Fires are raging across California in what’s been an early and deadly start to this year’s fire season. But the truth is: fire season never really stopped. “We’re responding to wildland fires year round now,” California Department of Forestry and Fire Protection (Cal Fire) spokesman Scott McLean told The Sacramento Bee.

In ways big and small, wildfires are human-made disasters, which means it’s up to us to stop them. To report this video, I spoke to Mike Flannigan, a wildfire expert at the University of Alberta in Canada. He told us about the ways humans are making fires worse. Then, The Verge’s video team went to see real-world proof by driving north toward the fires that have been scorching the state.

They saw smoke rising up around Lake Berryessa from the County Fire, which burned through more than 90,200 acres in Northern California before it was contained in mid-July. Cal Fire traced the fire back to a spark from an electric fence that had been installed incorrectly. It’s a painful reminder that humans cause 84 percent of the accidental fires in the US.

But humans don’t just make the sparks; we also put ourselves in harm’s way. Some studies estimate that more than 40 percent of new houses have popped up in fire-prone areas. Fires are key to keeping ecosystems in the West healthy and preventing fuel from building up to dangerous levels. But the presence of people makes it harder for land managers to let controlled fires burn. “Allowing fire back on the landscape in many ecosystems will help prevent some of these large, intense, catastrophic fires,” Flannigan says. “The problem becomes if you have a landscape that has lots of human activity on it, it’s difficult to allow fire to take its natural course.”

We’ve also created ideal conditions for catastrophic fires, and that’s probably due to climate change. After all, warmer temperatures mean drier fuels. And researchers project that drought risk in California will only get worse as global temperatures rise. 

“You’ve got fuel, you’ve got conducive fire weather, you’ve got ignition,” Flannigan says. “As long as we got those three ingredients, we’ll always have fire.” But since fires are human-made disasters, that means we also have possible solutions. We can bury power lines, like the ones linked to the deadly fire siege in October 2017; build fire breaks into communities; do more controlled burns; and, in the long term, cut back on the greenhouse gases we pump into the atmosphere, Flannigan says. “Every human-caused fire is preventable.”