Habitat-based blue carbon credits from tropical and temperate mangrove, saltmarsh and seagrass projects, quantified using IPCC Wetland Supplement Tier 2 methods with site-specific Tier 3 calibration where the evidence base supports it.
Methodology overview
Methodology for quantifying carbon sequestration from seagrass meadow restoration and conservation activities. Includes sediment carbon accumulation and avoided emissions from degradation.
Eligibility criteria
●Tropical or temperate mangrove, saltmarsh or seagrass habitat with ecological feasibility evidence (hydrology, salinity, sediment supply, donor stock).
●Documented land or seabed tenure for the full crediting period, with written community consent where customary rights exist.
●Historical baseline of at least 10 years of land-cover and degradation data (Sentinel-2 / Landsat back-cast).
●Additionality demonstrated through barrier analysis: aquaculture pressure, encroachment, sediment starvation or active dieback.
●Permanence plan implementing buffer pool drawdown (Option C) plus methodology-specific reversal monitoring.
●MRV plan covering soil/sediment carbon, above- and below-ground biomass, and lateral export with site-specific defaults.
●Contribution-first claims only — no neutralisation language, no fungibility with non-marine pools.
Quantification approach
Carbon pools and crediting metrics
●Above-ground biomass (AGB) — allometric or LiDAR-derived
●Soil / sediment organic carbon (SOC) — top 1 m unless deeper cores are justified
●Dead wood and litter (de minimis; reported but not credited unless > 5% of stock)
●Lateral DIC / POC export (subtracted from gross removal where measurable)
Equations (in plain language)
1.Net removals = (stock change in AGB + BGB + SOC) minus (project emissions + leakage + lateral export).
2.Stock change uses paired plots or chronosequence with project / control design — not single-year snapshots.
3.SOC change is gain-loss where direct cores exist, or stock-difference where modelled with site-calibrated sequestration rates.
4.Lateral export defaults are conservative until two consecutive verifications produce site-specific data.
Reference methodology — starting point
IPCC 2013 Wetland Supplement (Chapter 4, Coastal Wetlands) is the starting reference. Tier 2 default factors are used as a floor; Tier 3 calibration is required before any uplift above default sequestration rates can be credited.
Where MCC improves on the reference
✓Mandatory ex-ante drawdown of buffer pool credits before issuance — not a paper reserve.
✓AI-assisted change detection on Sentinel-2 NDVI and Sentinel-1 SAR, with anomaly review by human verifiers within 14 days.
✓Lateral export accounted for explicitly rather than assumed-zero.
✓Contribution-first crediting unit: removals are reported in tCO2e but never marketed as offsets.
Buffer pool (ex-ante)
15%
15% ex-ante drawdown for mangrove and saltmarsh; 20% for seagrass given higher reversal uncertainty. Drawdown is reviewed every verification cycle and may increase if reversal events occur.
Crediting period
30 years
30-year crediting period, renewable once after a full additionality and baseline re-test. Permanence monitoring continues for 100 years after last issuance.
Monitoring requirements
Required data sources
●Sentinel-2 NDVI / NDWI — quarterly, 10 m resolution
●Sentinel-1 SAR backscatter — annual, for canopy and inundation under cloud
●Sediment carbon density samples — LECO CN628 dry combustion every 3 years
●Permanent plot AGB / BGB measurements — every 5 years, 30 plots minimum per 1,000 ha
●GPS-tagged photo points — biannual, minimum 1 per 50 ha
●Tide-gauge / sediment-elevation tables (SET) where elevation accretion is claimed
Frequency
Continuous remote sensing with quarterly cadence; field campaigns every 3 to 5 years depending on parameter.
Verification cadence
Independent third-party verification at year 1, year 3, then every 3 years. A reversal-trigger event forces an out-of-cycle verification within 6 months.
KPIs that must be tracked
Habitat extent change (ha)Canopy fractional cover (%)SOC density (Mg C / ha) by depthAGB / BGB stock (Mg C / ha)Reversal events count and areaBuffer pool balance (post-drawdown)
Eligible co-benefits — SDG mapping
F-family F01 contributes to the following Sustainable Development Goals. Indicators flagged as required must be reported at every verification; optional indicators may be claimed where the project chooses to report them.
RequiredSDG 13Climate Action
RequiredSDG 14Life Below Water
RequiredSDG 15Life on Land
OptionalSDG 5Gender Equality
OptionalSDG 1No Poverty
Public consultation and community engagement
30-day public consultation is mandatory at PDD stage. For projects that overlap customary or indigenous tenure, FPIC documentation must accompany the PDD and be re-confirmed at every verification. Local-language summaries (minimum 1,500 words) are required.