The Aviation Non-CO₂ Expert Network (ANCEN) has published three new Background Notes that clarify how aviation’s CO₂ and non-CO₂ emissions affect the climate and what this means for future mitigation strategies. Developed under the Horizon Europe “NONCO2” research action, these notes are designed to support policymakers, industry stakeholders and the wider community with concise, science-based information.
The first note, Climate effect of aviation contrails, summarises current scientific understanding of contrails and contrail-cirrus clouds and their contribution to human-induced warming. It highlights that, while individual contrails can be short-lived, their aggregated climate effect is potentially significant and remains subject to important uncertainties that ongoing research aims to narrow.
The second note, Time scales of the climate effects of aviation CO₂ and non-CO₂ emissions, explains why CO₂ effects persist over decades to millennia, whereas most non-CO₂ effects are shorter-lived but can be large in the near term. The note highlights that reducing CO₂ emissions is crucial to limit long-term warming, while also emphasising the potential for targeted reductions in non-CO₂ emissions to yield more rapid climate benefits.
The third note, Benefits of changes in fuel composition on aviation non-CO₂ emissions, describes how fuel properties such as hydrogen content, aromatics, naphthalene and sulphur influence non-CO₂ emissions, including soot and particulate matter. It summarises recent evidence that Sustainable Aviation Fuels (SAF) and other high-hydrogen, low-sulphur fuels can substantially reduce particle emissions and associated contrail ice crystal formation, with the potential to lower contrail-cirrus related climate impacts.
These three publications are part of ANCEN’s Task 7 work to provide clear communication materials on aviation non-CO₂ effects and to place them in context with CO₂ impacts. These initial Background Notes complement previous ANCEN outputs and will inform future discussions on effective mitigation measures at the EU and international level. Further Notes on other relevant topics linked to non-CO2 impacts will follow.
The Background Notes are available in the download section of ANCEN (NONCO2) – Aviation Non-CO2 Experts Network (ANCEN) | EASA.
