Estimation of mangrove blue carbon stock in Ghana, West Africa

Mangrove ecosystems are globally recognized for their disproportionate role in carbon sequestration (‘blue carbon’). However, blue carbon stock in West Africa and the regulatory mechanisms controlling its distribution remain largely unexplored.

This study provides the first comprehensive national‐scale assessment of mangrove carbon stocks in Ghana, where mangroves cover approximately 72.4 km ² across four coastal regions. We quantified above‐ground vegetation carbon, below‐ground root carbon and sediment organic carbon (SOC) at eight representative sites across the Volta, Central and Western Regions, and identified the dominant environmental drivers of SOC distribution.

Ghana's mangroves store an estimated 1.29 million Mg of organic carbon, with a mean ecosystem carbon density of 118 Mg C ha ⁻¹ . SOC constitutes approximately 78% of this stock (mean ~93 Mg C ha ⁻¹ ), far outweighing carbon in living biomass. Both species and region significantly affect SOC, with vegetation type explaining a greater proportion of variance than geographic site. Random forest analysis revealed that SOC was primarily influenced by salinity, pH and climate conditions. Above‐ground and root biomass together account for the remaining approximately 22% (total biomass carbon (TBC) approximately 281,000 Mg C; mean ~26 Mg C ha ⁻¹ ).

Synthesis and applications . Ghana's mangroves store lower carbon per hectare than global mangrove averages, reflecting regional differences in mangrove height, sediment depth and disturbance history. Nevertheless, their national carbon stock is substantial and highly concentrated in soils. These findings provide a field‐based baseline for incorporating mangroves into Ghana's Nationally Determined Contributions under the Paris Agreement, national greenhouse gas inventories, blue carbon accounting and coastal conservation planning.