Contrails are a major driver of aviation’s climate impact

Peer-Reviewed Publication

Chalmers University of Technology

News Release 16-Dec-202

Aviation’s climate impact extends beyond carbon dioxide emissions. A new study from Chalmers University of Technology and the University of Gothenburg, Sweden, and Imperial College, UK, reveals that contrails can represent a significant portion of aviation’s overall climate cost. The study also shows that climate impact can be reduced by optimising flight routes.

Aviation’s climate impact extends beyond carbon dioxide emissions. A new study from Chalmers University of Technology and the University of Gothenburg, Sweden, and Imperial College, UK, reveals that contrails can represent a significant portion of aviation’s overall climate cost. The study also shows that climate impact can be reduced by optimising flight routes.

In a new article in Nature Communications, The social costs of aviation CO₂ and contrail cirrus, the researchers demonstrate that both CO₂ emissions and contrail formation contribute materially to aviation’s climate impact – and that the associated societal costs differ substantially depending on weather patterns and routing decisions. They find that, at the global level, contrails account for about 15 percent of aviation’s climate impact when measured in economic terms.

After also analysing nearly half a million flights across the North Atlantic, the research team has generated new insights that can support both industry and policymakers in guiding aviation towards more climate optimal operations. Drawing on extensive flight and meteorological data, in combination with a contrail model and an advanced climate-economy model, the researchers estimated the climate and societal cost attributable to each emission source.

“Our research provides a basis for strategies to reduce the climate impact of contrails. Our calculations can be used for optimisation of flight routes where climate impact is considered alongside, for example, fuel cost and travel time. The results give airline operators and air traffic management new tools for climate optimisation. This could bring significant climate and societal benefits,” says Susanne Pettersson, postdoctoral researcher at the Department of Space, Earth and Environment at Chalmers.

The study shows that 38 percent of flights generate contrails that have a warming effect. It also shows that it would be beneficial from a climate perspective to reduce the formation of contrails of almost all these flights through minor rerouting, to avoid contrail formation, even if this results in slightly higher carbon dioxide emissions.

“The new knowledge also provides a foundation for designing new regulations and policy instruments to reduce aviation’s climate impact. The European Commission is currently working on proposals to steer aviation towards lower climate impact, and our new study can hopefully support this process,” says Daniel Johansson, associate professor at the Department of Space, Earth and Environment at Chalmers and one of the lead authors of the next IPCC climate report.

Learn more on contrails, aviation and climate change: Read an article written by the researchers as a Resources For the Future (RFF) issue in brief.