Blue carbon
Carbon stored in coastal and marine ecosystems, often referring to mangroves, tidal marshes and seagrasses.
Example
Protection can prevent carbon losses while supporting coastal habitats.
The catch
Carbon estimates and management outcomes vary by ecosystem and site.
Related terms
Ecosystem, Afforestation, Biodiversity, Carbon sink, Carbon stock, Deforestation
In more depth
Blue carbon, explained.
Blue carbon ecosystems bury carbon in waterlogged sediments where the lack of oxygen slows decay, so their soils can keep it for centuries. Hectare for hectare, mangroves and salt marshes can hold more carbon underground than many land forests. When people drain or clear them for ponds and ports, that carbon stock starts to escape as CO₂. They also shelter young fish and blunt storm surges, ecosystem services that coastal communities value on their own account.
The term is sometimes stretched to cover the open ocean or seaweed farming. The IPCC applies it to marine carbon that is amenable to management, which mainly means these coastal habitats. Rising seas add a further risk, since marshes can migrate inland only where sea walls and buildings leave them room, a problem known as coastal squeeze.