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Ninety-five percent of wildfires that ravaged California in the past 100 years were caused by humans, according to a forthcoming study in the International Journal of Wildland Fire.

“In most of California, if we could stop ignition during extremely high winds and drought and heat spells, like now, that will be an effective approach,” lead author and U.S. Geological Survey wildfire expert Jon Keeley told The San Jose Mercury News of his soon-to-be-published study.

While the public debate largely rages around global warming’s role in wildfires, Keeley’s study shows that human interaction with the landscape, no matter the climate, is causing most fires. (RELATED: Scientist Calls Out Media ‘Misinformation’ On Wildfires And Global Warming)

Motorized equipment, from gas-powered weed-wackers to lawn mowers and generators, are the main cause of fires, Keeley said. Arson, burning of debris, kids messing around with fire, smoking, vehicles and utility lines are also major causes of wildfires, Keeley said.

The western U.S. has warmed in the past few decades, but it’s population has also boomed, meaning more people are living in wildfire-prone areas. The increased human presence means more chances of ignition in paces and at times where fires tend not to naturally occur without lightning.

Power lines account for much of the historical are burned from wildfires, Keeley said. That included 12 fires that burned through Northern California in 2017 that ravaged thousands of acres and caused at least 15 deaths.

Keeley said the number of fires peaked in 1979 and has been declining ever since, which is probably an indication of better education about the dangers of wildfires, Keeley said. However, area burned in California increased in some parts of California in recent decades.

Keeley’s study also comes as a 51-year-old man accused of starting the Holy Fire in California’s Cleveland National Forest. Forrest Gordon Clark was charged by authorities with “aggravated arson and criminal threats, among other offenses,” CNN reported.

Clark is set to appear in court Friday for his arraignment and bail review. The fire he allegedly started consumed more than 22,000 acres and forced 21,000 residents to flee their homes. Firefighters have contained about half the blaze as of Monday.

Wildfires ripped through more than 680,000 acres of California so far in 2018, according to the National Interagency Fire Center. The biggest blaze, the Mendocino Complex Fire, has scorched more than 328,000 acres, but is more than 50 percent contained.