Carbon release potential from enhanced sulfuric acid-mediated weathering is alarming for retreating Himalayan glaciers

Achieving targets of net-zero carbon emission requires a large-scale drawdown of carbon dioxide from the atmosphere. A sustainable solution provided through rock weathering of silicate and carbonates at glaciers has shown some carbon drawdown potentials, yet we still lack to fully understand this natural process for mitigating climate change. Conventional view of rock weathering recognizes carbonic acid mediated weathering of silicate and carbonate minerals as CO₂ sink, yet we emphasize that weathering of sulphur bearing minerals (i.e., FeS₂) counterbalance this CO₂ sink for mountain glaciers. We studied the Dokriani glacier basin, central Himalaya as model system for long-term (1992-2018) and tested the CO₂source or sink mechanism. Our results suggest a clear trend of CO₂ release from Himalayan glaciers. Results suggests atmospheric CO₂ sink driven through carbonic acid-mediated reactions during the early ablation periods, while a clear CO₂ source through sulfuric acid-mediated reactions superseding the CO₂ sinks during peak and late ablation periods was observed. The former tips the balance of the CO₂ budget of the Himalayas from sink-to-source. The other glaciers of the central and western Himalayas are in good agreement with the present estimates. We surmise that these patterns are broadly applicable to the other orogenic systems of the world. These findings enhance our understandings for CO₂ release potentials of mountain glaciers through glacial weathering, atmosphere and terrestrial systems.