Climate patterns derived from piedmont glaciation during the LGM in the Central Himalaya

Abstract

Quaternary glaciers serve as vital proxies for reconstructing the palaeoenvironment and palaeoclimate on the Tibetan Plateau (TP). However, the scarcity and unevenly distributed observations impede our understanding of the interactions between glacier and climate changes at a regional scale. In this study, we explored the advance and retreat of the piedmont glaciers during the Last Glacial Maximum (LGM) in Central Himalaya, using a combination of field investigation and glacier modelling. The thirty ¹⁰Be exposure ages from six moraines shows the piedmont glaciers in the north slope of the Central Himalaya occurred extensive advance during 17.4 ± 2.6 ka to 19.6 ± 1.2 ka. Then, glacier extents, ice thickness, and equilibrium line altitude (ELA) were reconstructed using a 2D coupled ice-flow and mass balance model. The modelling results were well-matched with our dated moraines and previously published observations, confirming that the glacier area in the Central Himalaya during the LGM was approximately 11.6 times larger than that of modern glaciers, with the area and volume of 9985 km² and 1885 km³. The regional average ELAs during the LGM was 5293 ± 218 m, about 347 ± 110 m lower than the present. The palaeo-ELAs were lower on the southern side (5190 ± 220 m) but higher on the northern side (5348 ± 195 m) of Central Himalaya influenced by regional topography, geology, and atmospheric circulations. The ELAs in the central region (4850 ± 268 m) were 85 ± 66 m lower than at the western Gurla Mandhata (4935 ± 334 m) and 185 ± 13 m lower than at the eastern Mansell Snow Mountains (5008 ± 255 m) due to differences in mountain range orientation and orographic effects. This study provides a framework for large-scale regional palaeoenvironment and palaeoglacier reconstructions and contributes to understanding the heterogeneity in glacier fluctuations.