Coastal carbon storage, mangroves, salt marshes, seagrass, tidal wetlands, carbon sinks, sequestration, soils, sediment, restoration, avoided emissions, sea level rise, biodiversity, fisheries, water quality, coastal protection, and climate policy
Blue carbon
Blue carbon is carbon captured and stored by ocean and coastal ecosystems, especially mangroves, salt marshes, seagrasses, and their waterlogged soils.
What blue carbon is
Blue carbon is carbon captured by ocean and coastal ecosystems. In everyday climate work, the term often focuses on vegetated coastal habitats such as mangroves, salt marshes, and seagrass meadows that store carbon in plants and soils.
How coastal habitats store carbon
Plants take in carbon dioxide through photosynthesis and turn it into leaves, stems, roots, and organic matter. In wet coastal soils, low oxygen can slow decomposition, allowing carbon-rich material to accumulate and become buried.
Why soils matter
Much of the long-term blue carbon in marshes, mangroves, and seagrasses is stored below ground. Roots, trapped sediment, and organic material build layers of carbon-rich soil that can persist if the habitat is not drained or eroded.
Beyond carbon
Blue carbon habitats also protect shorelines, support fisheries, filter water, provide wildlife habitat, and help coastal communities adapt to storms and sea level rise. Carbon storage is one benefit among several ecosystem services.
Loss and emissions
When blue carbon habitats are drained, filled, dredged, eroded, or converted, stored carbon can be exposed to oxygen and released as greenhouse gases. Habitat loss also removes future carbon uptake and many coastal protection benefits.
Restoration and conservation
Blue carbon strategies include protecting existing wetlands, restoring tidal flow, replanting mangroves or marsh vegetation, improving water quality, reducing erosion, and allowing habitats to migrate inland where sea level rises.
Measurement challenges
Blue carbon accounting needs measurements of plant biomass, soil carbon, burial rates, methane and nitrous oxide emissions, permanence, project boundaries, and what would have happened without conservation or restoration.
Why it matters
Blue carbon connects climate action with coastal habitat protection. Done carefully, it can help value ecosystems that store carbon while also supporting biodiversity, fisheries, cleaner water, and more resilient shorelines.