Mass balance of a slope glacier on Kilimanjaro and its sensitivity to climate

Meteorological and glaciological measurements obtained at 5,873 m a.s.l. on Kersten Glacier, a slope glacier on the southern flanks of Kilimanjaro, are used to run a physically-based mass balance model for the period February 2005 to January 2006. This shows that net shortwave radiation is the most variable energy flux at the glacier-atmosphere interface, governed by surface albedo. The majority of the mass loss (~65%) is due to sublimation (direct conversion of snow/ice to water vapour), with melting of secondary importance. Sensitivity experiments reveal that glacier mass balance is 2-4 times more sensitive to a 20% precipitation change than to a 1 °C air temperature change. These figures also hold when the model is run with input data representative of a longer-term (1979-2004) mean period. Results suggest that a regional-scale moisture projection for the 21st century is crucial to a physically-based prediction of glacier retention on Africa’s highest mountain.