Circumpolar patterns of arctic-boreal fire activity

Intensifying wildfires in high-latitude forest and tundra ecosystems are a major source of greenhouse gas emissions, releasing carbon through direct combustion and long-term degradation of permafrost soils and peatlands. Several remotely sensed burned area and active fire products have been developed, yet these do not provide information about the ignitions, growth and size of individual fires. Such object-based fire data is urgently needed to disentangle different anthropogenic and bioclimatic drivers of fire ignition, spread and extinction.

We developed an object-based fire tracking method to map the evolution of fires at a sub-daily scale using Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detections. The dataset includes ignitions and sub-daily perimeters of individual fires between 2012 and 2021, which are corrected using finer-scale information on waterbodies. Here, we present first results of this circumpolar arctic-boreal fire atlas. We show circumpolar patterns of arctic-boreal fire activity and disentangle the spatially varying influence of drivers of fires. Most fires, as well as the largest fires, occur on the Eurasian continent. Latitudinal differences in fire characteristics and drivers are important, yet regional and continental differences emerge. Knowledge about regional differences in fire regimes and their drivers is required to better understand contemporary arctic-boreal fire regimes and to constrain models that predict changes in future arctic-boreal fire regimes.