The multi-decadal hazard cascade of a tropical mountain wildfire

Abstract. Climate change is driving wildfires to higher elevations, yet the hazard cascades that follow the burning of pristine tropical mountain ecosystems remain largely unexplored. Here, we analyse the long-term cascade following a February 2012 wildfire that burned 31 km² of forest and wetland in Uganda's Rwenzori Mountains National Park. Combining remote sensing, humanitarian records, field surveys, and interviews, we document ten major floods since 2012, including two debris floods that required large-scale humanitarian responses. Post-fire increases in erosion and mass movement have widened the River Nyamwamba sevenfold since 2012, breaching copper-cobalt mine tailings and mobilising an estimated 744,000 tonnes of waste into the river. Slow vegetation recovery at high altitudes and positive feedbacks between hazards have prolonged this high-risk state, underscoring the susceptibility of tropical mountain ecosystems to long-term post-wildfire cascades. More monitoring and research are required to characterise key hazard interactions after tropical mountain fires, which can guide entry points for management seeking to mitigate and impede future cascades.