We measured carbon emissions and water chemistry in 50 headwater rivers draining 780,000 km2 of the Tibetan Plateau.

The rivers flow in landscapes underlain by continuous permafrost and landscapes in which the permafrost has retreated since the last glacial maximum. They collect organic carbon from soils and dissolved inorganic carbon that is fixed by rock-weathering.

Where the permafrost cover is continuous, rivers emit CO2 from degrading (permafrost) soil carbon. Weathering reactions in these catchments are relatively slow.

In landscapes with (almost) no permafrost, carbon fluxes from weathering are faster than CO2 emissions from rivers.

Thus, as permafrost landscapes transition to landscapes without permafrost cover, chemical weathering reactions may play an ever more important role in riverine carbon cycling.

Interestingly, weathering can affect the carbon cycle in different ways. Where sulfide minerals are present, weathering reactions can emit CO2. Where silicate minerals dominate, weathering draws down CO2 from the atmosphere.

About: Zhang, L.^§, Bufe, A. ^§, Dean, J.F., Rocher-Ros, G., Sponseller, R.A., Stanley, E.H., Karlsson, J., Butman, D.E., Liu, R., Hou, L., Ding, J., Piao, S., Xia, X., Battin, T.J. (2026). Rock weathering can counteract river CO2 emissions induced by permafrost thaw. Nature. Journal Link
^§ L.Z. and A.B. contributed equally to this work.