The Snows of Kilimanjaro: A critical comment on Numerical Simulations of the Role of Land Surface Conditions on the Climate of Mt. Kilimanjaro Region

Widespread retreat of glaciers and ice caps is one of the clearest visible indications of the effects of climate change. The IPCC Fourth Assessment Report estimated that between 1990 and 2003, there was an average global loss of mass from glaciers and ice caps (excluding the ice sheets of Antarctica and Greenland) of 280 ± 79 billion tonnes per year (Gt/yr). This mass loss has contributed an average of 0.77 ± 0.22 mm/yr to sea level rise (Lemke et al., 2007). Glaciers and ice caps are retreating in all regions of Earth, including the tropics, where they have shrunk from a maximum in the mid-19th century, generally following the global trend. The wastage of tropical glaciers, including those on Mt. Kilimanjaro, East Africa (30°4’S, 37°21’E), has been strong since the 1970s and, as in other mountain ranges, the smallest glaciers are more strongly affected.

However, the images published on the front cover of CLIVAR Exchanges (No. 47; Vol 13#4, Heuser and Semazzi, 2008) give a very wrong impression of the magnitude of the retreat of glaciers on Mt. Kilimanjaro. These images of Kilimanjaro’s highest peak, Kibo (5893 m), in February 1993 and February 2000 merely show changes in the transient snow cover – not the glaciers. These images originally appeared on the NASA Earth Observatory website (http://earthobservatory.nasa.gov/IOTD/view. php?id=3054) on December 20, 2002 and have been frequently misinterpreted. The caption on this NASA website was modified in 2005 to make it clearer that the images cannot be used as an indication of the rate of the loss of ice.