Seen from above, the dozens of people trekking through the Rwenzori Mountains might have looked something like an ant farm branching across the landscape, said Klaus Thymann. The expedition into the range on the border between Uganda and the Democratic Republic of the Congo included Thymann, an environmental scientist; Heïdi Sevestre, a glaciologist at the Arctic Monitoring and Assessment Programme; guides from the Uganda Wildlife Authority (UWA); and—predominantly—interested community members there to help with logistics.
The group was there in August 2024 to survey ice on the range’s three tallest peaks and to create the first 3D model of the glaciers on Mount Stanley, whose apex, Margherita Peak, is the third highest in Africa at 5,109 meters (16,763 feet).
“It’s really a team work, and a very good one,” said Thymann, founder and director of Project Pressure, a nonprofit organization focused on environmental issues.
Their newly analyzed data confirmed that Mount Speke, the second-highest peak in the range, no longer hosts a glacier (only static ice) and that Mount Baker, the third highest, is practically ice free. The researchers found that the surface area of the Stanley Plateau glacier fell by 29.5% between 2020 and 2024.
“Glaciers worldwide are shrinking or disappearing, so that’s not a surprise,” Thymann said. “I think what is surprising is how rapid it’s going.”
Jim Russell, a climate scientist and geochemist at Brown University who was not involved in the research, has been making expeditions to the Rwenzori Mountains since 2006. He called these glaciers a “canary in a coal mine.”
“The recent retreat is really significant, and it’s illustrating substantial climate change is happening at high elevations,” he said.
Sleeping Bags, Licorice, and Drones
“There’s no roads, there’s no helicopters, there’s not even a donkey.”
Aside from essentials, such as sleeping bags and licorice (“It’s all about the amount of flavor you can get with the least amount of volume,” Thymann explained), the crew carried an array of equipment, including a generator, fuel and cables for the generator, three drones, and GPS hardware.
“There’s no roads, there’s no helicopters, there’s not even a donkey,” Thymann said. “Everything has to be carried in, so that makes science challenging because the logistics are difficult.” With the weight of equipment and the need to acclimate to the elevation, it’s a 5-day trek from the entrance of Rwenzori Mountains National Park up through tropical, bamboo, and alpine forests to the Stanley Plateau.
A man stands on a snowy mountain next to a boxy structure. He looks off into the distance at a peak.
Uganda Wildlife Authority guide Muhindo Rogers stands outside a hut. Behind him is Mount Baker, the third-highest peak in the Rwenzori range, which once hosted a glacier that has now melted. Credit: Project Pressure
Thymann led expeditions to the area in 2012, 2020, and 2022. In 2020, the team captured images of the plateau with consumer drones, then used photogrammetry to create a digital elevation model of the area.
When they returned in 2024, they went one step further. They used a surveying system to determine the precise GPS coordinates of eight points along the plateau, then set up a brightly colored target on each point. When they flew drones over the area to capture more than 850 photos, they could not only create a model but also anchor it to precise GPS coordinates. They also used the points to retroactively anchor the 2020 model. By comparing the two models, they determined the extent of ice loss on the plateau.
Sevestre, the glaciologist, also used ground-penetrating radar to determine the depth of the glaciers. “If you want to know volume, you have to know three dimensions. You have to know the x, the y, and then the z,” Thymann said. “Nobody knew the z, so nobody knew the depth.”
Four people stand on a snowy mountain around a green and orange square of fabric. They are wearing climbing gear and warm jackets.
Klaus Thymann (left) works with Kule Jocknus Bwabu Solomon and Muhindo Rogers of the Uganda Wildlife Authority to set up precision GPS points for photogrammetric survey. Glaciologist Heïdi Sevestre (right) joined the expedition to scan the ice with ground-penetrating radar. Credit: Project Pressure
The researchers expect to publish more detailed findings, including glacier volume, in late 2025.
Russell said he was “amazed” the researchers were able to do this work in this remote area. Though there is no standard way of mapping glaciers, he added that the Rwenzori Mountains’ glaciers have historically been mapped simply by tracing the movement of their edges. The Project Pressure team is “not just tracing the lowest elevation of the glacier,” he said. “They’re also able to kind of see the sides, see how that’s shrinking, potentially see it thinning from the top.”
Protecting the Home of Gods
The dwindling of Rwenzori’s ice may be a bellwether of glaciers’ futures worldwide, but closer to home, its effects are already being felt.
The ice on the mountain range is the highest source of water for the River Nile and holds water that millions of Ugandans rely upon. Trekking tourism to Rwenzori Mountains National Park, a United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site, also bolsters the local economy.
“This ice supports the people of the communities living around it, 100%,” said Masereka Solomon, a tour guide in Uganda who began working with Thymann in 2012. Solomon has lived in the area for 34 years—his whole life—and has watched the ice retreat firsthand. For him and other Bakonzo people who live in the foothills of the Rwenzori Mountains, the glaciers also hold a deep religious and cultural significance, as they believe that their gods live in the ice atop the mountains.
“We believe if we protect this mountain, if we fight hard to maintain the small ice, or the small glaciers that [remain], our gods will not be homeless.”
“We believe if we protect this mountain, if we fight hard to maintain the small ice, or the small glaciers that [remain], our gods will not be homeless,” Solomon said.
Thymann emphasized the role of the dozens of community members during the expeditions, from helping transport equipment up the mountain to spotting the drones and returning regularly to maintain time-lapse cameras. He and the other Project Pressure researchers analyze the data and share the results with UWA and locals.
He added that though the Bakonzo people understand that the retreating ice is caused by climate change, he hopes that this more detailed data can “empower” the community and that sharing these findings widely will raise awareness of Uganda’s shrinking glaciers.
—Emily Dieckman (@emfurd.bsky.social), Associate Editor
Citation: Dieckman, E. (2025), A new 3D map shows precipitous decline of Ugandan glaciers, Eos, 106,https://doi.org/10.1029/2025EO250126. Published on 3 April 2025.
Text © 2025. AGU. CC BY-NC-ND 3.0
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