How weather driven by climate change helped fuel the Southern California fires

The wildfires that ravaged the Los Angeles area last month were driven by monthslong, climate change-fueled weather patterns, according to scientists studying the meteorological factors behind them.

Research released last week by World Weather Attribution, a collaboration of scientists studying the influence of climate change on extreme weather events, found that human-caused global warming made the conditions that drove the Los Angeles-area wildfires about 35% more likely. 

The Palisades and Eaton fires razed a total of 37,000 acres. They are the second- and third-most destructive wildfires in California history, respectively, after the 2018 Camp Fire. 

Santa Ana winds helped stoke both blazes; wind gusts originating in the Great Basin, some exceeding 150 mph, blew down the Sierra Nevada to the Los Angeles area just as the Palisades Fire began spreading in the Santa Monica mountains on Jan. 7. The winds arrived after a year when drought followed periods of intense rain — ideal conditions for intense wildfires, said Alexander Gershunov, a climate scientist with the Scripps Institution of Oceanography at the University of California, San Diego. 

“We hadn’t had any significant precipitation, and we were on our third significant Santa Ana wind event of this year,” Gershunov said. “So the winds are right on schedule. It’s the rain that’s late.”

Heavy rain last winter fueled dense plant growth in Southern California, then a prolonged drought beginning in October dried out the new brush, creating tinder for wildfires. Climate change played a role in both phenomena: Extreme atmospheric river events in California are becoming more common as global temperatures rise, since a warmer atmosphere traps more moisture. And although drought is a natural part of California’s climate, climate change is also making drought periods longer and more severe, according to the California Department of Water Resources. 

For some parts of Southern California, the winter wet season got its latest start this year in over 150 years of recordkeeping, Gershunov said.  

“I don’t think we’re adapted to the climate that we have, let alone climate change, which is expected to make it even more volatile in terms of the variability of the total rainfall that we get from year to year,” he said, adding, “We really need to control ignitions, and we need to be very thoughtful about how we expand the growing population into that sloping backcountry.”

Across the Western United States, wildfire season is getting more intense and up to three weeks longer, according to a study published last year by the research organization Climate Central.

“I really think we need to come to terms with the fact that wildfire is a part of this life here in California, and we need to learn how to control it from spreading into places where people are put in harm’s way,” Gershunov said.