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Tinder-Dry Canadian Peatlands Becoming a Ticking Carbon Bomb

Simon Huguet/Wikimedia Commons

Recent work by Canadian ecohydrologists on the devastating 2018 peatland fire near Parry Sound, Ontario has confirmed related findings from around the globe: the Earth’s peatlands are drying out as temperatures rise, creating carbon-bomb tinder boxes.

Scattered around the planet, “peatlands are estimated to store about 550 gigatonnes of carbon, more than all of the forests in the world combined,” reports [1] the Globe and Mail. About 25% of peatlands are found in Canada, “with particularly dense concentrations in the Hudson Bay Lowlands and the Mackenzie River basin.”

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These peatlands, and the carbon they contain [3], are under increasing threat from wildfire: witness the infernos that devastated peatland-rich Siberia this summer, conflagrations that “loosed about as much CO2 into the atmosphere as the Greater Toronto Area has generated over the past five years.”

Speaking with the Globe about the Parry Sound study, recently published in the journal Environmental Research Letters, co-author Sophie Wilkinson of McMaster University described a “desolate” ecosystem harrowingly damaged by the intensity of the fire. “There was so little soil left that most of the trees had fallen over after they had burned,” she said. The Globe says all peat deposits less than 70 centimetres thick “were completely incinerated.”

While deeper stores of peat did survive “and stay wet enough to rebound,” the Parry Sound study contributes to what Earth systems scientists at the University of East Anglia describe as a “now indisputable” trend toward more frequent and severe wildfires around the globe—especially in drought-stricken places like Australia and California, but also in formerly unexpected locations, like wet bogland.

The East Anglia brief, released in late September, “examined 116 separate studies and found that all of them either directly strengthen or are consistent with evidence that climate change is increasing the frequency and severity of wildfires,” reports the Globe. Scientist Matthew Jones said studies using climate models “are all pointing to this situation getting worse the more the temperature rises.”

In northern Canada, the rising incidence of wildfire, especially in peatland regions, bears close watching, said Natural Resources Canada fire scientist Daniel Thompson. Also of growing concern: the crumbling interface between peatlands and permafrost in the north. After millennia providing insulation to the frozen land beneath, burned peatlands leave behind a “blackened, sooty surface”, one that is unfortunately ideal “for absorbing sunlight and warming up the ground.”

The Globe also flags the phenomenon of “zombie fires [4]” that smoulder in peatlands through the winter, a slow burn that accelerates the community-devastating thawing of permafrost already under way as the climate warms.

And scientists are concerned “that melting permafrost is releasing methane, a potent greenhouse gas, creating another feedback loop that can further accelerate climate change,” a scenario to which wildfire “adds another boost.”

There is complexity, too, in the interaction between peat, permafrost, and wildfire: for example, the Globe notes that melting permafrost may actually suppress fire, at least for a little while. This new understanding of how fire is shaping northern ecosystems has peatland scientist calling for further research.

“The field is in urgent need of a coordinated and multidisciplinary effort to track the new reality in the North, and how changing fire conditions are playing into the story,” the Globe writes, citing Merritt Turetsky, director of the Institute of Arctic and Alpine Research at the University of Colorado, Boulder.