Tweaking the routes of just a few flights could halve contrail warming by 2040 — and would cost passengers less than €4 per ticket, a new study by research group Transport & Environment (T&E) finds.
Contrails — the white lines in the sky created when planes fly through cold, humid air — make up a significant share of the aviation sector’s contribution to climate change. In most cases, they dissipate within a few minutes; but in certain parts of the world where atmospheric conditions allow, they can persist and become artificial cirrus clouds with a net warming effect.
Just 3% of all flights generate 80% of all contrail warming. T&E’s study says slightly rerouting these flights to avoid contrail hotspots would be a cheap and easy solution — though the authors warn that much more needs to be done to reduce the industry’s emissions.
How it works: On the few flights where rerouting would happen, a little extra fuel would need to be burned (5% or less) but contrail warming would be slashed by 80%. The gains would outweigh the extra fuel emissions by between 15 and 40 times, test flights show, and will “go up as technology advances.”
“There are very few climate solutions that can be implemented so quickly, at so little cost and with little impact to industry and consumers,” says Carlos Lopez de la Osa, aviation technical manager at T&E.
A flight from Paris to New York would cost less than €4 more per ticket to re-route so that it avoids the damaging contrail hotspots, the study finds. This accounts for the extra fuel needed and all technologies associated with contrail avoidance, such as humidity sensors and satellites.
Per tonne of carbon dioxide-equivalent abated, this is more than 15 times cheaper than other climate solutions like carbon capture and storage, per T&E.
Some airlines, start-ups and other organisations (including Google) are already working to avoid harmful contrails.
In 2023, a pilot project involving 70 flights — just over half of which mitigated their contrails — showed a fleet-wide increase in fuel burn of just 2%.
To ensure this solution is deployed at scale, T&E recommended that contrails be monitored on all flights departing from and arriving to the EU from 2027. Policymakers could also offer incentives to early mover airlines and manufacturers until these technologies become standard, it says.
