Tropical glacier loss in East Africa: recent areal extents on Kilimanjaro, Mount Kenya, and in the Rwenzori Range from high-resolution remote sensing data

Abstract

Over recent decades, the retreat of Kilimanjaro’s glaciers has been portrayed as a beacon of climate change. The decline in glacier area within the 20th century, however, is evident for all tropical glaciers in East Africa, including those of Mount Kenya and the Rwenzori Range. Being mainly controlled by high-altitude hygric seasonality, these glaciers are par-ticularly valuable indicators of tropical climate variability and climate change. More recent studies have focused on Kilimanjaro and Mount Kenya but the Rwenzori Range has not been considered for nearly two decades, which introduces an uncertainty about the remaining glacierization in East Africa. Therefore, the present study provides insights into the most recent glacier extents of all three mountain regions using a manual, multitemporal analysis of high-resolution satellite images for the years 2021/2022. Accordingly, the glacierization in East Africa is estimated to be 1.36 km2, with a glacier area of 0.98 km2 on Kilimanjaro, 0.069 km2 on Mount Kenya and 0.38 km2 in the Rwenzori Range. The uncertainty is deter-mined to be smaller than 12 %. Compared to previous estimations, the overall area has de-clined by more than a half of its early 21st century extent. These recent results demonstrate the continuing influence of retreat processes, which were found to be driven by Indian Ocean warming and high-elevation snowfall changes in previous studies.