• 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.
• The aviation industry is united in its support for CORSIA. Back in 2008, leaders from all sectors of the industry (airlines, airports, air navigation service providers and manufacturers) gathered together to announce a global climate action plan, which consisted of three global goals underpinned by a four-pillar strategy. The agreement of CORSIA will allow aviation to achieve its shared goal of carbon-neutral growth from 2020.

What is CORSIA?

• As the name suggests, CORSIA is a global offsetting scheme, whereby airlines and other operators will offset any growth in CO2 emissions above 2020 levels. This means that aviation’s net CO2 emissions will be stabilsed while other emissions reduction measures (such as technology, sustainable aviation fuel, operations and infrastructure options) are pursued. You can read more about offsetting and the other economic measures that were considered by ICAO 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 will CORSIA work?

• Although nearly all 191 states represented at ICAO agreed to the introduction of CORSIA, the scheme will not cover all states and operators from the outset. While the aviation industry had always been in favour of a mandatory global scheme, it was simply not possible to secure the political agreement needed from all ICAO members, due to differing circumstances and capabilities. As a compromise, it was decided that the timeline would be divided into three sections – two initial, voluntary phases (2021-2023 and 2024 – 2026) and a mandatory phase that would take place from 2027.
• During the initial stages, CORSIA will only apply to international flights between states that have volunteered to take part from the outset, meaning that all other 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 (what states are covered by these definitions are set by the UN). 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 (those whose share of global RTK is below 0.5%);

The number of volunteering states has been positive and the industry has been working hard to encourage as many as possible to volunteer before offsetting requirements begin after 2020. You can see which states have volunteered to participate in the early stages here.

As things stand, well over 80% of CO2 emissions growth over 2020 levels will be covered by the scheme and industry is hopeful that more states will volunteer as the technical requirements become clearer as we approach 2020.

Who will be offsetting?

• The question of how offsetting obligations would be divided was a source of much discussion at the ICAO technical groups that were tasked with developing the structure of the scheme. Would they be divided on an ‘individual’ level (i.e. each operator only offsets their own growth above 2020 levels) or on a ‘sectoral’ level (i.e. the overall growth in emissions in the sector would be divided between operators, based on their overall emissions)? Each approach would be beneficial to some operators and disadvantageous to others.
• To provide the highest level of fairness, it was decided that over the course of the scheme, obligations would be divided between the sectoral and individual approach, gradually moving from sectoral to individual. This approach will allow operators to become familiar with CORSIA and act accordingly. The graphic below shows how the timeline for CORSIA will work.