An exceptional mix of environmental conditions has created an ongoing firestorm without known historical precedent across southern California this week.
The ingredients for these infernos in the Los Angeles area, near-hurricane strength winds and drought, foretell an emerging era of compound events – simultaneous types of historic weather conditions, happening at unusual times of the year, resulting in situations that overwhelm our ability to respond.
On Wednesday, Joe Biden pledged the assistance of the Department of Defense to reinforce state and local firefighting capabilities, a rare step that highlighted the extent to which the fast-moving fires have taxed response efforts.
As of Wednesday evening, the Palisades and Eaton fires have each burned more than 10,000 acres and remain completely uncontained. About one in three homes and businesses across the vast southern California megacity were deliberately without power in a coordinated effort by the region’s major utilities to contain the risk of new fire starts due to downed power lines.
The Palisades fire now ranks as the most destructive in Los Angeles history with hundreds of homes and other structures destroyed and damage so extensive that it exhausted municipal water supplies. In Pacific Palisades, wealthy homeowners fled by foot after abandoning their cars in gridlocked neighborhoods. In Pasadena, quickly advancing fire prompted evacuations as far into the urban grid as the famous Rose Parade route.
Early estimates of the wildfires’ combined economic impact are in the tens of billions of dollars and could place the fires as the most damaging in US history – exceeding the 2018 Camp fire in Paradise, California.
Fire crews have been facing a second night of fierce winds in rugged terrain amid drought and atmospheric conditions that are exceedingly rare for southern California at any time of the year, let alone January, in what is typically the middle of the rainy season – weeks later (or earlier) in the calendar year than other historical major wildfires have occurred.
The next few days will be a harrowing test. Lingering bursts of strong, dry winds into early next week will maintain the potential for additional fires of similar magnitude to form. In a worst-case scenario, the uncontained Palisades and Eaton fires will continue to spread further into the urban Los Angeles metro, while new fires simultaneously and rapidly grow out of control – overtaking additional neighborhoods and limiting evacuation routes more quickly than firefighters can react. In conditions like these, containing a wind-driven blaze is nearly impossible.
These fires are a watershed moment, not just for residents of LA, but emblematic of a new era of complex, compound climate disaster. Conditions for a January firestorm in Los Angeles have never existed in all of known history, until they now do.
The short answer is that the greenhouse gases humans continue to emit are fueling the climate crisis and making big fires more common in California.
As the atmosphere warms, hotter air evaporates water and can intensify drought more quickly.
Melting Arctic ice creates changes in the jet stream’s behavior that make wind-driven large wildfires in California more likely. Recent studies have found that Santa Ana wind events could get less frequent but perhaps more intense in the winter months due to the climate crisis.
The more complicated answer is that these fires are an especially acute example of something climate scientists have been warning about for decades: compound climate disasters that, when they occur simultaneously, produce much more damage than they would individually. As the climate crisis escalates, the interdependent atmospheric, oceanic and ecological systems that constrain human civilization will lead to compounding and regime-shifting changes that are difficult to predict in advance. That idea formed a guiding theme of the Biden administration’s 2023 national climate assessment.
In the 16 months since the city’s first tropical storm encounter, southern California has endured its hottest summer in history and received just 2% of normal rainfall to start this year’s rainy season – its driest such stretch on record. The grasses from 2023’s tropical storm deluge are still around, adding to the fuel for fires.
On its own, that would be a recipe for disaster. But add to that this week’s historic Santa Ana wind storm, which on its own has broken wind speed records across the region for any time of the year, with gusts as high as 100mph early on Wednesday. These have combined to create extreme conditions suitable for wildfire that, on their own, would tax the state’s resources even during even the heart of the summer fire season – let alone during January when many firefighters are on leave and equipment has been moved into storage.
This is how tipping points happen.
This scene is playing out all over the world, not just in fires.
The 2020 and 2021 hurricane seasons saw a combined seven major hurricanes affect Louisiana and the broader central Gulf coast, sometimes just weeks apart. A similar hurricane swarm happened last year in Florida. In 2023, wildfires burned an area of Canada more than double the previous record, sending plumes of smoke across the continent and raising public health concerns for tens of millions of people downwind.
In the weeks and months ahead, when the rainy season resumes and the next atmospheric river arrives, Los Angeles will be at an elevated risk for catastrophic flooding in the burn scars of the Palisades and Eaton fires, again compounding the disaster for local residents.
• Eric Holthaus is an American meteorologist and climate journalist
• This article was amended on 9 January 2025 to correct that it was southern California that had its hottest summer on record in 2024 not Los Angeles.
