Wildfires send Canada's carbon emissions soaring. And our peatlands emit even more

CBC

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It's been another smoky summer, with estimates suggesting that 2025 is set to be Canada's second-worst wildfire season year. Already, more than 5.5 million hectares have burned, almost triple the 10-year average for this time of the year.
But it's not just the forests that are burning. Canada is home to a quarter of the world's peatlands — boggy wetlands that are a rich store of carbon from millions of years of decaying plant and animal life.
They are burning, too. But the scale of emissions from fires in the peatlands is not accounted for in current government statistics.
However, that's all about to change, with a new government effort to estimate peatland emissions and their impact on climate change.
"The better able I am to quantify these impacts, the better able we might be able to mitigate them," said Kelly Bona, who is leading the effort to produce a Canadian model for peatland emissions at Environment and Climate Change Canada.
Bona said the new data could be included as early as next year in Canada's official greenhouse gas reporting to the UN. Its inclusion would provide a new look at the severity of the problem, which researchers say is getting worse.
Why peatland fires are a climate problem
Much of Canada's peatlands are in the boreal forest zone, where trees like black spruce — which are prone to burning — are common. The presence of those trees, along with rich carbon deposits in the soil, can make peatlands very flammable, especially during dry periods.
Peat fires also smoulder over longer periods, rather than going up in one giant flame. Some of these fires can burn for months or years, according to researchers, releasing large amounts of their stored carbon into the atmosphere.
Greg Verkaik, a peatlands researcher and PhD candidate at McMaster University, collects post-fire field measurements to estimate the emissions. He painstakingly measures the depth of the peat at various points to figure out how much has been burned.
His time in the field provides him with a close look at the impact of climate change and worsening wildfires.
"You get days where you just can't go into the field because everything's smoky and it's hard to breathe and it's not safe for you to be out there," he said.
"You are sort of seeing that more frequently, especially over these last couple of fire seasons where it's been really bad."
Wildfire emissions don't count toward Canada's anthropogenic (human-caused) totals, but they are still reported to help inform the public and keep track of how forests are doing.
In recent years, the statistics have been sobering — wildfire emissions in 2023, the worst fire year in Canada's history, reached one billion tonnes — significantly more than the 694 million tonnes of emissions attributed to human activity.
The feedback loop is that climate change has made fire weather more frequent and severe, and those fires are worsening climate change itself.
In the peatlands, research has shown wildfires speed up permafrost melt, which in turn releases carbon, according to David Olefeldt, a peatlands researcher and assistant professor at the University of Alberta.
Olefeldt also said that peatlands continue emitting carbon long after a fire, as all the carbon in the soil takes longer to be lost to the atmosphere.
"If you want to understand the full impact of wildfire, you need to understand what happens in the years and even the decades after the fire," he said.
A study published in 2024 used the Canadian-developed model to estimate greenhouse gas emissions from Canada's boreal and temperate peatlands. Preliminary results suggest that fire-related emissions are about 11.5 million tonnes annually but noted estimates can vary significantly from one year to the next.
Wildfires over the past few years highlight those variations. 2020 was a mild fire year, with emissions of only 13 million tonnes, while 2021 was a more severe season, with emissions skyrocketing to 270 million tonnes.
According to the study, peatlands are generally a carbon sink, absorbing and storing more carbon than they emit, therefore helping counteract the effects of climate change.
But during a severe fire season, they become a carbon source, and release more than they absorb.
How could better peatland emissions numbers be used?
The new data would have a range of practical uses, both for resource development as well as conservation in the peatlands.
Bona said the data could be used in conducting environmental assessments for peatland projects. Olefeldt noted that knowing more about peatland emissions — including identifying ones those that are most at risk — could help aid in discussions about protecting them.
Maria Strack, a professor at the University of Waterloo who leads Can-Peat, a major research collaboration on the peatlands, pointed out that most peatlands are in regions where there's an interest in resource extraction.
The new data could help inform future decisions on developing mines and other infrastructure in those areas, she said.
"There's risks of mining disturbing more peat and all the infrastructure like roads to access those mines will also change the hydrology of peatlands, which could lead to more emissions."
She also sees them as a nature-based solution to combating climate change.
"We have about one-fourth of all the world's peat soil carbon stock, and I just think most Canadians don't even know what a peatland is," she said.