Positive glacial regulatory processes promote sustainability of Asian glacier water resources

Abstract

Glacier response to climate change results in rapid glacier water resource loss. Positive glacial regulatory processes (GRPs) are processes that buffer glacier water resource losses. Nevertheless, these processes are not systematically quantified, which may lead to uncertainty in glacier water resource sustainability assessments. Here, we employ a glacier water balance model to track glacier water resource transport trajectories and quantify contributions of positive GRPs across High Mountain Asia (HMA). The combined impacts of positive GRPs could mitigate ~236-255 Gt of HMA glacier water resource loss (~9%-13% of total mass loss) in the 21st century (2015-2100), suggesting underestimated glacier water resource sustainability. These contributions result from precipitation pattern transition (~0.9%-1.9%), nonlinear fluctuations in glacier dynamics (~4.7%-7.1%), rapid expansion of dead ice (~2.0%-2.4%), and retention of glacial meltwater by exposed depressions (~1.0%-1.3%). We highlight the importance of accurately assessing glacier water resource loss for water sustainability and sea level rise projections.