ISO 14064

An international standard for quantifying, reporting and verifying greenhouse gas inventories.

ISO 14064 comes in three parts: organisational inventories, project-level reductions, and — in part 3 — the requirements for validating and verifying a claim.

Part 3 is the one that matters for trust. It sets out what a verifier does and what evidence they need, which is why it is referenced whenever a figure is described as assured rather than merely reported.

It overlaps substantially with the GHG Protocol on method; the difference is the emphasis on verifiability as a defined process.

Official source: ISO 14064-1 ↗

GHG Protocol The most widely used standard for corporate greenhouse gas accounting; the origin of Scope 1, 2 and 3.
Verifiable, not verified A record anyone can check for themselves is not the same as one an accredited body has audited. Both are useful; they are not interchangeable.