Article available on the Nature website or upon request to Andreas Kääb or me
A pre-print was also compiled by Andreas Kääb here
News & Views by Graham Cogley here A summary by Jane Qiu here Visual material (photos, figures, etc...) is available here |
Abstract
Glaciers are among the best indicators of terrestrial climate
variability, contribute importantly to water resources in many
mountainous regions and are a major contributor to global sea
level rise. In the Hindu Kush-Karakoram-Himalaya region
(HKKH), a paucity of appropriate glacier data has prevented a
comprehensive assessment of current regional mass balance.
There is, however, indirect evidence of a complex pattern of glacial
responses in reaction to heterogeneous climate change signals.
Here we use satellite laser altimetry and a global elevation model to
show widespread glacier wastage in the eastern, central and southwestern
parts of the HKKH during 2003-08. Maximal regional
thinning rates were -0.66±0.09 m/yr in the Jammu-Kashmir region.
Conversely, in the Karakoram, glaciers thinned
only slightly by a few centimetres per year. Contrary to expectations,
regionally averaged thinning rates under debris-mantled ice
were similar to those of clean ice despite insulation by debris
covers. The 2003-08 specific mass balance for our entire HKKH
study region was 0.21±0.05 m/yr water equivalent, significantly
less negative than the estimated global average for glaciers
and ice caps. This difference is mainly an effect of the balanced
glacier mass budget in the Karakoram. The HKKH sea level contribution
amounts to one per cent of the present-day sea level rise.
Our 2003-08 mass budget of 12.8±3.5 Gt/yr is more negative than recent satellite-gravimetry-based
estimates of 5±3 Gt/yr over 2003-10. For the
mountain catchments of the Indus and Ganges basins, the glacier
imbalance contributed about 3.5% and about 2.0%, respectively, to
the annual average river discharge, and up to 10% for the Upper
Indus basin.
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