Boreal peatlands across northwestern Canada with permafrost have accumulated vast amounts of carbon (C) over millennia despite regularly burning in natural wildfires. Ongoing climate change increases fire frequency and intensifies fire severity, possibly transforming the ecosystems of this vast region into long-term future C sources. Losses of C occur during wildfire but also in the years post-fire due to reduced uptake of the greenhouse gas carbon dioxide (CO2) by vegetation and through decomposition of exposed drier peat on the surface.