Minor changes to the flight plans of only very few flights could reduce contrail warming by as much as half by 2040, a new study has found. The analysis, by sustainable travel NGO group, Transport and Environment (T&E), focuses on contrail avoidance as a climate solution, highlighting that it is “particularly cheap, as it would cost less than €4 per flight.”
What are contrails and why do some flights produce more of them?
Contrails – the giant white streaks of condensation left across the sky when planes pass overhead – have a net warming effect on the planet, which is “at least as important as the one caused by aviation’s CO2 emissions,” T&E notes. This is despite the fact that only relatively few flights are responsible for the worst contrail pollution.
“Only a minority of flights (3%) generate 80% of contrail warming,” T&E found, meaning that slight alterations to just a few flight paths could radically reduce overall contrail warming, by as much as 50% in only 15 years.
Geography and flight latitude are major factors when it comes to whether or not a contrail produces a warming effect. “Flights over North America, Europe and the North Atlantic region accounted for more than half of global contrail warming in 2019,” T&E said. Time of day and season also affect the climate impact of contrails, with wintertime, evening and night flights among the worst warmers.
Does changing flightpaths burn more fuel?
Critics might argue that adjusting flightpaths, which may entail burning more fossil fuel, is a counter-productive way to reduce global warming. However, the study emphasises that any extra fuel burnt is offset by the beneficial effect of the contrail reduction, as found in a 2023 trial where over half of contrails were reduced with only a 2% fuel burn penalty.
What’s more, only 0.5% extra fuel would be burnt by tweaking flightpaths across the fleet as a whole, T&E says, adding that, “on those few flights where rerouting will happen, 80% of the contrail warming of the flight can be avoided, with an extra fuel burn of 5% or less.”
“Simple and cheap” but emissions still matter
Carlos Lopez de la Osa, aviation technical manager, called for prompt action, saying “There are very few climate solutions that can be implemented so quickly, at so little cost and with little impact to industry and consumers. The aviation industry is being offered a simple and cheap way to reduce its climate impact.”
However, the body also warns that, “while avoiding contrails would lead to significant climate benefits, it does not make it any less urgent to reduce the CO2 emissions of the aviation sector, whose impact on the climate remains as significant as before.”
Call for monitoring, regulation, and incentives
To work towards the “huge” benefits of contrail control, T&E is urging EU authorities to put contrail monitoring into place for all EU arrivals and departures from 2027, to raise awareness while regulatory frameworks for contrail reduction in European airspace are drawn up. As well as those levers, incentives should be made available, T&E said, for research and technical innovation in contrail control and for early adopters of contrail reduction.
