Why do northern wildfires release more carbon than thought?
Hidden emissions from smouldering soils raise carbon totals
Recent reconstructions of wildfire emissions in northern landscapes reveal that the climate impact of boreal and Arctic fires is larger than commonly estimated. Researchers analyzed wildfire cases and atmospheric data to separate immediate combustion of vegetation from prolonged smouldering of organic soils—peat, deep turf and other carbon‑rich layers. Those smouldering fires can burn slowly for long periods, releasing carbon that has been stored underground for decades to millennia.
Conventional emission inventories and many climate models tend to focus on flaming combustion and quickly measurable smoke plumes. They often undercount or miss extended smouldering phases and the release of ancient soil carbon, which can be substantial in northern peatlands and permafrost regions. By reconstructing total emissions from specific Swedish wildfire events and accounting for soil carbon losses, scientists found that current methods may be underestimating how much carbon these high‑latitude fires add to the atmosphere.
Implications for climate science and policy
- Carbon budgets: underestimated wildfire emissions mean national and global carbon accounting could be too optimistic for high‑latitude regions.
- Feedback risk: releasing ancient soil carbon accelerates atmospheric greenhouse‑gas accumulation and could amplify regional warming, making future fires more likely.
- Monitoring and modelling: better observation strategies (ground and remote sensing) and updated emissions factors that include smouldering are needed to close the gap.
Uncertainties persist about how common deep‑soil smouldering is across the boreal and Arctic in different seasons and under varied weather. Still, the work highlights a blind spot in how wildfires’ full carbon costs are tallied and underscores the need to revise models and national inventories to reflect these hidden emissions.