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FAQ: Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) explained

Here we explain the ins and outs of the UN’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) and why it is not fit to navigate airlines towards greener horizons.

What is CORSIA?

CORSIA stands for Carbon Offsetting and Reduction Scheme for International Aviation. It is a global mechanism developed by the International Civil Aviation Organisation (ICAO) to address and offset the growth in carbon dioxide emissions from international aviation above a standard reference level, with the goal of achieving what it describes as “carbon-neutral growth”.

To date, CORSIA has failed in its conflicting objective to compensate CO2 emissions while promoting growth in the aviation sector.

How does CORSIA work?

Airlines must monitor and report their emissions, and any emissions exceeding a set baseline need to be offset through the purchase of “eligible emissions” units, that is carbon credits. Initially, the baseline was set at the average of 2019-2020 emissions level, but due to the COVID-19 pandemic, and following intense lobbying from the aviation sector, in June 2020, the ICAO Council agreed to use 2019 emissions only as CORSIA’s baseline for 2021-2023. Finally, at its 41st assembly, ICAO set 85% of 2019 emissions as CORSIA’s baseline from 2024 until the end of the scheme in 2035.

The result of this lowering of the baseline is that the unambitious CORSIA has become even less ambitious, with the climate paying the price.

When did CORSIA enter into force?

The initial phase of CORSIA, called the pilot phase, ran from 2021 to the end of 2023. The first phase covers 2024 to  the end of 2026. From 2027 to 2035, there will be the second (and possibly last) phase of the mechanism. Airlines will have to demonstrate their compliance at the latest two years after the end of every three-year period.

Who is participating in CORSIA?

As of 1 January 2023, 115 states had announced their intention to participate in CORSIA. In addition, 11 more States announced their intention to participate in CORSIA from 1 January 2024, bringing the total number of participating States to 126. 

Which programmes can sell eligible units to airlines under CORSIA?

For the 2021-2023 compliance period, 11 programmes were approved by the ICAO Council: the American Carbon Registry (ACR), Architecture for REDD+ Transactions (ART), BioCarbon Fund for Sustainable Forest Landscapes (ISFL), China GHG Voluntary Emission Reduction programme, Clean Development Mechanism (CDM), Climate Action Reserve (CAR), Forest Carbon Partnership Facility (FCPF), Global Carbon Council (GCC), The Gold Standard (GS), SOCIALCARBON and Verified Carbon Standard (VCS). For some of these, various additional restrictions apply. For example, REDD+ units from the VCS are not eligible under CORSIA.

Regarding the 2024-2026 Compliance Period, only two programmes have so far received approval from the ICAO Council: the American Carbon Registry (ACR) and the Architecture for REDD+ Transactions (ART).

Is CORSIA an effective scheme for reducing aviation emissions?

No, CORSIA is not an effective scheme.  Despite being defended by the airline industry and many countries, CORSIA is an ineffective tool for decarbonising aviation. Major concerns relate to the fact that the mechanism is voluntary until 2027 when the mandatory phase will start. However, even after it becomes mandatory, there are many uncertainties on whether all countries will participate in and/or enforce the scheme. In addition to this, CORSIA only covers a small share of the aviation sector’s total climate impact. It does not deal with non-CO2 impact, it only covers international flights, and it does not cover any emissions below the baseline set by ICAO.

Moreover, the price signal of carbon offset credits is too low and will not incentivise airlines to reduce their emissions. In addition, the practice of offsetting itself is highly problematic. Finally, most of the credits that airlines have to purchase are of inadequate quality because they do not lead to permanent emissions reductions or do not provide additional benefits to the climate than would otherwise have occurred.

Note: This FAQ was updated on 29 February 2024.


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