The Role of Blue Carbon in Climate Change Mitigation: A Review

Abstract

Blue carbon ecosystems comprising mangroves, seagrass meadows, and salt marshes that have garnered substantial scientific and policy attention as nature-based solutions for climate change mitigation, owing to their exceptional capacity for atmospheric carbon dioxide sequestration and long-term organic carbon storage. This review synthesizes current knowledge on the role of blue carbon in climate change mitigation, with a focus on sequestration mechanisms, ecosystem diversity, global carbon stocks, anthropogenic and climatic threats, and relevant policy frameworks. These coastal vegetated ecosystems capture atmospheric CO₂ through photosynthesis and efficiently store it in both living biomass and anoxic sediments, where anaerobic conditions substantially reduce microbial decomposition rates, enabling carbon residence times spanning centuries to millennia. Despite occupying a relatively limited global surface area, blue carbon ecosystems contribute disproportionately to marine carbon burial relative to many terrestrial systems. Anthropogenic pressures including coastal development, land-use change, pollution, and aquaculture expansion in conjunction with climate-driven stressors such as accelerating sea-level rise and ocean warming, are placing these ecosystems under intensifying threat. The degradation and loss of blue carbon habitats not only diminish their future sequestration potential but also triggers the release of previously stored carbon stocks, thereby converting natural carbon sinks into net greenhouse gas sources. This review further examines the role of blue carbon within global climate governance frameworks, particularly its integration into Nationally Determined Contributions (NDCs) under the Paris Agreement, voluntary carbon markets, and emerging blue carbon financing mechanisms.  Critical knowledge gaps persist in carbon accounting methodologies especially for macroalgal systems as well as in the permanence and verifiability of sequestered carbon stocks under changing climatic conditions. Advancing standardized measurement, reporting, and verification (MRV) protocols, alongside robust governance and conservation frameworks, is essential for maximizing the climate mitigation potential of blue carbon ecosystems. This review underscores the necessity of mainstreaming blue carbon into integrated coastal zone management, Sustainable Development Goal (SDG) frameworks, and international climate policy to support global decarbonization trajectories.