Google and the UK government launch an AI trial to reduce heat-trapping aircraft contrails over the Atlantic

A 30-month scientific and field trial named Project Blue Skies has launched in the UK with 5 million pounds in total funding, testing the ability of AI models to predict where contrails and heat-trapping cirrus clouds form from aircraft exhaust and to reroute flights around them. The trial focuses on the Shanwick Oceanic airspace in the eastern half of the North Atlantic corridor, an airspace patch responsible on its own for around 5 percent of total global warming caused by aircraft contrails.

These contrails form when hot exhaust gases from aircraft engines meet cold air at high altitudes, producing ice crystals that usually dissipate quickly, but can linger and spread in very cold and humid conditions to become clouds that trap heat radiating from Earth.Dr Paul Hodgson, technical lead for the initiative at Google, explains that warming caused by these clouds accounts for roughly a third of aviation's total climate impact, noting that while exact estimates vary, the scientific community agrees on the scale of this substantial environmental impact.

The trial's technical mechanism relies on Google processing satellite imagery and historical flight data to identify routes where contrails formed, then combining this with weather patterns from the UK Met Office to forecast airspace regions likely to form new clouds. These predictions are sent directly to the National Air Traffic Services, where air traffic controllers direct pilots to adjust their altitude by roughly 2,000 feet up or down, a routine procedure already used to avoid turbulence and severe weather without passengers noticing any real difference, according to Ian Jopson, head of sustainability at the agency.

Field tests are being conducted on selected evenings and nights during the winters of 2026/2027 and 2027/2028, when air traffic is lighter, involving researchers from the University of Cambridge and Imperial College London.Estimates suggest around 10,000 flights will cross this airspace during the trial periods, with only a small fraction needing to change cruising altitude. The UK Department for Transport is contributing 2.65 million pounds to the project, while Google is providing 1.4 million pounds in AI research, engineering expertise, and computing infrastructure.

Altitude adjustment manoeuvres raise questions about increased fuel consumption, though Aviation Minister Keir Mather noted that the project tests minor adjustments to transatlantic flight paths to make flying cleaner.Computational models show that a full diversion to avoid contrails consumes roughly 100 extra kilograms of fuel per affected aircraft, an increase in carbon emissions of less than 1 percent. Hodgson stresses that the climate benefit of avoiding contrails far outweighs this minor fuel increase, citing earlier trials that achieved a 60 to 70 percent reduction in heat-trapping cloud formation, with full results scheduled for publication in peer-reviewed academic journals.