No safe landing: ICAO must adopt a more ambitious climate goal for international aviation

In this blogpost, we argue why the current proposals are inadequate for the aviation sector to contribute its fair share for achieving the Paris Agreement goals.

In October 2022, the Assembly of the International Civil Aviation Organization (ICAO) will meet to discuss a long-term climate goal. In this blogpost, we argue why the current proposals are inadequate for the aviation sector to contribute its fair share for achieving the Paris Agreement goals. We recommend that ICAO should take action to address the non-CO2 effects which are responsible for about two thirds of the radiative forcing from aviation and should adopt a clear pathway for reducing emissions within the sector.

Total CO2 emissions from the aviation sector were about 905 Mt which equals about 2.4% of global CO2 emissions in 2018 (Lee et al. 2021, IATA 2019). If considered a country, aviation would be the sixth largest emitter globally. The total global warming effect of aviation is even larger if non‑CO2 effects are considered.

Taken together, the climate impact of aviation is three times higher than from aviation’s CO2 emissions alone. In addition, aviation emissions are expected to continue to grow considerably. The figure shows the historic and projected CO2 emissions from international aviation which represents the largest share of global aviation emissions. Reducing aviation’s climate impact is thus critical for achieving the goals of the Paris Agreement.

Figure: CO2 devellopment in aviation, Quelle: Öko-Institut

41st ICAO-Assembly: a chance for climate commitments

From the 27th of September to the 7th of October 2022, member states of ICAO come together at the 41st Assembly to further discuss potential climate commitments for the sector and ways to reduce emissions. So far, ICAO member states agreed to improve the fuel efficiency of international aviation by 2% annually until 2050 and on “carbon neutral growth” from 2020 onwards.

The latter has been implemented mainly through a global carbon offsetting scheme, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). At their 41st Assembly, ICAO member states will now consider the adoption of a ‘long-term aspirational goal’ (LTAG) for international aviation.

A growing number of countries, jurisdictions and companies have already adopted long-term climate goals, committing to net zero emissions or climate neutrality targets. Such long-term goals are important because they set a vision which can shape the adoption of pathways and policies needed to achieve these goals. In contrast to international shipping, the international aviation sector does not yet have an internationally agreed long-term goal for 2050.

Many actors in the aviation industry have, however, already committed to net zero CO2 emission targets, like the industry’s International Air Transport Association (IATA). Another example is the International Aviation Climate Ambition Coalition (consisting of 23 state representatives) which committed to the goals of the Paris Agreement while referring to a target of net zero CO2 emissions by 2050 for ICAO.

Proposed long-term goal lacks clarity and ambition

At a high-level meeting of ICAO member states ahead of the 41st Assembly in September 2022, countries concluded that they aim to agree on a LTAG of net-zero carbon emissions in 2050. While this may sound great at first glance, the current proposal has several problems:

  1. Aviation’s main climate impact is not addressed: The term ‘carbon’ emissions implies that only CO2 emissions are considered, but no other greenhouse gases and climate impacts. These non-CO2 effects could be rapidly reduced at relatively low costs, such as by re-routing flights to zones where certain clouds are not formed. It is thus urgent that ICAO takes action to reduce these climate impacts.

  2. Lack of clarity whether the target is achieved by reducing emissions within the aviation sector or through offsetting: The proposed ‘net-zero’ goal is silent on the share of in-sector emission reductions versus the use of carbon offsets. The largest share of aviation’s climate impact can be reduced within the sector. Emissions can be mitigated through alternative fuels, such as hydrogen, synthetic fuels produced from renewable electricity, fuels derived from biowaste, alternative propulsion systems as well as by reducing demand for air traffic. Relying on offsetting in 2050 would be problematic. By that time, emissions need to be reduced to zero in all sectors where this is technically feasible. The supply of carbon offsets will be limited, as it would need to come from negative emission technologies, such as direct air capture (DAC) or afforestation. Afforestation is, however, vulnerable to reversal and cannot guarantee long-term carbon storage. For these reasons, the limited number of carbon offsets available should be used for compensating emissions that are truly unavoidable. If offsetting is used in 2050 in the aviation sector, it should thus be used to address parts of the unavoidable non-CO2-effects from aviation but not for its CO2



  3. No interim steps on the pathway to 2050: At the high-level meeting ahead of the Assembly, member states did not seem to consider any concrete interim steps or waypoints to the long-term goal. Such steps are important to ensure that emission reductions are not delayed and initiated in time. The interim emission goals are also useful for reviewing on where the sector stands, where it is going and what new measures might be needed to stay on the path towards net zero.

Recommendations for a fair contribution to global efforts of Paris Agreement

We recommend that the current proposals are enhanced to ensure that international aviation contributes its fair share to global efforts of staying with the Paris Agreement temperature goal. Specifically, we recommend that ICAO member states:

  • Adopt a long-term goal of climate neutrality by 2050 or earlier,

  • Complement this goal by an in-sector goal to reduce CO2

    emissions to zero by 2050, using carbon credits only to balance out unavoidable non-CO2


    emissions and using only high-quality carbon credits based on negative emission technologies;


  • Agree on a work program to establish interim targets on the pathway towards climate neutrality by 2050 and to develop or enhance current policies to ensure that these goals are met, for adoption at the next ICAO assembly in 2025.


Nora Wissner is a researcher in the Oeko-Institut’s Energy and Climate Division in Berlin. Her main area of work is climate policy and climate change mitigation in shipping and aviation. Dr. Martin Cames is Head of Energy & Climate Protection at the Oeko-Institut in Berlin. Here he is concerned with national and international climate policy and market-based instruments for reducing greenhouse gas emissions in international aviation and maritime transport. Dr. Lambert Schneider is Research Coordinator for International Climate Policy at Oeko-Institut in Berlin. He is also a member of the CDM Executive Board.

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