Determinants of wildfire risk in the low Arctic and northern subarctic of Canada

Abstract Growing evidence suggests that the frequency and intensity of fire is increasing across the tundra biome. A change to tundra fire regimes is concerning because it will impact carbon emissions, permafrost conditions, vegetation, and habitat. In northern Canada little is known about the relative impact of climate and terrain factors on the risk of fire. In this study we used imagery from the Landsat satellite archive to identify and manually digitise the boundaries of tundra and northern taiga fires that burned in northcentral and northwestern Canada between 1985 and 2023. Our mapping shows that the area burned between 2005 and 2023 is higher than the period from 1985 to 2004, largely because the size of individual fires has increased. A random forests analysis using our fire inventory and spatial data on climate and terrain factors indicates that fuel conditions and mean summer temperature (June–September) are key determinants of fire occurrence. Geospatial modelling also suggests that ongoing climate change will increase the frequency of tundra fire and that future risk will be mediated by landscape characteristics.