Why the Dixie Fire won't stop burning

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Wildfires aren't supposed to burn like this.

The nearly one-month-old Dixie Fire, at over half a million acres burned as of Aug. 12, is already the largest single wildfire in California history. The mega-blaze is not nearly done burning, and an idea of when firefighters might largely contain the fire remains elusive.

Yet, crucially, it's not just the amount of land burning that's the problem: After all, millions of acres likely used to burn in California in prehistoric times every year, before European settlement. The problem is how the Dixie Fire is burning. In today's Western fire regime, fires are often burning severely, destroying ancient, fire-resistant trees; creating giant plumes of smoke; and rapidly destroying towns.

The Dixie Fire is a potent example of these unusually intense fires. Its ferocity is made possible by the mix of a century of methodical U.S. fire suppression (leading to grossly overgrown forests), a rapidly warming climate, and severe drought, among other factors.

"Everything just comes together, and once it gets going, it's going to turn into a big event," explained Tim Brown, a wildfire researcher and director of the Western Regional Climate Center, an environmental research program. "This is just one of those fires."

The Dixie Fire has spawned towering thunderstorms, called pyrocumulonimbus clouds, created by the fire's prodigious rising smoke and heat. Lightning ensues, sparking more flames. The fast-moving fire destroyed large swathes of Greenville, a historic mountain town.

These infernos are often impossible to fully control because of their extreme severity. They're not like most of the fires of centuries ago, which often cleared dead and dry vegetation from forest floors, kept forests healthy, and cracked open seed-bearing pine cones — and thus new life. They were similar to the mellower fires set by Indigenous peoples to help keep ecosystems healthy. Insects could walk through them, explained Don Hankins, a professor of geography and planning at California State University, Chico. You could stand next to them, he said.

"The ideal is low-intensity fire," said Brown. "Not destructive, high-severity events."

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The Dixie Fire perimeter (as of Aug. 11, 2021) is circled in red. Credit: cal fire / screenshot

Trouble ahead

The Dixie Fire, currently 30 percent contained (as of Aug. 12), has decidedly favorable fire conditions ahead. Specifically, extreme drought and forests dried out by extreme heat.

"[It's] burning in what will likely be the hottest summer the area has seen in at least 125 years," said John Abatzoglou, a fire scientist at the University of California, Merced. That's compounding the drought stress left by a second terribly dry winter, he added.

This heat and dryness parch trees, grasses, and vegetation — some of which hasn't burned in 100 years, noted Abatzoglou — which allows fire to rip through the mountains. This isn't normal dryness: The moisture in the fuels (vegetation that can burn) "are historically low," according to the federal government's wildfire information page.

It's little surprise firefighters are experiencing unprecedented flames. "We're seeing truly frightening fire behavior, I don't know how to overstate that," Plumas National Forest Supervisor Chris Carlton told CNN. "We have a lot of veteran firefighters who have served for 20, 30 years and have never seen behavior like this, especially day after day, and the conditions we're in."

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Climate change is exacerbating what would already be extreme fire behavior. In other words, the extremes are growing more extreme. The warming climate's greatest impact on wildfire is how it amplifies the drying of vegetation, making it more flammable — sometimes historically so.

"The warming from climate change is making a lot of difference here. It's one of the major impacts," said Brown. Drought naturally comes and goes in the West, he emphasized, but with increasingly warm summers (California just experienced its hottest June and July on record), the warm, dry atmosphere pulls more moisture from plants and soil.

"That increases the fuel flammability," explained Brown. "You're really setting up conditions for explosive fire behavior."

"The warming from climate change is making a lot of difference here."

Add in normal bouts of windy conditions, then all you need is a spark. And humans or human infrastructure — cars, power lines, accidents — are all around to spark some 84 percent of U.S. wildfires. Utility equipment may have sparked the Dixie Fire, though the investigation is still ongoing.

The end game

Containing a fire of Dixie's size, under such extreme fire conditions, is a challenge for any fire agency. Widespread containment might not come until the region receives a decent cooling spell. Early this week, Cal Fire, the state's giant wildfire protection agency, expected containment by Aug. 30. Now, the containment plans are "to be determined."

The big picture in the years and decades ahead, however, requires blunting the intensity of modern wildfires. The West, like the world, will continue to warm for at least a few decades, as heat-trapping CO2 has skyrocketed in the atmosphere. This means more extreme, and likely worsening, fire conditions. Yet, governments and communities can significantly reduce the amount of overcrowded forest, or fuels, available to burn. This means intentional, prescribed fire (strategic burning often at cooler times of the year), and letting certain wildfires burn through forests (though this comes with controversy and risk).

"If we don't do something to minimize the hazardous fuels, it's going to burn big time," said Brown.

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There's no other alternative, according to fire experts and foresters. As John Bailey, a forestry researcher at Oregon State University, told me during the severe Western fires of 2020: A forest is a magnificent, spiritual, and providing place. "But it's also fuel. It's fuel and it is going to burn," he said.

"Talk to any firefighter," noted Brown. "They'll say it's not a matter of if, but when."

The Dixie Fire, still burning strongly, is currently the largest single blaze in California history. But under the current fire regime, that's almost certainly a tenuous record, waiting to be broken.

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