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Abstract

Glaciers provide an indispensable freshwater source for socio-economic development in extensive regions of High Mountain Asia (HMA) and neighborhoods. In this study, a novel glacier model integrating glacier dynamics (Open Global Glacier Model, OGGM) is employed to project glacier mass and runoff changes over HMA in the 21st century. A two-stepwise method is adopted to calibrate the model parameters, and its performance is validated with the annual mass balance observations. Glacier mass and runoff changes are projected by 10 GCMs (General Circulation Models) forced by six climate scenarios from CMIP6 (Coupled Model Intercomparison Project Phase 6). The results indicate that glacier mass will specifically lose between 46 ± 3% (SSP119) and 70 ± 4% (SSP 885) in HMA by the end of the century relative to 2000. In addition, the glacier runoff in HMA will most likely hit a maximum value (i.e., peak water) between 2029 and 2056 under all climate scenarios. However, the spatiotemporal variability of the glacier mass and runoff are very significant in different regions of HMA due to the magnitude of climate warming and glacier initial conditions (for example, the glacier volume). The Karakoram anomaly will slow down and even vanish in the long-term projection runs under the high emission scenarios and unsustainable development pathway. This study is poised to improve the understanding of glacier mass and runoff changes in HMA and provide a scientific basis for government decision-making for regional socio-ecological sustainability development.