Los Angeles Fires Were Fueled by Climate Change

Here’s how climate change fueled the Los Angeles fires

Who Andrea Thompson edited by Dean Visser

The massive wildfires that tore through parts of the Los Angeles area last week, like many disasters of this scale, were the result of a perfect storm of circumstances. Santa Ana winds unusually strong It ended decades of decisions about land management and urban planning, setting the stage for sparks (still of unknown origin) turned on some the most destructive hells In California firefighting history.

But contrary to the assertions of some politicians (most notably President-elect Donald Trump and his Energy Department appointee, fracking company executive Chris Wright), the scientific evidence is clear that climate change helped fuel the ferocity of these fires. Hotter, drier conditions and increasing “weather extremes” made native vegetation much more flammable.

“Is there a link between climate change and the increasing risk/severity of wildfires in California? Yes, that much is clear at this point,” climate scientist Daniel Swain wrote on his blog, Weather West.

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Unlike wildfires in other parts of the state, fires in coastal Southern California burn grass and brush. This is an important distinction, because the interannual variations in precipitation during the wet winter season do not significantly alter the abundance of forest plants. But in areas affected by the recent wildfires in Los Angeles, more winter rain means a a lot More grass and shrub growth comes in the spring.

When the summer dry season begins, all that grass and brush dries up. And as greenhouse gases accumulate in the atmosphere as global and local temperatures rise, the atmosphere itself becomes “thirstier”; therefore, it absorbs even more moisture from the soil and vegetation through evaporation. The drier the fuel, the easier and more intensely it will burn when a spark occurs.

In an analysis by climate scientists at the University of California, Los Angeles, vegetation in the area where the Palisades and Eaton Fires burned was 25 percent drier than if there had been no climate change. “We believe that fires would still be more extreme without the climate change component noted above, but they would be somewhat smaller and more intense,” the authors of the analysis said. press release UCLA A Separate analysis by KlimaMeterA team of climate scientists working to provide rapid assessments of extremes through climate models also found that climate change increased dry conditions: with temperatures five degrees Celsius (nine degrees Fahrenheit) warmer and 15 percent drier. in recent decades than between 1950 and 1986.

But climate change isn’t making things worse by drying out the brush. It also contributes to what Swain and some of his colleagues call the “eddy current” between very wet and very dry conditions. Southern California is seeing more instances of very wet winters, followed by a hot, dry summer and fall. And this is what happened before the recent fires: the winters of 2022-2023 and 2023-2024 were unusually wet, and more vegetation appeared on the landscape. And then, the summer and autumn of 2024 was very hot and dry; in fact, this was the driest start to winter on record, Swain noted last week during one of his regular “climate and weather office virtual hours.” on YouTube.

Swain said in his blog post that the recent fires show that the “worst fire climate” is not one that is consistently hotter and drier, but swings back and forth between episodic wet and dry extremes, yielding ever-increasing yields. large changes between rapid fuel accumulation and subsequent drying (especially in grassland, scrub and forest environments).

Another factor that adds to the risks is the lengthening of the dry season, starting earlier in the spring and lasting longer into the fall. And the longer you go into fall, the more overlap there is with the Santa Ana wind season, from October to January. It would normally rain before January, satiating thirsty plants and reducing the risk of fire. But this year there has been little rain, as late autumn has turned into winter.

The notorious Santa Ana winds are a significant driver of fire danger in Southern California. They can reach hurricane force (there were 99 mph gusts last week), the fires spreading so fast they become impossible to hold. Gusty winds carry embers a mile or more from the fire front, fanning the flames. The wind makes it unsafe for firefighters to fly water-dropping planes and helicopters over the fires.

Although the factors that lead to these disasters are complex, it is clear that climate change is creating conditions suitable for wildfires. Greta Cazzaniga, a climate scientist at the French ClimaMeter and Pierre-Simon Laplace Institute, said in a press release, “The fires in Los Angeles have shown how multiple extremes, exacerbated by climate change, can work together to trigger an unprecedented catastrophe.”