What's shaping up to be one of the worst wildfire disasters in US history had many causes. Before the blazes raged across Los Angeles last week, eight months with hardly any rain had left the brush-covered landscape bone-dry. Santa Ana winds blew through the mountains, their gusts turning small fires into infernos and sending embers flying miles ahead. As many as 12,000 buildings have burned down, some hundred thousand people have fled their homes, and at least two dozen people have died.
As winds picked up again this week, key questions about the fires remain unanswered: What sparked the flames in the first place? And could they have been prevented? Some theorize that the Eaton Fire in Pasadena was caused by wind-felled power lines, or that the Palisades Fire was seeded by the embers of a smaller fire the week before. But the list of possible culprits is long -- even a car engine idling over dry grass can ignite a fire.
"To jump to any conclusions right now is speculation," said Ginger Colbrun, a spokesperson for the US Bureau of Alcohol, Tobacco, Firearms and Explosives, the lead agency investigating the cause of the Palisades Fire, to the Los Angeles Times. Figuring it out will likely take months. It took the bureau more than a year to conclude that the fire in August 2023 that devastated Lahaina, Maui, which was similarly lashed by high winds, was started by broken power lines.
Even given enough time, the causes of the Los Angeles fires might remain a mystery. According to a recent study, authorities never find the source of ignition for more than half of all of wildfires in the Western US -- a knowledge gap that can hamper prevention efforts even as climate change ramps up the frequency of these deadly events. If authorities can anticipate likely causes of a fire, they can help build more resilient neighborhoods and educate the public on how to avoid the next deadly event.
"Fire research is so incredibly difficult. It's more difficult than looking for a needle in the haystack," said Costas Synolakis, a professor at the University of Southern California who studies natural disasters. Synolakis said fires with especially high temperatures, such as those in Los Angeles, often obliterate the evidence. "That's why it's so challenging to mitigate fire losses," he said. "You just don't know what triggers them."
The US Forest Service is teaming up with computer scientists to see if artificial intelligence can help crack old cases. A study led by data scientists at Boise State University, published in the journal Earth's Future earlier this month, analyzed the conditions surrounding more than 150,000 unsolved wildfire cases from 1992 to 2020 in Western states and found that 80 percent of wildfires were likely caused by people (whether accidentally or intentionally), with lightning responsible for just 20 percent. According to Cal Fire, people have caused 95 percent of California's wildfires.