2. What is CORSIA and how does it work?

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​According to Assembly Resolution A39-3, paragraph 4, the role of a global MBM scheme is to complement a broader basket of measures to achieve the global aspirational goal (of carbon-neutral growth from 2020 onwards).

Paragraph 5 of the Assembly Resolution decides to implement a global MBM scheme in the form of the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) to address any annual increase in total CO2 emissions from international civil aviation (i.e. civil aviation flights that depart in one country and arrive in a different country) above the 2020 levels, taking into account special circumstances and respective capabilities.

According to the Assembly Resolution, the average level of CO2 emissions from international aviation covered by the scheme between 2019 and 2020 represents the basis for carbon neutral growth from 2020, against which emissions in future years are compared. In any year from 2021 when international aviation CO2 emissions covered by the scheme exceed the average baseline emissions of 2019 and 2020, this difference represents the sector's offsetting requirements for that year.

As in paragraph 9 of the Assembly Resolution, the CORSIA is implemented in phases, starting with participation of States on a voluntary basis, followed by participation of all States except the States exempted from offsetting requirements, as follows:

  • Pilot phase (from 2021 through 2023) and first phase (from 2024 through 2026) would apply to States that have volunteered to participate in the scheme; and
  • Second phase (from 2027 through 2035) would apply to all States that have an individual share of international aviation activities in RTKs in year 2018 above 0.5 per cent of total RTKs or whose cumulative share in the list of States from the highest to the lowest amount of RTKs reaches 90 per cent of total RTKs, except Least Developed Countries (LDCs), Small Island Developing States (SIDS) and Landlocked Developing Countries (LLDCs) unless they volunteer to participate in this phase.

States that voluntarily decide to participate the CORSIA may join the scheme from the beginning of a given year, and should notify ICAO of their decision to join by June 30 the preceding year.

In addition to paragraph 9 on the participation of States in the CORSIA, paragraph 10 defines the coverage of the scheme on the basis of routes between States: a route will be covered by the scheme if both States connecting the route are participating in the scheme; similarly, a route will not be covered by the scheme if one or both of States connecting the route are not participating in the scheme.

Once participation of States and routes covered by the CORSIA is defined in a given year from 2021, and offsetting requirements in the given year (i.e. increased emissions beyond the average baseline emissions of 2019 and 2020) are set, the requirements are distributed among aircraft operators participating in the scheme, as per the formula in paragraph 11 of the Assembly Resolution.

Paragraph 11 of the Assembly Resolution includes a concept of “a dynamic approach” for the distribution of offsetting requirements, which moves gradually from the use of 100 per cent sectoral approach (and 0 per cent individual approach) from 2021 to 2029, towards the use of individual approach of at least 20 per cent from 2030 to 2032; and at least 70 per cent from 2033 to 2035. “Sectoral approach” represents the international aviation sector’s global average growth factor of emissions in a given year, while “individual approach” represents an individual operator’s growth factor of emissions in a given year.

 

  • What are the design elements in the CORSIA to address “administrative simplicity”, “environmental integrity” and “cost-effectiveness”?

  • What are the design elements in the CORSIA to address “differentiation” in a practical way without impacting non-discrimination?

  • What is the rationale for the phased implementation of the CORSIA?

  • What is the difference between the pilot phase (from 2021 through 2023) and the first phase (from 2024 through 2026)?

  • Which criteria determine the participation or exemption from offsetting requirements for States under CORSIA in its 2nd phase from 2027? What is the relation of these criteria? How are RTK shares calculated?

  • What is the rationale for the route-based approach?

  • What does it mean by “participation of States and the route-based approach” and do those exempted States and operators need to do anything under CORSIA?

  • According to the route-based approach, can the characterization of a route as “covered” or “not covered” by the CORSIA change over time?

  • What would happen to the emissions coverage by CORSIA if an operator of a non-participating State flies on the routes between participating States (e.g. fifth-freedom traffic right)

  • What would happen to the emissions coverage by CORSIA if a State without an operator undertaking international flights decides to participate in CORSIA?

  • How will the CORSIA apply to aircraft operators that will initiate activities after the entry into force of the scheme (so called “new entrant”)?

  • Does the CORSIA include provisions for very low international aviation activities?

  • How are aircraft operator’s offsetting requirements calculated?

     

    According to paragraphs 9, 10, 12 and 13 of A39-3, the coverage of emissions for CORSIA offsetting requirements is based on the participation of States in different phases and the route-based approach, together with the exemptions for new entrants and for very low international aviation activities. As the total emissions covered by CORSIA are expected to increase year by year, the emissions increase above the baseline levels would be the total amount of CO2 emissions to be offset in a given year. Paragraph 11 of the Assembly Resolution A39-3 addresses the distribution of the total amount of CO2 emissions to be offset in a given year among individual aircraft operators participating in the scheme. A dynamic approach for the distribution of offsetting requirements is introduced in this paragraph, starting from the use of 100 per cent sectoral approach (and 0 per cent individual approach) and moving gradually to higher percentages of individual approach in accordance with the following steps:

    a) for the pilot and first phases as well as the first compliance cycle of the second phase (from 2021 through 2029), 100 per cent sectoral approach (and 0 per cent individual approach) would be applied. “Sectoral approach” represents the international aviation sector’s global average growth factor of emissions in a given year, which will be solely used as a single factor to all individual operators participating in the scheme for their calculation of offsetting requirements; and

    b) from the second compliance cycle of the second phase (2030 through 2032), at least 20 per cent individual approach would be applied; and at least 70 per cent individual approach would be applied from 2033 to 2035, with the Council recommending to the Assembly in 2028 whether and to what extent to adjust the individual percentage. “Individual” represents an individual operator’s growth factor of emissions in a given year, which will start to be used from 2030 together with the sectoral percentage, gradually to higher percentages of the individual percentage, in order to calculate the offsetting requirements of individual operators participating in the scheme.

    In the Assembly Resolution, dynamic approach is applied from 2030, rather than from the start of the second implementation phase (2027), which provides equal treatment between aircraft operators participating in the first and second phase of the CORSIA in terms of calculation offsetting requirements.



  • Please explain the details of the formula used to distribute offsetting requirements to individual operators.

  • Why does the baseline of 2019-2020 average emissions need to change over time?

  • How does a new entrant (or operator) affect the baseline?

  • What is the difference between the “growth factor” used by the formula under CORSIA and the generally-used term “growth rate”?

  • Why do we need to know total emissions from international aviation? Why aren’t the total emissions covered by CORSIA sufficient?

  • Does the CORSIA include provisions to review its implementation and make adjustments if needed?

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