Advancing understanding on aviation's non-CO2 climate effects

Non-CO2 emissions contribute to climate effects from aviation in the same order of magnitude as carbon dioxide (CO2) emissions. However, the non-CO2 effects, comprising e.g., ozone and methane induced from NOx emissions, together with contrails, or the indirect aerosol effects, are associated with much larger uncertainties. While CO2 and non-CO2 effects in general introduce a warming effect for climate change, some indirect effects might result in a relatively large cooling component. The EU Aeronautics project ACACIA (Advancing the SCience for Aviation and ClimAte) explored the climate impacts of non-CO2 effects which show a strong dependence on atmospheric conditions and synoptic situation. An overview on current scientific understanding, as well as open research questions will be provided. Acknowledgements ACACIA (Advancing the scienCe for Aviation and ClImAte) receives funding from the European Unions Horizon 2020 research and innovation programme under grant agreement No 875036.