The past valley glacier network in the Himalayas and the Tibetan ice sheet during the last glacial period and its glacial-isostatic, eustatic and climatic consequences (Retracted article. See vol. 485, pg. 333, 2010)

• Published in: Tectonophysics
• Main Author: Kuhle, Matthias
• Format: Conference Object
• Language: unknown
• Published: Elsevier Science Bv 2007
• Subjects: Ela; Ice Sheet
• Online Access: https://resolver.sub.uni-goettingen.de/purl?gro-2/48801; https://doi.org/10.1016/j.tecto.2007.06.007

Since 1973 new data were obtained on the maximum extent of glaciation in High Asia. Evidence for an ice sheet covering Tibet during the Last Glacial Period means a radical rethinking about glaciation in the Northern Hemisphere. The ice sheet's subtropical latitude, vast size (2.4 million km(2)) and high elevation (6000 m asl) are supposed to have resulted in a substantial, albedo-induced cooling of the Earth's atmosphere and the disruption of summer monsoon circulation. Moraines were found to reach down to 460 m asl on the southern flank of the Himalayas and to 2300 m asl on the northern slope of the Tibetan Plateau, in the Qilian Shan region. On the northern slopes of the Karakoram, Aghil and Kuen-Lun mountains, moraines occur as far down as 1900 m asl. In southern Tibet radiographic analyses of erratics suggest a former ice thickness of at least 1200 m. Glacial polish and roches moutonnees in the Himalayas and Karakoram suggest former glaciers as thick as 1200-2700 m. On the basis of this evidence, a 1100-1600 m lower equilibrium line (ELA) has been reconstructed, resulting in an ice sheet of 2.4 million km(2), covering almost all of Tibet. Radiometric ages, obtained by different methods, classify this glaciation as isotope stage 3-2 in age (Wurmian = last glacial period). With the help of 13 climate measuring stations, radiation- and radiation balance measurements have been carried out between 3800 and 6650 m asl in Tibet. They indicate that the subtropical global radiation reaches its highest energies on the High Plateau, thus making Tibet today's most important heating surface of the atmosphere. At glacial times 70% of those energies were reflected into space by the snow and firn of the 2.4 million km(2) extended glacier area covering the upland. As a result, 32% of the entire global cooling during the ice ages, determined by the albedo, were brought about by this area-now the most significant cooling surface. The uplift of Tibet to a high altitude about 2.75 Ma ago, coincides with the commencement of the ...