Current Status and Potential Assessment of China's Ocean Carbon Sinks

The role of ocean carbon sinks in global climate changemitigation and carbon neutrality is still affected by lack of research.Aiming at overcoming the present limitations, a comprehensive andholistic framework and accounting method of ocean carbon sinkevaluation are proposed in this study, which consider both carbon sinktypes and their characteristic carbon storage cycle timescales. Theresults show that (1) China's total ocean carbon sink is 69.83-106.46Tg C/year, among which the mariculture, coastal wetlands, andoffshore carbon sinks are 2.27-4.06, 2.86-5.85, and 64.70-96.55 TgC/year, respectively; (2) ocean-based solutions such as coastalprotection and restoration, mariculture development, ocean alkaliza-tion, ocean fertilization, and marine bioenergy with carbon capture andstorage have substantial mitigation potential, but further investigation is required before large-scale deployment; (3) althoughChina's ocean carbon sinks only counterbalanced 3.27-4.99% of its fossil fuel emissions, their tremendous enhancing potential andspecific advantages cannot be ignored, and enhancing measures must be taken according to regional characteristics; (4) someuncertainties and limitations still exist, and problems such as double counting, carbon sink offset, and so forth need to be furtherconsidered. In a word, this study provides a basis for the development of ocean-based solutions on closing climate mitigation gaps.