Twenty-first century emergence of alpine fire in Central African mountains

Wildfires are an escalating global hazard that threaten ecosystems, air quality and societies^1,2. Although tall tropical mountains have generally been considered too cool and moist to burn³, the recent occurrence of high-elevation wildfires on Africa's highest mountains suggests the emergence of a new and potentially transformative threat. A lack of historical records of fire in these environments limits our understanding of fire activity, its environmental impacts and the resilience of Afromontane ecosystems. Here we show that a twenty-first century fire was the first to affect Afroalpine elevations (>3,800 m above sea level (a.s.l.)) over the past 12 thousand years in the Rwenzori Mountains, Central Africa. At mid-elevations (2,990 m a.s.l.), fire increased abruptly around 2 thousand years ago, coincident with regional evidence for changing human activity⁴, and this was followed by an increase in bamboo-dominated ecosystems. Our results highlight the role of humans as an important driver of Afromontane fire activity and show that high-elevation tropical Afroalpine fire is a new twenty-first century disturbance that could transform high-elevation tropical ecosystems.