In CarbonMeld’s data, most carbon removal projects outside forests and soils are listed by a handful of registries: Puro.earth, Global C-Sink, Isometric, the Rainbow Standard and Oncra, and, for biochar, also by Verra and the Climate Action Reserve. The table below counts, for each type of removal, the project records each registry lists in CarbonMeld’s data on 10 November 2026, by the methodology the record states.
Removal types and the registries that list them
| Removal type | Registries (project records) | Methodologies |
|---|---|---|
| Biochar | Global C-Sink 135, Puro.earth 79, Isometric 43, Verra 16, Climate Action Reserve 9 | Global C-Sink’s biochar and artisan C-Sink; Puro.earth biochar; Isometric biochar; Verra VM0044; the Reserve’s biochar protocol |
| Biomass burial and storage | Rainbow Standard 45, Puro.earth 8, Isometric 6 | Rainbow’s BiCRS methodology; Puro.earth terrestrial storage of biomass; Isometric biomass and bio-oil geological storage and subsurface biomass storage |
| Carbonated materials and construction | Oncra 16, Puro.earth 13, Global C-Sink 8 | Oncra’s construction protocol; Puro.earth carbonated materials; Global C-Sink construction C-Sink |
| Enhanced rock weathering | Puro.earth 6, Oncra 5, Isometric 1 | Puro.earth enhanced rock weathering; Oncra’s rock protocol; Isometric enhanced weathering |
| Geological storage of captured CO₂ (direct air capture, biogenic CO₂) | Puro.earth 4, Isometric 1 | Puro.earth geologically stored carbon; Isometric biogenic carbon capture and storage |
| Alkalinity in water | Isometric 3 | Isometric wastewater alkalinity |
Biochar is by far the largest group: 282 records across five registries, more than the five other groups together (116). Each of the other groups is listed by two or three registries, and the alkalinity group by one.
How to read the counts
- A record is a project as the registry lists it. Being listed is not the same as having credits: credits are issued only after each verification of the project’s results.
- Each record counts under the methodology it states. Records that state no methodology in CarbonMeld’s data are not counted, so a registry can list more removal projects than its row shows.
- Forest, soil and other nature-based removals are not in this table, and neither are methodologies for using or storing captured CO₂ or other greenhouse gases that can come from fossil sources (Verra’s VM0040, VM0043 and VM0049, ACR’s carbon capture and storage).
Where to look further
Each methodology has its page in CarbonMeld’s database, with its projects: for example Puro.earth biochar, Global C-Sink biochar, Rainbow’s BiCRS methodology, Puro.earth enhanced rock weathering and Puro.earth geologically stored carbon. The biochar sector page ranks the biochar projects CarbonMeld has rated. For two direct air capture plants on Puro.earth, compare their announced capacity with the credits issued; before buying any of these credits, our carbon credit due diligence checklist lists the documents to read.
