France’s ‘Zombie Fire’ still alive after 1½ years

The soil under the Hostens Forest in Gironde, France is burning. Not only have numerous rains not been enough to snuff out the flame, but time itself seems to have had no effect.

Four major wildfires over the summer of 2022, totaling around 69,000 acres between July and August, caused the evacuation of 46,000 locals. Authorities suspect human involvement and an investigation has been launched.

Satellite images showing the impact of the wildfire in Gironde between 12 and 17 July 2022
Satellite images show the impact of the wildfire in Gironde in July 2022. Click for more.

Ever since, the fire has traveled from the surface to underground; it’s still burning despite weeks of rainfall. The underground fuel was partially created by an old lignite (brown coal) mine that produced electricity for the region until it shut down in 1964. After he heard it was partly the reason the fire was still burning, a reader of the Sud Ouest daily newspaper shared images of a field trip he’d taken to the mine as a child.

The continuous fire’s other cause, though, is the land itself. The Landes forest region, where the fires are burning, used to be an extensive marshland filled with moors. That changed in the early 1800s when the area’s sand dunes were stabilized by humans so they could set up plantations and plant a vast pine forest for timber purposes.

The drained, dried-out peatland is as perfect a fuel as you could find for a wildfire. Making matters worse, the artificial forest standing on top of the peat has dried out as well — a result of severe ongoing drought. The combination has forced French authorities to essentially gut the area of all vegetation until all fires are out.

“We are constantly on guard,” said Pascale Got, who handles environmental issues for the Gironde département, according to The Local. “When vegetation starts to grow again, we cut it down. Given the amount that we have cut down so far, I don’t think there will be a resumption of wildfires, unless there is an exceptional drought.”

This kind of continuous fire, or “zombie fire,” isn’t unheard of. A similar fire in Louisiana’s Bayou Sauvage Urban National Wildlife Refuge burned for two months before it was extinguished on December 4. The continual burning plagued the area with “noxious” smoke.

Overwintering fires, wildfires that continue to burn deep in a fuelbed until weather favors flaming behavior and firespread, have also occurred with increased frequency in North America’s boreal forests. Research published in 2021 found that flare-ups from these overwintering fires could partially be predicted by monitoring edges of fire perimeters from the preceding year.

Officials worry that another period of severe drought could start new fires; according to the Connexion, Gironde officials plan to reforest the area in France once the fires have been completely resolved.