At its 37th Assembly held in 2010, the ICAO adopted the control of carbon dioxide (CO₂) emissions from international civil aviation as one of its principal policy objectives. The first concrete step taken in this direction was the adoption of the “Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA)” at the 39th Assembly in 2016. CORSIA constitutes the first global market-based measure in this field. In essence, it is a programme requiring airline operators to purchase “carbon credits” within certain quotas and, in other words, to contribute indirectly to the reduction of global greenhouse gas emissions through an offsetting mechanism.

In line with the principle of “common but differentiated responsibilities and respective capabilities (CBDR-RC)”, which is well established in climate change law, CORSIA seeks to ensure a fair distribution of obligations among countries with differing levels of development. Accordingly, a balance has been struck between countries whose aviation sectors have reached a certain level of maturity, such as the United States and European Union member states, and countries with emerging aviation markets experiencing more rapid growth. In this context, CORSIA consists of a voluntary “pilot phase” (2021–2023), a likewise voluntary “first phase” (2024–2026), and finally a mandatory “second phase” (2027–2035), in which participation is envisaged for all countries whose aviation sectors exceed a specified economic threshold. Least Developed Countries (LDCs), Small Island Developing States (SIDS), and Landlocked Developing Countries (LLDCs) are exempt from CORSIA.

CORSIA has become part of Annex 16 to the Chicago Convention, which sets out environmental standards, while the detailed rules governing its implementation are published as the ICAO documents.

Türkiye has been among the voluntary participants in CORSIA since its inception. As of 1 January 2026, the number of States that have declared their intention to participate in CORSIA stands at 130.

ICAO’s second major step in the field of climate change and decarbonization was the adoption of the Long-Term Aspirational Goal (LTAG) on carbon emissions at the 41st Assembly in 2022. LTAG aims to achieve net-zero carbon emissions from international aviation by 2050 in support of the temperature goals of the UNFCCC Paris Agreement. This objective represents a historic consensus reinforcing ICAO’s leadership on matters relating to international aviation and climate change.

LTAG does not impose specific obligations or commitments on States in the form of individual emission reduction targets. Rather, it considers the particular circumstances and capabilities of each State, including factors such as levels of development, the maturity of aviation markets, and the sustainable growth of international aviation.

Sustainable Aviation Fuels (SAF) are defined as renewable or waste-derived aviation fuels that meet sustainability criteria. ICAO considers SAFs to hold the greatest short- and medium-term potential for reducing CO₂ emissions from international aviation. For this reason, SAFs meeting ICAO-established criteria are encouraged, under both CORSIA and LTAG, to be produced on a larger scale and gradually replace conventional fossil-based aviation fuels.