The ocean, covering over 70% of the planet, has absorbed about 30% of human-produced planet-warming emissions since the 1980s – a fact that has been largely taken for granted until recently.
As countries and companies become more conscious of their carbon footprints while striving to achieve net-zero (completely eliminating or negating the amount of greenhouse gases produced by human activity), some have started to look to the ocean – particularly its coastal areas. These areas are seen as an untapped source of ‘blue carbon,’ which refers to the carbon captured and stored in coastal and marine ecosystems, such as mangroves and seagrass meadows.
Blue carbon is gaining popularity among carbon credit project developers, who have primarily focused on generating “green” carbon credits from land-based ecosystems like forests. Each credit represents one ton of carbon dioxide emissions removed from the atmosphere through reforestation or prevented from being released, such as by preserving a forest from deforestation. Companies purchase these credits to offset their carbon footprints.
Although coastal habitats do not cover extensive areas, they can be efficient carbon sinks. Research has shown that the carbon stored in mangroves or seagrass meadows can be up to three times more than in tropical rainforests, allowing for more credits to be sold per unit area. Blue carbon credits can also demand higher prices due to their positive impacts on coastal fisheries and job creation for local communities.
Asia could potentially benefit from this rush for blue carbon. A study by the National University of Singapore’s Centre for Nature-based Climate Solutions discovered that the top three countries for financially viable mangrove blue carbon are located within Southeast Asia.
Proponents of carbon projects argue that putting a price on blue carbon helps slow the loss of these habitats and allows them to persist in the face of competing uses. This is crucial since wetlands are among the world’s most endangered habitats due to land clearance, rising sea levels, and pollution.
However, establishing a blue carbon project is not straightforward. There are few existing blue carbon projects, and those that have been established, such as the Delta Blue project in Pakistan, involve mangroves – considered the most thoroughly studied of all blue carbon ecosystems.
A significant obstacle is the difficulty in quantifying the carbon that some blue carbon habitats can keep out of the atmosphere. For example, it is unclear how underwater carbon capture from seaweed or seagrass can reduce atmospheric carbon dioxide.
Greater recognition of the value of other benefits that a coastal habitat can offer beyond just carbon is needed.
The absence of a mechanism to accurately quantify carbon in an ecosystem means developers do not receive reliable estimates of their financial returns. Coupled with other political and technical concerns, such as overlapping land tenure rights and the transboundary nature of some blue carbon ecosystems, these projects are challenging to scale up. There needs to be an alternative approach to viewing these ecosystems so their fate does not solely depend on how much carbon they can store.
Although credits from blue carbon projects can command higher prices due to the numerous co-benefits they provide, these projects are seldom established solely because of these services. The basis for setting up a carbon project is still the ability to quantify the carbon stored or removed by the habitat. If such estimates are difficult to obtain for some ecosystems, it becomes harder for them to receive protection as carbon projects.
Nonetheless, these ecosystems offer many services to communities. For example, healthy coral reefs promote thriving fisheries and protect coastal infrastructure from climate-related extreme events, while mangrove habitats provide protection against rising sea levels.
Additionally, these habitats might offer services that we are unaware of or know little about, such as seagrass reducing bacteria and disease prevalence in nearby corals and mitigating the impacts of ocean acidification. This service could have implications for aquaculture farms in Southeast Asia and the health of the region’s rich marine biodiversity.
If recognising a coastal ecosystem’s numerous benefits beyond carbon sequestration and storage is the first step towards a more holistic view of blue carbon habitats, the next step should be realising that losing these habitats would entail costs, particularly for those living in the area.
Coastal development, as well as dams and shipping, in the Sundarbans, the world’s largest mangrove forest, in Bangladesh, is causing erosion that undermines the ability of these coastal protectors to hold back the tides. Consequently, land is permanently lost, along with people’s homes and livelihoods.
These costs should also be considered when making decisions that could determine the fate of a natural habitat. The loss of coral reefs could result in diminished ecotourism revenue, and the removal of natural habitats like seagrass beds could lead to additional expenses for farms that need to invest in water filtration technology to maintain their stock.
The global carbon markets and the emergence of blue carbon could offer a mechanism to help save Southeast Asia’s diverse coastlines from destruction. However, valuing these habitats solely for their carbon would be akin to missing the forest for the trees.
This article was first published on the Asian Development Blog and can be read here.
Audrey Tan
Ms. Audrey Tan was previously an assistant news editor and environment correspondent at The Straits Times, Singapore’s national broadsheet, where she covered environmental issues and climate change for about a decade. Audrey holds a master’s degree in climate science and policy from the Scripps Institution of Oceanography. She is an advisory committee member of the Pulitzer Center’s Rainforest Journalism Fund for Southeast Asia.
Francesco Ricciardi
Prior to joining ADB, Francesco worked for about ten years as a researcher focusing on the impact of environmental contamination on natural ecosystems and wildlife. After leaving academia, he has worked as an environment and ecology consultant in several projects around Asia, including renewable energy plants, large coastal infrastructures, and natural resources development and protection.
