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. (....)