AI to help planes avoid climate-warming 'sky graffiti'

AI is set to assist aircraft in preventing the formation of climate-warming "sky graffiti," a term for contrails, which are ice crystals resulting from plane exhaust fumes.

Everyone has observed the white streaks planes leave across the sky. These icy formations, known as contrails, contribute to climate change, and scientists have been seeking solutions to mitigate them.

Now, a £5 million UK initiative will investigate whether artificial intelligence can help by forecasting where these warming contrails are likely to form, enabling planes to steer clear of those zones.

The 30-month "Operation Blue Skies" project unites Google, the UK government, the Met Office, air traffic control provider National Air Traffic Services (NATS), and academic researchers. Its focus will be the Shanwick Oceanic airspace, located in the eastern North Atlantic corridor, which accounts for roughly 5% of global contrail warming.

Contrails develop when the hot exhaust from aircraft engines mixes with the cold, high-altitude air, forming ice crystals. While many dissipate quickly, under particularly cold and humid conditions, they can persist and expand into clouds that trap heat that would otherwise escape Earth.

Dr. Paul Hodgson, Google's technical lead for Operation Blue Skies, shared with the BBC's Tech Life program that his five-year-old child has a more vivid description for these white lines: "sky graffiti."

He stated, "We think that contrail warming is responsible for something like a third of all aviation climate warming." Dr. Hodgson acknowledged the uncertainty surrounding the exact figure but affirmed scientists' confidence that it is "either quite a large problem or a very large problem."

This project also coincides with the government's support for expanding UK airports, raising the broader question of whether technological solutions can adequately reduce aviation's environmental impact as the demand for air travel increases. Google is also among numerous major tech companies investing billions in new data centers—massive, power-intensive arrays of computer chips that power AI—which environmentalists worry will further exacerbate climate change.

Contrails, or condensation trails, are a common sight in our skies. The premise of the trial is that if scientists can predict atmospheric areas prone to contrail formation, aircraft can avoid them. Google will utilize satellite imagery and flight data to pinpoint where planes have previously generated contrails. This information will then be combined with weather patterns to forecast conditions conducive to new contrail formation.

The data will be relayed to NATS, where air traffic controllers can guide pilots to bypass these areas. Rather than significantly altering a flight's route, the trial will primarily involve adjusting an aircraft's altitude by approximately 2,000 feet. This is a routine practice for avoiding turbulence and adverse weather, so passengers are unlikely to notice.

Ian Jopson, NATS's director of sustainability, commented that it should be "pretty much business as usual using existing procedures for the operators on the North Atlantic." Testing will occur during selected evenings and nights in the winters of 2026-27 and 2027-28, when air traffic is lower. Around 10,000 flights are anticipated to traverse the airspace during the trial periods, though only a fraction will need to alter altitude specifically to avoid contrails.

The Department for Transport is contributing £2.65 million to the program, while Google is providing £1.4 million through AI research, engineering, and computing infrastructure. Aviation Minister Keir Mather stated that the project would test "small tweaks to flight paths over the Atlantic" that could help make flying cleaner. He added, "This is a world-first, and it's British ingenuity leading the way."

Adjusting an aircraft's altitude can lead to increased fuel consumption, prompting the obvious question: could avoiding contrails simply generate additional carbon emissions elsewhere? Hodgson indicated that previous trials suggested the extra fuel usage was considerably less than the climate benefit of preventing a warming contrail.

He explained, "The CO2 penalty is in the order of less than 1%, compared to the contrail cost, which is of a similar order magnitude to all of the CO2 of aviation." Modeling for Operation Blue Skies suggests that a full deviation through Shanwick would entail approximately 100kg of additional fuel per affected aircraft. According to Hodgson, previous airline-level trials have achieved reductions of about 60-70% in contrail formation or warming.

The findings of Operation Blue Skies are expected to be published in academic literature and subjected to broader scientific scrutiny.