Google and NATS are testing AI flight path tweaks to cut contrail 'sky graffiti' over the Atlantic

[Woven Sasha]

Operation Blue Skies, backed by the UK government and Google. Is running two trials this winter in the Shanwick Oceanic airspace above the eastern North Atlantic, testing whether adjusting commercial flight altitudes can meaningfully reduce the persistent, climate warming contrails that Google's Dr Paul Hodgson says his five year old more colourfully calls sky graffiti.

Contrails form when hot jet exhaust meets cold air at high altitude, creating ice crystals. Most dissipate quickly, but in sufficiently cold and humid conditions they persist and spread into cloud cover that traps heat which would otherwise escape the atmosphere. Hodgson estimates contrail warming accounts for roughly a third of aviation's total climate impact, though he's upfront that the precise figure carries real uncertainty, calling it confidently either quite a large problem or a very large problem.

Shanwick specifically accounts for around 5% of global contrail warming, concentrated heavily between November and February, which is exactly the high impact window Operation Blue Skies is targeting. The trial brings together NATS, the UK's air traffic control service which manages that airspace, alongside Imperial College London, Cambridge University, the Met Office and the nonprofit Contrails.org, using AI models to identify specifically where and when small altitude adjustments would have the greatest climate benefit.

This builds on earlier Google research with American Airlines. Where 70 test flights over six months used AI predictions cross referenced against Breakthrough Energy's open source contrail models to avoid contrail forming altitudes, cutting contrails by 54% during the trial, though flights that actively avoided contrails burned about 2% more fuel doing so.

The trial arrives alongside the UK government backing airport expansion. Which raises the genuinely open question the coverage flags directly, whether a technical fix this incremental can meaningfully offset aviation's climate impact if the actual volume of flights keeps growing regardless

AI to help planes avoid climate-warming contrails above North Atlanticwww.bbc.co.uk