Increasing Ambition with Blue Carbon: Protecting Coastal Wetland Ecosystems as a Carbon Dioxide Removal Strategy to Meet the Paris Agreement’s Goals

In 2015, the historic Paris Agreement set a global goal of limiting warming to “well below 2 degrees” through a robust, country-driven framework. Unfortunately, just two years later, it is increasingly clear that the global community is not on track to meet this objective. This is evidenced by a number of recent studies projecting that temperatures may increase by between 2.7-3.7°C by 2100, and continue to rise for many centuries thereafter given inertia in the climatic system. Further, the IPCC is increasingly including Negative Emissions Technology (NETs) in their models in order to achieve the 2-degree target. While many hear the term ‘CDR’ and think of Bioenergy and Carbon Capture and Storage (BECCS) or Direct Air Capture (DAC), blue carbon is a lesser-known but low-cost and effective CDR option that can help meet the goals set out in Paris.

The basic idea is to protect coastal wetland ecosystems – mangroves, seagrass beds and salt marshes – because the plant biomass and soils sequester and store carbon at rates up to 50 times higher than their terrestrial counterparts.[1] While sequestration and storage can vary greatly across geographies and ecological conditions, it is estimated that global blue carbon systems store at least 45 Mt CO2 per year.[2] It is further estimated that if coastal wetlands were restored to their extent in 1990, annual carbon sequestration would increase to 160Mt CO2 yr-1.[3] Blue carbon ecosystems also provide a suite of co-benefits, including mitigating sea level rise, providing critical fisheries habitat, and nutrient filtration.

However, these highly valuable, carbon-rich systems represent only a small portion of the Earth’s surface. More importantly, they are also some of the most threatened, with as much as 50 percent of all coastal wetlands having been lost over the past 50 years.[4] The loss of these ecosystems results in substantial economic loss and environmental damage, not least of which is increased greenhouse gas emissions. In fact, according to some estimates, up to 19 percent of global emissions from deforestation are attributable to coastal wetland loss.[5] Protecting these systems to avoid emissions is critical, as many of these powerful carbon sinks are becoming sources due to degradation. Between 0.15-1.02 Gt CO2 per year of emissions are a result of the loss of these systems.[6]

Protecting and enhancing coastal wetland ecosystems boasts a multitude of ecosystem and livelihood co-benefits and can be used to increase the ambition of mitigation and CDR efforts.

The primary mechanism for Parties to the Paris Agreement to meet its objectives are their Nationally Determined Contributions (NDCs), the connective tissue between national policymaking and international climate objectives. Over 50 Parties to the Paris Agreement have already included protection of coastal wetland systems in their NDCs in some form, and five (Seychelles, Saudi Arabia, UAE, Philippines, and Bahrain) explicitly use the term ‘blue carbon,’ and highlight projects to increase coastal wetland conservation.[7] However, many countries with blue carbon ecosystems have not included their protection as part of their NDCs, while others have asked for additional guidance from the high-level international bodies on how to do so more effectively.

One way to increase inclusion of coastal wetlands in NDCs and other climate policies is through additional guidance on carbon accounting. The IPCC released a 2013 Wetlands Supplement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. The Supplement provides updated methodological guidance specific to coastal wetlands, including methods to prevent double counting, assessment of the impacts of different management practices, and restoration methodologies. These accounting guidelines are currently voluntary, and the UNFCCC is accepting submissions on the lessons learned by Parties in relation to the supplement. These guidelines will be updated 2019, and will hopefully become a mandatory part of countries’ greenhouse gas accounting methodologies.

Blue carbon is also being discussed in the context of markets such as the Verified Carbon Standard (VCS), REDD+, payment for ecosystem services, and debt swaps. This is an effective way to ensure that the benefits attendant to blue carbon are available to the Global South, and that such countries can draw upon the decades of lessons learned in the land-use and forestry sectors.

The next few years will be critical for the implementation of the Paris Agreement, as the world approaches the first global stocktake and the second round of NDCs. The Paris “Rulebook”, a framework that will ultimately inform the operationalization of the agreement, is currently being negotiated. It will guide ambition, including the implementation of current NDCs, the development of the next round of NDCs, and long- term action strategies. We must also continue to evolve the equity-based pillars of the Paris Agreement, such as offering financial resources, technology transfer, transparency, and capacity building.

Blue carbon is not a silver bullet. But it can be a low-cost CDR tool with multiple livelihood co-benefits and ecosystem services. Protecting coastal wetlands is a win-win for communities and the climate and should be an integral part of all coastal countries’ climate plans.

Chelsey Bryson recently graduated with an MA in Global Environmental Policy from American University. During her graduate program, she interned with The Nature Conservancy’s Global Oceans and International Climate Change teams. She has a B.S. Marine Science from the University of Hawaii and before coming to DC she worked as a coral reef research diver in Seychelles. Her research interest lies in the intersection between international climate policy and marine conservation.



The Forum for Climate Engineering Assessment does not necessarily endorse the ideas contained in this or any other guest post. Our aim is to provide a space for the expression of a range of perspectives on climate engineering.

[1] Elizabeth Mcleod, et al., “A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2.” Frontiers in Ecology and the Environment 9 (2011)

[2] Gail Chmura, Shimon Anisfeld, Donlad Cahoon, James Lynch, “Global carbon sequestration in tidal, saline wetland soils.” Global Biogeochemical Cycles 17:4 (2003)

[3] Dorothee Herr and Emily Landis, “Coastal blue carbon ecosystems: Opportunities for Nationally Determined Contributions.” IUCN and TNC (2016)

[4] Elizabeth Mcleod, et al., 2011

[5] Linwood Pendleton, Daniel C. Donato, Brian C. Murray, Stephen Crooks, W. Aaron Jenkins, Samantha Sifleet, Christopher Craft, James W. Fourqurean, J. Boone Kauffman, Núria Marbà, Patrick Megonigal, Emily Pidgeon, Dorothee Herr, David Gordon, and Alexis Baldera, “Estimating Global ‘Blue Carbon; Emissions from Conversion and Degradation of Vegetated Coastal Ecosystems,” PLoS ONE 7 (2012)

[6] Pendleton et al. 2012

[7] Herr and Landis 2016