northern
ice field
southern
ice field
The views from the top of Mount
Kilimanjaro—a 5,895-meter (19,341-foot) dormant stratovolcano in
Tanzania—are as surreal as they are spectacular. After ascending through multiple
ecosystems—including cropland, lush rainforest, alpine desert, and a
virtual dead zone near the summit—climbers can find themselves peering down on
a thick blanketof
clouds below that seems to stretch endlessly in the distance.
But in the immediate foreground, ice dominates the view. Looking
north, a shelf-like block of ice with a sharp vertical cliff sits on an
otherwise featureless, sand-covered plateau. In the other direction, a second
ice field spills off the edge of the plateau, down the mountain’s southern
face.
Kimberly
Casey, a
glaciologist based at NASA’s Goddard Space Flight Center, was savoring the
views from Kilimanjaro’s summit and caldera when she snapped these panoramic
images of Kilimanjaro’s northern (middle) and southern (bottom) ice fields. The Advanced
Land Imager on
NASA’s Earth Observing-1 satellite
acquired the top image, which shows some of the same ice fields from above on
October 26, 2012.
Casey was taking part in a September 2012 research expedition to
Kilimanjaro to study the ice at the summit. For scale, bright tents that were
part of the scientists' base camp are visible in the lower left of the northern
ice field image.
Despite Mount Kilimanjaro’s location in the tropics, the dry and
cold air at the top of the mountain has sustained large quantities of ice for
more than 10,000 years. At points, ice has completely surrounded the crater. Studies of ice core samples show that
Kilimanjaro’s ice has persisted through multiple warm spells, droughts, and
periods of abrupt climate change.
But trends beginning more than a century ago suggest
Kilimanjaro’s peaks may soon be ice-free. Between 1912 and 2011, the mass of
ice on the summit decreased by more than 85 percent. Researchers say it’s no
longer a question of whether the ice will disappear but when. Estimates vary,
but several scientists predict it will be gone by 2060.
Rising air temperatures due to global
warming could
be contributing to the ice loss, but a number of other factors are just as
important, if not more so. An increasingly dry regional atmosphere, for
example, is starving the mountain of the fresh snow needed to sustain the ice
fields. Drier air is also reducing cloud cover and allowing more solar energy
to warm the ice surfaces.
Casey and colleagues noticed yet another ominous sign during
their 2012 expedition. The northern ice field, which had been developing a hole
since the 1970s, has separated. “This was the first year that the northern ice
field completely divided into two,” said Casey. “We were able to walk on
land—or we could have even ridden a bicycle—directly throughthe
rift.”
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