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The Cryosphere An interactive open-access journal of the European Geosciences Union
The Cryosphere, 11, 133-138, 2017
http://www.the-cryosphere.net/11/133/2017/
doi:10.5194/tc-11-133-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Brief communication
18 Jan 2017
Brief communication: Thinning of debris-covered and debris-free glaciers in a warming climate
Argha Banerjee Earth and Climate Science, Indian Institute of Science Education and Research, Pune, India
Abstract. Recent geodetic mass-balance measurements reveal similar thinning rates on glaciers with or without debris cover in the Himalaya–Karakoram region. This comes as a surprise as a thick debris cover reduces the surface melting significantly due to its insulating effects. Here we present arguments, supported by results from numerical flowline model simulations of idealised glaciers, that a competition between the changes in the surface mass-balance forcing and that of the emergence/submergence velocities can lead to similar thinning rates on these two types of glaciers. As the climate starts warming, the thinning rate on a debris-covered glacier is initially smaller than that on a similar debris-free glacier. Subsequently, the rate on the debris-covered glacier becomes comparable to and then larger than that on the debris-free one. The time evolution of glacier-averaged thinning rates after an initial warming is strongly controlled by the time variation of the corresponding emergence velocity profile.

Citation: Banerjee, A.: Brief communication: Thinning of debris-covered and debris-free glaciers in a warming climate, The Cryosphere, 11, 133-138, doi:10.5194/tc-11-133-2017, 2017.
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Short summary
Measurements of debris-covered and debris-free glaciers in the Himalaya-Karakoram show similar decadal scale thinning, despite a suppression of melt under the debris. Using physical arguments, supported by simulations of 1-D idealised glaciers, we analyse the evolution of thinning rates on both glacier types under a warming climate. The dynamics of the emergence velocity profile control the thinning rate evolution in general and lead to the observed trends in the thinning rate data.
Measurements of debris-covered and debris-free glaciers in the Himalaya-Karakoram show similar...
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