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Fire crews battle the Kenneth Fire on Jan. 9, 2025, in Los Angeles’ West Hills section. (AP) Fire crews battle the Kenneth Fire on Jan. 9, 2025, in Los Angeles’ West Hills section. (AP)

Fire crews battle the Kenneth Fire on Jan. 9, 2025, in Los Angeles’ West Hills section. (AP)

Caleb McCullough
By Caleb McCullough January 21, 2025

Los Angeles wildfires were worsened by climate change, despite claim to the contrary

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  • High temperatures dried out the vegetation surrounding Los Angeles, which fueled the wildfires. About one-quarter of the dryness can be attributed to climate change, a preliminary report from University of California, Los Angeles found. 

  • Other factors that fueled the blaze, such as the unusually high winds, were likely not caused by climate change, the report said. 

  • A full understanding of how much climate change worsened the fires will take more research.

Donald Trump Jr. said "bad policy and incompetence" — not the planet’s changing temperatures — are to blame in the Los Angeles wildfires. 

"So we are abundantly clear it has nothing to do with climate change or Donald Trump," Trump Jr. wrote in a Jan. 14 Instagram post, which included a clip from the business and tech podcast "All-In."

PolitiFact asked Trump Jr., President Donald Trump’s eldest child, for evidence behind his claim. We reached out through his website and contacted the Trump Organization, for which Trump Jr. is executive vice president. We received no reply. 

Climate scientists PolitiFact spoke to disagreed with Trump Jr. and said climate change contributed to the Los Angeles fires’ size and destructiveness. Numerous studies have linked human-caused climate change to the western U.S.’ worsening wildfires.

In a Jan. 13 analysis, scientists at the University of California, Los Angeles attributed about 25% of the brush dryness around Los Angeles to human-caused climate change. Increased heat over the summer and fall dried out the brush that fueled the fire, the report said.

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The fires would likely have been destructive even without climate change’s influence, the report said, but would have been "somewhat smaller and less intense."

Fully understanding what contributed to the fires — and how much climate change worsened them — will take more research, the report said. Nevertheless, the report identified factors in which "human-induced climate change is very likely to play a role in the wildfires."

Climate change has contributed to more intense wildfires in the western U.S. in recent decades, primarily through higher temperatures, which suck more moisture out of vegetation and make it easier to burn, said University of California, Los Angeles climate scientist Chad Thackeray, who contributed to the new report. Fires have not become more frequent, Thackeray said, but they have become larger and burned more acres.

A 2021 study the National Oceanic and Atmospheric Administration commissioned found that 68% to 88% of the increase in vapor pressure deficit (a measure of the air’s dryness) from 1979 to 2020 linked to human-caused warming, rather than natural atmospheric changes.

A 2016 study, funded partly by Columbia University and NASA, found human-caused climate change "has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting."

High temperatures over the past summer and fall dried out the brush surrounding Los Angeles and were the main contribution climate change made to the current fires, Thackeray said. 

"This occurs because a warmer atmosphere is ‘thirstier’ meaning it has a greater demand to evaporate water from vegetation/soil," he said. 

Average temperatures in California — and around the globe — have increased steadily since 1900, an effect linked to carbon dioxide and other greenhouse gas emissions into the atmosphere. 

"While dry weather is not unprecedented in the US West, 2024 was exceptionally dry in Southern California and through model experiments and statistical analysis, it’s demonstrable that part of that dryness can be attributed to climate change," University of California, Davis climate modeling professor Paul Ullrich said in an email.

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Some of the growth in wildfires in recent decades can also be attributed to forest management practices, he said, but climate change plays a major role.

Another possible climate change-related contributor to the fire is heavy rainfall during previous rainy seasons. The rain spurred vegetation growth, and the vegetation dried out during dry months, giving the fire more fuel. UCLA’s study estimated climate change may have contributed around 10% of the excess rainfall from 2023 to 2024. 

In contrast to previous wet years, Southern California received virtually no rain during the current wet season, which began in October. Although models predict that climate change will delay the rainy season’s onset, Thackeray said research continues and there isn’t enough evidence to attribute the lack of rain in the last few months to climate change. 

"The observed decline may be simply a regression to the mean after an extended period of unusually wet falls in the mid-1900s," the UCLA report said.

The strong Santa Ana winds that worsened the fires in their initial days were stronger than usual for this time of year, but not unprecedented and not attributable to climate change, the report said.

During his Jan. 15 Senate confirmation hearing, Chris Wright, President Trump’s nominee to lead the Energy Department, faced questions about his 2023 description of climate-related wildfire warnings as "hype to justify more impoverishment from bad government policies." Wright said he stood by his comment, but he acknowledged the scientific consensus on climate change.

Our ruling

Trump Jr. said the Los Angeles wildfires have "nothing to do with climate change." 

There is ample evidence that higher temperatures have made California wildfires bigger and more destructive in recent decades. For these fires in particular, a preliminary report found that high temperatures, worsened by climate change, made the vegetation in Southern California dryer, contributing to the fires. 

We rate Trump Jr.’s claim False. 

Our Sources

Donald Trump Jr., Instagram post, Jan. 13, 2025

Email interview with Paul Ullrich, regional and global climate modeling professor at the University of California, Davis

Email and phone interview with Chad Thackeray, climate scientist at the University of California, Los Angeles

University of California, Los Angeles, Climate Change A Factor In Unprecedented LA Fires, Jan. 13, 2025

National Oceanic and Atmospheric Administration, Wildfire climate connection, accessed Jan. 17, 2025

Nature, Yes, Climate Change is Raising the Risks—and Stakes—of Extreme Wildfires, July 9, 2024

Proceedings of the National Academy of Sciences, Quantifying contributions of natural variability and anthropogenic forcings on increased fire weather risk over the western United States, Nov. 1, 2021

Proceedings of the National Academy of Sciences, Impact of anthropogenic climate change on wildfire across western US forests, Oct. 10, 2016

California Office of Environmental Health Hazard Assessment, Air temperatures, accessed Jan. 17, 2025

CNBC, Chris Wright testifies before Senate at confirmation hearing for energy secretary, Jan. 15, 2025

NPR, Trump's energy secretary nominee faces questions over climate posts and LA fires, Jan. 16, 2025

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Los Angeles wildfires were worsened by climate change, despite claim to the contrary

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