How Did the Park Fire in Northern California Get So Big?
The Park fire, which started on July 24 near Chico, Calif., quadrupled in size within just a few days. It now covers an area more than 12 times the size of San Francisco. On Tuesday, it became the fifth-largest blaze in California history.
The fire has destroyed at least 192 structures, with 4,200 more threatened, Cal Fire said. Thousands of people are under evacuation orders.
Extreme heat in June and July was the most likely cause of the fire’s rapid growth, said Park Williams, a professor of geography at the University of California, Los Angeles. “It’s the record-breaking hot and dry weather that’s singed the fuels and made them as ready to burn as they could possibly be,” Dr. Williams said.
Heat has been breaking records all summer, and Dr. Williams said records will probably continue to fall over the next several years as the burning of fossil fuels continues to add greenhouse gases to the atmosphere.
July 22, two days before the fire began, was Earth’s hottest day on record. June was the 13th consecutive month to break a global heat record. Some areas burned by the Park fire saw their single-hottest 30-day periods on record just before the blaze broke out.
Dr. Williams compared the dry conditions to those preceding California’s second-largest wildfire, the 2021 Dixie fire, which began during a drought and burned almost one million acres. The state has since emerged from drought, which makes the heat’s effect on fuels even more notable, he said.\
“It was an exceptional heat wave, and an exceptional drying of the vegetation,” said Daniel Swain, a climate scientist at U.C.L.A. and the National Center for Atmospheric Research. Wetter winters led to less-severe fire seasons in 2022 and 2023. But extreme heat this summer, with more hot weather in the forecast, means “we’ve kiln-dried all that extra fuel,” Dr. Swain said.
Officials said the Park fire is believed to have been sparked by a man accused of pushing a burning car into a gully, sending it 60 feet down an embankment. The authorities have charged Ronnie Dean Stout II, a 42-year-old from Chico, with felony arson, according to court records.
Mr. Stout has two prior felony convictions and could face life in prison if convicted, according to the complaint filed against him. He will have a court appearance on Thursday to enter a plea, according to the Butte County district attorney, Mike Ramsey. Mr. Stout’s public defender did not immediately respond to a request for comment.
The dry vegetation that allowed the Park fire to burn so quickly had a very clear fingerprint of climate change, Dr. Swain said.
The “whiplash” between very wet conditions and extreme heat could become a new signature of climate change in California, he added. A warmer atmosphere can hold more water vapor, so when it rains, it pours. More intense downpours during wet periods, followed by record-breaking heat and high evaporation levels, could create a yo-yo effect between seasons of extreme precipitation and flood risk, and extreme dryness and wildfire risk.
What’s more, there’s not only dry fuel, but a lot of it. The blaze has spread across parts of the state that haven’t experienced fire in decades. Fire suppression practices have allowed vegetation to build up over long periods, in contrast to the frequent burns that were a common forest management tool of Indigenous tribes in California pre-1850, said Hugh Safford, a research ecologist at the University of California, Davis, and a former ecologist for the United States Forest Service in California. Those policies mean the rapid spread of the Park fire was “absolutely not surprising at any level,” he said.
The fire could continue to burn for weeks, if not months, and has the potential to become the biggest fire in state history, Dr. Swain said on Saturday.
The fires were also influenced by higher-than-normal nighttime temperatures, which can lead to more extreme fire conditions, said Tim Brown, a research professor at the Desert Research Institute. Nighttime temperatures are increasing more rapidly than daytime temperatures under climate change.
Erratic atmospheric conditions have also created tornado-like wind conditions over the Park fire and they could eventually lead to a larger storm, according to David Peterson, a meteorologist at the United States Naval Research Laboratory in Monterey, Calif. Fire-generated storms can produce hail, high winds, lightning and tornadoes and impede fire fighting. Such storms occurred recently during wildfires in Canada that destroyed about half the town of Jasper, Alberta.
On Monday, Northern California was at Preparedness Level 4, the second-highest level of emergency response to a wildfire, with more than 5,000 people fighting the Park fire. In a region where resources are already spread thin, with wildfires burning across Oregon and Washington, the heat could become an even bigger problem, said Jatan Buch, a postdoctoral research scientist at Columbia University.
“If it continues to be as hot and dry as it’s forecast to be for the next two weeks, it could potentially be pretty terrifying not just for the Park fire specifically,” Dr. Buch said, “but for the fire outlook broadly for California and Oregon.”
Dr. Williams said much of the forested areas of Northern California and the Western Sierra Nevada have not burned in the last decade and could burn next.
“Those areas should be ready to go,” Dr. Williams said. “It’s very, very dry out there.”
California has set a goal of treating one million acres of land per year beginning in 2025 by removing dense vegetation with machines or by prescribed burn, a huge scale-up of what the state has historically accomplished, said Patrick Brown, co-director of the climate and energy group at The Breakthrough Institute, a global research firm focused on environmental issues.
The Park fire, he said, could provide “more motivation” for California to reach its goal.
John Yoon contributed reporting.
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