“Blue carbon” is the carbon stored by coastal and marine ecosystems: mangrove forests, tidal salt marshes and seagrass meadows. These habitats pack a lot of carbon into waterlogged soils, and they are being lost. Credits from protecting and restoring them are rare, often expensive and come with strong co-benefits for coasts and fisheries. This page explains how they work and what to check. It is part of our guide to carbon credit project types.
How blue carbon projects work
Ecosystem Marketplace defines blue carbon projects as those that reduce or remove carbon dioxide from marine and coastal environments by restoring, conserving or managing ecosystems, including wetland, mangrove and seagrass habitatsSource 3.
Restoration projects replant mangroves or restore water flows to degraded wetlands. Verra’s VM0033 methodology quantifies the net greenhouse gas reductions and removals from restoring tidal wetlands, which come from increasing both biomass and the soil organic carbon the ecosystem produces itselfSource 6. Conservation projects instead protect existing mangroves from being cleared.
Matched shop
Buy blue carbon credits
- Registry serial numbers
- Retirement certificate
- Project documentation
Why mangroves matter
The ICVCM describes mangroves as among the most carbon-rich ecosystems on the planetSource 4.
- Their carbon storage potential is four to five times higher than that of terrestrial forests, and their deep, waterlogged soils can store carbon for hundreds or even thousands of yearsSource 4.
- Mangrove loss accounts for roughly 10% of emissions from global deforestation, despite mangroves covering only 0.7% of the world’s landSource 4.
- More than half of all mangrove ecosystems are at risk of collapse by 2050 because of human activities and climate changeSource 4.
The IPCC lists blue carbon management among methods that can enhance biodiversity, ecosystem functions, employment and local livelihoods, depending on contextSource 8. It also puts its global removal potential at the lower end, under 1 GtCO₂ a yearSource 8.
Removal, avoidance or both?
Blue carbon credits can be either, or both at once. Ecosystem Marketplace lists blue carbon projects, including mangrove restoration, among nature-based projects that produce credits representing both reductions and removalsSource 3. Restoration grows new carbon stocks; protection stops existing ones being released.
Check which part of a credit is which. Some buyers also fund coastal ecosystems for nature goals. The Oxford Principles note that an organisation may have a nature or biodiversity target for which investing in nature-based credits is appropriate, separate from efforts to compensate residual emissionsSource 9. For guidance on why the difference matters, read removal vs avoidance credits.
Permanence and reversal risk
Coastal carbon is stored in living systems, so it can be lost. The IPCC notes that carbon stored through vegetation and soil management can be reversed by human or natural disturbances and is prone to climate change impactsSource 8. The Oxford Principles say nature-based storage can last centuries to millennia only if ecosystems are maintained and not destabilised by climate changeSource 9.
As with other land-based credits, standards use buffers. The ICVCM requires measures to address and compensate reversals where there is a riskSource 10, and Verra assesses potential carbon losses for its land-use projects over 100 years to size their buffer contributionsSource 11.
Measurement is still evolving
Soil carbon in tidal wetlands is harder to measure than tree biomass. Verra opened consultation on a major revision, VM0033 v3.0, in September 2026, proposing a modular structure, a new dynamic performance benchmark, an updated approach to leakage and updates to reflect the latest tidal wetland scienceSource 7.
What do blue carbon credits cost?
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| Year | Average price (USD per tCO₂e) | Volume traded (MtCO₂e) |
|---|---|---|
| 2023 | 8.33 | 0.4 |
| 2024 | 29.72 | 0.2 |
As of Oct 2026
Ecosystem Marketplace recorded a 257% rise in the average blue carbon price in 2024Source 3. Ecosystem Marketplace links the rise to buyer demand for removals: average prices for ARR, agroforestry and blue carbon credits rose by 19%, 22% and 257% respectivelySource 3. With volumes this small, a handful of deals can move the average sharply, so treat it as a rough guide. Our carbon credit prices page covers the wider market.
Risks and integrity issues
- Small, young market. Few projects means few track records and wide price differences.
- Measurement. Soil carbon accounting is central to the credit and, as Verra’s revision shows, methods are still being updatedSource 7.
- Leakage. Protecting one mangrove area can push clearing elsewhere; the VM0033 revision proposes an updated approach to leakageSource 7.
- Climate pressures. The ICVCM notes climate change is among the pressures putting mangroves at riskSource 4.
Ask what was restored, and where
A credible project can show the restored area, the methodology and monitoring reports, and the registry record. Vague promises about “ocean carbon” without those details are a warning sign.
Standards and methodologies
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| Methodology | Status |
|---|---|
| Isometric Mangrove Restoration Protocol v1.0 | CCP-approved, May 2026 |
| Verra VM0033 Tidal Wetland and Seagrass Restoration v2.1 | Active; revision v3.0 in consultation |
As of Oct 2026
Standards named in this table
Isometric
Verra
Logos identify the organisations named; no endorsement is implied.
The ICVCM approved Isometric’s mangrove protocol in May 2026Source 5. At the time no credits had been issued under it, with three projects in the pipeline that could issue up to 2 million removal credits by 2030, according to IsometricSource 4. VM0033’s status comes from Verra’s pageSource 6.
Buying blue carbon credits
- Check whether the credit is restoration, conservation or both.
- Ask for the methodology and whether credits carry the CCP label.
- Expect small volumes and compare quotes.
- Verify retirement; see how to verify carbon credits.
Compare with land-based reforestation and forest protection (REDD+), or use blue carbon as one part of a portfolio approach.