Blue carbon
Blue carbon is carbon captured and stored by ocean and coastal ecosystems. In most management and climate-policy contexts, the term focuses on coastal vegetated ecosystems such as mangroves, tidal marshes, and seagrass beds, where carbon accumulates in biomass and especially sediments and can be released when habitats are degraded or drained.
In simple terms
Coastal plants take up carbon dioxide through photosynthesis, and organic matter can become buried in waterlogged, low-oxygen soils where decomposition is slow. Definitions vary: broad scientific usage can include carbon across the ocean, while coastal blue carbon initiatives commonly focus on mangroves, tidal marshes, and seagrasses that can be managed and measured. Disturbance may stop future carbon sequestration and expose stored carbon, turning a sink into a source.
Why it matters
Protecting and restoring blue-carbon ecosystems can preserve long-lived carbon stores while supporting fisheries, biodiversity, shoreline protection, water quality, and community resilience across the watershed. Climate claims still require careful baselines, greenhouse-gas accounting, permanence, leakage, and safeguards. Carbon value should not displace the ecosystems' wider ecological and social importance.
Example
For example, a tidal-marsh restoration project may reconnect natural water flow, allow native vegetation to recover, and monitor changes in soil carbon and greenhouse-gas fluxes. Its climate accounting would also consider project emissions and reversal risk while documenting habitat and flood-protection outcomes separately.
How it differs
Carbon sequestration
Blue carbon identifies carbon stored through ocean and coastal systems; carbon sequestration is the broader process of capturing and storing carbon across biological, geological, or technological pathways.