Though covering a much smaller area, mangroves, tidal saltmarshes and seagrass meadows can store up to ten times the carbon of terrestrial forests.
What makes blue carbon so attractive, however, is also what makes it technically difficult. Measuring a mangrove forest isn’t just a matter of counting trees: a project may need to establish how much carbon sits in sediment, where that carbon came from, what would have happened without the intervention, and how secure those stores are against erosion, storms or future sea-level rise.
For businesses, the opportunity is therefore unusually interesting: blue carbon can combine climate finance with coastal restoration, biodiversity and community livelihoods. But those benefits only become a credible carbon credit when the underlying accounting can withstand scrutiny.
What are blue carbon credits?
Blue carbon is carbon captured and stored by coastal and marine ecosystems. In the voluntary carbon market, the established coastal blue carbon ecosystems are mangroves, tidal saltmarshes and seagrass meadows.
A mangrove forest can hold very large carbon stocks, much of them in saturated soils and sediments. Generating a carbon credit requires more than the presence of stored carbon. The project needs an eligible intervention, a baseline, an approved accounting method, monitoring, independent verification and issuance under a carbon programme.
Mangroves also protect coasts, provide fish nursery habitat and support livelihoods. Those outcomes may be central to the value of a project, but they answer different questions from the carbon accounting.
Kelp and other forms of ocean carbon dioxide removal are sometimes grouped loosely under “blue carbon”. We keep them separate here. Coastal wetland crediting has an established body of methods and project experience; engineered and open-ocean removal pathways raise different accounting and durability questions.
How are blue carbon credits created?
The project intervention comes first. A restoration project might re-establish mangroves on degraded land, restore tidal flow to a wetland or recover seagrass habitat. A conservation project may protect existing mangroves facing a credible risk of deforestation or degradation.
The accounting then compares the project outcome with the expected baseline. Depending on the methodology, that normally involves defining the project boundary, demonstrating additionality, identifying the relevant carbon pools and greenhouse-gas sources, monitoring changes, accounting for leakage and uncertainty, and submitting the result for independent validation or verification.
Credits or certificates can only be issued for outcomes recognised under the applicable programme and methodology. Retirement comes later, when an issued unit is used for an eligible climate claim or contribution.
Carbon already present in an ecosystem and carbon attributable to the project are two different quantities. The methodology has to establish the change caused by the intervention.
Blue carbon removals and avoided emissions
Restoring mangroves, saltmarsh or seagrass can remove carbon dioxide from the atmosphere as vegetation recovers and organic carbon accumulates in biomass and sediment. Protecting a mangrove forest that would otherwise be cleared can prevent stored carbon from being released. That is an avoided emission.
Some projects do both. Plan Vivo lists Mikoko Pamoja in Kenya and Tahiry Honko in Madagascar as undertaking afforestation/reforestation and avoided deforestation.
A company buying specifically for a removal strategy therefore needs to check the units being offered rather than infer the outcome from the words “blue carbon”. The same precision should carry into public claims.
Buying a credit does not change the buyer’s Scope 1, 2 or 3 inventory. Operational reduction and external climate finance remain separate.
How are blue carbon credits measured?
Much of the scientific difficulty sits below the waterline.
Mangrove projects may account for above-ground and below-ground biomass as well as soil organic carbon. In tidal wetlands and seagrass systems, sediment can be the dominant pool. Field sampling, site conditions and the origin of the stored carbon can materially change the result.
A 2024 global analysis in Nature Communications found that mangrove sediments contain carbon produced within the mangrove system and carbon transported in from terrestrial or marine sources. Mangrove-derived organic carbon was the largest single source in the top metre of sediment across both estuarine and marine settings, but external sources could still make up a substantial share. For crediting, the presence of carbon in sediment is not enough to show that the project created it.
Local measurements can also depart sharply from global averages. A 2026 study of 135 sediment cores across 47 seagrass sites in Fiji found soil-carbon stocks two to 12 times lower than global averages, depending on the comparison. Applying generic Tier 1 defaults would have overestimated national stocks by roughly an order of magnitude.
A project using sediment carbon should therefore be able to show what was measured locally, which pools were included, how uncertainty was treated and where default values were used. We also check how the method handles hydrology, methane where relevant, erosion, storms, sea-level rise and other sources of reversal risk.
Which blue carbon standards and methodologies apply in 2026?
The methodology and version matter more than the programme name on its own.
| Programme | Blue carbon methodology or protocol | Position at 8 October 2026 | What to check |
|---|---|---|---|
| Verra VCS | VM0033 v2.1, Methodology for Tidal Wetland and Seagrass Restoration | v2.1 remains active. Verra consulted on a major v3.0 revision from 3 September to 5 October 2026. | Confirm the methodology version. The proposed v3.0 changes baselines, leakage, soil accounting and the methodology structure, but is not yet the active version. |
| Gold Standard | Sustainable Management of Mangroves v1.0 | Published 22 August 2024. | The current methodology applies to reforestation of native mangroves and is primarily a removal route. |
| Isometric | Mangrove Restoration Protocol v1.0 | Certified 13 January 2026; CCP-Approved by ICVCM on 11 May 2026. | It is a carbon-removal protocol. Credits issued under the approved version can use the CCP label subject to the applicable programme rules. |
| Plan Vivo | Coastal Blue Carbon Methodology; Mangrove Conservation Module; Simplified Mangrove Restoration Module | These remain in Plan Vivo’s methodology pipeline rather than its approved methodology list. | Existing Plan Vivo blue-carbon projects may have been certified under earlier project-specific approaches and standards. |
Plan Vivo became a CCP-Eligible programme in August 2026 for projects registered under PV Climate Project Requirements v5.7 or later and validated and verified by accredited VVBs. Programme eligibility is not the same as methodology or unit-level CCP approval.
Our two blue carbon projects, Mikoko Pamoja and Tahiry Honko, are listed by Plan Vivo under PV Climate Version 4, so we do not describe their credits as CCP-approved on the strength of the programme announcement.
What makes a high-integrity blue carbon credit?
The project documents usually tell us more than the sales description. The 2026 second edition of the High-Quality Blue Carbon Practitioners Guide treats climate, nature and people as connected parts of project quality. In coastal projects, land and resource rights, community participation and long-term stewardship can affect whether the intervention lasts.
Baseline and additionality
The project should explain what would happen without carbon finance and how that baseline was established. In a conservation project, the assumed rate and location of future loss can dominate the number of credits generated. In restoration, the baseline determines how much future carbon accumulation can be attributed to the intervention.
A weak baseline can undermine an otherwise sophisticated monitoring system.
Carbon pools and attribution
Check which pools are credited: above-ground biomass, below-ground biomass, soil or sediment, dead wood, litter or others. Where sediment carbon is important, the methodology should make clear how externally sourced carbon is treated.
The useful figure is the additional climate benefit attributable to the project, not the total amount of carbon found within a hectare.
Permanence and reversal risk
Mangroves and tidal wetlands are dynamic systems. Erosion, storms, sea-level rise, changes in sediment supply and future land use can all affect stored carbon. Verra’s active VM0033 methodology, for example, requires use of the current non-permanence risk tool to assess erosion and submergence risk from sea-level rise.
For biological storage, we look at the programme’s buffer, monitoring and reversal arrangements rather than relying on a general claim of permanence.
Leakage and hydrology
Protecting one mangrove area can shift harvesting or land-use pressure elsewhere. Restoration can fail when tidal flow, salinity or sediment conditions are wrong. Planting counts for little if the hydrology cannot support the forest that is supposed to follow.
Community rights and benefit sharing
Coastal communities may depend directly on mangroves and fisheries. The project should show who holds or controls the relevant land and resource rights, how consent and participation work, how grievances are handled and how carbon revenue is shared.
Governance affects the carbon outcome as well as the social one. A project that depends on local stewardship cannot treat the people doing that work as an appendix to the methodology.
Verification, issuance and retirement
Project quality and unit status need separate checks. A strong project can have future tonnes that have not yet been verified or issued, while a monitoring report may describe progress without creating units available for retirement.
We ask for the latest monitoring and verification records, the registry entry, the vintage and quantity being sold, and the retirement evidence that will follow the purchase.
What are you buying with different blue carbon projects?
| Project type | Typical climate outcome | Main carbon pools | Questions worth asking first |
|---|---|---|---|
| Mangrove restoration | Carbon removals, sometimes alongside avoided emissions | Biomass and sediment/soil carbon | Was hydrology restored? Are soil stocks locally measured? What survival and monitoring evidence exists? |
| Mangrove conservation | Mainly avoided emissions, sometimes combined with restoration removals | Existing biomass and large sediment carbon stocks at risk | How credible is the deforestation/degradation baseline? Is leakage addressed? Who controls harvesting and land use? |
| Saltmarsh restoration | Usually removals and/or avoided emissions depending on intervention and methodology | Vegetation and sediment carbon | How were tidal conditions restored? How are methane, erosion and sea-level risk treated? |
| Seagrass restoration | Removal potential where an eligible methodology and site support it | Biomass but especially sediment carbon | Are local sediment stocks measured? How stable is the meadow? Are global default values being used where site-specific data are needed? |
Two mangrove projects can sit in the same category and still have very different baselines, carbon pools, monitoring requirements and risks. The project type is only the first filter.
How much do blue carbon credits cost?
Ecosystem Marketplace’s 2025 market report recorded an average blue carbon transaction price of $29.72 per tCO2e in 2024, up from $8.33 in 2023. Reported transaction volume fell from 0.4 MtCO2e to 0.2 MtCO2e, while total market value rose from $3.2 million to $5.2 million.
The figures describe a small, thinly traded segment of the voluntary market. They are useful historical evidence, not a current price list.
Project economics vary widely. Field monitoring, hydrological restoration, community governance, methodology, vintage and limited supply can all affect price. We do not use the market average to value a specific project without looking at what is actually being offered.
For broader market pricing, see our Carbon Credit Price guide.
Blue carbon projects in practice: Mikoko Pamoja and Tahiry Honko
Our portfolio includes two Plan Vivo blue carbon projects whose histories make some of these distinctions concrete. C Level has a commercial interest here: we offer credits from these projects when units are available. Availability, vintage and volume vary, so those details are confirmed before any purchase.
Mikoko Pamoja in Kenya
Plan Vivo describes Mikoko Pamoja as the world’s first community-led blue carbon project. It began in 2010 in Gazi Bay, Kenya, and is coordinated by the Association for Coastal Ecosystem Services.
Plan Vivo currently records 22,169 Plan Vivo Certificates issued to date, with the project certified under PV Climate Version 4. Its activities are listed as afforestation/reforestation and avoided deforestation, and 1,081 households participate.
The community owns the project. Plan Vivo records investment in school materials, school buildings and clean drinking water alongside the mangrove work. The formal carbon record still needs to be read on its own terms, which is why we describe the issued units and project activities separately rather than compressing them into a single removal figure.
Tahiry Honko in Madagascar
Tahiry Honko began in 2018 in southwest Madagascar and is coordinated by Blue Ventures. Plan Vivo records 895 participating smallholder households and lists the project activities as afforestation/reforestation and avoided deforestation under PV Climate Version 4.
Plan Vivo and Blue Ventures describe it as the world’s largest community-led mangrove conservation carbon project. The programme combines mangrove protection and restoration with alternative livelihoods including seaweed and sea-cucumber farming and mangrove beekeeping.
At the project’s formal inauguration in October 2019, Blue Ventures reported Joel François, a member of the Velondriake LMMA Association, saying:
“We inherited these mangroves from our ancestors … I want to ensure we can pass these forests on to our children.”
Are blue carbon credits right for a business climate strategy?
Blue carbon can suit a company that wants external climate finance to support coastal restoration or conservation while also funding biodiversity, resilience and local livelihoods.
We match the project to the company’s purpose first. A removal-only strategy narrows the available units. A broader beyond-value-chain programme may have room for high-quality avoided emissions as well as removals. Claims and procurement requirements then need to match the evidence attached to the specific units.
Co-benefits can strengthen the case for a project, but they cannot compensate for weak carbon accounting. The best blue carbon projects have convincing evidence on both sides.
How to buy blue carbon credits
Start with the outcome the business wants to fund, then ask for the evidence behind the project and the units being offered.
For a serious purchase, we expect to see the methodology, project design document, latest monitoring and verification records, registry status, vintage and quantity. Governance belongs in the same review: land or resource rights, community participation, benefit sharing and the arrangements for monitoring after issuance.
The final question is whether that evidence supports the company’s intended use and claim.
We work with community-led nature projects and help businesses compare project evidence, choose an appropriate portfolio and retain the documentation behind the purchase. See our guide to buying carbon credits or explore Mikoko Pamoja and Tahiry Honko.
Sources and methodology
The factual and technical points in this guide were checked against current primary or research sources on 8 October 2026.
- Verra, VM0033 v2.1. The active methodology for tidal wetland and seagrass restoration. View the methodology.
- Verra, VM0033 v3.0 consultation. The consultation on a major revision ran from 3 September to 5 October 2026. View the consultation.
- Gold Standard, Sustainable Management of Mangroves v1.0. Published 22 August 2024. View the methodology.
- Isometric, Mangrove Restoration Protocol. Certified 13 January 2026. View the announcement.
- ICVCM, May 2026 assessment decisions. Isometric Mangrove Restoration Protocol v1.0 approved for the CCP label. View the decision.
- Plan Vivo, methodology pipeline. The Coastal Blue Carbon Methodology and mangrove modules remain in the pipeline. View the pipeline.
- ICVCM, Plan Vivo programme decision. PV Climate is CCP-Eligible for projects registered under Project Requirements v5.7 or later, subject to stated conditions. View the decision.
- Plan Vivo, Mikoko Pamoja. Project status, activities, participants and certificates issued. View the project record.
- Plan Vivo, Tahiry Honko. Project status, activities and participants. View the project record.
- Blue Ventures, Tahiry Honko. Project history and the community quotation. View the article.
- Nature Communications (2024). A global assessment of where mangrove sediment carbon comes from, and what that means for allocating credits. View the paper.
- Global Biogeochemical Cycles (2026). The Fiji seagrass soil-carbon study. View the paper.
- ORRAA and Conservation International (2026). The second edition of the High-Quality Blue Carbon Practitioners Guide. View the guide.
- Ecosystem Marketplace, State of the Voluntary Carbon Market 2025. Source for the 2024 blue carbon volume, value and average transaction price. View the report.