Wildfires

View of a fire, from a rooftop in West Hollywood, on Jan. 8. (Credit: Wikimedia) As catastrophic wildfires continue to burn southern California, most of us have seen stunning images of the destruction and heard heart-wrenching accounts of narrow, harrowing escapes. Wind-driven infernos in the Los Angeles area have killed at least two dozen people, forced hundreds of thousands of residents from their homes and transformed once-vital communities into piles of smoldering debris. Tens of thousands of firefighters are on the front lines trying to contain the Palisades, Eaton and Hurst fires and others – which have already burned a 60 square-mile area north of downtown LA including 12,000 structures – and will doubtless be counted among the most destructive and costliest in state (and perhaps U.S.) history. As we consider the staggering losses, the question on many minds is, how did this happen? The exact cause(s) of the fires will be under investigation likely for months but regardless of what ignited them, several major factors conspired to intensify the blazes, most setting the stage for destructive fire long before they sparked. Changing climate. Drought and wind events in California are overlapping as never before due to human-caused climate change. Our shifting climate has made wildfires more ferocious, long-lasting and destructive, a trend we’re now seeing across the American West. Australian researchers recently showed that both the frequency and intensity of extreme wildfires more than doubled from 2003 through 2023. Other research shows that climate change will continue to increase temperatures. At the same time, it will worsen drought conditions – and the threat of destructive wildfires. Wind-fed fires. An “atmospheric blow dryer” is what UCLA climate scientist Daniel Swain called the high winds that have blasted the area over the past week. In the days leading up to the fires, he predicted the intense gusts. There was a “significant risk of fast-moving and destructive wildfires throughout a pretty broad swath of southern California,” said Swain, who is also a research fellow at the National Center for Atmospheric Research in Boulder, Colorado. Ultimately, winds near the Palisades Fire reached 98 mph–equivalent to a Category 2 hurricane–in the worst high wind event to hit that part of the state in over a decade. Those gusts dried area vegetation to tinder and caused fire to spread much faster than it could possibly be contained. Embers rained down even miles from their source, starting new ignitions in a perverse game of whack-a-mole that firefighters were powerless to win. That pattern of destruction tracks with analysis recently published by researchers in Colorado and California who found that the deadliest and most destructive fires in U.S. history are “fast fires” that are becoming more common. The team analyzed daily growth rates of more than 60,000 fires across the contiguous U.S. and found that, from 2001 to 2020, peak daily growth rates more than doubled in the West. Those fires were also responsible for more than 75% of the structures that burned during that time. Severe drought conditions and high temperatures. Those powerful Santa Ana winds start out as cold desert air that gets pushed west over the Sierra Nevadas. The winds accelerate as they course over mountain passes and squeeze through canyons like a river through a narrowing gorge. The winds are typical for this time of year – and even winds as strong as those seen lately are not unprecedented – but they normally hit during the region’s rainy season. Winter is generally the wettest time of year in SoCal but precipitation totals for LA over the past several months have been barely measurable. From early May to date, just 0.16 inches of rain has fallen there, though several inches is typical, according to the National Weather Service. Higher temperatures have also conspired to dry out a region that’s home to over 2 million people. When the fires started on Jan. 7, LA County was parched after experiencing its hottest summer in roughly 130 years. High temps, which persisted into fall, drew moisture out of vegetation leaving it extremely thirsty and vulnerable to a spark. Abundant fuels. Whether they’re looking at a forest or a subdivision, firefighters see fuel, which Southern California has in abundance. The recent drought and wind events came on the heels of two previous wet winters when atmospheric rivers brought record-breaking precipitation to the area. That caused a superbloom of grasses and brush – what firefighters call “flashy fuels” because they burn so easily. Dry conditions then sucked out all that moisture in a seesaw phenomenon researchers call “hydroclimate whiplash.” In much of the West, millions of acres of national forests are overgrown, following over a century of policies focused on putting out fires. In recent decades, forest management has shifted gears to thin forests of young trees and perform prescribed burns. But with tens of millions of forest acres needing treatment, the task is daunting. Whether clearing landscape-level brush would have made a difference to fire suppression efforts will be hotly debated because of the complex dynamics of the area’s native chaparral shrublands (where, unlike in forested areas, clearing can harm the ecosystem). Given the extreme wind and drought conditions, it’s unlikely that vegetation thinning would’ve made a major difference. Homes, of course, are also fuel and the LA fires started adjacent to densely-populated areas in what’s called the “wildland-urban interface.” According to the U.S. Fire Administration, more than 60,000 communities are currently at risk for WUI fires. Despite the risks, the WUI continues to expand by roughly 2 million acres each year. Looking Ahead So what do we do to prevent the next conflagration? During or soon after disasters never feels like the right time to talk about how we’re causing the problem we’re suffering from but, unfortunately, climate change is the elephant in our big global room. Last year was the warmest year on record (as was 2023 before that). While human activities continue to raise atmospheric levels of carbon dioxide and other greenhouse gases, the climate impacts will continue to accelerate – which means a future with more deadly and destructive wildfires. As we approach irreversible climate tipping points, I’m reminded of Joan Didion’s 1969 essay, “The Santa Anas,” in which she wrote, “The wind shows us how close to the edge we are.” Heather Hansen spent 18 months embedded with the City of Boulder Wildland Fire Division while writing a book on fire in the West. She is a science writer and regular contributor to The Story Exchange.

Wildfires

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