The role of the Indian summer monsoon and the mid-latitude westerlies in Himalayan glaciation: review and speculative discussion

New dates for late Quaternary glaciations in the Himalayas show that, during the last glacial cycle, glaciations were not synchronous throughout the region. Rather, in some areas glaciers reached their maxima at the global glacial maximum of c. 18–20 ka bp, whereas in others glaciers were most extensive at c. 60–30 ka bp. Comparison of these data with palaeoclimatic records from adjacent regions suggest that, on millennial timescales, Himalayan glacier fluctuations are controlled by variations in both the South Asian monsoon and the mid-latitude westerlies.