In 2019, Sarah Miller wrote one of the definitive depictions of the coming climate dystopia. Titled “Heaven or High Water,” the essay tracked her efforts to gauge the concern and honesty of Miami-area real estate agents as they worked to sell outrageously expensive properties in an area that science tells us will soon be something akin to Atlantis. If Atlantis had skyscraping luxury apartment towers, we might today know where it was, had it existed. Miami, we’ll be able to spot.

Miller’s piece gets new attention every time there’s a new manifestation of climate change, which means it gets attention often. This is not something that she enjoys, because as a resident of a heavily forested area near the California-Nevada border, she’s constantly concerned about another manifestation of the warming planet: uncontrolled wildfires. For the past several weeks, with massive swaths of California burning, she has been documenting the effects of that uncertainty on her, her dog and her community. In the past 18 months, we have all gained a new appreciation for the fragility of the things we used to take for granted; Miller and those who live near her can’t avoid how that instability lingers. Literally: You can smell it and, at more alarming moments, see it.

It is not new that California would be on fire. The state has a very experienced agency generally referred to as CalFire that is tasked with preventing and combating the regularly emerging conflagrations. It has robust documentation of where fires have emerged over time, records that have gotten more precise and detailed over the past several decades. That data shows us how common fire has been in the state over the past 150 years, like so.

Areas depicted in gray are cities and other urban communities. The red splotches, obviously, are the fires. The darker the red, the more fires in a place over time. So you can see that there have been a lot more fires in the outskirts of the cities in Southern California than, say, on the eastern side of the San Francisco Bay area. That’s in part because the Bay Area is better insulated from the worst droughts California faces than is the more desert-heavy southern part of the state.

Those extreme droughts are very much what scientists have predicted as a result of climate change: more heat wicking moisture out of soil, smaller snowpacks limiting spring and summer melt.

The fire map above shows every recorded fire since the 1870s. If we color-code the fires by decade, you get a better sense of scale and recency.

There is a lot of data in that map that bears a closer examination. (You can view a high-resolution version here.) So consider this area near Rancho Cucamonga, a bit east of Los Angeles.

There were fires in the area at the center of that indicated circle in 1919, 1921, 1957, 1968, 1970, 1980, 1988 and 2003. But also notice how much of that region has been touched by fire at one point or another.

CalFire’s data on wildfires gives rough windows for when parts of the state burned, allowing us to roughly estimate how much of California’s land area was on fire in any given month. Its data indicates that, through June, about 2.5 percent of the state had burned over the prior 12 months.

Since June, though, the state has recorded two of its largest fires in history. At the moment, more than 1 in 100 acres of California’s land area are part of an active wildfire. That includes the still-burning Dixie Fire, the second-largest in state history. The largest on record began in August of last year. In 2020 and 2021, more than 5 percent of the state’s land area has burned. In 2018, Popular Science estimated that the same acreage had burned over the preceding five years.

In one of her recent essays, Miller quoted the head of CalFire.

“Every acre can, and will, burn someday in this state,” he said last month.

That’s an exaggeration, but not by much. The real question in any particular place is when “someday” arrives.