Satellite-based estimates of glacier mass change in High Mountain Asia since the 1960s

Abstract:

The response of glaciers across High Mountain Asia (HMA) to climate change is of high societal importance because of their role in the Asian water tower. In this study, we quantify glacier mass change over the last six decades in eight climatically different glacierized regions across HMA using Corona KH-4, ASTER, SPOT 6-7, GeoEye, TerraSAR-X and Pleiades imageries. Substantial glacier mass loss occurred in each region, although much temporal variability is evident in the evolution of glaciers towards their current state. In the Northern Tien Shan, Western Nyainqentanglha, Poiqu and Mt. Everest region (both located in central Himalaya), moderate glacier mass loss rates (-0.18 ± 0.11 to -0.30 ± 0.10 m w.e. a^-1) occurred between the 1960s and 1980s. Mass loss rates more than doubled between our earliest and most contemporary time periods in Northern Tien Shan (-0.45 ± 0.13 m w.e. a^-1 during 2012-2016) and increased also markedly in Western Nyainqentanglha (-0.46 ± 0.15 m w.e. a^-1 during 2012-2018) and central Himalaya (-0.42 ± 0.11 m w.e. a^-1 during 2004-2018 for Poiqu and -0.45 ± 0.11 m w.e. a^-1 during 2009-2018 for Mt. Everest). We measured periods of neutral glacier mass balance or even slight mass gain at the Purogangri Ice Cap (Central Tibet), at Gurla Mandhata (Western Himalaya) and at the Muztag-Ata massif (Eastern Pamir). Increasing rates of ice mass loss now prevail at all three sites, however. To better understand how climate change drove HMA glacier mass changes, we evaluated these rates of mass loss against meterological data from weather stations and ERA5 Land surface model data. We find that the dependence of glacier mass balance on temperature and precipitation changes is variable for climatically different regions in HMA but note summer temperature increases as the strongest driver of glacier mass loss in several regions.