International Aviation

Critically Insufficient4°C+ World

This rating indicates that the target is consistent with warming of greater than 4°C if all other sectors were to follow the same approach.

Highly insufficient< 4°C World

This rating indicates that the target is consistent with warming between 3°C and 4°C if all other sectors were to follow the same approach.

Insufficient< 3°C World

This rating indicates that the target is consistent with warming over 2°C and up to 3°C if all other sectors were to follow the same approach.

2°C Compatible< 2°C World

This rating indicates that the target is consistent with holding warming below, but not well below, 2°C if all other sectors were to follow the same approach.

1.5°C Paris Agreement Compatible< 1.5°C World

This rating indicates that the target is consistent with the Paris Agreement’s 1.5°C limit.

Target overview

2020-2035	Target	Carbon neutral growth from 2020
	Coverage	CO₂ only
2050	Target	Net zero carbon by 2050
	Coverage	CO₂ only

2050	Target	Net zero carbon by 2050
	Coverage	CO₂ only

Net zero target

ICAO’s long-term aspirational goal of “net zero carbon” by 2050 lacks any real emissions reductions commitments and is unlikely to incentivise the deep reductions needed in the aviation sector. The ICAO Assembly did not specify to what extent the target will be met by real emission reductions within the sector, leaving the door open to the use of contentious offsetting outside of the sector (ICAO, 2022d; ICAO Assembly, 2022a).

The long-term target is not underpinned by a clear decarbonisation plan or interim reduction targets, meaning there is no clear signal for deep decarbonisation in the short and medium term. The ICAO Assembly placed prime responsibility for reducing aviation emissions with national governments, giving the ICAO Council a coordinating role (ICAO Assembly, 2022a; Mithal & Rutherford, 2023). However, since the adoption of the long-term aspirational goal, none of the countries with high aviation emissions have submitted a concrete State Action Plan to ICAO, outlining how their national efforts will contribute to decarbonising the aviation sector (for more information on country action, see the National policies section).

While non-CO₂ emissions and climate impacts, such as NOx and contrail cirrus, are estimated to account for two-thirds of aviation’s radiative forcing impact (Lee et al., 2021), ICAO’s long-term target does not cover these.

We could not quantify ICAO’s aspirational long-term target due to a lack of information on what residual emissions are expected to remain by 2050 and beyond. Any residual emissions from the aviation sector would need to be counterbalanced with carbon dioxide removals (CDR).

Ahead of the 41st Assembly, during which ICAO Member States adopted the long-term goal, ICAO’s Committee on Aviation Environmental Protection (CAEP) developed three scenarios on this goal. These scenarios lead to CO₂ emission levels in a range of 70% below 2019 levels to 50% above 2019 levels (200–950 MtCCO₂) by 2050. These emission levels lie above the Paris Agreement 1.5ºC compatible level. If ICAO’s agreed long-term aspirational goal of “net zero carbon” falls within the range of emission levels explored by the CAEP, the CAT would rate the target as ‘2ºC compatible’ at best and ‘Critically insufficient’ at worst, consistent with at least 2˚C of warming, if not 4˚C.

Carbon neutral growth

In 2013, the ICAO Assembly set an aspirational goal for international aviation of carbon neutral growth from 2020 levels (ICAO, 2013). Carbon neutral growth means that net CO₂ emissions from international aviation remain constant compared to the baseline. Originally, ICAO set the baseline as the average of 2019 and 2020 CO₂ emissions (paragraph 11, ICAO Assembly, 2016).

However, due to the COVID-19 pandemic, aviation’s emissions dropped by over 50% between 2019 and 2020, meaning the 2020 baseline for carbon neutral growth would have been substantially lower than anticipated and the target more ambitious. Following a request from IATA, the ICAO Council changed the reference year for CORSIA’s pilot phase to 2019, missing an opportunity to commit to a more ambitious target (IATA, 2020; ICAO, 2020d). At the 41st ICAO Assembly in October 2022, Member States agreed to a baseline of 85% of 2019 emission levels (515 MtCO₂) for the first and second phase, from 2024 to 2035 (ICAO, 2022d; ICAO Assembly, 2022b).

We rate the target of carbon neutral growth from 2020 as ‘Highly insufficient’. Under the CAT’s rating methodology, the target in 2030 would be rated ‘Insufficient’. We downgrade the rating to ‘Highly insufficient’ for three reasons: (1) the international aviation sector plans to rely on offsetting through CORSIA emissions units and alternative fuels that are unlikely to deliver sufficient real emission reductions, (2) the target is likely to cover less than 50% of international aviation’s emissions, and (3) it does not address indirect GHG emissions and impacts, such as NOX and contrail cirrus, which are responsible for an estimated two-thirds of aviation’s effective radiative forcing impact (Lee et al., 2021).

To be Paris Agreement compatible, carbon emissions from international aviation should be below 350 MtCO₂ in 2030 and decrease to zero by 2060. The sector should also take measures to substantially reduce non-CO₂ climate impacts. The carbon neutral growth goal is insufficient to reach these required emission levels.

Impact of COVID-19 on the CORSIA baseline

By deciding to take 2019 emissions as the baseline for CORSIA’s pilot phase and 85% of 2019 emissions for the first and second phase, ICAO watered down the already weak goal of ‘carbon neutral growth’.

As emissions from international aviation were below CORSIA’s baseline in 2021 to 2023, aircraft operators faced very limited offsetting obligations to date. We expect that emissions in 2024 will reach 2019 levels and continue to increase over the coming years, so offsetting obligations will become more significant.