Blue carbon

Blue carbon is the carbon captured by the world's oceans and coastal ecosystems. The carbon captured by living organisms in oceans is stored in the form of biomass and sediments from mangroves, salt marshes, seagrasses and potentially algae.

Historically the ocean and terrestrial forest ecosystems have been the major natural carbon (C) sinks. New research on the role of vegetated coastal ecosystems have highlighted their potential as highly efficient C sinks, and led to the scientific recognition of the term "Blue Carbon". "Blue Carbon" designates carbon that is fixed via ocean and coastal ecosystems, rather than traditional land ecosystems, like forests. Although the ocean’s vegetated habitats cover less than 0.5% of the seabed, they are responsible for more than 50%, and potentially up to 70%, of all carbon storage in ocean sediments.Mangroves, salt marshes and seagrasses make up the majority of the ocean’s vegetated habitats but only equal 0.05% of the plant biomass on land. Despite their small footprint, they can store a comparable amount of carbon per year and are highly efficient carbon sinks. Seagrasses, mangroves and salt marshes can capture carbon dioxide (CO₂) from the atmosphere by sequestering the C in their underlying sediments, in underground and below-ground biomass, and in dead biomass. In plant biomass such as leaves, stems, branches or roots, blue carbon can be sequestered for years to decades, and for thousands to millions of years in underlying plant sediments. Current estimates of long-term blue carbon C burial capacity are variable, and research is ongoing. Although vegetated coastal ecosystems cover less area and have less aboveground biomass than terrestrial plants they have the potential to impact longterm C sequestration, particularly in sediment sinks. One of the main concerns with Blue Carbon is the rate of loss of these important marine ecosystems is much higher than any other ecosystem on the planet, even compared to rainforests. Current estimates suggest a loss of 2-7% per year, which is not only lost carbon sequestration, but also lost habitat that is important for managing climate, coastal protection, and health.

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