Researchers have discovered that the majority of wildfire smoke originates from carbon stored in the ground rather than burning trees. The study, published in Geophysical Research Letters, highlights that 75% of these emissions stem from the ground during intense fire events.
The 75% carbon shift from trees to soil
A new study in Geophysical Research Letters reveals that three-quarters of wildfire emissions are actually released from carbon trapped in the soil. This finding, led by McMaster University's Alemu Gonsamo, suggests that the visible burning of trees is only part of the story.
The research utilized field data from Canada's massive 2023 wildfire season to distinguish between above-ground vegetation and the forest floor. According to the report, the layers of decaying organic matter that make up the forest floor act as a much larger and denser storehouse of carbon than the visible branches and leaves. If the soil is sufficiently dry, it will burn readily, releasing massive amounts of smoke and carbon relative to the surface vegetation.
In Northwestern Ontario , the top meter of soil contains between 20 and 60 kg of carbon per square meter. When these areas become dry enough to burn, they produce significant emissions; areas with more than 90 kg of carbon per square meter can produce even greater amounts.
The disconnect between Trump's tariffs and soil science
Political leaders have used the smoke to target Canadian policy, specifically U.S. President Donald Trump. As reported by the source, Trump has blamed Canada for mismanaging its forests and has threatened to impose new tariffs because of the smoke affecting major cities like New York and Chicago.
However, the new research suggests that the logic behind these assertions is flawed. Because the majority of the smoke comes from the soil, the production of these emissions has very little to do with traditional forestry management practices aimed at controlling surface vegetation.
A 150,000 square kilometre wake of destruction
The scale of the 2023 Canadian fires was unprecedented, consuming 150,000 square kilometers of land. This area, representing roughly 4 percent of Canada's forests, is more than double the size of New Brunswick.
Sander Veraverbeke of Vrije Universiteit Amsterdam noted that the carbon released by these fires was comparable to the fossil-fuel emissions of an entire large country. Beyond the immediate impact on air quality in North America, the results carry significant implications for global carbon cycles.
Which measurement model captures the true 2023 carbon surge?
Significant questions remain regarding the exact total of carbon emissions released during the 2023 season. While several research teams attempted to estimate the total, they relied on different methodologies that may yield different results. For instance, Europe's Copernicus Atmosphere Monitoring Service uses space-based observations and computer models, while other teams rely on measuring carbon monoxide concentrations. it remains to be seen if these diverse approaches will eventually reach a consensus on the total volume of carbon released.
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