For the first time in at least 40,000 years, fire has burned in the alpine zone of Africa's high mountains. Researchers have documented that the Rwenzori Mountains in Uganda, a region long considered too wet and cold to burn, are now experiencing wildfires at elevations above 3,000 meters.
A landscape that never burned
The alpine zone of the Rwenzori Mountains sits above the tree line, a world of giant lobelias, mossy bogs, and year-round chill. Until the 21st century, this ecosystem had no history of fire. Scientists analyzed sediment cores from a lake in the range and found no charcoal evidence of fire for the past 40 millennia. The landscape was simply too damp to ignite.
That changed in the 2000s. The study, published in Nature, shows that charcoal deposits began appearing in the sediment record around the year 2000. The fires have continued into the 2010s and 2020s. The researchers, led by Andrea L. Mason and colleagues from institutions in the United States and Uganda, identified the shift as a clear departure from the region's long fire-free past.
Why local communities are watching closely
The Rwenzori Mountains are a critical water tower for Uganda and neighboring countries. Their glaciers and peatlands feed rivers that millions of people depend on for drinking water, irrigation, and hydropower. Alpine fires threaten those peatlands, which store vast amounts of carbon. When they burn, they release that carbon into the atmosphere and can take centuries to recover.
Local people have also relied on the mountains for tourism and as a source of traditional medicines and plants found nowhere else on Earth. The fires put those resources at risk. Ugandan scientist Bob Nakileza, a coauthor of the study, has been documenting the ecological changes on the ground as the flames move higher.
The researchers linked the emergence of fire to warmer and drier conditions in the alpine zone. As temperatures rise and moisture declines, the once sodden vegetation becomes fuel. The study did not attribute the fires to any single cause, but the timing aligns with broader climate shifts across tropical Africa.
A signal from the sediment
The evidence came from a lake in the Rwenzori range. By drilling into the lakebed and analyzing layers of ancient mud, the team reconstructed a 40,000 year record of fire history. They found no trace of burning until the topmost layers, which correspond to the past two decades. The charcoal particles in those layers were small and abundant, typical of grass fires moving through alpine vegetation.
This finding matters because it shows that even the most remote and resilient ecosystems are not immune to rapid change. The alpine zone of Central Africa has been a refuge for unique species and a stable source of water for centuries. That stability is now gone.
The study does not predict what comes next. But it makes clear that a fundamental threshold has been crossed. Fire is now part of the alpine landscape in Uganda, and that is something that has never happened before in human memory or in the long record written in the mud.
