CNN
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The fires that ravaged Los Angeles over the past week were larger and burned hotter than in a world without planet-warming fossil fuel pollution, a new analysis suggests.
Climate change could be blamed for about 25 percent of the fuel available for fires, according to a rapid study by scientists at the University of California, Los Angeles. The report clearly states that the fires would likely have occurred in a world without climate pollution, but it concludes that they would have been “somewhat smaller and less intense.”
This result raises the question of whether the fires could have been contained without the fire-stoking effects of climate change. The UCLA scientists view their analysis as a “starting point” for further study.
Twelve fires have broken out in the Los Angeles area since Jan. 7, when a once-in-a-decade Santa Ana wind storm swept across Southern California’s drought-parched landscape. Since then, more than 60 square miles have been charred and more than 12,000 structures have burned, such as homes, businesses, sheds and garages.
Four days after they started, the Eaton and Palisades fires had grown enough for CalFire to rank them as the first and second most destructive fires in Southern California history.
Some of the climate-related factors that contributed to the increase in fuel available for the fire were excessive humidity from previous winters, unusually warm southern California summers and autumns, and a significantly delayed rainy season until present during the winter of 2024-2025.
Two winters in a row, downtown Los Angeles saw twice as much rain as a normal winter, the researchers noted. This in itself is a calling card of human-caused climate change, which promotes greater humidity in the atmosphere, leading to greater precipitation totals in the wetter years. The rain stimulated the growth of “a lot more” grasses and shrubs than normal. Vegetation in the Los Angeles area was among the greenest since 2000, they noted.
When the weather pendulum swung dry last summer, grasses and shrubs – which Southern California’s wildfires feed on – began to dry out. The exceptionally late arrival of the rainy season further contributed to this drying.
The status quo in Southern California is characterized by extreme fluctuations between dry and wet, the UCLA researchers noted, but the lack of precipitation since May 2024 was exceptional. With just 0.29 inches of rain between May 1, 2024 and January 8, the period ranks as the second driest period behind 1962-1963, with records dating back to 1877.
At the time the first fires broke out, the moisture content of dead vegetation was the 6th lowest on record, according to the report.
These massive shifts from dry to wet conditions — known as “weather whiplash” — are becoming more common as the planet warms due to fossil fuel pollution, CNN previously reported. These fluctuations increase the severity and risk of hazards such as wildfires and flash floods.
Although the extremely dry conditions were enough to fuel a dangerous fire, this event was also triggered in part by an unusually strong wind in Santa Ana. The UCLA researchers found that the winds were “indeed a very unusual event in Santa Ana, but perhaps not entirely unprecedented.” They also noted that there is no physical explanation for how global warming from fossil fuel pollution could lead to more extreme winds in Santa Ana.
The researchers concluded that given the clear link between the size and intensity of wildfires, and knowing that fires will continue to get worse as the planet warms, the focus should be on ” aggressive suppression” during times of high wildfire risk, strategies to prevent homes from easily catching fire. and avoiding high-risk areas when developing new urban areas.
January is typically the second wettest month in Southern California. February is the wettest month. The forecast for Los Angeles suggests the prospect of a completely dry January. At the very least, below normal precipitation is expected to persist through February.