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

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

Emergy-based evaluation of world coastal ecosystem services.

The current lack of research on the evaluation of marine ecosystem services makes the value of marine protection, development and restoration underestimated during the decision-making process. Based on the non-monetary ecosystem service evaluation framework, a marine ecosystem service classification and accounting method has been established in this study, and the world's coastal ecosystem services have been measured as an example. The results show that (1) the world's coastal ecosystem service value is about 4.13E+23 sej/yr, of which Asia and North America contribute about 55% of the total service value; (2) the top ten countries in terms of the world's coastal ecosystem service values are Canada, Indonesia, Australia, the United States, Brazil, the Russian Federation, Norway, the Philippines, Mexico, and China, which contribute about 60% of the total service value; (3) estuaries have the highest ecosystem service values, followed by mangroves, seagrass beds, tidal flats, salt marshes, and warm water coral reefs; (4) developed countries can make better use of their coastal resources and pay more attention to the marine protection while the opposite is true in developing countries, which means that developed countries still occupy an advantageous position in the process of marine protection, development and utilization. This study assesses the coastal ecosystem service values in various coastal countries from the perspective of ecosystem contributors, emphasizes the importance of protecting them in marine management, and provides a certain reference basis and theoretical support for decision-makers in formulating marine-related protection and development strategies.