"Blue forests" are coastal and marine ecosystems, including mangrove forests, seagrass meadows and tidal salt marshes. They play an important role in protecting marine biodiversity and supporting the livelihoods of coastal and island communities by providing habitats for fisheries, filtering water, guarding shorelines and creating opportunities for tourism and recreation.

Coastal blue carbon refers to the carbon stored in the biomass and sediments of in coastal and marine ecosystems (e.g., blue forests), in both plant biomass and sediments below. Vegetated coastal habitats are estimated to bury 70 per cent of the carbon sequestered in oceans, despite only comprising 0.5 per cent of the ocean’s surface area.

Oceanic blue carbon includes the carbon stored through the actions of marine life, from krill to whales. Understanding how marine vertebrates contribute to carbon storage can help recognize their potential role in climate change mitigation. Recent science has identified that marine life may have a role to play in the global climate challenge through natural mechanisms of carbon cycling in all marine ecosystems, from shallow coasts to ocean depths. Marine management and sustainable fishing practices, which support healthy populations of marine vertebrates, may help secure the capacity of the oceans to take up and store carbon, and thereby mitigate the impacts of climate change. 

Beyond carbon sequestration, the many co-benefits of blue forests include: protection from erosion, storm surge and flooding, water filtration through the absorption of nutrients and sediments, supporting ocean biodiversity, providing nutrients and habitats for fish and crustaceans, and providing sustainable resources, such as food for humans and animals, and materials for building or ingredients for medicine and cosmetics.

Between the UNFCCC and the Paris Agreement, a range of specific policy instruments for implementing and financing climate mitigation actions through nature-based activities are provided, some of which are of direct relevance to coastal ecosystems (and blue carbon). These include Reducing Emissions from Deforestation and Forest Degradation (REDD+), National Appropriate Mitigation Actions (NAMAs), the Land-Use, and some Land-Use Change and Forestry (LULUCF) activities including those implemented under the Clean Development Mechanisms (CDM).