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What's a 'zombie fire'? Dangerous underground fires spark record-setting wildfires in Arctic Circle

Jordan Culver
USA TODAY

Correction & clarification: A prior version of this story misstated the name of the World Wildlife Fund.

In a year where fires in the United States and Australia have already set devastating records, scientists are seeing more fire issues in the Arctic Circle. 

Wildfires primarily in Russia's Sakha Republic have caused a spike in carbon dioxide emissions this year when compared to 2019, according to the World Wildlife Fund. Wildfires early in the season are believed to have been sparked by "zombie fires," which burned underground during the winter, the agency reported. 

The Copernicus Atmosphere Monitoring Service (CAMS), part of the European Union's Earth observation program, reported from January 1 to August 31, the estimated carbon dioxide emissions for the Arctic Circle "were 244 megatonnes, compared to 181 megatonnes for the whole of 2019." 

According to data from the CAMS Global Fire Assimilation System (GFAS), which uses satellites to "produce daily estimates of wildfire and biomass burning emissions," The  Eastern Federal District of Russia "emitted a total of approximately 540 megatonnes of CO2, which surpasses the previous highest total emissions, for the year 2003, in the GFAS dataset."

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“More severe and frequent fires in recent years have had devastating impact on human health, wildlife, economies, and the climate," Fran Price, Global Lead for Forests at WWF said in a statement. "We need real and effective actions focused on forests, including boreal forests in the Arctic."

Here's what to know about "zombie fires": 

What is a 'zombie fire?'

"Zombie fires" burn underground and get their name because they continue to burn even after surface fires are put out. Plus, they are "nearly impossible" to extinguish, Peter Winsor, Director of WWF’s Arctic Program, said in an email to USA TODAY. 

"Zombie fires" start with permafrost. According to Winsor, permafrost is a "layer of frozen soil, composed of silt, gravel, and sand bound together by frozen water." It sometimes contains other organic materials (like frozen plants and animals) and can be hundreds of meters thick. It's also thawing 70 years earlier than predicted, Winsor said. 

"The increased frequency of permafrost fires is a result of a warmer Arctic," he said. "When permafrost thaws, highly flammable gases like methane are released and can cause the fire to move from the surface to deep underground."  

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Why is a 'zombie fire' dangerous?

"Zombie fires" are part of a dangerous "feedback loop," Winsor said in a statement.

“The growing number of extreme wildfires in the Arctic are unprecedented in the past 10,000 years," he said. "These “zombie fires” can burn underground for years, thawing permafrost and releasing huge amounts of carbon into the atmosphere, creating feedback loops resulting in accelerated warming and more thawing permafrost."

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He added, "The combination of wildfires and permafrost thaw can cause loss of life, landslides, floods, and coastal erosion threatening Arctic communities, infrastructure and wildlife.”

What's going on in the Arctic Circle? 

The peak of the Arctic fire season was in July and early August, according to CAMS. Still, increased fire activity continued in Sakha Republic and Chukotka throughout August. 

Smoke plumes from the fires in the Arctic Circle have covered the equivalent of more than a third of Canada, CAMS scientists reported in a news release. 

“The Arctic fires burning since middle of June with high activity have already beaten 2019’s record in terms of scale and intensity as reflected in the estimated CO2 emissions," he said.