Blue carbon sequestration in seagrass ecosystems: A global synthesis with an emphasis on India's situation, difficulties and possibilities

Abstract

Blue carbon ecosystems consisting of seagrass meadows, mangroves and salt marshes play a major role in mitigating climate change through long-term carbon sequestration. Among these ecosystems, seagrass meadows are increasingly recognised for their carbon storage potential, but so far remain underrepresented in global carbon accounting efforts, particularly in developing nations like India. India’s seagrass habitats spanning approximately 500 km², particularly in Palk Bay, the Gulf of Mannar, and the Andaman and Nicobar Islands, are highly vulnerable to anthropogenic disturbances and environmental changes, with annual losses ranging from 0.7 to 7 %. The blue carbon potential of Indian seagrass is inadequately defined compared to mangroves; nevertheless, estimates suggest that its storage is approximately 6.7 TgC. This review combines the global and Indian literature on seagrass blue carbon dynamics, assessing biomass, sedimentary carbon storage, and region-wise sequestration capacities. It highlights the key environmental drivers, such as hydrodynamics and nutrient availability, as well as anthropogenic impacts that affect the carbon storage. It also identifies the methodological inconsistencies and critical research gaps that impede the integration of seagrass blue carbon into national policy frameworks. These gaps are addressed to strengthen India’s role in global climate mitigation, blue carbon credit systems, and to promote ecosystem-based coastal management.