Changes in African Glaciers Since the 19th Century
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Climate Science. Please check back later for the full article.
In equatorial East Africa, glaciers still exist on Mount Kenya, Kilimanjaro, and Ruwenzori. The decreasing ice extent is documented by field reports since the end of the 19th century and a series of mappings. For Mount Kenya, the mappings are of 1947, 1963, 1987, 1993, and 2004, with more detailed mapping of Lewis Glacier in 1934, 1958, 1963, 1974, 1978, 1982, 1985, 1986, 1990, and 1993. For Kilimanjaro, the sequence is 1912, 1953, 1976, 1989, and 2000. For Ruwenzori, the scarcer information is of 1906, 1955, and 1990. Photographs are valuable complementary evidence. At Lewis Glacier, on Mount Kenya, measurements of mass budget and ice flow have been conducted over decades. The climatic forcing of ice recession in East Africa at the onset in the 1880’s was radiationally controlled, affecting the most exposed locations. Later warming caused the further ice shrinkage, except on the summit plateau of Kilimanjaro, above the freezing level. Whereas the ice recession in the Ecuadorian Andes and New Guinea began in the middle of the l9th century, plausibly caused by warming, the late onset in East Africa should be appreciated in the context of large-scale circulation changes evidenced by the historical ship observations in the equatorial Indian Ocean.