EU ETS vs ETS2: Who Is Responsible for the Uncertainty Basis?

In both EU ETS and ETS2, the regulated party remains responsible for the quality of the monitoring basis and the defensibility of the reported emissions figure. Verification is important, but it does not transfer ownership of the basis, assumptions, or evidence chain.

Why this matters

For ETS work, the real issue is not just one uncertainty number attached to a meter. It is whether the whole monitoring basis is defendable: methodology, data sources, metering basis, emission factors, calculations, controls, and evidence trail.

EU ETS: the operator owns the monitoring basis

Under the existing EU ETS framework, responsibility typically sits with the installation operator. That includes the monitoring plan, the chosen methodology, the evidence behind it, and the annual report that is put forward for verification.

ETS2: the responsibility shifts upstream

Under ETS2, the principle of ownership remains, but the regulated party is usually upstream. In practice, that means the fuel supplier or equivalent regulated entity becomes responsible for the monitoring basis and report rather than the downstream user.

What the verifier is responsible for — and what they are not

The verifier assesses whether the report is free from material misstatement and whether the methodology has been applied in line with the rules and approved plan. The verifier does not become the owner of the uncertainty basis.

What the competent authority is responsible for

The authority approves and oversees the framework. It does not carry the regulated party's operational responsibility for the data chain or assumptions behind the report.

Common misconceptions

• If it is verified, the uncertainty basis is not suddenly the verifier's problem.
• If the authority approved the plan, that does not remove the duty to implement it correctly.
• Uncertainty is not just a meter issue. It sits in the wider monitoring basis.

Final takeaway

The cleanest summary is this: under EU ETS, the installation operator usually owns the monitoring basis. Under ETS2, that ownership usually moves upstream to the regulated entity. The verifier checks it. The authority oversees it. But the responsibility for the basis itself remains with the regulated party.