International Aviation

Note: This page does not reflect the announcements made at the ICAO Assembly in September 2022. The next update will.

The International Civil Aviation Organization (ICAO), the UN agency responsible for regulating international aviation, has no long-term climate target, and none of the scenarios for upcoming discussions around a ‘Long-Term Aspirational Goal’ are anywhere near Paris Agreement compatible. To bring the sector into line with the Paris Agreement 1.5˚C temperature goals, the international aviation industry needs to reduce CO₂ emissions by 90% below 2019 levels by 2050 (70 MtCO₂), along with making deep cuts to non-CO₂ emissions.

Ahead of the 41st meeting of the ICAO Assembly (starting 27 September 2022), ICAO’s Committee on Aviation Environmental Protection (CAEP) has developed three scenarios to inform discussions on the long-term goal. However, these scenarios lead to CO₂ emission levels in a range of 70% below 2019 levels to 50% above those levels (200–950 MtCO₂) by 2050, well above the Paris Agreement compatible level, and they also do not address aviation’s non-CO2 emissions and other impacts. The CAT would rate a target within this range as ‘Highly insufficient’ at best and ‘Critically insufficient’ at worst, consistent with at least 3˚C of warming, if not 4˚C.

While the other key industry body, the International Air Transport Association (IATA), has committed to net zero carbon from aviation by 2050, this target depends on offsetting for about 20% of reductions and also does not address non-CO₂ emissions. The CAT evaluates this target as ‘Highly insufficient’.

It is notable that as a result of the failure of ICAO to take appropriate action over the past 25 years the EU, USA and UK are gradually moving to bring international aviation emissions within their domestic emissions limits and targets.

Prior to the outbreak of the COVID-19 pandemic, international aviation emitted about 600 MtCO₂ per year, or 1.2% of global GHG emissions. CO₂ emissions from international aviation were 50% lower than in 2019 in both 2020 and 2021. We estimate that CO₂ emissions in 2022 will amount to approximately 475 Mt, or 75% of 2019 levels. Based on ICAO’s projections, we estimate that without strong action to address them, emissions from international aviation will double or even triple between 2019 and 2050 and reach 1100 to 1850 MtCO₂ by 2050.

In 2013, ICAO adopted the aspirational goal of ‘carbon neutral growth from 2020’. This means net CO₂ emissions would have to remain constant on a net basis compared to 2020. The CAT rates the ICAO goal of carbon neutral growth from 2020 levels as ‘Critically insufficient’. Significant shortcomings to this goal are that it is based on offsetting the sector’s CO₂ emissions rather than real emission reductions, and that non-CO₂ climate impacts are addressed. Carbon dioxide emissions from the aviation sector account for only a third of the overall climate impact of aviation. Indirect greenhouse gases, notably NOx and the effects of control formation and contrail cirrus have a combined warming effect, greater than the direct CO₂ warming effect. Efforts to reduce the climate impact from international aviation must include the full scope of climate effects of aviation and hence include measures to reduce NOx emissions and to minimise and reduce contrail cirrus formation.

In the absence of meaningful action by ICAO, the aviation sector and a few countries have started to address international aviation emissions themselves. However, few of these proposed strategies involve a reduction in the growth of demand for aviation, which is projected to grow exponentially. Most of the strategies rely on carbon offsets, which will not neutralise the climate effects of CO₂ emissions, due to lack of permanence and fundamental concerns about additionality. The limited global potential for carbon dioxide removal and storage should be used to balance out residual emissions and achieve global net zero by 2050, rather than to accommodate the stark projected growth in aviation activity.

Just four countries are responsible for a quarter of international aviation emissions. In order of magnitude, they are the European Union, the United States, China and the United Kingdom.

The European Union emissions trading system (EU ETS) originally included emissions from flights to and from

the European Economic Area (EEA) – which covers all 27 EU member states, Norway, Liechtenstein and Iceland. However, from 2012, to allow for the development of a global approach to limited emissions from international aviation through ICAO, the EU ETS’s coverage is (temporarily) limited to flights taking off and landing within the EEA. The European Commission, the European Parliament and the 27 Member States through the Council of the EU are now negotiating new rules for the EU ETS’s coverage. Whereas the European Commission proposed to apply CORSIA on flights between the EEA and countries that participate in CORSIA, the European Parliament wants the EU ETS to cover all departing flights from airports within the EEA, regardless of whether these flights are covered by CORSIA. Notably, the European Parliament also proposed extending the EU ETS to cover non-CO₂ emissions from aviation by the end of 2026 at the latest.

The United States has committed to net zero GHG emissions from the US aviation sector by 2050. This goal encompasses both the emissions from domestic aviation, and international emissions deriving from all flights from US operators between two different ICAO Member States (even if outside the US). The US Aviation Climate Action Plan proposes actions such as operational improvements, new aircraft technologies and sustainable aviation fuels. The US government recognises that offsetting may be needed to bring the aviation sector to net zero, but provides no further details.

The United Kingdom includes emissions from outgoing (international) flights in its sixth carbon budget and will extend its 2050 net zero target to cover emissions from international bunkers (aviation and shipping), which are both positive developments. However, the government’s July 2022 Jet Zero strategy to bring domestic and international aviation emissions to net zero by 2050 is unambitious and insufficient. The strategy shows that the UK Government understands ‘net zero aviation’ to mean increasing real CO₂ emissions from 19 MtCO₂ in 2019 to 33 MtCO₂ in 2050 and reaching net zero through accounting with the UK ETS, CORSIA and other offsetting measures.

Notably, the EU, US and UK do not mention specific measures for reducing demand for international aviation, which is a key measure in decreasing emissions and bringing the aviation sector in line with the Paris Agreement temperature limit.

To the best of our knowledge, China has not set any targets for the reduction of international aviation’s climate impact.

CORSIA rules weak, lack environmental integrity

ICAO expects its offsetting scheme, CORSIA, to play a key 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 covered by the scheme through the purchase and retirement of emission units. To be effective these units 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.

CORSIA is likely to cover less than 50% of international aviation CO₂ emissions over its planned timespan of 2021–2035. 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.

IATA set a net zero carbon goal for aviation by 2050 but has not committed to a clear emission reduction target. The organisation projects an increase in demand for aviation and currently expects that improved operations, new aircraft technologies, and SAFs can bring CO₂ emissions down by about 80% by 2050. The remaining 20% of 2050 emissions would need to be balanced out with carbon offsets. This would equal about 200 MtCO₂ residual emissions by mid-century.

IATA has made no commitment to reduce the non-CO₂ emissions and impacts from aviation, nor does it outline more detailed information on the offset credits it would use.