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 Belgium's largest recorded wildfires. This event is ecologically significant as it affected carbon-dense peatlands vulnerable to smouldering combustion and carbon (C) release. This study provides a satellite-based assessment of the fire and uses its pre-fire hydro-climatic conditions to benchmark similar meteorological exposure across the High Northern Latitudes (HNL). Sentinel-2 imagery delineated a 25.43 km² burn scar with heterogeneous spectral severity. VIIRS data further showed the High Fens event was the largest peatland-dominated active fire cluster in Western Europe during 2012–2026. To contextualize ignition preconditions, we used a sequential feature selection algorithm over the 7 days prior to ignition to select maximum vapor pressure deficit, daily evapotranspiration, and surface soil moisture to represent distinct, relatively weakly correlated aspects of the extreme pre-fire environment. Upscaling this empirical benchmark across the HNL revealed comparable extreme conditions concentrated along southern margins of the high-latitude domain. Intersecting this exceedance footprint with global peatland and MODIS MCD64A1 fire-history data identified 319,076 km² of peatland with no MCD64A1-detected burned area during 2001–2025 containing 45.1 Gt C of soil organic carbon, alongside 104,183 km² of previously burned peatland (12.6 Gt C). Translating this widespread meteorological exposure into emission estimates requires precise understanding of belowground fire behavior. The High Fens reserve's accessibility and existing pre-fire data offer a unique opportunity for field-based validation of peat combustion and recovery.