March 13, 2012
The snows of Mount Kilimanjaro are more famous, but Mount Kenya is even closer to the equator and host to a number of glaciers that are rapidly diminishing. The Tyndall Glacier is the second largest glacier on the mountain. Stephen Hastenrath, University of Wisconsin in particular has documented the changes of Mount Kenya glaciers. In a color version of the map from the WGMS FOG 9that Hastenrath produced on page 9 of the link above the changes in the glacier from 1893 to 2004 are shown. The glacier retreated from Tyndall Lake in the late 1920’s. By 2004 the glacier was 275 meters from the lake. In the more recent Google Earth imagery the retreat is 360 meters Mizuno (2005) observed retreat rates of 3 meters per year from 1958 to 1997 and 10 meters per year from 1997-2002. The Google Earth imagery of 2011 indicates that the terminus is still retreating at 9-10 meters per year. The photographic sequence below from Mizuno (2005) indicates considerable thinning of the glacier even its upper reaches. This suggests the glacier not only has strong negative mass balance but also lacks a persistent accumulation zone, without which it cannot survive (Pelto, 2010). The last image below is the current Google Earth view tilted to provide a comparable view to the time sequence. Mizuno (2005) also focussed on the vegetation of the newly deglaciated terrain observing that pioneer species such as groundsel , alpine rockcress, mosses, and lichen recolonized the area at a rate similar to the glacier retreat rate. The first colonizers developed within five years of glacier retreat. Hastnerath (2006) observes that increased net shortwave radiation led to the initial recession in the late nineteenth century and that recently the increased retreat on Mount Kenya is due to the greenhouse effects. The retreat of Mount Kenya glacier is similar to the scale seen in the Rwenzori Range. The largest glacier on Mount Kenya is Lewis Glacier which averages just 18 meters in thickness and has lost 90% of its volume since 1934. This suggest Tyndall Glacier is also quite thin (Prinz et al, 2011).