"ANCHORAGE, Alaska - In the boreal forests of the planet’s far north, where the climate is warming faster than almost anywhere else in the world, some wildfires are surviving winter snows and sparking back up again in spring.
Now scientists from the Netherlands and Alaska have figured out how to calculate the scope of those “zombie fires” that smolder year-round in the peaty soil.
From 2002 to 2018, an average of about 1% of the burning in Alaska and in Canada’s Northwest Territories was caused by overwintering fires that survived from one summer to the next, according to a study , published Wednesday in Nature. But in one year, zombie fires accounted for 38% of the region’s burning.
“We know that fires can start in the fire season by lightning and humans. Now we can have another cause of burned area,” said co-author Sander Veraverbeke, a landscape ecologist at Vrije Universiteit Amsterdam. “If it happens near a fire scar from the year before, early in the season, and there’s no lightning and it’s not human, then it’s an overwinter fire.”"