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.
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.