Carbon and credits
Retirement
Retirement is the permanent cancellation of a carbon credit in a registry so that it can never be sold or claimed again. Until a credit is retired, nobody has offset anything. It is the only step in the chain that is unambiguous and publicly checkable.
Because retirement is recorded against a named beneficiary in a public registry, it is the one part of a carbon claim a buyer can verify in a few minutes without trusting anyone.
Tonnes retired is the figure worth reporting, because it is the one that has actually taken effect.