January 17, 2025
4 minimum read
How climate change caused the Los Angeles wildfires
Many factors contributed to the recent devastating wildfires in the Los Angeles area, including high winds in Santa Ana and city planning decisions. But the evidence is clear that climate change has contributed
Smoke obscured the sun as it rose over the Altadena Town and Country Club, which was destroyed by the Eaton Fire in Altadena.
Will Lester/MediaNews Group/Inland Valley Daily Bulletin (Getty Images)
The horrific wildfires that tore through parts of the Los Angeles area last week were, like many disasters of this magnitude, the result of a perfect storm of circumstances. Santa Ana’s unusually high winds reversed decades of land management and urban planning decisions and set the stage for a spark (the source of which is still unknown) that caused the most destruction in recognized fire-prone California history. caused some of that hell.
But contrary to claims by some politicians (particularly President-elect Donald Trump and Chris Wright, a fracking company executive nominated to be Secretary of Energy), climate change has not contributed to the ferocity of these fires. This is clear from scientific evidence. Hotter, drier conditions and an increase in “weather whiplash” have made local vegetation even more flammable.
“Is there a link between climate change and a widespread increase in wildfire risk/severity in California? Yes; it’s clear at this point,” climatologist Daniel Swain writes on his blog, “Weather West”.
About supporting science journalism
If you enjoyed this article, please consider supporting our award-winning journalism. Currently subscribing. By subscribing, you help ensure future generations of influential stories about the discoveries and ideas that shape the world today.
Unlike wildfires in other parts of the state, fires in coastal Southern California burn grass and brush. This is an important distinction because although the amount of precipitation that falls during the wet winter season varies from year to year, the amount of plant life in the forest remains virtually unchanged. But in areas like those affected by the recent Los Angeles fires, increased winter rains can many In the spring, the grass and bushes will grow even more.
When the summer dry season begins, all the grass and bushes die. And as global and regional temperatures rise due to the buildup of greenhouse gases in the atmosphere, the atmosphere itself becomes “thirsty” and therefore draws more moisture from the ground and vegetation through evaporation. When the fuel is dry, it burns more easily and violently when a spark occurs.
An analysis by climate scientists at the University of California, Los Angeles, found that vegetation in areas affected by the Palisades and Eaton fires is 25 percent drier than it would have been without climate change. “We believe that without the climate change factors listed above, the fires would still have been intense, but would have been somewhat smaller and less intense,” the analysis’s authors said in a press release from UCLA. . Climate scientists working to quickly assess extreme weather using climate models say climate change will amplify drier conditions, with temperatures as much as 5 degrees Celsius (9 degrees Fahrenheit) warmer and temperatures as high as 15 degrees Celsius (9 degrees Fahrenheit) warmer. We also found that the temperature had increased. Over the past few decades, aridity has improved by % compared to the period 1950-1986.
But climate change isn’t just making the situation worse by drying out the bushes. It also contributes to what Swain and some of his colleagues call “whiplash” between very wet and very dry conditions. Southern California is increasingly experiencing very wet winters followed by hot, dry summers and fall. And that’s exactly what happened before the recent wildfires. The winters of 2022-2023 and 2023-2024 were unusually wet, causing more plants to grow across the landscape. And the summer and fall of 2024 were extremely hot and dry — in fact, it was the start of the driest winter on record, Swain said last week in his regularly scheduled “Virtual Climate and Weather said during one of his office hours. YouTube.
In a blog post, Swain wrote that the recent fires are “the worst climate for wildfires”, which is not actually one that gets steadily hotter and drier, but rather a transition between the extremes of episodic wetness and dryness. “This suggests that we may be in a climate where more and more damage will occur.” Large fluctuations occur between rapid fuel accumulation and subsequent desiccation (particularly in grassland, shrubland, and forest environments). ”
Another factor that increases the risk is the fact that the dry season begins early in the spring and lasts long into the fall. And the longer fall lasts, the more it overlaps with the Santa Ana wind season, which lasts from October to January. Normally, rain would arrive before January to hydrate thirsty plants and reduce the risk of fire. However, this year, as late autumn turned to winter, there was almost no rain.
The infamous Santa Ana winds are a major source of fire danger in Southern California. They can reach hurricane force (with wind gusts of up to 99 mph recorded last week) and spread fires so quickly that they become impossible to suppress. Fierce winds can carry embers more than a mile beyond the fire front, igniting them. The wind also makes it dangerous for firefighters to fly water spray planes or helicopters over the fire.
Although the factors that cause these disasters are complex, it is clear that climate change is creating the perfect conditions for wildfires. Greta Cazzaniga, a climate scientist at France’s Climameter and the Pierre-Simon Laplace Institute, said in a recent press statement: disaster. “
