Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA)


In October 2016, the 39th General Assembly of ICAO Contracting States reconfirmed the 2013 objective of stabilising CO2 emissions from international aviation at 2020 levels. In addition, the States adopted Resolution A39-3 [81], aiming to introduce a global marketbased measure, namely the ‘Carbon Offsetting and Reduction Scheme for International Aviation’ (CORSIA), to offset international aviation’s CO2 emissions above 2020 levels through international credits. This major milestone, almost 20 years after the Kyoto Protocol to the UN Framework Convention on Climate Change, had called on States to work through ICAO to address international aviation emissions, and after the entry into force of the Paris Agreement, came as a result of the strong and sustained support by European States to address international emissions from aviation at a global level.

Since the end of 2016, international experts have been working in ICAO on the technical elements necessary for CORSIA’s implementation. In June 2018, the ICAO Council approved the associated Standards and Recommended Practices (SARPs). To date, work is continuing on the additional ‘Implementation Elements’, which notably include rules on eligible fuels and emission units that can be used to comply with CORSIA offsetting requirements. Participating States will have to adopt the necessary national law in order to implement the provisions of CORSIA.

Europe’s commitment towards CORSIA
On 3 September 2016, before the 2016 ICAO Assembly, the Directors General of Civil Aviation of EU Member States and the other Member States of the European Civil Aviation Conference (ECAC) signed the ‘Bratislava Declaration’. This signalled their intention to fully implement CORSIA from the start of the pilot phase, provided that certain conditions were met, notably on the environmental integrity of the scheme and global participation. The Bratislava Declaration illustrated the commitment of the EU and ECAC States to address the growth of CO2 emissions from international air transport and to achieving overall carbon neutral growth from 2020.

CORSIA scope and timeline

All aeroplane operators with international flights producing annual CO2 emissions greater than 10,000 tonnes from aeroplanes with a maximum take-off mass greater than 5,700 kg, regardless of whether their administering State is participating or not in the offsetting phases, will be required to monitor, verify and report their CO2 emissions during 2019 and 2020. Humanitarian, medical and firefighting operations are exempted. The average yearly CO2 emissions reported during that period will represent the baseline for carbon neutral growth from 2020. Beyond 2020, the aviation sector will be required to offset its international CO2 emissions above this level.

CORSIA comprises of three implementation phases: the pilot phase (2021-2023), a first phase (2024-2026) and a second phase (2027-2035). During the pilot phase and first phase, offsetting requirements will only be applicable to flights between States that have volunteered to participate. As of 5 November 2018, 76 States have officially notified ICAO that they intend to voluntarily participate in the pilot and first phase of CORSIA, representing approximately 76% of international aviation activity in terms of Revenue Tonne Kilometres (RTKs). States can notify their intentions for the year 2021 up until 30 June 2020, and thereafter on an annual basis during the voluntary period. The second phase will apply to all ICAO Member States within the agreed applicability scope, with certain exemptions:

  • States with an individual share of international aviation activities in RTKs in year 2018 below 0.5% of total RTKs;
  • States that are not part of the list of States that account for 90% of total RTKs when sorted from the highest to the lowest amount of individual RTKs; or
  • Least Developed Countries (LDCs), Small Island Developing States (SIDS) and Landlocked Developing Countries (LLDCs).

However, States covered by the exemption criteria above can volunteer to participate. The contribution of CORSIA to stabilise international aviation emissions at 2020 levels is to some extent reliant on the level of participation of States in CORSIA.

CORSIA operates on a route-based approach and applies to international flights, i.e. flights between two ICAO States. A route, defined by a pair of States, is covered by CORSIA offsetting obligations if both the State of departure and the State of destination are participating in the Scheme, and in this case the obligations are applicable to all aeroplane operators on the same route.


Figure 6.320

20 Based on the information from ICAO website on States that have communicated their intention to volunteer to participate in offsetting CO2 emissions from 2021 to 2026, accessed 5 November 2018, and latest 2016 ICAO data on States’ individual share of the total international RTKs.

CORSIA in practice

Each international flight within the scope of CORSIA is attributed to an aeroplane operator, and each aeroplane operator is attributed to a State to which it has to submit an Emissions Monitoring Plan. Aeroplane operators monitor, verify and report their fuel use according to the approved plan, while their annual emissions offsetting requirements are calculated by the State. The monitoring of emissions applies to all flights, including those not subject to offsetting requirements. Offsetting requirements are calculated according to a dynamic approach to take into account the growth of the aviation sector and that of an individual aeroplane operator.

Aeroplane operators meet their offsetting requirements on a 3-year compliance period basis by purchasing and cancelling CORSIA eligible emissions units. Details on the cancellation of units, which must be verified by an independent verification body, are finally submitted by the aeroplane operator to its State. Aeroplane operators can reduce their offsetting requirements by using CORSIA eligible fuels that meet CORSIA sustainability criteria.

Capacity building activities

In 2013 the European Commission launched a project entitled “Capacity building for CO2 mitigation from international aviation”, with a total budget of €6.5 million covering 12 African States and 2 Caribbean States. This 4.5-year project, implemented by ICAO, improved the capability of less developed countries to measure, manage and reduce their aviation emissions in order to support their submission of ICAO State Action plans. The project contributed to international, regional and national efforts to address growing emissions from international aviation through a complementary set of activities.

Preceding the ICAO Assembly of October 2016, a declaration of intent was signed between Transport Commissioner Violeta Bulc and ICAO Secretary General Dr Fang Liu, announcing their intention to continue cooperation in addressing climate change, which included the implementation of CORSIA. Various EU international cooperation projects have subsequently been put in place during 2017 and 2018 to provide capacity building and technical assistance in the regions of China, South Asia, South East Asia, Africa and Latin America, including the Caribbean. While operating in different contexts each with their specificities, these projects all share the objective to pave the way for the practical implementation of CORSIA and the establishment, or further development, of effective State Action Plans targeting aviation emissions.

EASA and EUROCONTROL are also supporting the European Commission on the implementation of CORSIA both within Europe and internationally. This includes developing CORSIA functionality based upon the ETS Support Facility with a focus on collecting and harmonising data for monitoring, reporting and verification processes, and the execution of international cooperation programmes to continue capacity building that addresses aviation’s climate impact around the world.

What is the difference between the EU ETS and CORSIA?

The EU Emissions Trading System (ETS) is a cap-and-trade system, which sets a limit on the number of emissions allowances issued, and thereby constrains the total amount of emissions of the sectors covered by the system. In the EU ETS, these comprise operators of stationary installations (heat and power as well as industry) and aircraft operators. The total number of emissions allowances is limited (‘capped’) and decreases over time, thus ensuring that the objective of an absolute reduction of the level of CO2 emissions is met at the system level. In the case of the EU ETS, this is expected to lead to an economy-wide emissions reduction of 43% in 2030 compared to 2005 levels for the sectors covered by the ETS. The gradually more limited supply of allowances drives operators in need of additional allowances to buy them on the market from other sectors in the system – hence cap-andtrade. The need for additional allowances is determined by an operator’s free allocation of allowances and actual emissions. The supply and demand for allowances establishes their price under the ETS, and the higher the price, the stronger the incentive to reduce emissions. As of September 2018, EU Allowances for CO2 emissions were being traded at over €20 per tonne.

The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is an offsetting scheme. An offsetting scheme is a cost-effective solution for the aviation industry, as emissions reductions that cannot be achieved in the aviation sector can be compensated through emission reductions in other sectors where the potential for quicker reductions is greater and the associated costs are lower. This is based on the premise that greenhouse gas emission reductions benefit the climate irrespective of the sector in which they occur. The objective of CORSIA is to reach Carbon Neutral Growth 2020 - that is, to ensure that the emissions from international aviation do not exceed the 2020 levels. To that end, aeroplane operators will be required to purchase offset credits in order to compensate for emissions exceeding the 2019-2020 baseline. These offsets, also known as emission units, will be made eligible under CORSIA for purchase by aeroplane operators, provided that they comply with an established set of Emission Unit Criteria adopted at ICAO level. The eligible units contribute to achieving emissions reduction in various sectors of the economy, such as renewable energy or waste management. Each offset credit represents the certification that a tonne of CO2 has been reduced or avoided compared to a scenario without CORSIA, meaning that the reduction would not have occurred in the absence of the offset-generating activity.

It is worth noting that ETS allowances are not currently accepted under CORSIA, and international offset credits, including those deemed to be eligible under CORSIA, will not be accepted under the ETS as of 1 January 2021.