Accelerated glacier mass loss in the southeastern Tibetan Plateau since the 1970s

The southeastern Tibetan Plateau (SETP) is a region in High Mountain Asia with the most serious glacier mass loss. However, long-term and large regional-scale studies that estimate glacier mass balance in this area remain limited. In this study, we generated a KH-9 Digital Elevation Model (DEM) (covering 87.6% of the glacier area) for the 1970s from KH-9 Hexagon imagery and quantified geodetic glacier mass over the SETP from the 1970s to 2020 using KH-9 DEM, NASADEM and ICESat-2 ATL06 data. The results show that the SETP was in a state of serious mass loss (at a rate of −0.35 ± 0.03 m w.e. per year) from the 1970s to 2020, and the rate of mass loss accelerated from −0.15 ± 0.05 to −0.56 ± 0.10 m w.e. per year between the 1970s–2000 and 2000–2020. Within the SETP, the glacier mass balance revealed a remarkable spatial heterogeneity. The maximum mean glacier mass loss rate was observed in the Hengduan Shan. Nyainqentanglha exhibited the highest acceleration in the mass loss rate since the 1970s. The warming of air temperature and decreasing snowfall can partly explain the accelerated glacier mass loss in the SETP. The study provides a new long-term glacier mass balance estimation covering almost the entire SETP that suggests the acceleration in glacier mass loss observed in the SETP since the 1970s is a regional tendency, which is crucial for understanding the relationship between glaciers and climate changes.