![]() Once it’s on fire, peat can provide a habitat for fires to smolder on long after their surface flames have abated-for days, weeks, months, or even years. Most peat in North America is younger, but still thousands of years old. These fires are starting to burn soils that evolved alongside Homo sapiens,” she says. “These are ancient soils,” says Jessica McCarty, an Arctic scientist at Miami University in Ohio. But under the kinds of climate-changed conditions becoming more common there-long, hot summers with particularly acute heat waves that suck the moisture out of plants and soils-the damp underlying peat can ignite. In the Arctic, fires usually start at the surface too, sparked by summer lightning or occasionally by humans. Today, peatlands cover some 4 million acres of the Arctic and store an estimated 415 billion tons of carbon, many times more than the forests above them and as much as all the trees on Earth.Įlsewhere in the world, soils don’t usually contain much burnable organic material, so fires feed on what they encounter-trees, shrubs, homes-at the surface. Peat reserves build over centuries or millennia soils just a few feet deep can be thousands of years old. It forms in damp and chilly parts of the world, where organic material degrades slowly. Peat is made up of dead vegetation-mosses, flotsam of trees and shrubs, other Arctic plants- that hasn’t broken down all the way. In 2020, Arctic fires released almost 250 megatons of carbon dioxide, about half as much as Australia emits in a year from human activities and about 2.5 times as much as the record-breaking 2020 California wildfire season. Scientists have found that fire frequency today is higher than at any time since the formation of boreal forests some 3,000 years ago, and potentially higher than at any point in the last 10,000 years.įires in boreal forests can release even more carbon than similar fires in places like California or Europe, because the soils underlying the high-latitude forests are often made of old, carbon-rich peat. Between 20, burned acreage continued to creep up, particularly in Alaska, which had its second worst fire year ever in 2015 and another bad one in 2019. In the first decade of the new millennium, fires burned 50 percent more acreage each year in the Arctic, on average, than any decade in the 1900s. But unlike many forests in the mid-latitudes, which thrive on or even require fire to preserve their health, Arctic forests have evolved to burn only infrequently.Ĭlimate change is reshaping that regime. Like all forests, the wooded stretches of the Arctic sometimes catch on fire. “The sheer fact that this is happening is a testament to how quickly the region is changing,” he says. But Veraverbeke’s team found that their occurrences are tightly linked to climate change, happening more often after hot, long summers with lots of fire and suggesting that these still-rare events could become more frequent. Zombie fires aren’t an entirely new phenomenon in the Arctic fire managers have noted occasional flare-ups in past decades. What he saw on the satellite images were “zombie fires,” remnants of burns from the previous year that somehow stayed alive, smoldering underground, through the long, cold winter. “I was like, what the hell is going on?” says Veraverbeke, an Earth scientist at the Vrije Universiteit of Amsterdam in the Netherlands. So scientist Sander Veraverbeke was confused when in May of 2016 he saw little flecks of fire on some satellite images from Alaska and the Northwest Territories. In the far North, fire season usually doesn’t start until June, when snow has melted away and summer lightning storms sweep into the region.
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