Wildfires play an important role in rejuvenating forests, but there is nothing natural about the devastating blaze that has consumed 4,000 acres near Clear Lake in Northern California. Authorities have said that the fire, dubbed the Clayton fire, is the direct result of the actions of a onetime inmate firefighter who now faces 11 counts of arson.
Arson ranks as the most obvious in a long list of the ways that humans cause and worsen wildfires, making them disasters that are less than natural. Nine out of 10 wildfires are the direct result of human activity, a long list that includes poorly attended camp fires, discarded cigarette butts and equipment use. More than 2.4 million acres burn each year as a result of human-caused fires, according to a National Interagency Fire Center report.
Human-caused global warming has also contributed to more frequent and severe wildfires, scientists say. Warm weather and a lack of water kills trees, creating kindling for fires, and heat increases the length of the wildfire season. And, because temperatures tend to be hotter and drier than in previous generations, firefighters often struggle to put out blazes. The length of fire season increased by 19% between 1979 and 2013, according to recent research, as temperatures have spiked due to climate change.
See Inside the Blue Cut Fire’s Explosive Growth and Devastation
![Blue Cut fire burns near Los Angeles A firefighter keeps an eye on the Blue Cut fire line, north of Los Angeles, Calif, Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-06.jpg?quality=75&w=2400)
![Blue Cut Fire burns near Los Angeles, California A house burns on a hill near Cajon Junction, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-08.jpg?quality=75&w=2400)
![A chicken runs by a chicken coop that burns with animals still inside at the so-called Bluecut Fire in the San Bernardino National Forest in San Bernardino County A chicken runs by a chicken coop that burns with animals still inside at in San Bernardino National Forest in San Bernardino County, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-09.jpg?quality=75&w=2400)
![TOPSHOT-US-WEATHER-FIRES-CALIFORNIA Firefighters battle the Blue Cut wildfire near Cajon Pass, north of San Bernardino, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-13.jpg?quality=75&w=2400)
![Blue Cut Fire burns near Los Angeles, California A melted sign shows the damage after a wildfire swept through Cajon Junction, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-01.jpg?quality=75&w=2400)
![California Wildfires Burned property at Hess Road and Highway 138 shows the devastation of the Blue Cut fire in West Cajon Valley, Calif., Aug. 17, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-14.jpg?quality=75&w=2400)
![TOPSHOT-US-WEATHER-FIRES-CALIFORNIA An air tanker drops fire retardant on the Blue Cut wildfire in Lytle Creek, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-05.jpg?quality=75&w=2400)
![APTOPIX California Wildfires San Bernardino County Firefighter, Engineer, and Paramedic, Jeremy Pendergraft, helps a couple evacuate out of their home as she cries off of Hess Rd. as a wildfire off of Hwy 138 quickly approaches in San Bernardino, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-02.jpg?quality=75&w=2400)
![TOPSHOT-US-WEATHER-FIRES-CALIFORNIA Flames burn next to Interstate 15 as the Blue Cut wildfire rages near Cajon Pass, north of San Bernardino, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-12.jpg?quality=75&w=2400)
![US-WEATHER-FIRES-CALIFORNIA The Blue Cut wildfire burns structures and trees near Cajon Pass, north of San Bernardino, Calif., Aug. 16, 2016.](https://api.time.com/wp-content/uploads/2016/08/blue-cut-fire-11.jpg?quality=75&w=2400)
Not all wildfires have human fingerprints on them and the phenomenon can actually improve the health of forests by clearing debris and nourishing the soil, functions wildfires have carried out for ages. But officials estimate that only 10% of wildfires have natural causes, almost entirely lighting strikes. The cause is not yet known for the latest wildfire to hit California, a fast-moving blaze that had engulfed nearly 47 square miles in the southern part of the state by Wednesday.
Wildfires often rank among the most devastating natural disasters in the U.S. Last year, more than 10 million acres burned across the country, at a cost of more than $1 billion to the federal government.
More Must-Reads from TIME
- Welcome to the Noah Lyles Olympics
- Melinda French Gates Is Going It Alone
- What to Do if You Can’t Afford Your Medications
- How to Buy Groceries Without Breaking the Bank
- Sienna Miller Is the Reason to Watch Horizon
- Why So Many Bitcoin Mining Companies Are Pivoting to AI
- The 15 Best Movies to Watch on a Plane
- Want Weekly Recs on What to Watch, Read, and More? Sign Up for Worth Your Time
Write to Justin Worland at justin.worland@time.com