Burning peat and soil organic matter produced about 75% [2] of greenhouse gas emissions during Canada's 2026 wildfire season.
This discovery shifts the understanding of wildfire impacts, as it highlights that the most significant climate contributions come from beneath the surface rather than from the visible burning of forests.
Researchers at McMaster University analyzed the emissions from the 2026 season, which saw approximately 15 million hectares [1] of land burn across the country. The study focused on boreal forest and peat-rich regions, where organic matter accumulates in thick layers over centuries. While the sight of burning trees dominates the imagery of these disasters, the data shows that the soil is the primary driver of carbon release.
Peatlands act as massive carbon sinks, storing vast amounts of carbon in water-logged organic material. When these areas ignite, they release carbon dioxide and other greenhouse gases more intensely than the combustion of above-ground vegetation. This process creates a feedback loop where the loss of soil carbon further destabilizes the local ecosystem, making the land more susceptible to future fires.
The findings suggest that traditional models focusing on tree canopy loss may underestimate the total atmospheric impact of boreal fires. Because peat fires can smolder underground for long periods, they continue to emit gases even after the visible flames have been extinguished.
McMaster University researchers said the data underscores the vulnerability of Canada's peat-rich landscapes. The scale of the 2026 season provided a critical window into how these subterranean fires operate on a national scale.
“About 75% of greenhouse gas emissions originated from peat and soil carbon rather than from trees.”
This research indicates that wildfire mitigation and climate modeling must prioritize the protection of peatlands over simple forest management. Because the majority of emissions are subterranean, the long-term atmospheric impact of a fire is determined by soil depth and moisture levels rather than just the number of trees burned, complicating efforts to calculate national carbon budgets.
