Regional mass variations and its sensitivity to climate drivers over glaciers of Karakoram and Himalayas

Abstract

The regional scale mass change provides a substantial understanding to the influence of climate change on the glacier surface. However, the scarce ground observations and large spatial extent limit the use of field-based mass balance estimation. In this study, the Gravity Recovery and Climate Experiment (GRACE) satellite data were used to estimate the regional glacier mass variation over the Karakoram and Himalayas (KH) region during 2002–2019 hydrological years. Our study showed that the total mass change rate over the KH region was – 55.0 ± 8.7 Gt yr–1 for the study period. We have identified four positive/negative clusters of mass change over the KH region, with the eastern part of the Karakoram (KK) and part of the Central Himalaya (CH) regions have experienced a positive mass change. In contrast, the junctio n area between the Western Himalaya (WH) and CH region observed an extreme negative mass change. The results demonstrated that the annual mass change for WH become negative or nearly zero from 2007/08 onwards, while for CH and Eastern Himalaya (EH) regions, it became negative since 2005/06. The GRACE-derived mass change was validated with the published in-situ mass balance data, which reveals a high correlation (r = 0.77) over the region. The performance of obtained results were also compared with Ice, Cloud, and Land Elevation Satellite-1 (ICESat-1) data for the period 2003–2009, indicating a correlation of 0.87 and 0.91 for monthly and annual scale, respectively. Moreover, the interannual mass change in the glaciated region was analyzed using hydro-climatic data and energy fluxes, suggesting a higher correlation of mass change with total precipitation and snowfall over the spatiotemporal scale. However, this correlation fails at locations where evaporation, runoff, and radiation have prominently influenced the mass loss. The uncertainty and sensitivity test for mass change demonstrated that snowfall and temperature have a strong influence on the response of mass change. Overall, this study provided regional mass change and their relationship with hydro-climatic variables, which will provide a better understanding related to the water availability in the downstream areas.