Cross-Shelf Carbon Transport in the East China Sea and Its Future Trend Under Global Warming

The cross-shelf carbon transports across a section along the 100 m isobath from Taiwan to Cheju are estimated based on carbon concentration observations and ocean currents simulated by a regionally zoomed ocean-atmosphere coupled model. Results show that the net cross-shelf particulate organic carbon, dissolved organic carbon, and dissolved inorganic carbon transports are in the offshore direction at 1.81 ± 0.22, 51.8 ± 2.85, and 783 ± 58.9 TgC yr, respectively, which are high in spring and summer and low in winter and fall following the seasonality of the offshore volume transport. The carbon is transported into the East China Sea (ECS) mainly by the Taiwan Warm Current and the Yellow Sea Warm Current, whereas they are carried out of the ECS mainly by the East China Sea Current extension and the recirculation north of Taiwan. Assuming steady biological activity, future net total organic carbon transports are projected to increase by 5%∼19% offshore at the end of the 21st century, with the maximum increase in winter, in a high greenhouse gas emission scenario of RCP8.5. The increased carbon transports are due to the increased offshore volume transport, transferring more carbon-rich coastal water away from the shelf in the warming future than at present. The results quantify cross-shelf carbon burial in the ECS in the background of global warming.