For the full ERC, see the pull request: Add ERC: Tokenized Carbon Credits with Retirement by sehyun-wincl · Pull Request #1965 · ethereum/ERCs · GitHub
Abstract
This proposal defines an interface for representing carbon credits as semi-fungible tokens on top of ERC-1155 ( ERC-1155: Multi Token Standard ). Each token encodes a (projectId, creditId) pair into a single uint256 identifier and carries a fixed metadata schema aligned with the attributes published by carbon registries: project name, methodology, vintage, country of issuance, total issued volume, and expiry. The interface also defines retirement, the act of using a credit to offset emissions. Retiring subtracts from the holder’s transferable balance and records an equal, permanent, non-transferable retired balance, so issuance, transfer, and retirement can all be audited directly from the ledger.
Feedback on the retirement model, the metadata schema, and interoperability with existing registry conventions (Verra/Gold Standard) is very welcome.