The locations,magnitudes,variations and mechanisms responsible for the global CO2 sink are uncer-tain and under debate.Here,we show,based on theoretical calculations and evidences from field monitoring results,that there is a possible important CO2 sink(as DIC-dissolved inorganic carbon)by the global water cycle.The sink constitutes up to 0.8013 Pg C/a(or 10.1% of the total anthropogenic CO2 emission,or 28.6% of the missing CO2 sink),and is formed by the CO2 absorption of water and subsequent enhanced consumption by carbonate dissolution and aquatic plant photosynthesis.Of the sink,0.5188 Pg C/a goes to sea via precipitation over sea(0.2748 Pg C/a)and continental rivers(0.244 Pg C/a),0.158 Pg C/a is released to the atmosphere again,and 0.1245 Pg C/a is stored in the continental aquatic ecosystem.Therefore,the net sink could be 0.6433 Pg C/a.This sink may increase with the global-warming-intensified global water cycle,the increase in CO2 and carbonate dust in atmosphere,and reforestation/afforestation,the latter increasing soil CO2,and thus the concentration of the DIC in water.
