We Once Thought That Peat Deposits In Alaska, Canada Too Wet To Burn. Well, Guess What?

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For all the drama of trees lighting up like matchsticks, it’s what lurks below the forest that could be a major wildcard for future warming. Large reserves of peat make up a large portion of the soil, swamps and bogs in the northern reaches of the globe. Flannigan refers to it as “legacy carbon,” an accumulation of centuries of plant matter that sequesters vast amounts of carbon from the atmosphere.

Despite covering slightly less area than tropical forests, boreal forest soil stores three times as much carbon as its tropical counterpart. They currently operate as carbon sinks, taking up more carbon than they emit each year. Wildfires could flip the script, though, turning boreal forests into sources of carbon emissions as fires burn through the vast reserves of carbon locked in the trees and soil (something already happening in California). If that happens, it could rapidly warm the climate.

“Up until about 10 years ago, the prevailing dogma was peatlands just didn’t burn,” Merritt Turetsky, an ecologist at the University of Guelph, said. “They were way too wet and fire played little to no role in these ecosystems. Over time, we’ve seen that just isn’t true.” As warming dries out forests and precipitation patterns change, the water table is dropping in once swampy areas. That makes peat susceptible to burning and when it does catch fire, centuries’ worth of carbon can burn up in the span of a few hours if fires are intense enough.

Peat fires are also notoriously resilient, smoldering for days, weeks or even popping up again after a winter of smoldering beneath the surface. Turetsky said it’s akin to throwing a wet log in a fireplace and that she plans to use satellite data to see if fires that scorched the Northwest Territories last summer managed to smolder through the winter and re-emerge this summer.

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http://www.climatecentral.org/news/climate-change-alaska-wildfires-19181