At the border between Uganda and the D.R. of Congo, the Rwenzoris (0.386°N; 29.872°E) form a remote and high-altitude mountain range stretching near the equator, through the East African Rift System. With heights of 4-5 km, they include Africa's third highest peak (Mt. Stanley, 5109 m) as well as some of the last African glaciers. The combined area of the Rwenzori glaciers declined by more than 80% during the 20th century, and halved between 1987 and 2006. This extreme mass loss may have strong implications for the local ecosystems and communities, and recent estimates suggest that the glaciers will disappear in the next decade(s). This trend correlates well with similarly dramatic glacier retreats on Mt Kilimanjaro (TZ) and Mt Kenya (KE) in the same period, and is attributed to debated causes like increased air temperature or reduced humidity/cloud cover. Despite recent work on the evolution of glacier extent in the last decades, the measured glacier retreat, as well as the interpretation of the responsible driving climatic factors, remain controversial partly owing to the lack of data.
In order to better understand the dynamics of this recession, a detailed survey of the current state of the two largest Rwenzori glaciers, Stanley and Speke glaciers, was made using a panel of remote sensing, geophysical and geochemical methods. These included, first, satellite-based monitoring of glacier extents over the last decades, mapping of the current glacier extent and main features using differential GPS, and assessing the glacier thicknesses using ice-penetrating radar. Second, a weather station data recording main climatic parameters was installed in the glacier vicinity in order to better understand the glacier sensitivity to the changing climate. These results were compiled with a view to provide a first estimate of modern, past and future ice budgets in the area of interest.
Given the limited expected time period before Rwenzori glaciers disappear entirely, the RIDEC project represented a unique opportunity to investigate, before they melt completely, the invaluable body of information retained in them.
