Carbon Offsetting and Reduction Scheme for International Aviation

CORSIA is a global scheme that requires covered airlines to compensate for part of their carbon dioxide emissions from international flights. Developed by the International Civil Aviation Organization (ICAO), it combines emissions monitoring, recognition of eligible aviation fuels, and cancellation of approved carbon credits to address emissions growth.

What emissions does CORSIA address?

CORSIA addresses CO2 emissions from international aviation, rather than domestic flights or all climate effects of flying. It complements aircraft efficiency improvements, operational improvements and cleaner fuels.

• CORSIA is an offsetting scheme, not an absolute ceiling on aviation emissions: flights and their emissions may grow while airlines meet compensation obligations.
• For 2024-2035, its baseline is 85% of international aviation CO2 emissions in 2019; this provides the reference for calculating emissions growth subject to offsetting.
• The baseline does not mean that every airline must physically reduce its own emissions by 15%.

How the compliance mechanism works

The scheme links measured emissions to a calculated compensation obligation. Its effectiveness therefore depends on reliable accounting and credible emissions reductions.

• Under monitoring, reporting and verification, covered operators measure fuel use, calculate CO2 emissions and submit independently verified emissions reports through their administering states.
• An operator's offsetting requirement is calculated using emissions on covered routes and the applicable growth factor, rather than simply treating all its emissions as requiring offsets.
• Verified life-cycle emissions reductions from CORSIA eligible fuels, including qualifying sustainable aviation fuels, can reduce an operator's offsetting requirement.
• The operator must cancel sufficient CORSIA eligible emissions units to meet its remaining obligation; each unit represents one tonne of CO2-equivalent emissions reductions or removals.
• Eligibility rules address credit quality and seek to prevent double counting, so the same reduction is not claimed more than once.

Participation and environmental limits

Implementation is phased, and offsetting coverage depends on the states connected by a flight.

• The 2021-2023 pilot phase and 2024-2026 first phase involve voluntary state participation; the 2027-2035 second phase expands participation under ICAO rules, with specified exemptions.
• Offsetting generally applies to routes between two participating states, irrespective of the airline's nationality.
• CORSIA does not itself eliminate aircraft emissions: its climate value depends on genuine fuel-related reductions, credible credits and effective compliance.