In 2018, wildfires burned an unusually high 8.5 million acres. Conversely, 2017 was a very wet year—but that was part of the problem.

Heavy rain brings more foliage, which the next year becomes fuel. Wet years are often followed by high-fire years.

Wildfires are a natural process, and in many ways can be beneficial: they clear out dead plant matter, control insects and plant disease, return nutrients to the soil, and make way for new growth.

It’s even thought that, in the geologic past, fires regulated Earth’s oxygen levels, to keep them in an optimum range for life.

But fires are also dangerous to humans and our property.

So what to do about that?

Forest management helps. Clearing forests and especially slopes of deadwood helps keep fires from spreading. Allowing them to burn is controversial but reduces fuel buildup.

Better fireproofing helps, too. Some embers from wildfires are very tiny—small enough to slip between roof tiles and ignite underlying wood. New codes in fire-prone areas call for fire-resistant roof decking.

Perhaps most important, we can better monitor ourselves. A new study found that 84 percent of wildfires are set by humans. Accidentally, through downed power lines or untended campfires. Or intentionally, through arson.

It may sound obvious, but to avoid becoming victims of fires, we need to become better at not setting them.