CORSIA Explained: Global Carbon Offsetting for International Flights

In 2016, the International Civil Aviation Organisation (ICAO) adopted the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA).

CORSIA aims to tackle CO2 emissions from international aviation through a market-based carbon credit scheme.

Under this scheme, aviators must offset their emissions according to a specified threshold.

Operators whose total CO2 emissions from international flights are greater than or equal to 10,000 tonnes must sign up to CORSIA’s Monitoring, Reporting, and Verification (MRV) system.

Once enrolled in the MRV, aviators who exceed the CORSIA baseline must offset their emissions.

This can be done in several ways. Airline operators can either purchase and retire eligible carbon credits called Eligible Emissions Units, or EEUs.

Alternatively, airline operators can claim emissions reductions from fuels that meet defined sustainability criteria. These CORSIA eligible fuels (CEF) include sustainable aviation fuels (SAF), which are renewables, as well as “lower carbon aviation fuels,” which are fossil-based.

What is CORSIA: Exploring Global Carbon Offsetting for International Flights

The purpose of CORSIA, according to the ICAO, is to “complement other aviation in-sector emissions reductions efforts such as technological innovations, operational improvements and sustainable aviation fuels to meet the ICAO goal of carbon neutral growth.”

In this way, CORSIA can be thought of as a way of encouraging decarbonisation. Where an airline's international emissions exceed their allocated share, that airline will then need to acquire credits representing equivalent CO₂ reductions achieved elsewhere.

While some national carbon pricing schemes do exist, such as the UK ETS, these alone aren’t enough to combat the climate cost of international aviation.

Placing a price on carbon creates the incentive for emissions reductions in a cost effective and technology-neutral way, while mobilising the private sector to invest in emissions reduction measures.

CORSIA is designed to help achieve ICAO’s medium-term goal of carbon-neutral growth from 2020, by ensuring that the growth in emissions above the baseline is offset by an equivalent reduction in emissions in other sectors meaning net emissions remain at the baseline level. 

How CORSIA Aviation is Being Implemented

ICAO recognised from the outset that implementing a genuinely global scheme across nearly 200 member states with vastly different economic circumstances and aviation sectors would require a phased approach.

With this in mind, until 2027, the first phase of CORSIA will remain voluntary. However, for the 130 or so participating states who have volunteered, it will be compulsory.

However, from 1^st January 2027 onwards, with some exemptions, such as Least Developed Countries (LDCs) and Small Island Developing States (SIDS), participation will become mandatory.

At this point, ICAO member states will be obligated to offset any CO2 emissions that exceed the baseline. These offsets can be achieved by purchasing SAF credits, or CORSIA-eligible emissions units (EEUs).

Additionally, as a key component of both the phases, airlines will need to engage in Monitoring, Reporting, and Verification (MRV). The MRV framework ensures that emissions are properly tracked and externally verified. In some circumstances, operators may be eligible to use a simplified monitoring protocol to estimate their emissions.

This can be done through ICAO’s own CORSIA CO₂ Estimation and Reporting Tool (CERT).

In most instances, however, to ensure accuracy, airlines will be required to monitor actual fuel consumption per flight.

This can be done using the ICAO’s CO₂ Estimation Models (CEMs).

CORSIA Aviation in the Climate Policy Landscape

Within the climate policy landscape CORSIA's role is to complement existing climate frameworks, such as voluntary carbon markets and the EU and UK ETS. The UK and EU ETS, for instance, typically cover domestic flights or flights within their respective regions.

CORSIA picks up where these regional schemes leave off, targeting international routes that fall outside the UK ETS’s domestic scope and the EU ETS’s jurisdiction.

The scheme's design allows for strategic interaction with other carbon pricing mechanisms through specific exemption rules.

Flights already covered by another emissions trading system (e.g., intra-EEA routes under the EU ETS) are excluded from CORSIA's offsetting requirements to prevent double regulation of the same emissions.

The exemption extends to routes where both departure and arrival states have opted into regional carbon pricing, creating a hierarchy where regional schemes take precedence over CORSIA's global framework.

At present, airline operators calculate their offsetting commitments based on the sector’s overall emissions growth. From 2030, however, the offsetting methodology will change: airlines will face obligations tied directly to growth on the specific routes they operate.

For instance, if the emissions on a New York to London route increase by 15%, carriers flying that route will bear offsetting requirements proportional to that growth. This shift is intended to incentivise emissions reductions on high-emission international routes while maintaining CORSIA’s global scope.

Understanding CORSIA's Practical Implications

For businesses involved in international operations, CORSIA creates both compliance requirements and strategic considerations. To ensure CORSIA's environmental integrity, the ICAO Council periodically approves a list of programmes that can supply CORSIA Eligible Emissions Units (EEUs) to be used for compliance.

The Council's decision is informed by recommendations from the Technical Advisory Body and guided by environmental criteria to guarantee that emissions units deliver the required CO₂ reductions. These criteria are based on principles commonly applied under existing trading mechanisms and well-accepted carbon offset certification standards.

According to projections from September 2024, the demand for CORSIA EEUs in the First Phase (2024 to 2026) is expected to lie between 146 – 236 million tonnes.

However, one of the most significant barriers to CORSIA compliance concerns the delay in the issuance of letters of authorisation and performance of "corresponding adjustments".

This process must be conducted by host countries (where CORSIA EEUs are generated) to address concerns regarding double claiming - ensuring that host countries do not count emissions reductions claimed by aircraft operators under CORSIA towards their Paris Agreement pledges.

Navigating CORSIA: Strategic Planning with CFP Energy

CORSIA plays a pivotal role in aviation’s effort to manage emissions growth.

To comply with CORSIA international airline operators must monitor, report and verify their CO2 emissions, while setting out a roadmap for offsetting emissions where the baseline is exceeded. 

At CFP Energy, we can create a bespoke compliance strategy to ensure you stay on target.

We supply eligible carbon offset credits to comply with the CORSIA scheme.

With 20 years’ experience in carbon markets, and as a winner of 3 Environmental Finance awards in spot trading and options & futures, our team is perfectly placed to help you meet your CORSIA obligations.

Our team can supply instant access to CORSIA-eligible carbon credits. These ensure that your emissions status remains compliant within the CORSIA framework, even if you go above the baseline.

Our extensive offering in sustainable fuels also means we can supply SAF credits.

To stay informed about ongoing CORSIA developments, or to access our carbon or SAF credit solutions, please contact our team today.