New Scientist (21 April 2012) reveals that the Karakoram glaciers grew slightly between 1999 and 2008, according to satellite data. The Karakoram is a large mountain range next to the Himalayas.
Scientists (geologists) and
mountaineers compare photographs and satellite images taken over a period of
many years, and even centuries, to detect evidence of glacial activity.
Glaciers are masses of ice
surging down wide mountain passes into the sea.
A 2007 Intergovernmental Panel
on Climate Change (IPCC) report raised the concern that Himalayan glaciers may
be shrinking and may even disappear by 2035. However, the new study found that
ice is stable in the Karakoram Mountains, a northern range of the Himalayas.
Dirk Scherler of the University of Potsdam in Germany, in his study of the
Himalayan glaciers (Nature Geoscience, 23 January 2011), indicated that an
estimated 65% of the glaciers observed were shrinking, but in Karakoram 58% of
the studied glaciers were stable or slowly expanding up to 12 metres per year.
Scherler viewed 286 satellite images collected between 2000 and 2008.
Scherler’s reason for the
expanding glaciers in the Karakoram involved what was on top of them. As air
warms above glaciers, the ice melts. Thin layers of dust, grit, on top of
glaciers will darken them, thus increasing the amount of heat they absorb and
increasing the warming process. However, once the depth of cover (called a rock
cover) exceeds several centimetres, it will act as an insulator – therefore
protecting the ice from the sun. Scherler found that in some Karakoram
glaciers, there was a rocky blanket of debris covering them. Some rock debris
included house-sized boulders. Therefore, he believes that the rocky rubble
eroded from the uphill peaks which served to prevent the glacial ice from melting
and therefore stopping the glaciers from shrinking. He found that areas where
there was zero to low debris, there was a higher rate of melting, whereas where
there was debris cover greater than 20%, there was stability. The growth in
glacial ice may also be due to increased snowfall during the nine years.
The new findings are
consistent with studies by Kenneth Hewitt of Wilfred Laurier University in
Waterloo, Ontario, in Canada, who stated that the effects of climate change in
alpine Asia were much more complicated than first thought. Hewitt noted that
data from India and China suggested that glacial debris is not merely rocks and
grit, but included soot from local industries, traffic and cook stoves which
might also be darkening the parts of the glaciers. This thin layer of pollution
on areas where there are no thick covers of rock would then increase glacial
melting. So it seems that some parts of the Himalaya glaciers are shrinking
while other parts are increasing.
The satellite data does not
detect the density (thickness) of the glaciers. This requires ground
measurements, which is difficult to conduct in the high altitude and remote
regions of the Himalayas. Nevertheless, the new study on the Karakoram glaciers
appear to be contradictory to global trends of glacial shrinking, and thus
further study may be required over a longer period of time.
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