Global Ocean Negative Carbon Emissions (Global-ONCE) is a United Nations Ocean Decade Program, initiated from a newly recognized carbon sequestration mechanism—the microbial carbon pump (MCP)—that transforms organic carbon from labile states to refractory states for long-term storage of carbon in the ocean. Global-ONCE integrates the four ocean carbon pumps—Biological pump, Carbonate pump, MCP and Solubility pump (BCMS)—providing a nature-based marine biotechnological solution​ for ocean negative carbon emissions. This approach is aligned with the Biodiversity Beyond National Jurisdiction (BBNJ) Agreement that enters into force in 2026. Application scenarios, including wastewater-coupled ocean alkalinity enhancement, integrated sea-farming, and land–sea coordination, demonstrate how the BCMS roadmap can be translated into carbon sequestration innovations​ spanning observational, experimental, and management pillars. These practices support ecosystem-based climate governance, mitigate global warming, and promote ecosystem sustainable development, exemplifying how advancing ONCE contributes to both ecosystem resilience and societal well-being.

Keywords. Global Ocean Negative Carbon Emissions (Global-ONCE), Microbial carbon pump (MCP), Biodiversity Beyond National Jurisdiction (BBNJ) Agreement, Ecosystem sustainable development