T&E Study: Avoiding contrails on night and winter flights is aviation’s fastest climate win

A new analysis by European clean transportation NGO T&E shows that 25% of European aviation’s contrail-related global warming comes from night flights in autumn and winter, which make up just 10% of European air traffic.

Contrail warming is highly seasonal and concentrated in time: in 2019, 75% of European contrail warming occurred between January to March, and October to December and 40% during late evenings and nights. Combined, night flights in autumn and winter accounted for 25% of European contrail warming, with only 10% of air traffic. These periods create ideal conditions to adjust a small number of flights with minimal effects on air traffic and major climate benefits.

Contrails, the white lines left by planes in the sky, can spread and persist in certain atmospheric conditions. This traps heat and warms the planet at least as much as aviation’s CO₂ emissions, contributing between 1% and 2% to global warming. Yet only 3% of flights caused 80% of this warming in 2019. Reducing contrails and the warming they cause could be easily achieved by adjusting the flight paths of just a few flights at specific times of the day and year.