What Route 7 is
R7 issues verified ex-post carbon removal tonnes from coastal and marine ecosystems: mangroves (tropical and subtropical), saltmarsh (temperate intertidal), and seagrass (subtidal marine). These ecosystems sequester carbon in two reservoirs. Living and dead biomass above and below ground holds carbon over decadal to centennial scales. Marine sediment, where the bulk of blue carbon is stored, can hold carbon stable over centennial to millennial scales, particularly in mangrove peat layers and saltmarsh organic-rich sediment.
R7 covers both restoration (re-establishing degraded coastal ecosystems) and protection (preventing the conversion of intact ecosystems to non-wetland uses). Both activity classes are recognized under coastal-specific methodologies in the major voluntary registries.
R7 is not a fisheries credit, a coastal-protection credit, or a biodiversity credit. Those instruments exist separately and may overlap with the same area; the protocol requires any such overlapping instruments to be retired or immobilized at S04 before R7 will issue carbon tonnes from that area.
The market reality R7 is built for
The blue-carbon market is small but high-quality. Industry estimates place annual issuance under 10 Mt globally, reflecting both the limited area suitable for blue-carbon projects and the difficulty of running the coastal MRV stack credibly. The supply-constrained dynamic produces a pricing premium relative to other nature-based routes.
What buyers value in blue carbon is the durability profile combined with verifiable evidence. Carbon stored in marine sediment is far more stable than carbon in terrestrial biomass alone, provided the ecosystem remains intact. The MRV stack (sediment cores + biomass + elevation + RS) produces stronger batch-level evidence than tropical forestry, which translates into less price haircut at sale.
R7 is positioned for the segment of buyers willing to pay for the durability and integrity. The design choices (elevated permanence buffer at S02, coastal-specific MRV at S03, explicit activity-shifting leakage assessment) all converge on producing tonnes that survive the audit at the high end of the market.
How R7 works
After the additionality gate passes (tenure documentation often complex for coastal and marine zones, FPIC, hydrology feasibility confirmation for restoration projects, risk class assessment for storm and sea-level rise), R7 locks the accounting plan. The plan specifies the methodology version, the baseline framework (including observed shoreline change and subsidence trends), the leakage budget (activity-shifting such as aquaculture or fish-farming relocation, and market leakage where material), the uncertainty deductions, and the permanence buffer (typically in the 15-25% range, elevated above terrestrial routes to reflect storm, erosion, and sea-level rise risk).
Measurement runs through the GRO evidence chain with a coastal-specific stack. Sediment cores measure bulk density and percent organic carbon by depth (typically with deeper coring than terrestrial soils to capture the millennial-scale sediment stocks). Biomass plot surveys capture above-ground stocks. Elevation monitoring (using rod surface elevation table with marker horizon, rSET-MH, where applicable) tracks subsidence and accretion over time, which is particularly important for understanding whether the project is gaining or losing elevation against sea level. Remote sensing measures area and ecosystem class.
GRO tokens mint per transect or stratum or interval to the project wallet. Each packet carries coordinates, timestamps, instrument and lab identifiers, and QA artifacts. The chain-of-custody on sediment samples is particularly important because lab analyses are time-consuming and the samples are physical evidence; the registered instruments and lab IDs are part of the GRO packet.
At S04, any overlapping biodiversity offsets, coastal-protection credits, fisheries payments, or other instruments for the same area are retired or immobilized in their source registry. At S05, an independent accredited verifier from the panel reviews the vintage batch dossier including the sediment core results, biomass plot data, elevation records, RS, accounting plan, and EAC retirement IDs; the cadence is often annual or semi-annual depending on data support. At S06, the CARBON_TONNE contract mints the vintage batch; the backing GRO is consumed-to-carbon and rendered permanently non-transferable.
Sale and stablecoin settlement at S07 follow the standard pattern. The supply-constrained dynamic in the blue-carbon market is reflected in published forward curves where buyers want price visibility.
The seven-stage diagram below shows the full path.
Permanence buffer and coastal risk
Coastal ecosystems face permanence risks that terrestrial routes do not. Storm events can strip mangrove stands within hours. Long-term subsidence can convert saltmarsh to open water. Sea-level rise can drown coastal ecosystems if their accretion rate cannot keep pace. R7's buffer-sizing reflects these risks at 15-25% of the gross issuable tonnes, elevated above the 10-20% typical for terrestrial forestry.
Reversal monitoring is continuous over the crediting period. A documented reversal event (cyclone or hurricane damage, levee failure, aquaculture conversion) triggers a buffer claim against the pool. Clawback provisions apply for deliberate loss (conversion of the project area to non-wetland use).
The buffer percentage is not uniform within R7. Mangroves in cyclone-frequent tropical zones receive higher buffers than mangroves in calmer subtropical zones. Saltmarsh in regions with high subsidence rates receives a higher buffer than saltmarsh on stable coasts. Seagrass receives buffer treatment that reflects both the lower per-area sediment stock and the higher sensitivity to water-quality reversal.
Stacking with other routes
R7 is compatible with the other carbon routes when they cover different areas: R5 (ARR inland), R6 (REDD+ or IFM on different forest land), R8 (soils or biochar on separate land). R7 is also compatible with energy routes (R1 or R2 on separate energy assets) and with Route 3 (community pool participation).
What R7 cannot stack with on the same coastal area is another instrument claiming the same unit of benefit. Biodiversity offsets, coastal-protection credits, fisheries enhancement credits, or nested coastal-zone instruments must all be retired or immobilized at S04 before R7 will issue tonnes from the overlapping area.
Different units of benefit on the same area can co-exist with proper accounting separation: blue carbon (R7) and biodiversity offsets (separate registry) on the same mangrove area is allowed where the methodology supports the separation and neither claim double-counts the other.
Where it stands
R7 is built on the same protocol-level architecture as the other carbon routes. The R7-specific dependencies are:
Coastal-MRV verifier panel. The independent verification firms accredited for coastal methodologies (a subset of the broader voluntary-market verifier roster) admitted to the Attestor Registry. Coastal MRV requires specific expertise; the panel is narrower than for terrestrial routes.
Methodology integration. The recognized coastal methodology modules under VCS and equivalents are tracked through the locked-plan mechanism at S02.
Hydrology and elevation data partners. Where the project's accounting plan requires baseline shoreline change or subsidence rate data, the protocol integrates the relevant geospatial and hydrological data sources.
Registry bridges. Verra VCS for the coastal modules; other voluntary registries as their coastal coverage develops.
R7 readiness depends on the coastal verifier panel onboarding and on the supply-side cadence of new blue-carbon projects reaching the gate. The supply-constrained dynamic that drives the pricing premium also limits how fast R7 can scale; the design priority is integrity and durability rather than volume. For the protocol-level architecture R7 depends on, see Proof-of-Verification, One-Claim Ledger, Attestor Registry, and the sibling carbon route pages: R5 Reforestation, R6 REDD+ / IFM, and R8 Soils & Biochar.
