Coastal Blue Carbon

© Kirsten Isensee
Blue carbon ecosystems on the coast of Brazil

Blue carbon is the carbon stored in coastal and marine ecosystems. Coastal ecosystems - mangroves, salt marshes and seagrass meadows - sequester and store large quantities of blue carbon in both the plants and the sediment below. Carbon sequestered in coastal soils can be extensive and remain trapped for very long periods of time (centuries to millennia) resulting in very large carbon stocks. In fact, total carbon deposits per square kilometre in these coastal systems may be up to five times the carbon stored in tropical forests. By sequestering and storing significant amounts carbon from the atmosphere and ocean, coastal ecosystems help mitigate climate change. On the other hand, the conversion and degradation of these ecosystems can cause a significant release of CO2 to the ocean and atmosphere.

Besides being an important factor in the global carbon cycle, mangroves, salt marshes and seagrass meadows have high biodiversity values. They provide breeding grounds and nurseries for fisheries and food security for many coastal communities around the world. They also provide ecosystem services that are essential for climate adaptation and resilience along coasts, including protection from storm surge and sea level rise, erosion prevention along shorelines and coastal water quality regulation.

Map courtesy of The Blue Carbon Initiative.

While mangroves are fairly well mapped, large areas containing seagrasses remain largely unsurveyed, and similarly the estimations of the global extent of coastal marsh or the rates of salt marsh loss show high variations. Previously studies have shown that between 1980 and 2005, 35,000 square kilometres of mangroves were removed globally – an area the size of the nation of Belgium – resulting in globally significant emissions of carbon dioxide into the atmosphere and ocean.

There is growing evidence and consensus that the management of coastal Blue Carbon ecosystems, through avoided emissions, conservation, restoration and sustainable use has strong potential as a transformational tool in effective climate change mitigation and adaptation. However, to date, many countries have not incorporated coastal blue carbon into their portfolio of climate change mitigation or coastal management policies and actions. To improve the assessments of coastal blue carbon ecosystems the IOC-UNESCO is actively taking part in the Blue Carbon Initiative.

The Blue Carbon Initiative

The International Blue Carbon Initiative is a coordinated, global programme focused on mitigating climate change through the conservation and restoration of coastal and marine ecosystems. It was created by the Intergovernmental Oceanographic Commission (IOC-UNESCO), together with Conservation International (CI) and the International Union for Conservation of Nature (IUCN), as an initial step in advancing scientific, management and policy actions.  

The Blue Carbon Initiative works to develop management approaches, financial incentives and policy mechanisms for ensuring the conservation, restoration and sustainable use of coastal blue carbon ecosystems.
It engages local, national, and international governments in order to promote policies that support coastal blue carbon conservation, management and financing.

The goal is to develop comprehensive methods for assessing blue carbon stocks and emissions, which will be implemented by projects around the world to demonstrate the feasibility of blue carbon accounting, management and incentive agreements.

The Initiative also aims to support scientific research into the role of coastal blue carbon ecosystems for climate change mitigation.

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