Increased solar radiance and decreased snowfall have been implicated as the true culprits in Kilimanjaro's glacier loss. The temperatures on Kilimanjaro's summits almost never rise above freezing, leading researchers to look for other causes for the ongoing glacial recession on Kilimanjaro's peak. Other studies have suggested that deforestation has severely impacted the arboreal microclimates that provide recharge precipitation to Kilimanjaro's glacial packs.
With reduced snowfall the summit's glaciers suffer degraded albedo (perhaps coupled with dirty snow) that progressively furthers the ongoing glacial recession.
Links:
Kilimanjaro's receding glaciers - Increased Solar Radiance and decreased snowfall:
http://www.sciencedaily.com/releases/2007/06/070611153942.htm
Kilimanjaro's receding glaciers - Deforestation & loss of microclimate precipitation:
http://news.nationalgeographic.com/news/2003/09/0923_030923_kilimanjaroglaciers.htm
Atmospheric
co2 
global warming 
climate change
