The experiment, called “Operation Blue Skies,” is being carried out by Google and the UK government to reduce contrails, the white streaks airplanes leave in the sky. It will run for 30 months in the Shanwick airspace over the North Atlantic.
If AI predicts the areas where contrails are likely to form, air traffic controllers will adjust flight altitude by about 600 meters. The goal is a low-cost climate measure that changes only the flight path, without replacing engines.
What are contrails?
Contrails form when water vapor freezes around exhaust from jet engines. They are more likely to appear when aircraft pass through cold, humid air. The long white lines stretched across a clear sky are contrails.
Although they look harmless, they are a burden on the climate. When contrails spread like thin clouds, they trap heat that should escape into space.
It is similar to keeping warmth from escaping under a blanket at night. Researchers estimate that contrails account for about one-third of aviation’s total climate impact. Even though they are a factor comparable to carbon dioxide emissions, efforts to address them have been delayed because they are not very visible.
Contrails are a scientifically measured phenomenon. They are unrelated to the “chemtrail” conspiracy theory that claims aircraft secretly spray chemicals.
Just a 600-meter change in flight path makes a difference
In the experiment, Google’s AI forecasting model identifies in advance the atmospheric regions where contrails are likely to form. Then controllers at the UK air traffic agency NATS will raise or lower the altitude of flights passing through those areas by up to 2,000 feet. Flights will remain within normal operating ranges. Passengers are unlikely to notice the route changes.
Only a small number of flights will be affected. During the experimental period, about 10,000 flights pass through Shanwick airspace each year, but only 1% to 5% will have their routes changed. Previous small-scale trials showed that AI forecasts can identify areas where warming contrails are likely to form.
Google is providing the forecasting model and will measure whether contrails actually decrease using satellite imagery and machine learning. It is supporting the project with a free contribution worth £1.4 million, rather than taking payment. According to AP, more than half of the total £5 million budget is being covered by the UK government. The UK Met Office, Imperial College London, the University of Cambridge, and the nonprofit organization Contrails are also contributing.
Could this become a low-cost climate solution?
Cutting emissions in aviation is an expensive and time-consuming challenge. Sustainable aviation fuel is still costly, and developing new engines takes decades.
Avoiding contrails requires no new aircraft; it only means adjusting flight paths. If the experiment succeeds, it could become the cheapest climate measure the aviation industry can use right away.
There are concerns that detours could increase carbon dioxide emissions because more fuel would be burned. If the forecast is wrong, the effort could also be wasted. This experiment will be the first to gather large-scale real-world data to weigh effectiveness against side effects.
Depending on the results, contrail avoidance could spread as a global air traffic standard. It is not just a distant issue for South Korea’s aviation industry, which has a large share of long-haul international flights. After two winters, the answer will be clear as to whether a single white line in the sky can change the order of aviation climate policy.