The 2023 wildfires in Canada burned a record-breaking area, contributing 23% of global wildfire carbon emissions that year. Yet, the relative contributions from live biomass versus soil and peat organic matter combustion were previously unknown. Our analysis reveals a total of 554 million tonnes of carbon released by the 2023 wildfires in Canada, with 76% originating from soil and peat combustion, and 24% from live biomass burning. As Canada stores about one-fifth of the world’s soil organic carbon, these findings underscore the growing vulnerability of northern soil carbon stocks to intensifying wildfires, amplifying climate feedback risks.

Additional coverage in the Globe and Mail, by Ivan Semeniuk: High proportion of Canadian wildfire smoke originates below ground, scientists report