Look up: a simple solution to cooling the planet is right above us
No new inventions are needed, and it’s inexpensive. Condensation trails - or contrails - from planes are responsible for 1-2% of human-induced global warming. The good news is that if we make minimal adjustments to how we fly, we can solve this problem fast. The bad news is that at a time when we urgently need to make climate progress, we're not implementing this simple solution. We founded Blue Lines to help solve this problem. See who we are and why we do this.
Why does it matter?
1. Contrails are formed when aircraft fly through very cold and very humid areas (click arrows to see more).
2. Water vapor from the engine exhaust freezes and turns into long ice clouds in the sky.
3. Some contrails can linger for hours and spread out to become big high-altitude clouds - called cirrus clouds.
4. These big cirrus clouds block heat from escaping Earth and keep the atmosphere warm.
5. But if planes avoid the cold and humid areas, they can also avoid making contrails.
6. If we slightly redirect 1 in 20 flights, we can eliminate 1-2% of global warming.
Learning contrail avoidance from the best
A few airlines already have experience with minimizing their contrail impact by running trials and implementing contrail avoidance into their operations. Now these first movers are sharing their knowledge in Blue Lines’ practical contrail avoidance playbook for airlines. How do you get started? What is needed? Who has to be involved? How do you design a trial, manage risk, get funding, and deal with uncertainty? It’s all in there and can be downloaded for free from this website.
Airline Contrails Index
See which airlines are addressing the major climate problem of condensation trails.
Until June 2026, FORTY airlines have publicly announced they are working on the problem – or at least acknowledge it. See who.
Blue Lines is the co-founder and co-organizer of the Copenhagen Contrails Conference. The first edition took place in the Danish capital in March 2025, ahead of Denmark taking over the presidency of the Council of the EU in July 2025.
To download presentations or watch videos of Day 1 sessions, please visit copenhagencontrails.org.