Promoting ocean carbon in the implementation of the BBNJ

While the carbon cycling services that underpin the role of the ocean in climate faces prominently among the general principles of the BBNJ agreement it has been little discussed how the agreement can further the carbon sequestration of the oceans. Combining scientific findings on the processes contributing to the biological carbon pump with legal doctrinal analysis, this paper examines the potential for using the BBNJ to better integrate ocean carbon in ocean management, thereby supporting the objectives of the Paris Agreement.

The ocean, as the world’s largest carbon sink, operates through physical and biological carbon pumps. While the physical carbon pump stores carbon in seawater, and thereby increases ocean acidification, the biological carbon pump contributes to sustainable long-term carbon storage in the seabed. Without increasing acidification, the biological carbon pump transfers CO2 fixed through photosynthesis at low trophic level, via complex biological-driven processes involving various marine species to the deep ocean. There is an untapped potential for increasing these effects, by e.g. increasing marine biomass and in particular species which are central for the function of the biological carbon pump.

However, preexisting law of the sea rules on marine living resources, guided primarily by Maximum Sustainable Yield (MSY) formula, overlooks the climate benefits of marine organisms, focusing instead on maximizing catch for human consumption. Maximum Carbon Sequestration (MCS) has been suggested as a complementary management goal to MSY, aimed at optimizing carbon sequestration by maintaining high biomass levels across key species. While existing legal frameworks provided no room for such reform, the implementation of the BBNJ represents a window opportunity for integrating MCS. Examining different potential future scenarios, we propose strategies for fostering an implementation of the BBNJ which promotes the policy integration of MCS. We also suggest action points to promote biological carbon sequestration in the implementation of the BBNJ rules on marine protected areas and environmental impact assessment.