Climate warming and strengthened hydrologic cycle accelerate CO2 release from rock weathering

Abstract

Global climate is modulated by the balance between CO₂ release from coupled sulfide-carbonate weathering and CO₂ sequestration through silicate weathering, yet how this balance evolves under climate change remains poorly constrained. Here we investigate the temporal variability in dissolved chemistry and isotopic ratios from two major rivers on the Tibetan Plateau, the Jinsha River and the Yalong River, over two periods within a nine-year span (2013–2014 and 2018–2021). In the evaporite-rich, permafrost-dominated Jinsha River basin, we detected exceptional increases in evaporite-derived elemental concentrations and fluxes, both interannually and during the monsoon season, compared with other mineral sources. These shifts reflect enhanced evaporite exposure driven by warming-induced thermal processes such as permafrost thaw, altered subsurface flow paths, and enhanced hydrologic connectivity between saline lakes and rivers. By contrast, weathering fluxes in the evaporite-poor Yalong River basin exhibit relatively small temporal changes. Sulfide oxidation offsets all silicate weathering–driven alkalinity in the Jinsha River basin and 40–98% in the Yalong River basin, with the offset intensifying during monsoon-driven permafrost-thaw- and high-flow periods. Concurrently, accelerated gypsum/anhydrite weathering could prompt CO₂ release from soils and streams by inducing secondary carbonate precipitation. Interannually, the growing dominance of sulfide oxidation also shifts the CO₂ balance toward net CO₂ release. These processes demonstrate that mineral weathering associated with permafrost thaw can strengthen CO₂ sources to the atmosphere and amplify the permafrost carbon-climate feedback. Overall, global warming and the associated acceleration of the hydrologic cycle could result in CO₂ release rather than drawdown from rock weathering in permafrost landscapes underlain by sulfide- and evaporite-rich lithologies.