Protecting the ocean, mitigating climate change ? State of the evidence and policy recommendations

The health and management of terrestrial carbon sinks have historically received most of the international attention –in research, advocacy, and policy developments, while the role of policy interventions aimed at the ocean and its coastal habitats in regulating the global climate system has been less developed in climate negotiations before UNFCCC COP21, in Paris . In recent years, the works of State- and NGO-led coalitions, the Intergovernmental Panel on Climate Change (IPCC) Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC), and the Ocean and Climate Change Dialogue held under the UNFCCC Subsidiary Body for Scientific and Technological Advice (SBSTA) in December 2020, have all contributed to turning the tide. The ocean is gradually becoming established as an important element of climate action, and the contribution of healthy marine ecosystems to climate change mitigation is receiving greater attention. While marine protected areas (MPAs) are increasingly being advocated as ocean-based climate solutions, the mechanisms through which MPAs can protect carbon pools and enhance carbon sequestration, as well as the magnitude of these effects still need to be better understood and quantified. These clarifications are necessary for MPAs to be integrated as actionable mitigation measures in national and international climate policies. With this purpose, this brief summarizes the findings of a comprehensive literature review focusing on the effects of MPAs on the carbon sequestration capacity of different marine carbon pools.

 

Key messages:

• The review found that MPAs can have a significant positive effect on the carbon stored in seagrass, mangroves, and sediments. For fish carbon, only the MPAs with full and high levels of protection were found to have a significant positive effect on carbon stored in living biomass. The results found for tidal marshes were positive, but not statistically significant. No study has assessed the contribution of MPAs to carbon storage in the biomass of macroalgae.
• “Blue carbon” ecosystems (mangroves, seagrass meadows, and tidal marshes) have been the most studied. They are the most efficient at storing carbon per surface unit, but their geographical extent is rather limited. Marine sediments, on the other hand, store less carbon per surface unit, but have enormous global extent and carbon sequestration potential. More research on sediments, and new or updated IPCC guidelines for including sediments and other marine carbon pools into national greenhouse gas accounting, would help making MPAs more actionable in climate change mitigation and including them into Nationally Determined Contributions (NDCs).
• MPAs are gradually being included in updated NDCs, mostly in the adaptation chapters. They should be considered when appropriate in mitigation chapters, when sufficient data is gathered to prove additionality, and in a complementary fashion alongside other economy-wide emissions reduction. Countries should also report on the associated national policy reforms (e.g., in fisheries) and the recognition and respect of rights, and especially those of Indigenous Peoples and Local Communities (IPLCs), that are necessary for the equitable and effective implementation of MPAs.