On October 6, 2016, the International Civil Aviation Organization (ICAO) finalized the details of a market-based measure (MBM) to offset most of the growth in aviation carbon dioxide emissions beginning in 2020. The measure, known as the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), was agreed upon at ICAO’s 39th Assembly in Montreal and marks the first time an MBM covers an entire international sector.
CORSIA will first be implemented as a voluntary system from 2021–2026 and will be mandatory from 2027–2035, when it will apply to all ICAO member countries, with the exception of some developing countries and small markets. CORSIA excludes domestic aviation activity and the emissions of other climate pollutants from aviation, notably black carbon, nitrogen oxides, and the precursors of aviation-induced cloudiness.
Based on the countries that have opted in thus far, the voluntary phases will offset about 64% of growth revenue tonne kilometers (RTKs) or about 11% of all international RTKs, whereas the mandatory phase will offset about 75% of growth RTKs or 32% of total international RTKs. Between 2021 and 2035, the MBM is expected to cover approximately 73% of growth RTKs and 25% of all international RTKs.