Contrail cirrus account for the major share of aviation's climate impact. This study presents unique observations from two DLR-NASA aircraft campaigns measuring exhaust and contrail characteristics of an Airbus A320 burning either standard jet fuels or low aromatic sustainable aviation fuel blends. Results show that soot particles regulate contrail cirrus ice crystals at current emission levels. Burning low aromatic sustainable aviation fuel resulted in a 50-70% reduction in soot and ice number concentrations and increased ice crystal size. Reduced contrail ice numbers cause less atmospheric energy deposition and less warming. Widespread adoption of low aromatic fuels and regulations to lower maximum aromatic fuel content could meaningfully reduce aviation's climate impact.

Christiane Voigt, Jonas Kleine, Daniel Sauer, Richard H. Moore, Tiziana Bräuer, Patrick Le Clercq, Stefan Kaufmann, Monika Scheibe, Tina Jurkat-Witschas, Manfred Aigner, Uwe Bauder, Yvonne Boose, Stephan Borrmann, Ewan Crosbie, Glenn S. Diskin, Joshua DiGangi, Valerian Hahn, Christopher Heckl, Felix Huber, John B. Nowak, Markus Rapp, Bastian Rauch, Claire Robinson, Tobias Schripp, Michael Shook, Edward Winstead, Luke Ziemba, Hans Schlager, Bruce E. Anderson