Ah, for the good old days, when zombies staggered across the countryside at a glacial pace, throwing themselves clumsily at farmhouse doors, looking to eat the brains of the terrified residents inside. Scary that they were, we could always rest easy knowing that, held within the border of the silver screen, zombies could never pose a real threat to hearth and home. Well, there’s a new zombie on the rise and though it isn’t interested in eating our brains, it does pose a threat to our home, Earth.
“Zombie fires”, also called “overwintering” or “holdover” fires, are a known phenomenon that occurs in Arctic forests across Alaska, Canada, Greenland and Russia. Even after surface wildfires are extinguished in these forests, zombie fires can smolder below ground undetected, fueled by the carbon-rich peat and methane gas that comprise Arctic soil: the soil literally catches fire. The peat provides a fuel source for these fires that can burn for weeks, months or even years. Hidden under winter snow, the zombie fire smolders. As the snow melts, spring temperatures rise and the soil dries out, zombie fires “come back to life”, gain strength, spread, and ignite new wildfires. Zombies = Bad.
Until the last few years, zombie fires were characterized by researchers as a “rare freak phenomenon” because the conditions that give rise to them - an unusually hot summer followed by a mild winter - aren’t typical for the Arctic. But there’s increasing concern that climate change, specifically its impact on Arctic seasonal temperatures, is creating the perfect storm for these zombies to rise in increasing numbers.
From 2000 to 2010, Arctic wildfires burned, on average, 50% more acreage each year than in any decade of the 20th century. Between 2010 and 2020, that number continued to creep up and in 2019, with the hottest June on record in the Arctic, an unprecedented number of wildfires blazed across Greenland, Siberia and Alaska, creating smoke plumes that could be seen from space, and decimating more than 2.5 million acres of forest in Alaska alone. As Winter turned to Spring that year in the Arctic, satellite imagery in early May 2020 showed smoke plumes rising from subsurface zombie fires in previously unseen numbers.
Arctic soils are carbon-rich with centuries worth of partially decayed plant matter. In 2020, Arctic forest fires, fueled by both surface and subsurface material, released nearly 250 megatons of carbon dioxide into the atmosphere; two and one-half times as much as the record-breaking California wildfires of that same year, and about half the total volume of CO2 emissions that human activity creates on the continent of Australia – in an entire year.
Smokey the Bear said that only we can prevent forest fires. In this case, even though they’re thousands of miles away, he’s right. By doing everything in our power to reverse the effects of climate change and its impact on the Arctic ecosystem, we can measurably reduce the number of forest fires that happen at the top of the world. And rid the world of zombies. Sounds like a superhero storyline if ever there was one.