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Humans are a wildfire threat multiplier

Data: CAL FIRE and US Forest Service, NOAA; Note: Lines of best fit created using LOESS smoothing; Chart: Harry Stevens/Axios

The fires that wiped out the town of Paradise, California, and burned all the way to the Pacific Ocean in Malibu are the latest in a 13-month string of the deadliest and most destructive blazes the state has ever seen.

The big picture: These fires have parameters in common — unusually warm and dry preceding conditions, strong winds that caused the fires to spread rapidly, extreme fire behavior and populated areas that are difficult to evacuate on short notice.

Between the lines: No single factor — not climate change, forest management or building practices — is responsible for the deadly blazes the state is now seeing, experts tell Axios.

  • Instead, it's their combination that's making an already dicey situation far worse. And the outlook in coming years, as climate change continues, is foreboding.
  • The state's fire season now stretches later into the fall and starts earlier in the spring.
  • “Fire season in California doesn’t have a well-defined boundary anymore, that’s been true for some time."— Brenda Belongie, US Forest Service meteorologist

Driving the news: Longer-term climate change and population growth are combining to increase wildfire risk in California and more broadly across the American West.

  • One of the starkest changes firefighters are contending with is an uptick in instances of extreme fire behavior, such as the massive EF-3 fire tornado that accompanied the Carr Fire in July.
  • The biggest climate change-related impact is manifested in the increased dryness of vegetation.

“The warming equals drying equals more explosive fire growth," said Neil Lareau, a researcher specializing in fire weather at the University of Nevada at Reno.

The housing factor: Another major factor in the impact of these fires is the increasing number of people living in the so-called wildland-urban interface, or WUI, where communities sit next to lands that typically burn. But simply stopping building in such regions is not necessarily a practical solution.

"Almost everywhere we live in the West is wildland-urban interface," said Lareau. "It's overly simple to say we shouldn't be building here."

The bottom line: The recent, deadly fires are the new normal in California, and residents of other Western states should be paying close attention, because they could be next.

Go deeper: A 30-year alarm on the reality of climate change

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