What is VM0033?
VM0033 is the Verified Carbon Standard methodology for tidal wetland and seagrass restoration. It provides the framework for quantifying and crediting greenhouse gas benefits from restoring mangroves, salt marshes, seagrass meadows and comparable tidal systems, and is currently at version 2.1.
It sits inside the Wetlands Restoration and Conservation project type within the VCS AFOLU category. As with any methodology, its applicability conditions decide whether a given project can use it, and those conditions are the first thing to read rather than the last.
Why is blue carbon accounted for differently from forest carbon?
In a terrestrial forest, most of the carbon a project is crediting is in the trees. In a tidal wetland, most of it is in the soil. Coastal sediments accumulate organic carbon over long periods and can hold substantially more than the vegetation growing above them, which shifts the measurement problem from counting biomass to characterising a soil profile.
- Soil organic carbon is the dominant pool, so sampling depth and bulk density matter enormously.
- Methane and nitrous oxide fluxes can materially offset carbon dioxide benefits, and salinity strongly influences them.
- Tidal inundation means the site's condition varies within a day, not merely across seasons.
- Restoration frequently involves hydrological change — reopening tidal flow — rather than only planting.
This is why a blue carbon project cannot simply reuse a forestry monitoring plan. The pools are different, the greenhouse gases in play are different, and the physical access constraints are severe: a mangrove site may be reachable on foot for only part of a tidal cycle.
What does this mean for monitoring a mangrove project?
A tidal restoration project has to produce evidence about a landscape that is hard to reach, changes with the tide, and holds most of its carbon below ground. Satellite observation and structured field capture answer different parts of that problem and are usually needed together.
Flora Carbon AI's role on mangrove work to date has been the spatial evidence layer — land screening and land-use and land-cover mapping through FloraScope. For the wider picture of how coastal projects are measured, see blue carbon projects; for the methodology text itself, go to Verra's own page linked below.