International Aviation

Critically Insufficient4°C+ World

NDCs with this rating fall well outside of a country’s “fair share” range and are not at all consistent with holding warming to below 2°C let alone with the Paris Agreement’s stronger 1.5°C limit. If all government NDCs were in this range, warming would exceed 4°C. For sectors, the 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

NDCs with this rating fall outside of a country’s “fair share” range and are not at all consistent with holding warming to below 2°C let alone with the Paris Agreement’s stronger 1.5°C limit. If all government NDCs were in this range, warming would reach between 3°C and 4°C. For sectors, the 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

NDCs with this rating are in the least stringent part of a country’s “fair share” range and not consistent with holding warming below 2°C let alone with the Paris Agreement’s stronger 1.5°C limit. If all government NDCs were in this range, warming would reach over 2°C and up to 3°C. For sectors, the 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

NDCs with this rating are consistent with the 2009 Copenhagen 2°C goal and therefore fall within a country’s “fair share” range, but are not fully consistent with the Paris Agreement long term temperature goal. If all government NDCs were in this range, warming could be held below, but not well below, 2°C and still be too high to be consistent with the Paris Agreement 1.5°C limit. For sectors, the 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 a government’s NDCs in the most stringent part of its “fair share” range: it is consistent with the Paris Agreement’s 1.5°C limit. For sectors, the rating indicates that the target is consistent with the Paris Agreement’s 1.5°C limit.

Role model<< 1.5°C World

This rating indicates that a government’s NDC is more ambitious than what is considered a “fair” contribution: it is more than consistent with the Paris Agreement’s 1.5°C limit. No “role model” rating has been developed for the sectors.

1.5°C Compatible< 1.5°C World

Overview

ICAO target	Formulation of target	Carbon neutral growth from 2020 onwards
	Coverage	CO₂ only

IATA 2050 target	Formulation of target	Net zero carbon by 2050
	Coverage	CO₂ only

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 – set at the average emissions level in 2019-2020 (paragraph 11, ICAO Assembly, 2016).

Due to COVID-19, aviation emissions in 2020 were substantially lower than anticipated, which would have meant the baseline for carbon neutral growth would have been lower than anticipated and the target more ambitious.

However, in June 2020, 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). Based on the outcome of the CORSIA periodic review, which starts in 2022, the ICAO Council will decide on the rules for CORSIA’s first and second phases starting in 2024.

Because the baseline for 2024 and beyond is currently uncertain, we use a range for the baseline. Emissions in 2019 form the upper bound and average emissions in 2019 and 2020 the lower bound. ICAO reports that 2019 emissions amounted to 606 MtCO₂ and 2020 emissions to 265 MtCO₂.

We rate the target of carbon neutral growth from 2020 as ‘Critically insufficient’. Under the CAT’s rating methodology, the upper end of the target range in 2030 alone would be rated ‘Highly insufficient’. Because the international aviation sector plans to rely on emission units and alternative fuels that are unlikely to deliver sufficient real emission reductions, we downgrade the rating to ‘Critically insufficient’. If the baseline were to be the average of emissions in 2019 and 2020, the 2030 target emission levels would fall in the ‘Insufficient’ range. The CAT would downgrade this rating to ‘Highly insufficient’ for the reasons mentioned above.

A further shortcoming of ICAO’s approach is it does not address indirect GHG emissions and impacts– such as NOX and contrail cirrus. These emissions and impacts 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 300 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

Researchers found that with 2019 emissions as the baseline for carbon neutral growth, aircraft operators face limited to no offsetting obligations in CORSIA’s pilot phrase from 2021 to 2023 (Schneider and Graichen, 2020). If the rules had remained unchanged and average 2019-2020 emissions had been taken as the baseline, COVID-19 would not have substantially changed the offsetting requirements that airlines face under the scheme because the lower baseline and lower future emissions would have cancelled each other out (Schneider and Graichen, 2020).