Reconstructing the glacial history of the Bhagirathi catchment in the Garhwal Himalaya from ∼ 80 ka to present

Abstract

A key challenge when evaluating mountain glacier change, particularly in the context of climate change, is that glacial geological research often operates within discrete timescales. Studies typically examine long-term glacier change over centuries to millennia or short-term change spanning days to decades. Bridging these temporal gaps is essential for refining projections of glacier mass loss and enhancing our understanding of the future of mountain glaciers, particularly in regions like the Himalayas. The closely monitored Gangotri Glacier in the Bhagirathi catchment of the Garhwal Himalaya provides an excellent opportunity to define the timing and drivers of late Quaternary glacier change from ∼80 ka to present. By integrating new and recalculated glacial geochronological datasets with instrumental and remote sensing data, we present a comprehensive glacial chronostratigraphy for the Bhagirathi catchment. Tracking of the glacier terminus position and equilibrium-line altitudes over the past ∼80 ka shows that Gangotri Glacier has been progressively retreating during this time. We provide strong evidence that Gangotri Glacier is sensitive to short- and long-term climate changes. The accelerated retreat in recent decades is likely driven by climate change-induced shifts in global temperature and precipitation patterns. This study highlights the importance of evaluating glacier change across multiple timescales, as this has enabled us to more confidently conclude that the retreat of mountain glaciers such as Gangotri Glacier will continue and possibly accelerate in response to ongoing climate change.