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January 8, 20254 min readPalisades and Eaton Fires Show Rising Dangers of Fast-Moving BlazesIn California and elsewhere, fast-moving fires are particularly damaging and expensive because they take people by surprise, making evacuations difficultStrong winds blow embers as the Palisades Fire burns homes on the Pacific Coast Highway amid a powerful windstorm on January 8, 2025 in Los Angeles, California. The fast-moving wildfire has grown to more than 2900-acres and is threatening homes in the coastal neighborhood amid intense Santa Ana Winds and dry conditions in Southern California. Apu Gomes/Getty ImagesThe Palisades and Eaton Fires rushing through the Los Angeles area enveloped thousands of acres in mere hours and forced the evacuation of tens of thousands of residents, some of whom were forced to abandon their cars and flee on foot. As of early Wednesday evening, at least five people have died in the fires.The fast-moving fires, driven by strong Santa Ana winds, are part of an unfortunate trend. According to a paper published in Science in October 2024, the average peak daily growth rate of fires in the U.S. West more than doubled between 2001 and 2020. In California the average peak growth rate went up by 398 percent. Fires are getting a lot faster in California, says Jennifer Balch, a fire ecologist at the University of Colorado Boulder who led the study.That research did not investigate why fast fires have become more common, but the cause is probably the same reason the U.S. West is becoming more fire-prone in general, Balch says. Were making it very easy for fire to spread when we warm the climate and effectively make fuels a lot drier, she says.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.Thats alarming, Balch says, because such fires are actually the most destructive. Though large fires often get more attention, speed matters more than size when it comes to damage. Balch and her colleagues found that 78 percent of structures destroyed in fires in the U.S. in the first two decades of the 21st century burned in fast-moving fires. In fact, a growth rate of more than 4,000 acres in a day was one of the best predictors of whether a fire would cause significant damage to homes and other buildings.When these fires do occur, they can quickly impact communities that have very little time to prepare or evacuate, says John Abatzoglou, a climate scientist at the University of California, Merced, who was not involved in the study. And thats effectively what were seeing with some of these fires in southern California.The largest of the fires, the Palisades Fire, has burned more than 15,000 acres since it started on Tuesday, according to the California Department of Forestry and Fire Protection. The Eaton Fire is close behind: it has burned 10,600 acres since Tuesday. Two more blazes, the Hurst and Woodley Fires, also ignited on Tuesday and Wednesday, respectively, and have collectively burned more than 700 acres, with most of that figure attributed to the Hurst Fire.This rapid destruction has occurred during a dry winter for southern California, following a dry fall, and these conditions came on the heels of a particularly wet winter last year. Thats a perfect recipe for large, fast fires, Abatzoglou says, because a wet year increases the growth of highly flammable small shrubs and grasses while an ensuing dry year turns those plants into crispy matchsticks, ready to catch ablaze. Weather whiplash is actually contributing to the probability of very large, fast-moving wildfires, says Katharine Hayhoe, a climate scientist at the Nature Conservancy and Texas Tech University, who studies climate impacts. The rising temperatures attributable to greenhouse gas emissions have disrupted natural fire patterns globally, she says, and reducing emissions is important to mitigate the effects.With fires driven by winds such as the Santa Anaswhich gusted at nearly 90 miles per hour in southern California on Tuesday nightembers are blown far out ahead of the fast-moving fire front, igniting new fires faster than they can be extinguished. These embers are what spell disaster for homes, says Yana Valachovic, county director for the University of California Cooperative Extension in Humboldt and Del Norte Counties. Most of our homes have not been built or retrofitted to be robust to protect against embers, she says.The Santa Ana winds are predicted to become less frequent in the fall and spring in a warming world, according to 2019 research, but their intensity is not expected to decline, and you really only need one Santa Ana wind event that occurs where fuels are dry to get this sort of disaster, Abatzoglou says. The wet season in southern California is becoming compressed, with less rainfall in fall and spring. That stretches out the fire season and the potential overlap with the typical Santa Ana wind season, which runs from October through January.Winter wildfire should be an oxymoron, Balch says. But L.A.s experience has been similar to another wind-driven event in Colorado: the Marshall Fire, which began on December 30, 2021. A warm, dry winter and a major wind event led to a fire that flashed over three miles in an hour, burning 1,000 structures and killing two people.The University of California Agricultural and Natural Resources Fire Network has created a checklist for what to do if youre in an area near an active wildfire that is not yet under an evacuation order. Steps as simple as moving flammable items away from exterior walls, sealing vents and closing pet doors can help harden a home against ignition, Valachovic says. Earlier steps include swapping out standard vent covers for fine mesh that resists embers, clearing vegetation within five feet of home walls and building the last few feet of wooden fence lines with a noncombustible material that wont wick fire directly toward the house.Both the Palisades and Marshall Fires hit suburban areas, often thought to be at low fire risk. But about a million U.S. homes were within a wildfire perimeter in the past two decades, and 59 million more are within about 0.6 mile of a past wildfire perimeter, Balch says. Thats a lot of risk were living with, she adds.
