Rapid satellite assessment of the 2026 High Fens fire

Dong Chen, Joanne Hall, Yanfei Li, Kristof Van Oost

Climate change is altering fire regimes across Europe, contributing to longer periods of favorable fire weather. In August 2026, the High Fens nature reserve experienced one of the largest wildfires in Belgium's recorded history. This event is ecologically and biogeochemically significant because the fire affected a landscape dominated by carbon-dense peatlands, where prolonged smouldering can cause substantial carbon (C) loss and greenhouse-gas emissions. This study provides a rapid satellite-based assessment of the 2026 High Fens Fire and uses the pre-fire hydro-climatic conditions as an empirical benchmark for examining their occurrence across northern high latitudes. Using Sentinel-2 imagery, we mapped a 25.43 km² burn scar with substantial spatial heterogeneity in spectral severity. A regional analysis based on Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detections indicated that the High Fens event was the only peatland-dominated cluster among the six largest fire clusters identified in our Western European VIIRS record between 2012 and 2026. To contextualize the severe hydro-climatic conditions preceding ignition, we combined anomalies in maximum air temperature, vapor pressure deficit, and surface soil moisture to define an empirical pre-fire benchmark. Upscaling this benchmark across the High Northern Latitudes (HNL) showed that comparable combinations of temperature, atmospheric dryness, and surface soil moisture occurred across a broad geographic footprint, particularly along the southern margins of the HNL, including parts of southern Canada, Europe, and Siberia. Intersecting this benchmark exceedance footprint with global peatland and Moderate Resolution Imaging Spectroradiometer (MODIS) MCD64A1 burned-area datasets identified ~253,000 km² of peatland with no MCD64A1-detected burned area during 2001–2025 and ~84,000 km² with detected burned area during the same period. The unburned peatland area contains an estimated 35.9 Gt C of soil organic carbon stock. An additional 10.1 Gt C was contained within peatland areas that had MCD64A1-detected burned area during 2001–2025. Translating this widespread meteorological exposure into reliable estimates of potential carbon emissions requires a precise understanding of belowground fire behavior. Because substantial uncertainty remains in estimating peat combustion and post-fire ecosystem recovery, the accessibility of the High Fens reserve and the availability of nearby peatland observations provide an opportunity for future field-based validation and long-term monitoring.