The graph of the mean front position with time clearly shows this rapidly accelerating retreat. Volume loss has been accelerating at an even greater rate. The sketch map shows the glacier front positions for each of the seven determinations since 1963. Note also that a small meltwater lake which first appeared at the ice front in our photographs in 1991 has continued to increase in size with retreat of the ice front and is roughly twice as large in 1998 as it was in 1991. The oxygen isotopic records from these cores indicate that the nineteenth and twentieth centuries were the warmest in the last 5,000 years.
Additional evidence exists for recent warming in the tropics.
The shrinking of these ice masses in the high mountains of Africa is consistent with similar observations at high elevations along the South American Andes.