Sharp Spike in 'Zombie Fires' Worries Canadian Officials

Feb 22, 2024

How Do Zombie Fires Work?

Canada dealt with a record number of wildfires in the summer of 2023. It battled 6,132 blazes that torched more than 16.5 million hectares (41 million acres) of land. The colder temperatures of winter brought needed relief. But it turns out the danger isn’t over. Many of those fires have taken root below ground. There, they smolder until spring’s thaws can summon them forth to wreak havoc anew.  

So-called “zombie fires” aren’t the villains of a horror movie. Rather, they’re an event caused by the unique soil of Canada’s forests and fields. Much of the nation’s land is covered by permafrost. It's a layer of frozen ground. Yet climate change has melted large portions of that permafrost in recent years. This has exposed the highly flammable peat soil below.    

When summer’s wildfires passed over peat-rich regions, many deposits were ignited. But the peat didn't burn with open flames. Insulation by the seasonal re-freezing of the ground restricted the burning. Yet the peat still smolders. A constant haze of smoke seeping from the ground is proof.  

"I've never experienced a snowstorm that smelled like smoke," Sonja Leverkus, a firefighter and scientist in British Columbia, told the BBC.

British Columbia is no stranger to zombie fires. They usually have five or six a year. But this year, officials are tracking 106 of the underground burns. And 57 more were logged in nearby Alberta. Those numbers have raised concerns. Some fear what may happen once the frost thaws again. The underground heat could ignite a fresh round of surface-level wildfires.    

Reflect: How does a name like “zombie fire” given to a natural phenomenon affect the way we view it?

Which word from the text means ‘to catch fire or cause to catch fire’? (Common Core RI.5.4; RI.6.4)
a. thaw
b. freeze
c. smolder
d. ignite
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