Multiple fires continue to burn in the Los Angeles area after flames have razed neighborhoods, forced mass evacuations and claimed at least 27 lives over more than a week. Some fires have been contained, but three are still active.
That includes two of the biggest and most devastating infernos, the Palisades fire in West Los Angeles and the Eaton fire in Altadena, which are already projected to be the most costly in U.S. history.
As the fires have spread, false or unsupported information about them — particularly about how they started and why they have been so severe — has also escalated.
Some people have cast the fires as largely the result of global warming, while others have denied any climate change connection and pinned blame on a lack of water or vegetation management. (As we’ve already written, many of the claims about water are bogus.) Meanwhile, some have baselessly pointed to lasers or directed energy weapons, among other fanciful conspiracies, as ignition sources.
Here, we explain what’s known about how the fires started and the factors that scientists do — and don’t — think contributed.
- What conditions allowed for the rash of catastrophic fires?
- What sparked the fires?
- Did climate change contribute to the fires?
- Was poor vegetation management to blame?
- What more can be done to prevent similar devastating fires in the future?
What conditions allowed for the rash of catastrophic fires?
Several unique conditions were in place that enabled multiple wildfires to begin and quickly spread.
With almost no rain since July and very low levels of moisture in the air and soil after an extremely hot summer, it was exceptionally dry in Southern California. The precipitation expected with the start of the wet season, which usually begins by December, had not yet arrived. This meant the vegetation, which primarily includes grasses and shrubs, or chaparral — as well as other materials — was highly flammable, and ready to ignite with any spark.
“In modern history, it has not been this dry this late in the ostensible rainy season,” University of California, Los Angeles climate scientist Daniel Swain, who has been closely following the L.A. wildfires, told the New Yorker. Even if a small amount of rain had fallen, he added, there wouldn’t have been the “explosively dry vegetation.”
The already parched conditions were worsened by unusually fierce Santa Ana–like winds, the seasonal dry winds that blow toward the ocean, which also rapidly spread flames and made fighting the fires incredibly difficult.
“When it’s that dry, wind has ultimate power,” University of California, Merced climatology professor John Abatzoglou told Cal Matters.
It’s typical for California to have strong, dry winds this time of year, but these winds were particularly powerful, with gusts reaching up to 100 miles per hour.
In addition to the unprecedented dryness and the stronger-than-normal winds, the amount of vegetation available to burn was also unusually high. That’s because for the two previous years, it had been wetter than normal, allowing plants — and particularly grasses — to grow more. The swing back to dryness meant there was now more fuel to burn, allowing the fires to become more intense.
As several UCLA scientists wrote in a preliminary analysis of the wildfires posted on Jan. 13, “It will require extensive research to fully understand the relative importance of the various factors underlying the fires, and how the factors interacted, but there is broad consensus as to what those factors might be: there was a buildup of fuels—i.e. vegetation—from 2022–2024, followed by a very warm summer in 2024. Then the winter rains that normally arrive in November and December largely failed to materialize. On top of all that, we saw a nearly unprecedented Santa Ana wind event that was critical for the rapid spread.”
What sparked the fires?
There are no definitive answers yet. State and federal officials are investigating possible sources, which for one or more fires include rekindled embers from a previous fire, a failure in energized power lines and arson.
In the information vacuum, social media is awash with misinformation about what started the fires. Some conspiracy theories repeat baseless claims that spread after the Maui fires in 2023, including suggestions that the fires were started with lasers or directed energy weapons or that they’re part of a plot to create smart cities controlled by the government. Other unfounded claims say that the fires were started by smart meters or electric car batteries — or were intentionally set by local officials, neighbors or the rich.
“One of the things that everybody wants to know is how did these fires start. And until the team of investigators concludes their investigations, we don’t really know,” U.S. Forest Service Chief Randy Moore told President Joe Biden at a briefing on the federal response to the fires on Jan. 14, answering a question about the spread of false claims. “And so, there’s a lot of speculation out there about how these fires started, but there’s no proof to validate a lot of these rumors that we’re — we’re hearing.”
The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives’ National Response Team was tasked with investigating the origin of the Palisades fire, which is the largest fire so far. It started the morning of Jan. 7, and as of Jan. 17, is just 27% contained and has burned over 23,700 acres.
Investigators continue to examine the area, gathering evidence and witness statements, but the investigation is likely to take months. (ATF’s team investigation of the Maui wildfires took nearly 14 months.)
A possible ignition source for the Palisades wildfire is a small fire that occurred on New Year’s Eve on a nearby hiking trail. The small fire, which may have been sparked by fireworks, was put out by firefighters. But officials are investigating whether remaining embers could have been rekindled, fueled by the strong winds — similar to how the Maui wildfire started.
The area, known as Skull Rock, is also frequently visited by hikers, who could have somehow sparked a fire. The New York Times reported there was “evidence of recent visitors” at the site. At least one lawyer is investigating if a downed utility line could have sparked the fire, according to the Times.
“Nothing is being ruled out at this point,” Doug Shores, a spokesperson for the ATF’s National Response Team, told us in an email.
In the case of the Eaton fire, which had burned over 14,100 acres and was 55% contained as of Jan. 17, investigators of the California Department of Forestry and Fire Protection are looking into possible failures on electrical towers owned by Southern California Edison over Altadena.
Utilities are required to report any electric incidents potentially associated with wildfires to the California Public Utilities Commission. On Jan. 9, SCE filed such a report “out of an abundance of caution” after social media posts showed flames under an electrical transmission tower and suggested the company’s equipment could be at fault. (Four lawsuits filed this week blamed SCE.) According to the report, the transmission tower lines in the area were energized when the fire started, but early analysis by the company “shows no interruptions or electrical or operational anomalies until more than one hour after the reported start time of the fire.”
David Acuna, battalion chief with CAL FIRE, told CNN that investigators are still gathering information and have not ruled out any cause of the Eaton fire.
“It’s really early in the investigation,” he said in the Jan. 14 interview. “Where we really want to focus right now is to understand that 95% of all fires are started by humans. That’s not all arson, it can be accidental.”
Given the ideal conditions for fire, it doesn’t take much to produce a spark. As an example, Acuna mentioned a mower hitting a rock, a vehicle dragging chains, a campfire or having some sort of combustible near grass.
A 2021 research article that examined Santa Ana wind fires from 1948 to 2018 found that “100% of the fires were caused by humans, either intentionally or accidentally.” The article, published in Science Advances, found that from 1948 to 1983, most fires were sparked by campfires. But later, from 1984 to 2018, most were sparked by arson or power line failures, with the latter dominating in the last decade.
SCE filed a separate report on Jan. 10 for an incident potentially associated with the Hurst fire, which burned nearly 800 acres and is fully contained. In that case, the utility reported a downed conductor at a tower in the vicinity, but says it doesn’t know “whether the damage observed occurred before or after the start of the fire.” Fire agencies are investigating if the equipment was involved in the ignition, according to the report.
Did climate change contribute to the fires?
It’s too early to know how much climate change contributed to the fires, but many climate scientists say it did play a role.
Climate change — as with any other contributing factor — is never the sole cause of a wildfire, which requires not only a spark, but also flammable conditions and something to burn. Fires are also far more devastating when they occur near populated areas and burn people’s homes. Instead, increasing temperatures due to climate change and the downstream effects of that extra heat can make certain events more likely or more severe.
In the case of these wildfires, the primary way climate change is thought to contribute is by drying out vegetation. As Swain, the UCLA climate scientist, has explained, the hotter temperatures increase atmospheric “thirstiness,” or how much moisture the air can suck up. Without increases in precipitation, this can make plants and other material drier and more flammable than they otherwise would be.
Another potential mechanism is related to the previously discussed wet-to-dry swing that occurred this year. Some research, including work led by Swain, suggests that climate change itself may be making such “hydroclimate whiplash” events more common.
As Swain put it in a blog post, “the ‘worst climate for wildfire’ may in fact not be one that becomes steadily hotter and drier, but instead one that increasingly lurches back and forth between episodic wet and dry extremes, yielding increasingly large swings between rapid fuel accumulation and subsequent drying (especially in grassland, shrubland, and woodland environments).”
Continued warming, combined with wider swings between wet and dry, he continued, “are likely to increasingly interact with California’s narrowing rainy season” to generate more frequent overlap of strong, dry winds with “critically dry vegetation conditions” — the exact recipe for catastrophic fires in the region.
In a Jan. 9 X post, Swain called the whiplash phenomenon “an emerging factor” for how climate change could be increasing the risk of wildfire in California.
Not all scientists, however, are convinced that the swing is necessarily related to climate change.
“Is that climate change or is it just, you know, an unfortunate timing of events?” Alexandra Syphard, a senior research ecologist at the Conservation Biology Institute, told us.
Syphard, who was a co-author of the Science Advances paper on wildfire ignition sources, noted that for wildfires specifically in Southern California, the role of climate change is “nuanced” and “often indirect.” For example, climate change-fueled drought conditions can lead to dieback of the native shrubs, including of the chaparral ecosystem that blankets much of Southern California. As those evergreen plants die, invasive grasses can come in, increasing the risk of fire.
“Climate change certainly exacerbates the situation, but in Southern California, the issues that we’re having right now have a lot more to do with human factors than climate factors,” she said. “And the reason for that is because Southern California already has climatically extreme conditions every year.”
As we have explained before, the weaker linkage to climate change for Southern California wildfires is different from the interior forests of California and elsewhere, where the connection is much more clear. Syphard said that in places such as Australia or the Sierra Nevada, climate change “is having a much more severe effect” and “is playing a massive role in those fires.”
In general, Syphard said she considered the role of climate change on fire in Southern California to be “minor to moderate.” In this particular case, she said, “we just don’t know” yet, but said it would be incorrect to say the fires are primarily the result of climate change.
Swain was more definitive, telling us in an email, “I do believe it is accurate to say that climate change is an ‘important/substantial/major’ contributor to the extremely high wildfire risk conditions that were in place the time these dual wildfire disasters unfolded, though it is far from the only relevant factor in why the disaster unfolded as it did.”
The UCLA rapid analysis estimated that climate change “may be linked to roughly a quarter of the extreme fuel moisture deficit when the fires began.”
For its estimate, the report, which has not been peer-reviewed, assumed that climate change did not play a role in the lack of rain, but did contribute to dryness due to the “anomalously warm summer and fall of 2024.” It also noted that “a small part (~10%) of the excess precipitation from during the 2022-2023 and 2023-2024 wet seasons, which led to abnormally high fuel loads, may be climate-change-driven.”
“The fires would still have been extreme without climate change, but probably somewhat smaller and less intense,” it concluded.
Was poor vegetation management to blame?
Soon after the L.A. wildfires began wreaking havoc, a common narrative emerged claiming that poor vegetation management was a key reason why these fires have been so bad.
Donald Trump Jr., for example, stated in an Instagram post mocking California Gov. Gavin Newsom that “proper brush mitigation was ignored for years.”
Other posts have highlighted President-elect Donald Trump’s previous comments blaming Newsom and a lack of forest “raking” or “clean[ing]” of forest floors for wildfires. “Still true,” an Instagram post said of a 2019 Trump tweet.
But as we explained then — and as experts told us once again — while proper forest management is an important part of reducing severe fire risk in forests, it’s a different situation in the grass- and shrubbery-dominated landscape where the current fires are burning in Southern California. (In a Jan. 13 interview with Newsmax, Trump repeated this and other false claims.)
Not only is vegetation management of that ecosystem not particularly helpful in reducing wildfire risk, but active management of the chaparral could backfire. “If the government had requested to remove more chaparral, in a way it could have created an even worse situation,” Syphard said.
That’s because when chaparral is removed, invasive grasses — which are more flammable — move in, heightening the fire risk.
Even putting in more fuel breaks, Syphard said, is not always a good idea, because if a person is not there to fight the fire, the break area can also increase fire risk.
“In Southern California, creating a fuel break means cutting down the chaparral and converting it to grass,” she said. “When you convert it to grass, if an ember lands on that fuel break, it might actually start a new spot fire.”
Particularly with the high winds typical of the season, wildfires will easily cross fuel breaks, Syphard added, noting that embers have jumped across 15-lane freeways.
“Landscape-scale reduction of chaparral will not stop wind-driven wildfires from spreading,” she said.
That’s not to say that property owners shouldn’t keep better tabs on their own plants. Removing vegetation around homes or other structures is recommended, Syphard said.
But other than better enforcement of defensible space rules, she said she did not think the government could have done anything more with vegetation management that would have helped with these fires.
“[L]ack of vegetation management is not what went wrong in these fires,” she said.
What more can be done to prevent similar devastating fires in the future?
Taking action on climate change could reduce some of the extra risk that increasing temperatures can pose to fires in the future. More immediately, however, experts say more attention should be paid to preventing ignitions, making structures more fire-resistant and not continuing to build in high-risk areas.
Reducing human ignitions, Syphard said, will mean fewer fires, which will help stop the so-called grass-fire cycle, in which human-sparked fires beget more grass, which begets more fire, which begets more grass and so on. Understanding the details of how fires start could allow people to develop customized prevention strategies, she said.
Syphard also recommended that people in high-risk communities come together to make their homes and other structures as fire resilient as they can. She cautioned that this work is “not a guarantee” — plenty of people who do all the right things will still lose their homes when wildfires do happen. But, she said, “it can minimize the damage.”
As Heatmap News has reported, California adopted the strictest building code standards for wildfire in the country in 2008, but the standards only apply to new buildings and many homes in the areas that are burning are quite old and may not be built to any code.
Finally, experts say a key way to avoid future disasters is to stop building in the most high-risk areas.
“In the future, if we keep putting more [structures] out there, that’s just putting greater numbers of people to start fires and to be affected by fires,” Syphard said. “So we really should consider where we put future development.”
Editor’s note: FactCheck.org does not accept advertising. We rely on grants and individual donations from people like you. Please consider a donation. Credit card donations may be made through our “Donate” page. If you prefer to give by check, send to: FactCheck.org, Annenberg Public Policy Center, 202 S. 36th St., Philadelphia, PA 19104.