Overview of non-CO2 Emissions from Aircraft and Fuel Composition Effects

Concawe Review 34.1 - Article 3: Aviation affects climate not only through CO2 emissions, but also through a range of short-lived non-CO2 effects. This article provides an overview of the main non-CO2 emissions from aircraft, including NOx, water vapour, aerosols/particulate matter and the formation of contrails and contrail cirrus. It explains how contrails form and why they have been identified as contributors to aviation’s climate forcing. The article then reviews how fuel composition, particularly hydrogen content, aromatics, naphthalenes and sulphur, can influence soot and volatile particle emissions. Finally, it evaluates what these fuel effects may imply for contrail formation and net climate impacts, including key trade-offs, the potential requirements for, or impacts on, existing refineries, and the benefits provided by blending sustainable aviation fuel.