For a long time, it has been widely accepted in the academic community that permafrost thaw unlocks large stores of organic carbon, thereby exerting a positive feedback on climate warming. However, a recent study published in Nature by Professor Xia Xinghui’s team from the School of Environment at Beijing Normal University, titled Rock weathering can counteract river CO emissions induced by permafrost thaw, together with their collaborators, offers an important complementary perspective: permafrost thaw intensifies watershed rock weathering, generating a previously underrecognized geological carbon dioxide sink that, to a certain extent, attenuates or even modifies the conventional carbon–climate feedback effect.

The abstract of the paper is as follows:

Climate-induced permafrost thaw unlocks large stores of organic carbon that are mineralized and emitted as carbon dioxide (CO₂) from rivers to the atmosphere. Concurrently, warming and permafrost thaw can increase mineral weathering rates, thus affecting the release and sequestration of inorganic carbon. Yet how these biological and geological carbon cycles interact and jointly affect CO₂ dynamics (emission compared with drawdown) in permafrost rivers remains unknown5. Here we combine CO₂ emissions, organic and inorganic solute concentrations, dual carbon isotopes (δ¹³C–Δ¹⁴C) and geochemical modelling to infer how permafrost thaw may affect river biogeochemistry over decades to centuries across the Qinghai–Tibet Plateau. Leveraging a gradient of thermal permafrost degradation, we find that river CO₂ emissions decline, whereas solute fluxes from rock weathering increase with decreasing permafrost cover. Across this region, net CO₂ drawdown fluxes from rock weathering are about 35% of river CO₂ emissions, varying from around 15% in catchments with continuous permafrost to more than 100% in catchments with discontinuous or isolated permafrost. Thus, carbon fluxes from chemical weathering may become increasingly important with ongoing permafrost thaw, potentially even outpacing river CO₂ emissions. Our findings disentangle the interplay between biological and geological carbon fluxes that are important for the cryosphere and the global carbon cycle.

Reference: https://www.nature.com/articles/s41586-026-10664-8