Climate-driven upward spread of forest fires in European mountain regions

Forest fires are an emerging threat to mountain regions yet changes in their elevational distribution and underlying drivers remain largely unknown. Here, we integrate satellite-derived burned area data, with climate, forest cover, and human footprint data into statistical models to assess fire activity and its drivers across eight European mountain regions. The analysis focuses on fires ≥800 m of elevation and burned area ≥30 ha for the period 2000-2025. We find that forest fires have spread upwards (~72 m per decade) and become more frequent after 2015, with fire occurrence increasing by 30% per year below 1400 m and 12% above that elevation. Changes in burned area are primarily driven by climate, including vapor pressure deficit, soil moisture, and precipitation. Fires above 1400 m are linked to extreme atmospheric aridity, indicating that climate change is enabling fire in ecosystems that have been historically buffered from burning. Further warming will increase fire susceptibility in European mountain regions, highlighting the need to protect mountain ecosystem functions and services through effective fire management.