Tackling contrails could avoid 10 years of aviation-related climate warming - new research

Contrails, the white lines left by planes, contribute to global warming at asimilar level to aviation’s CO₂ emissions, despite being produced by only a small share of flights. A new report by Klima Consulting, commissioned by T&E and authored by former IPCC scientist Olivier Boucher, finds that preventing their formation could delay aviation-related global warming by ten years. Aviation's contribution to global warming could reach 0.08°C in 2050 rather than in 2040. Starting in 2030, halving contrail warming could prevent around 0.025°C of warming by 2050 and 0.049°C by 2070. In other words, implementing contrail avoidance would free up 3–5 percentage points of the global 2025–2050 temperature budget in a 2°C pathway, which would otherwise be consumed by aviation.

If aviation’s growth continues unchecked, global aviation energy consumption could more than double by 2050 compared to 2019. At current traffic levels, halving global contrail warming could avoid between 67 and 225 MtCO₂e per year, measured over a 100-year period. This is equivalent to between 7% and 23% of global aviation CO₂ emissions in 2025, or the annual emissions of between 15 million and 50 million petrol-powered passenger vehicles. Tackling them by rerouting or rescheduling flights is one of the most cost-effective ways to reduce aviation’s climate impact. In 2019, only 3% of flights caused 80% of the contrail warming, with a large fraction of the most impactful flights occurring at night and during the winter.

“Contrails are the low-hanging fruit of aviation decarbonisation. We have in front of us a golden opportunity to tackle these accelerators of climate warming” Diane Vitry, T&E’s Aviation Director said. “Rerouting or rescheduling just a few flights could delay the aviation industry’s contribution to global warming by ten years. Avoiding valuable fractions of degrees provides a unique window of opportunity. Reducing contrails may be aviation’s only chance to stay on track with our climate goals. We know it works and it’s cheap, so why is the aviation industry opposing action?”

Despite their considerable impact, there are no binding measures at regional or global level to reduce aviation’s non-CO₂ climate impacts. This is partly the result of years of inaction, fuelled by aviation industry claims that the science of contrails is not yet sufficiently certain. In 2025, the European Commission began monitoring the non-CO₂ emissions of aviation and only recently, as part of the revision of the EU Emissions Trading System (EU ETS), proposed free allowances for airlines that successfully avoid contrails.

T&E’s new report reviews the current scientific understanding of aviation contrails. It finds that the scientific evidence is now sufficiently robust to support policy action on contrails under the precautionary principle. The authors identify areas where further research is needed but underline that none of these uncertainties prevents Europe from deploying contrail avoidance. This winter, a consortium including the UK government and air traffic control services, will conduct the world’s first oceanic airspace-scale trial to reduce contrail warming across the North Atlantic.

The temperature benefits of contrail avoidance persist only for as long as contrail avoidance measures are maintained. This underlines the importance of combining sustained contrail mitigation solutions with effective reductions in CO₂ emissions. Reducing contrails is not a substitute for cutting CO₂ emissions from the aviation sector as a whole.

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