boulder, described the fires as "climate enabled and weather-driven." On Friday, he tweeted that he woke up to the "overwhelmingly acrid smell of burnt homes."
  • According to data Swain cited, the past 90 days were the warmest and driest on the Front Range of Colorado since at least 1979. Additionally, the "vapor pressure deficit," a key wildfire risk indicator that measures how quickly the air robs plants of moisture, was at a record high on Thursday.
  • "Climate change is clearly increasing both temperatures [and] vapor pressure deficits across [the] Western U.S.," Swain tweeted.

The bottom line: The urban firestorm in Colorado caps off a year of jarring and devastating extreme weather events across the U.S., with scientists increasingly wondering if the pace and severity of climate impacts is proceeding faster than previously thought.

Go deeper: Fast-moving wildfires burn at least 580 homes near Denver

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