CORSIA Today: Where It Sits and What Comes Next
The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is entering a more substantive phase of implementation. After years of policy development and early testing, the scheme is now beginning to translate into real demand for emissions reductions from international aviation. While CORSIA will continue to evolve, it is increasingly shaping how airlines, governments, and project developers approach decarbonisation over the coming decade.
CORSIA in Context
International aviation contributes around 2–3% of global CO₂ emissions, with passenger demand expected to continue growing. While improvements in aircraft efficiency and operational practices are ongoing, and sustainable aviation fuels (SAF) are gaining momentum, these solutions alone are unlikely to fully address near-term emissions growth. SAF currently accounts for well below 1% of global jet fuel consumption, and large-scale deployment will take time.
CORSIA was established by the International Civil Aviation Organization (ICAO) to complement these longer-term solutions. The scheme aims to stabilise net CO₂ emissions from international aviation by requiring airlines to offset emissions above a defined baseline using eligible carbon credits or reductions achieved through SAF use. For the current compliance cycle, this baseline is set at 85% of 2019 emissions, reflecting adjustments following the disruption to aviation activity during the pandemic.
Where CORSIA Sits Today
CORSIA is currently in Phase I (2024–2026). Participation by States remains voluntary during this phase, although many major aviation States have opted in, meaning a significant share of international aviation activity is already covered.
Importantly, CORSIA is now moving beyond reporting. ICAO has published annual sectoral growth factors, allowing offsetting requirements for 2024 emissions to be calculated. At the same time, eligibility criteria for emissions units have been defined, establishing clearer parameters around which credits can be used for compliance.
While the pool of CORSIA-eligible credits remains limited at this stage, this is a natural feature of a scheme that places a strong emphasis on environmental integrity and alignment with international climate frameworks. As Phase I progresses, the foundations are being laid for increased credit availability and greater market participation.
Looking Ahead: Growing Demand and Supply Response
From 2027, CORSIA participation becomes mandatory for most States with significant international aviation activity, increasing demand for eligible emissions units. Even during Phase I, participating airlines are beginning to engage with the market, signalling the importance of early, credible supply.
Meeting this demand will require the development of high-quality projects that are designed from the outset to meet CORSIA’s eligibility and integrity requirements, including host country authorisation and robust monitoring and verification. As these frameworks mature, they provide clearer signals for long-term investment in emissions reduction projects.
Sustainable aviation fuels will continue to play an important role in reducing aviation’s carbon footprint, but offsets are expected to remain a core component of compliance for the foreseeable future, particularly during the 2020s.
Carbon Horizon’s Role in Supporting CORSIA
As CORSIA develops, the availability of emissions reduction projects that are designed to meet the scheme’s eligibility requirements is becoming increasingly important. Carbon Horizon is focused on the development of projects intended to generate CORSIA-eligible credits, with a view to supporting compliance during Phase I and into later phases of the scheme.
This work involves engaging with the evolving CORSIA framework, including eligibility criteria, host country authorisation processes, and requirements related to monitoring, reporting, and verification. By developing projects with these considerations in mind from an early stage, Carbon Horizon aims to contribute to a growing pool of credits that align with CORSIA’s integrity objectives.
As participation expands and demand increases over time, the role of project development will be central to ensuring that CORSIA functions as intended, providing airlines with access to credible emissions reductions while supporting broader climate goals.
Why CORSIA Matters
CORSIA represents an important step in addressing emissions from a global, hard-to-abate sector. While it is not a standalone solution, it provides a practical framework for managing near-term emissions growth while longer-term decarbonisation pathways develop.
As the scheme continues to mature, collaboration between regulators, airlines, and project developers will be key. With increasing clarity around rules and participation, CORSIA is helping to create a more stable and predictable environment for investment in high-integrity emissions reduction projects, supporting both aviation’s climate goals and the broader transition to a lower-carbon economy.
Written By: Benjamin Michelson
