CORSIA explained


Aviation emissions from international flights have not been included in the international climate regime administered by the United Nations Framework Convention on Climate Change (UNFCCC), as these fall outside of the scope of nationally-determined climate action. Instead, these emissions have been dealt with by the International Civil Aviation Organization (ICAO).

In October 2016, the member states of the International Civil Aviation Organization made the historic decision to adopt a global market-based measure for aviation emissions. This scheme, the Carbon Offsetting and Reduction Scheme for International Aviation – more commonly known as CORSIA – is the culmination of many years of work at ICAO, with the support of the industry.

As the name suggests, CORSIA is a global offsetting scheme, whereby airlines and other aircraft operators will offset any growth in CO2 emissions above 2020 levels. This means that aviation’s net CO2 emissions will be stabilised, while other emissions reduction measures, such as technology, sustainable aviation fuel, operations and infrastructure options, are pursued.

It is anticipated that CORSIA will mitigate around 2.5 billion tonnes of CO2 between 2021 and 2035, which is an annual average of 164 million tonnes of CO2. This is equivalent to the total annual CO2 emissions from the Netherlands across all sectors.

CORSIA helps aviation towards its mid-term goal of carbon-neutral growth from 2020 onwards.

Read more about the industry's climate action goals here.

CORSIA only applies to international flights. Domestic emissions fall under the purview of another UN agency, the UNFCCC, and are covered by the Paris Agreement.

How does CORSIA work?

To secure a political agreement in ICAO and address the concerns of developing countries, the implementation of CORSIA has been divided into three phases – two initial, voluntary phases (2021-2023 and 2024 – 2026) and a mandatory phase that would take place from 2027.

During the initial phases, CORSIA will only apply to international flights between states that have volunteered to take part, meaning that international flights to and from states that have not volunteered will be exempt.

During the mandatory stage, which begins in 2027, CORSIA will cover all international flights (including those travelling to or from states that had not volunteered for the early phases). There will, however, be some small exceptions:

  • Least developed countries, small island developing states and landlocked developing countries (the United Nations directs which states are covered by these definitions). However, these states can volunteer if they wish (and some have, showing great climate and aviation leadership)
  • States that have a very small share of international traffic

States which represent the vast majority of aviation activity have volunteered, and the industry continues to work hard to encourage as many states as possible to volunteer before offsetting requirements begin after 2020. You can see which states have volunteered to participate in the early stages here.

At the moment just under 80% of CO2 emissions growth over 2020 levels will be covered by the scheme, and the industry is hopeful that more states will volunteer as the technical requirements become clearer.

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Who will be offsetting?

Airlines and other aircraft operators will be subject to offsetting requirements, which will be determined by the CO2 they emit on flights subject to offsetting. This includes all aircraft operators, from large passenger airlines, cargo airlines, business aviation and even private aviation.

Monitoring, reporting and verification

As of 1 January 2019, all aircraft operators with emissions greater than 10,000 tonnes of CO2 will need to report their emissions to their national authority annually. To guarantee data accuracy, annual emissions reports will need to be verified by an independent third-party verification body prior to submission. Governments will then work with ICAO to inform airlines of the number of offset credits they need.

In 2018, ICAO adopted detailed requirements for the monitoring, reporting and verification of emissions as part of the Chicago Convention. These rules are essential to ensuring aircraft operators and states comply with the terms of CORSIA. Uniform requirements for the monitoring of emissions are critical to ensure all operators compete on similar terms and ensure the integrity of the scheme.

CORSIA - only one part of aviation's climate plan

We have already achieved so much. Did you know...
A flight today produces only half the CO2 it did in 1990

All sectors of the industry are working on ways to reduce fuel use and emissions further.

While the success of CORSIA is vital to aviation’s CO2 emissions plan, it is by no means the only action the industry is taking. In 2008, leaders from all sectors of the global aviation industry gathered to commit to three emissions reduction goals, Learn more about the industry’s climate action goals here [link].

Aviation is pursuing its climate action goals through a four-pillar strategy. Working to ensure the agreement on CORSIA is just one of those four pillars. To make long-term reductions in CO2, aviation is working hard to develop the other three pillars of new less carbon-intensive technology, more efficient operations, and better infrastructure. Through a combination of these four areas, aviation can reach its long-term goal of reducing CO2 emissions by 50% by 2050, compared to 2005 levels. Learn more about these pillars here.