Offset credit supply potential for CORSIA

This discussion paper assesses how robust accounting could be implemented under the Paris Agreement in order to avoid double counting between nationally determined contributions (NDCs) and the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) implemented under the International Civil Aviation Organization (ICAO). The paper focuses on how host countries of carbon-offset projects can account for the use of offset credits under CORSIA by reporting 'adjustments' in the 'structured summaries' of their biennial transparency reports prepared under Article 13 of the Paris Agreement. The paper finds that several accounting approaches considered in the international negotiations on Article 6 of the Paris Agreement for international transfers of mitigation outcomes between countries cannot not be implemented in the specific context of CORSIA where the offset credits are used by airline operators or may not robustly avoid double counting. The paper identifies nine options for how the use of offset credits under CORSIA could be accounted for by host countries and discusses their advantages and disadvantages. The paper also evaluates options to account for single-year targets in the context of CORSIA, as well as options for consistent consideration of Global Warming Potentials used under CORSIA and nationally determined contributions under the Paris Agreement. The findings of the paper are important for the ongoing negotiations under the Paris Agreement on the rules for international transfers of mitigation outcomes under Article 6 and the implementation of 'structured summaries' under Article 13.