Late Holocene glacier fluctuations in the Bhutanese Himalaya

Reconstructing high-resolution glacial fluctuation is critical for understanding glaciers response to climate change. Here, we present a detailed Late Holocene glacial record from the Bhutanese Himalaya based on 27 ¹⁰Be surface exposure ages. This record includes a glacial event 4180 ± 270 yr, followed by four glacial events at 2990 ± 190, 1780 ± 110, 1230 ± 80 and 500 ± 70 yr, respectively. These glacial events are synchronous with those in the Tibetan Plateau (TP) and its surrounding mountains, which likely reflect regional climatic forcing. The comparisons of regional climate data indicate that these Late Holocene glacial events occured in relatively cold and dry climatic conditions, reflecting the glacial fluctuations were more sensitive to temperature than to precipitation. In addition, the timing of these glacial events is roughly in agreement with the North Atlantic (NA) region's cooling events. It seems that the glacial fluctuations were teleconnected with the NA region's cooling events by the Westerlies, which acts as a cold-air conveyer between the NA and the TP during the cold intervals. Although the weakening of Indian summer monsoon would reduce the precipitation and glacier accumulation in the study area, the low temperature brought by the Westerlies greatly reduces the amount of glacial ablation, resulting in an increase in the net accumulation of glaciers.