Climate forcing and the initiation of glacier advance during MIS-2 in the North Sikkim Himalaya, India

Abstract The present study investigates the relics of the most extensive glacier advances and their retreat in the transitional climatic zone of the Chopta valley, northern Sikkim Himalaya with an aim to understand the forcing factors. The optically stimulated luminescence (OSL) dating of the stratigraphically oldest glacier advance and its retreat in the Chopta valley revealed that the glacier advanced at ∼28 ± 2.8 ka and sustained through the global Last Glacial Maximum (gLGM; 26.5 ka and 19 ka; Mix et al., 2001). The deglaciation is manifested by recessional moraine (ridge) dated at ∼18 ± 2.2 ka. Comparing the results of the present study with the existing glacial chronologies from the Himalayan region, it has been observed that irrespective of the geographical locations; the intensified mid latitude-westerlies during the gLGM and the associated decrease in winter temperature was the major driver of glacier advance during the MIS-2.