Geoscience Reference
In-Depth Information
1910, there were 150 glaciers within. This number is cur-
rently down to 26, and it is estimated that by 2030, at the
present rate of decrease, no glaciers will remain in the Park
[Hall and Fagre, 2003].
The ice on top of Mount Kilimanjaro has been photo-
graphed and mapped at irregular intervals since the early
twentieth century, but starting in 2000, a systematic study
has been underway to record and measure the rate of ice field
retreat. Using a combination of terrestrial photogrammetric
maps, satellite images, and aerial photographs, it has been
determined that the combined surface area of all the ice fields
on Kibo, the highest crater on Kilimanjaro, has decreased by
85% since 1912 when the
The Quelccaya Ice Cap in southern Peru adjacent to the
Amazon Basin is the largest tropical ice field on Earth. The
Qori Kalis outlet glacier, which
flows west from the main ice
field, has been measured and photographed since 1963. At
the beginning of the study, the end of the glacier extended
1200 m out from the margin, and there was no permanent
meltwater at the terminus. By the summer of 2008, 45 years
later, Qori Kalis had completely retreated to the margin of the
main ice
field, and a lake covering 34 ha and 60 m deep had
developed in its place (Figure 9). As on Kilimanjaro, contin-
uous monitoring of this glacier has documented an acceler-
ating rate of ice loss: the retreat was calculated as a rate of
about 6 m per year from 1963 to 1978, but Quelccaya lost ice
10 times faster on average than this initial rate from 1991 to
2006 [Thompson et al., 2006a]. This loss of ice from Quelc-
caya is not only occurring on the Qori Kalis Glacier but also
along the edge of the ice cap. Since 1978, 25% of this
tropical ice cap has disappeared. This reduction in the areal
extent of ice cover on both the Quelccaya Ice Cap and on the
Qori Kalis Glacier characterizes the larger-scale accelerating
glacier retreat throughout the Peruvian Andes (Figure 10).
Figure 11 graphically demonstrates the increasing rate of
retreat of three low-latitude alpine ice caps. Qori Kalis and
Kilimanjaro, which were discussed above, and Naimona
rst map was made [Thompson
et al., 2009]. At the current rate of retreat, it is estimated
that Kibo will be ice free in the next few decades for the
rst
time in 11,700 years. Continued monitoring of these ice
fields demonstrates the accelerating rate of their retreat. For
example, the deterioration of the Furtwängler Glacier, which
lies in the center of the Kilimanjaro crater, is shown in Figure
8 as a series of aerial photographs from 2000 to 2007, when
the glacier split into two sections. As it is shrinking in size, it
has also thinned rapidly from 9.5 m in 2000 to 4.7 m in 2009,
when the latest photographs were taken, and the ablation
stake inserted in the borehole to bedrock in 2000 was mea-
sured [Thompson et al., 2009, 2010].
nyi
on the Tibetan side of the southwest Himalaya Mountains are
'
Figure 9.
Retreat of the Qori Kalis outlet glacier on the Quelccaya Ice Cap. The shaded areas on the map outline the extent
of the glacier through time and the progression of the ice retreat. The photographs along the bottom provide a pictorial
history of the melting of this glacier from 1978 to 2006 and the formation of a proglacial lake.
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