Red, White, & Blue (Carbon): The Global Distribution of Blue Carbon Projects and Opportunities in the United States

by: Allyson Ulsh | January 19, 2023

Indonesia is home to the largest percentage of mangrove ecosystems globally. Mangroves are critical ecosystems that can sequester and store carbon dioxide, referred to as blue carbon due to their coastal nature.

Where is Blue Carbon Located?

Our team dove headfirst into the world of blue carbon in a previous blog post, Blue Carbon 101. Through exploring how blue carbon differs from ‘regular’ carbon, which ecosystems sequester it, and the interwoven community and biodiversity benefits, it’s clear that blue carbon projects have a fundamental role in addressing and mitigating climate change. Even with the understanding that mangroves, seagrass meadows, and tidal marshes are responsible for sequestering blue carbon, it’s difficult to envision precisely where these critical ecosystems are in the world.

Mangroves are found worldwide in the intertidal zones along coastlines, with a large percentage of the species’ density and diversity in Southeast Asia. Indonesia has over 3.3 million hectares (approximately 8.2 million acres) of mangroves along its coastlines, accounting for nearly 20% of the world’s global mangrove inventory [1]. Brazil, Nigeria, and Mexico jointly account for another 20% of total mangroves worldwide [2].

Seagrasses (not to be confused with seaweed) can be found globally along coastlines, including regions along the Artic circle. Similar to mangrove distribution, the density and diversity of seagrasses are highest along the coasts of Southeast Asian countries throughout the Pacific [3]. Tidal marshes, defined as the wetland areas along and between coastal areas that are inundated by daily tidal patterns, can also be found globally. The contiguous United States, excluding Hawaii and Alaska, has over 2.9 million hectares (7.2 million acres) of intertidal vegetated coastal wetlands, with mangroves and tidal marshes included in this inventory [4].

Unfortunately, mangrove, seagrass, and tidal marsh ecosystems face significant global threats. In addition to removing existing habitats, coastal development alters the hydrology and increases pollution and sedimentation, putting additional pressure on these blue carbon ecosystems. Mangrove ecosystems suffer from deforestation due to increasing pressures from coastal agriculture, including but not limited to shrimp farming, fishing, and salt production. Rising sea levels, changing salinities, and increasing temperatures all stress these critical environments, contributing to further habitat loss across all coastal ecosystems.

Seagrass meadows play an essential role in sequestering and storing blue carbon in the ocean.

Where Are Today’s Blue Carbon Projects?

Current blue carbon projects listed on Verra’s Verified Carbon Standard (VCS) and Community, Climate, and Biodiversity registries focus primarily on mangrove restoration across four continents. These mangrove projects highlight how carbon finance can be coupled with local conservation organizations to scale restoration efforts. Mirroring the mangrove hotspots discussed above, many of these projects are in the coastal regions of Indonesia, India, China, Nigeria, Senegal, and Mexico. There are currently 28 mangrove projects across 13 countries listed on the VCS registry at various points of project development.

Within the blue carbon space, ClimeCo has partnered with YAKOPI to fund and restore 6,000 acres of mangroves in Indonesia’s Aceh and North Sumatra regions. This mangrove restoration project involves the community throughout the entire process. Including collecting seeds from mangrove propagules, propagating the seeds in nurseries, assessing planting locations, planting the mangroves, and monitoring and maintaining the stand health. More details on this project will be shared in a forthcoming blog post highlighting the incredible community and project partners that have made this project possible.

While several mangrove restoration projects are listed on Verra’s registries, only one listed blue carbon project exists within the United States. This project involves the restoration of seagrass meadows through the direct seeding of seagrass species along Virginia’s coastline. With blue carbon ecosystems accounting for less than 1% of the United States’ natural land area, the opportunity for U.S. blue carbon projects exists but certainly with its own set of challenges.

Blue carbon project locations based on project information publicly available on Verra’s Verified Carbon Standard Registry. Smaller countries on the map may only have one icon representing multiple projects in proximity. 

A Louisiana Department of Wildlife and Fisheries Marsh Master moving through Louisiana’s tidal wetlands. Louisiana’s coastline is home to the largest, most productive tidal wetland area across the United States.

Coastal Blue Carbon in the United States

David Chen and I attended the Restoring America’s Estuaries: Coastal and Estuarine Summit early in December 2022 to learn more about the prospects of blue carbon projects in the United States. More than 1,375 coastal restoration professionals joined us to learn about opportunities and challenges surrounding blue carbon projects across the United States. Through attending several blue carbon sessions, we learned about topics such as seagrass carbon variability in California, the blue carbon market potential in Texas, and how to utilize blue carbon to support coastal wetland restoration in the Northeast.

While it’s clear that blue carbon projects have a fundamental role in addressing and mitigating climate change, it’s also evident that sea-level rise and its variable effects across different blue carbon ecosystems will complicate future project planning and development. Existing coastal marshes across the mid-Atlantic region are forecasted to be significantly vulnerable to sea-level rise. However, an opportunity exists for transitional zone habitats to migrate inland. Sea level rise will need to be accounted for in all aspects of blue carbon project development planning and implementation to ensure ecosystem, and subsequent carbon, permanence.

Additionally, there was a degree of uncertainty addressed in relation to the most effective restoration techniques for tidal marshes and seagrasses. Localized considerations, such as hydrology, in-land development, water quality, and salinity, among others, all play a role in the carbon sequestration rates across ecosystems. Careful consideration of the science behind blue carbon restoration will need to be accounted for in the quantification of carbon emission removals across landscapes.

Lastly are the challenges posed by jurisdictional claims. Carbon rights for the coastal and seafloor blue carbon ecosystems in the United States lie within different governmental agency jurisdictions. All blue carbon projects must involve the appropriate governmental agencies and foster relationships with the state legislature to ensure that projects and partners meet both state-led initiatives and voluntary carbon market standards. As sea-level rise affects these vulnerable ecosystems, the question of jurisdiction will become more complicated.

The scientific expertise and restoration partnership experience was unparalleled across the presentations. Our team’s overall takeaway from the conference was that while developing blue carbon projects in the United States is challenging across several facets, it is certainly possible. As a leader in developing and managing environmental commodities, we are excited to see how blue carbon projects will continue to expand and how we can be at the forefront of domestic blue carbon project development.

[1]  The Economics of Large-scale Mangrove Conservation and Restoration in Indonesia (worldbank.org)
[2]  Global Forest Resources Assessment (fao.org)
[3]  Seagrass and Seagrass Beds | Smithsonian Ocean (si.edu)
[4]  Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020

About the Author

Allyson Ulsh manages ClimeCo’s portfolio of nature-based solutions projects. From reforestation in tropical cloud forests to replanting bald cypress trees in Louisiana, Allyson understands the importance of coupling carbon finance with local stakeholder engagement to scale restoration efforts. Allyson is a Project Associate working within the Nature-Based Solutions project team. She received her Bachelor of Science degree in Environmental Resource Management from Pennsylvania State University, Schreyer Honors College.