Ongoing variations of Himalayan and Karakoram glaciers as witnesses of global changes: recent studies on selected glaciers

The glaciers located on the highest Asian mountain ranges (Pamir, Karakoram and Himalaya) represent the largest alpine glaciations in the world, outside the polar regions. Runoff from these glaciers feeds rivers (e.g. Indus, Ganges, etc.) that provide much-needed water supply for several hundred million people. In the Himalayan and Karakoram regions debris-covered glaciers (DCG) are the most common glacier type, which seems currently to be spreading in the world's mountain regions due to the feedback between ice thinning and rock-wall downwasting. To contribute to a better understanding of the complex relations between DCG and climate and to forecast on a decadal scale the glacier response to climate change and its impact on the runoff of high mountain regions, different studies have been carried out on some selected glaciers located in the Karakoram (Baltoro and Liligo in the K2 region) and in the Nepal Himalayas (Changri Nup in the Everest region). To quantify the recent and ongoing fluctuations of the ice masses, historical sources, e.g. maps and photographs, and satellite images have been processed and analysed. In addition, direct field measurements on selected glaciers were performed in order to validate the remotely sensed data and to investigate the variability and magnitude of surface ablation on the DCG tongues. © 2007 Elsevier B.V. All rights reserved.