While airline contrails have featured less in our skies during the pandemic, an EU study published today finds they are among the non-CO2 emissions which contribute twice as much to global warming as aircraft CO2. The research, by leading scientists, finds that jet engine emissions of nitrogen oxides, water vapor, soot and black carbon were responsible for two-thirds of aviation’s climate impact in 2018. Transport & Environment (T&E) said it is an acknowledgement by the European Commission that contrails finally need to be addressed.
Jo Dardenne, aviation manager at T&E, said: “It confirms that carbon emissions are only the tip of the iceberg when accounting for aviation’s climate impact. Contrails and other non-CO2 effects of aviation need to be urgently tackled to avert climate crisis. The EU should lead by ensuring air traffic doesn’t bounce back to pre-COVID levels while getting planes to fly smarter routes and use e-fuels from renewable sources.”
The report recommends using clean fuels to reduce the amount of pollutants released by jets and changing flight paths to fly at lower altitude, where contrail formation is avoided. The scientists note that rerouting less than 2% of flights in Japan had reduced the warming effect of contrails by nearly 60%. The report also says the EU could require the blending of e-fuels into all jet fuel sold in European countries.
T&E said the EU cannot afford to wait five to eight years to implement these measures, as the report proposes, and that they need to be included in the Commission’s upcoming Sustainable and Smart Mobility Strategy, due in December. Contrail avoidance also needs to be prioritised in the revision of the Single European Sky, given its potential to deliver substantial cuts to aviation’s climate impact. Pricing for non-CO2 emissions will also be needed to incentivise airlines to use eco-friendly flight paths.
Jo Dardenne said: “The European Commission was first tasked with addressing the non-CO2 emissions of flying in 2008. It shouldn’t waste any more time in implementing the solutions that are available today.”
Note to editors:
 "Using a derivative metric of the Global Warming Potential (100), the GWP, aviation emissions are currently warming the climate at approximately three times the rate of that associated with CO2 emissions alone."
pp. 35-36 of EASA report for European Commission, (2020). Updated analysis of the non-CO2 climate impacts of aviation and potential policy measures pursuant to the EU Emissions Trading System Directive Article 30(4).
 The study cites: Teoh, R., Schumann, U., Majumdar, A. & Stettler, M. E. J., (2020). Mitigating the climate forcing of aircraft contrails by small-scale diversions and technology adoption. Environmental Science and Technology, 54(5), pp. 2941-2950.