The International Civil Aviation Organization (ICAO), the UN agency responsible for regulating international aviation, set a goal of “carbon neutral growth from 2020” levels. The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) it has set up to achieve this goal is extremely unlikely to do so: it will probably cover less than half of international aviation emissions between now and 2035 and is likely to allow compensation without real emission reductions elsewhere. Further, CORSIA is planned to end in 2035 and ICAO currently has no plans for the period after that. The CAT rates the international aviation sector’s carbon neutral growth goal as ‘Critically insufficient’.
In recent years, international aviation emitted about 600 MtCO2 per year, or 1.2% of global GHG emissions. The sector’s share of global emissions is expected to increase in the future – both because other sectors will decarbonise and because demand for international aviation is expected to grow.
In 2013, ICAO adopted the aspirational goal of ‘carbon neutral growth from 2020’. This means that net CO2 emissions would remain constant on a net basis compared to 2020. A significant shortcoming of this aspirational goal is that it covers only CO2 emissions and not other GHG emissions and climate impacts. Efforts to reduce the climate impact from international aviation must include the full scope of climate effects and aim to bring all emissions to zero.
In 2016, ICAO established CORSIA, a global, market-based measure, which is expected to be the main international instrument to achieve the carbon neutral goal. CORSIA has significant shortcomings in that the scheme is highly unlikely to deliver the substantial reductions needed to achieve ICAO’s aspirational goal. Various countries, including the big emitters China, Brazil, India and Russia have filed “reservations” regarding critical aspects of CORSIA and are not participating in the scheme’s pilot phase, which started in January 2021 and runs until December 2023. Other large and fast-growing aviation markets will also not participate in the pilot and first phases through to 2027, which are voluntary. Assuming these countries continue their non-participation, CORSIA is likely to cover less than 50% of international aviation CO2 emissions in the period 2021-2035.
There are also concerns over the quality of emissions offset units allowed to be used within CORSIA and over the low emissions reduction potential of alternative fuels that airlines can use under CORSIA. Critically, CORSIA does not provide the required incentives for the industry to invest in mitigation technologies that can ultimately result in the required complete decarbonisation of the sector.
As a result of COVID-19, 2020 emissions are substantially lower than previously anticipated, which would have resulted in a more ambitious baseline. However, after pressure from the aviation industry, the ICAO Council decided to revise the rules for the baseline and take 2019 as the only reference year for CORSIA’s first three years. This decision is likely to eliminate any offsetting obligation under CORSIA’s pilot phase and substantially further weaken CORSIA. The ICAO Assembly will decide in 2022 whether 2019 emissions will also form the baseline for the rest of CORSIA’s planned scheme until 2035.
In 2020, demand for all aviation was 66% lower than in 2019, with demand for international aviation dropping by 76%. The International Air Transport Association (IATA) expects that demand for all aviation will be 50% lower in 2021 than in 2019, with a likely larger drop in demand for international air travel. We estimate that emissions will decrease at the same rate, as airlines fly with fully booked planes as much as possible. However, despite the substantial decrease in emissions from international aviation in 2020 and 2021, the CAT projects that international aviation emissions will double - and possibly almost triple - between 2015-2050.
The CAT now projects that emissions from international aviation could increase by 190-277% between 2015 and 2050, as compared to a 230-310% projected increase pre-COVID-19. The larger the increase in CO2 emissions, the more difficult it will be for international aviation to hold even “net” emissions to 2020 levels.
The CAT rates the target of carbon neutral growth from 2020 as ‘critically insufficient’. It is uncertain what CORSIA’s baseline will be after 2023, therefore we have taken a range for the baseline of carbon neutral growth. Emissions in 2019 form the upper bound (609 MtCO2) and average emissions in 2019 and 2020 the lower bound (445 MtCO2). The upper end of that range alone would be rated ‘insufficient’, but we have downgraded the rating of ‘carbon neutral growth’ to ‘critically insufficient’ as CORSIA has significant shortcomings and is unlikely to deliver this goal.
ICAO Member States have the potential to strengthen the sector’s emission target by retaining the original methodology agreed to establish its baseline; however further work is needed to set a Paris-compatible target, fix the shortcomings of CORSIA and incentivise the decarbonisation of the sector through sustainable fuels, energy efficiency improvements and demand management.
In the absence of meaningful action by ICAO, a few states have started to address international aviation emissions themselves. Specifically, the United Kingdom includes them in its sixth carbon budget and will extend its 2050 net zero target to cover emissions from international bunkers. As part of its ‘Fit for 55’ package, the European Union has proposed introducing a tax on kerosene on intra-EU flights, to require aircraft operators to blend a minimum of sustainable aviation fuel (SAF) into their kerosene from 2025 onward, and to amend the EU Emissions Trading System to reduce the overall cap, adjust the market stability reserve, and phase out the free allocation of allowances for aviation from 2026.
ICAO envisages that the carbon neutral growth goal will be met through a basket of measures, including improvements in the technology and operational aspects of aircraft, alternative jet fuel, and the use of CORSIA.
ICAO Member States expect CORSIA to play a major role in addressing any increase of CO2 emissions above the goal’s baseline. Under the scheme, aircraft operators can compensate for any increase in aggregate CO2 emissions on routes that are covered by the scheme through the purchase and retirement of emission units, which to be effective would need to represent real, additional and permanent emission reductions or removals elsewhere. Alternatively, aircraft operators may use ‘CORSIA eligible fuels’, which are defined as lower carbon or sustainable aviation fuels that meet the CORSIA sustainability criteria.
For CORSIA to deliver on the ICAO carbon neutral growth goal, it is crucial that all countries participate; that alternative fuels used to comply with the scheme deliver substantial emission reductions; and that the emissions units that airlines purchase and cancel represent real, additional and permanent emissions reductions elsewhere. It is, however, doubtful whether any of these conditions will be met. As noted above, CORSIA is likely to cover less than 50% of international aviation CO2 emissions over its planned timespan of 2021-2035. Also, the programmes generating emissions units eligible under CORSIA’s pilot phase (2021-2023) are heterogenous and inconsistent in how they meet the environmental integrity criteria approved by the national representatives on the ICAO Council.
The rules for what constitute CORSIA-eligible fuels are also weak. For instance, the rules require fuels that deliver at least a 10% emissions reduction compared to standard aviation fuels, which - depending on further rulemaking - could potentially allow for a wide range of fossil fuels to be used as ‘CORSIA eligible fuels’. Although rules for the lifecycle emissions of fuels could lead to a reduction of the carbon intensity of a share of the fuel used, they alone are unlikely to steer the sector towards the use of zero carbon synthetic fuels which need to be scaled up in order to reach the Paris Agreement goals.