The scientist Ptolemy thought they were the source of the Nile and called them the Mountains of the Moon because of the perpetual mists that covered them; Stanley claimed to be the first non-African to see their icecap; and the subsistence farmers who today live on the slopes of the fabled Rwenzori mountains in Uganda and the Democratic Republic of the Congo fear that warming temperatures are devastating their harvests.

While 20,000 people a year scale Mt Kilimanjaro in Tanzania, just a handful of trekkers tackle the lower, 5100m Rwenzori summits and witness the spectacular plant forms that grow in some of the wettest conditions on earth. The result is that little is known about the condition of the many tropical glaciers that descend off the three peaks of Mts Baker, Speke and Africa's third highest peak, Mt Stanley.

But in April, a micro-expedition led by London-based Danish photographer Klaus Thymann returned from Uganda with the best evidence yet that the 43 glaciers found and named in 1906 are still mostly there, but are in dire condition and can be expected to disappear in a decade or two.

Thymann, his journalist colleague Ian Daly and a team of nine local Ugandans spent 18 days recording Rwenzori's glaciers from both sides of the range that straddles the equator. "The vast majority have retreated massively on the east side of Mt Stanley, they have practically all gone on Mt Baker, along with the river, and the Grant and Speke glaciers on Mt Speke are now tiny or have practically gone," says Thymann.


Using an old map to hack through overgrown trails at 4500m, the group traversed the western, Congolese side of the range, where it is believed few, if any, people have been for many years because of insurgency and war.

Perpetual cloud cover makes aerial or satellite photography of the range hard, but going on foot was revelatory, says Thymann.

"It's like a white spot on the map, covered in cloud most of the year. It's very inaccessible. From the Congo side you can find glaciers unseen in 40 years. It was like rediscovering them. The west Stanley glacier has become detached from its accumulation zone, and the Edward 'Y' glacier on Baker has lost an arm."

Analysis of satellite data in 2006 suggested that the combined area of the Rwenzori glaciers halved from around 2sq km to just under 1sq km between 1987 and 2006.

"You can see clearly how the glaciers have retreated massively on the east side. The melt is super-intense. It was surprising to find some there at all. They probably don't have much time left," says Thymann.

Thymann heads Project Pressure, a collaboration of photographers, scientists, web developers and cartographers working to document the terminal decline of many of the world's glaciers and create a virtual record of ice on every continent.

Since 2008, Project Pressure has recorded fast-shrinking glaciers in Argentina, Alaska and Montana, Iceland, Uganda, Nepal, Ecuador, Spain, Switzerland, Chile and Norway.

This year, researchers will visit Greenland, Colombia and Bolivia, and expeditions are being planned to New Zealand and Kamchatka in the Russian far east.