Surface-exposure cosmogenic dating of Southern Tibet moraines reveal glaciations coincident with the Northern Hemisphere

The extent and timing of glacial fluctuations during the Late Quaternary provide essential information on past climatic changes, which in turn enhance our ability to predict future climate change. Controversy exists with regard to the glacial history of the Himalayas and Tibet, particularly on the geologic signature, timing and magnitude of the Last Glacial Maximum (LGM) relative to previous advances. Indeed, Quaternary glaciations in Tibet and the Himalayas, and in other parts of the Northern Hemisphere may have been asynchronous. Here, based on cosmogenic radionuclide (CRN, 10Be) dating of 17 glacial features (250 samples), we demonstrate a clear signature of an LGM glacial advance in Southern and Western Tibet, but also that the largest glaciation (in terms of preserved deposits) took place ~40 ka ago (Marine Isotope Stage MIS-3). Further, it appears that most of the global and local temperature minima in the various climate proxy curves (e.g. Marine oxygen Isotope Stages MIS, Specmap) were coeval with the prominent glacial advances found in Tibet. These data indicate that glacial advances in Tibet and elsewhere in the Northern Hemisphere are synchronous and modulated by global climate variability, but that their extent may vary due to local conditions.