Together with seagrass beds and salt marshes, mangrove forests such as the one pictured account for 70% of the ocean's carbon storage capacity.
Credit: iStockPhoto
Mangrove forests, seagrass beds and salt marshes cover only around 0.5% of the seabed, but account for some 70% of the ocean's carbon storage capacity.
These three marine environments soak up and store carbon dioxide in their biomass and sediments, where they keep it locked up for centuries. Together with the carbon held in the rest of the ocean, this is known as 'blue carbon'.
Blue carbon is also the name of a new strategic approach to make use of the large carbon capture and storage potential of coastal ecosystems. If this carbon could be quantified and sold on international carbon trading markets, this could help fund preservation and restoration projects, which would also help capture more carbon and ease the effects of climate change.
Apart from sequestering carbon quicker than the same area of rainforests can, these three ecosystems provide other 'eco-services' which are especially valuable for vulnerable coastal communities in developing countries. These include food and energy, protecting shorelines from flood and tsunamis, filtering water, as well as recreation and tourism.
But aquaculture, agricultural development and pollution are now responsible for loss of these ecosystems at a rate of up to four times that of rainforest loss. Around 20% of mangroves and more than 50% of seagrass ecosystems have been lost in the last 25 years, and salt marshes are being lost at a rate 1 to 2% per year.
Because of the huge amount of carbon stored in mangroves, the global emissions from mangrove deforestation account for around 10% of all emissions from deforestation, despite making up just 0.7% of tropical forest area.
"Some of the coastal ecosystems are 50 or even up to 75 times more efficient than a same type of area of land in terms of sequestering carbon, and that's a wonderful opportunity for us, but it's one we're squandering," says Carl Gustaf Lundin, director of the Global Marine and Polar Programme at the International Union for Conservation of Nature (IUCN) based in Switzerland. "We're doing a lot silly things in the ocean, we're doing land reclamation projects, we're doing very destructive things in the marine environment and if we stop those and actually start restoring, then we'll at least help our carbon footprint."
Last month, a new research initiative was launched at the Eye on Earth summit in Abu Dhabi, United Arab Emirates to understand how the blue carbon strategy would work. This will feed into the negotiations for the U.N. Conference on Sustainable Development Rio+20 in Brazil later this year.
According to the organisations driving it, Conservation International, IUCN and UNESCO, this is the first global initiative to mitigate climate change through the conservation and restoration of coastal marine ecosystems. "Blue carbon is an opportunity or us, first to take into account what we as humans are doing to the environment, [and] an opportunity for us to be able to factor those resources and in turn use this as a platform for solutions," Rolph Payet, special adviser to the president of the Republic of Seychelles, an island country in the Indian Ocean, and president of University of Seychelles, told the summit.
Blue carbon aims to link eco-services, including but not exclusively carbon storage, with market-based payment mechanisms to help mitigate and adapt to climate change, conserve biodiversity, and ensure sustainable delivery of those ecosystem services to people.
But one of the key problems with linking economics of blue carbon trading with marine conservation is a lack of comparable baseline data on blue carbon. This 'data deficiency' is a key barrier to effective planning and decision-making in the coastal and marine environment, according to a white paper prepared for the summit. It also hampers the inclusion of these environments into international conventions and financing mechanisms that exist for land habitats, such as forests through the U.N.'s Programme on Reducing Emissions from Deforestation and Forest Degradation in Developing Countries (REDD).
