Large-scale CO2 removal by enhanced carbonate weathering from changes in land-use practices

Continental rock weathering exerts a negative feedback on global warming by removing atmospheric CO 2 . Carbonate weathering contributes most of the dissolved inorganic carbon measured in inland waters , chiefly as HCO 3 − , though carbonate rock covers only a minor proportion of continental surface (~15%). The fast kinetics of carbonate weathering leads the trace carbonate to contribute greater HCO 3 − loads than silicate even in silicate catchments. Thus, the uses of carbonate powders on continental surface with silicate via agricultural liming can potentially enhance the CO 2 removal. Here, using an equilibrium modeling approach and results of the CMIP6 GCM model, we estimate the actual total CO 2 removal ( ATCR ) by the weathering of both carbonate bedrock and carbonate-rich soils, at the global scale. The potential CO 2 removal ( PCR ) which can be achieved by spreading carbonate powders on non‑carbonate lands is also estimated. The results show that the ATCR at present is approximately 0.166 Gt yr −1 , which is similar to the previous result estimated from the global river data base. The PCR is 0.843 Gt yr −1 , five times the ATCR . Future climate and land-use changes may strongly increase the ATCR . Therefore, we suggest that carbonate weathering enhancement by land-use changes can potentially help mitigate the current climate trends.