Contrails were slashed by 54% in this AI experiment - but we shouldn’t use it as an excuse to fly more.
AI is being used to help mitigate the climate impact of contrails - the thin white clouds that planes leave in their wake.
Contrails - or condensation trails - can trap heat in the atmosphere and are responsible for more than a third of aviation’s global warming impact, according to the 2022 Intergovernmental Panel on Climate Change (IPCC) Report.
Using AI-based predictions based on satellite imagery, weather and flight path data, Google identified routes that avoided the atmospheric conditions needed to create these clouds. In a series of test flights, pilots were able to reduce contrails by 54 per cent.
The experiment, led by Google Research, American Airlines and Bill Gates’s Breakthrough Energy, has been praised for its potential to mitigate the climate impact of flying.
But climate campaigners have warned against using the technological breakthrough as an excuse to fly more.
How do contrails form?
Contrails are created when ice crystals form around tiny particles of carbon emitted by a plane’s engines.
They form when aeroplanes fly through layers of humidity and can hang around for anywhere between a few minutes and 18 hours, depending on the atmospheric conditions.
Contrails contribute to global warming by trapping heat in the Earth’s atmosphere.
Avoiding flying through areas with atmospheric conditions that allow contrails to form could help to reduce this warming effect.
Can flight paths be changed to avoid contrails?
Over a period of six months, American Airlines pilots took 70 test flights on routes that avoided altitudes likely to create contrails.
The routes were determined by Google’s AI-based predictions and contrail models from Breakthrough Energy.
Satellite imagery following the flights was analysed showing that contrails were reduced by 54 per cent.
Flights that took routes to avoid creating contrails were also found to burn 2 per cent additional fuel, however.
Google says only a small percentage of flights need to be adjusted to avoid the majority of contrail warming, minimising the additional fuel required.
AI breakthroughs must be accompanied by a reduction in air traffic
While contrail avoidance could be a significant step towards reducing the climate impact of flying, environmental groups warn against viewing it as a silver bullet.
“It is vital that we address the climate-wrecking impact of contrails but this must be accompanied by an urgent reduction in air traffic,” says Hannah Lawrence of Stay Grounded, a global network promoting climate-friendly alternatives to flying.
She says technological improvements such as this are important, but alone they are not enough.
“While these routes reduced contrails, there is a huge flaw in the fact that they used more fuel,” Hannah continues.
Finlay Asher of Safe Landing, an industry group that campaigns for a sustainable future for aviation, notes that previous research carried out by UK-based aerospace company Satavia and NATS (National Air Traffic Services) has shown that routes designed to avoid contrail formation could actually save on fuel.
However, he warns against airlines viewing it as a form of carbon credit.
"We don’t think it’s right at all to say that by avoiding warming contrails, our airlines should then have a licence to pump ever more CO2 into the atmosphere," says Finlay.
He believes that the climate impact of flying should be better regulated through an emissions pricing system instead, which would provide an incentive to reduce all emissions.
“In the midst of climate breakdown, we need effective action and we cannot allow insufficient measures by industry to postpone the urgent action required," adds Hannah.