Construction of ocean carbon sink functional system and exploration of planning-driven carbon neutrality pathways

Against the backdrop of global climate change, the ocean, as the Earth's largest active carbon reservoir, holds significant but still underdeveloped potential for contributing to carbon neutrality goals. Marine Spatial Planning (MSP) is a key instrument for coordinating maritime activities, yet its role in ocean carbon sink protection, enhancement, and risk control remains insufficiently specified. This study constructs an ocean carbon sink functional system by combining mechanism-based classification, comparative analysis of various MSP cases, expert elicitation, and compatibility assessment. The proposed system includes six functions: ecosystem restoration for carbon sink enhancement, ocean carbon sink protection, fishery-based carbon sink enhancement, carbon sink research and practice, sub-seabed carbon sequestration engineering, and coordinated land-sea carbon sink management. The study further examines how these functions relate to major MSP-covered activities and how they can be adapted to zoning-based and policy-driven MSP frameworks. Rather than providing a validated carbon accounting model, the system is intended as a planning-oriented screening tool that helps identify potential synergies, conflict-prone combinations, and conditions requiring further assessment. The results provide conceptual and practical guidance for integrating ocean carbon sink objectives into MSP and for developing planning-driven pathways toward carbon neutrality in ocean and coastal areas.