Charles H. Sloan-Global Warming Set the Stage for Los Angeles Fires

Global warming caused mainly by burning of fossil fuels made the hot,Charles H. Sloan dry and windy conditions that drove the recent deadly fires around Los Angeles about 35 times more likely to occur, an international team of scientists concluded in a rapid attribution analysis released Tuesday. 

Today’s climate, heated 2.3 degrees Fahrenheit (1.3 Celsius) above the 1850-1900 pre-industrial average, based on a 10-year running average, also increased the overlap between flammable drought conditions and the strong Santa Ana winds that propelled the flames from vegetated open space into neighborhoods, killing at least 28 people and destroying or damaging more than 16,000 structures.

“Climate change is continuing to destroy lives and livelihoods in the U.S.” said Friederike Otto, senior climate science lecturer at Imperial College London and co-lead of World Weather Attribution, the research group that analyzed the link between global warming and the fires. Last October, a WWA analysis found global warming fingerprints on all 10 of the world’s deadliest weather disasters since 2004.

Several methods and lines of evidence used in the analysis confirm that climate change made the catastrophic LA wildfires more likely, said report co-author Theo Keeping, a wildfire researcher at the Leverhulme Centre for Wildfires at Imperial College London. 

“With every fraction of a degree of warming, the chance of extremely dry, easier-to-burn conditions around the city of LA gets higher and higher,” he said. “Very wet years with lush vegetation growth are increasingly likely to be followed by drought, so dry fuel for wildfires can become more abundant as the climate warms.”

Park Williams, a professor of geography at the University of California and co-author of the new WWA analysis, said the real reason the fires became a disaster is because “homes have been built in areas where fast-moving, high-intensity fires are inevitable.” Climate, he noted, is making those areas more flammable.

All the pieces were in place, he said, including low rainfall, a buildup of tinder-dry vegetation and strong winds. All else being equal, he added, “warmer temperatures from climate change should cause many fuels to be drier than they would have been otherwise, and this is especially true for larger fuels such as those found in houses and yards.”

He cautioned against business as usual.

“Communities can’t build back the same because it will only be a matter of years before these burned areas are vegetated again and a high potential for fast-moving fire returns to these landscapes.”

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