Aug 24, 2023 - Climate

People caused most of California's wildfires over the past 30 years

A firefighter stands with a hose over his shoulder putting out flames of a wildfire along a road that's engulfing the brush.

A firefighter battles the Valley Fire in Jamul, California in September 2020. Photo: Sandy Huffaker/AFP via Getty Images

The vast majority of the more than 250,000 wildfires that blazed through California over the past three decades were caused by people.

Why it matters: With climate change increasing wildfire risk in the West, fires can quickly spread, destroy property and become deadly.

  • Changing human behavior could help reduce the devastating threat.

By the numbers: About 86% of wildfires in California between 1992 and 2020 were spurred by human activity, burning 63 acres on average, U.S. Forest Service analysis of wildfire data found.

  • Meanwhile, Cal Fire officials say 95% of fires are human-caused currently.

Of note: Lightning strikes accounted for the other fires with known causes, mostly in the northeastern and mountainous parts of the state that border Nevada.

Details: The top three human activities known to have led to these blazes were from equipment and vehicles, arson and debris burning, the data shows.

  • That includes accidental incidents and neglect, such as leaving a campfire unattended or a malfunctioning catalytic converter spitting a molten substance out of an exhaust pipe.

Between the lines: While firearms and explosives caused 0.2% of wildfires, they led to the largest human-caused blazes, at 380 acres on average.

Data: Short, 2022, Spatial wildfire occurrence data for the United States; Note: Only includes fires with known origins. White areas had no reported fires; Map: Erin Davis/Axios Visuals

The big picture: This summer's extreme weather and simultaneous climate disasters are the new reality across North America with unprecedented wildfires, heat waves and storms.

Zoom in: Five wildfires in San Diego County have burned nearly 800 acres so far this year, with three this month.

What they're saying: The San Diego area is particularly fire-prone and susceptible to destructive blazes, partly because there's a lot of rural land in East County, Cal Fire Capt. Mike Cornette told Axios.

  • With houses and brush intermixed, it's "more difficult to get in there and defend those homes."
  • "And then we get the seasonal Santa Ana winds that can spread those fires very quickly and sometimes outpace firefighters," he said.

Be smart: To help prevent fires, do yard work and agricultural burns with the right tools and avoid hot, dry, windy weather.

  • Keep at least a 50-foot buffer around your home as a "defensible space" to create a barrier to slow or stop a fire from engulfing your property.
  • Get an evacuation plan in place and have a "go-kit" ready at a moment's notice.

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