What do contrails do

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Go Paperless with Digital. Get smart. Sign up for our email newsletter. Sign Up. Support science journalism. Knowledge awaits. New research out of the UK has found two silver linings in the cloudy conundrum. The first is that just 2. The better news, Stettler and his coauthors report, is that those planes can avoid making most contrails with minor altitude changes. Contrails form only when the air is heavily saturated with water molecules that can attach to soot particles from engine exhaust and condense, grow into ice crystals, and join into clouds.

Often, though, that saturation is confined to a narrow band of altitude, and airplanes can find drier areas by moving up or down. By Katie M. Palmer and Matt Simon. And unlike the CO 2 already living the high life, contrails do damage only during their brief lifetime. Stettler and his fellow authors based their findings on flights over Japan in , which offered the best data they could access on the exact positions of actual flights. And I have the impression that [companies] such as Lufthansa and Airbus, are really interested, as it is low cost and effective," she says.

Royal Aeronautical Society fellow, Prof Keith Hayward, is optimistic it may only need a software tweak to adjust many flight plans to avoid contrail creation, and that this could be done at a relatively low cost.

Prof Hayward says the next challenge is for airlines to work out how altitude changes of a "few thousand feet" can be made mid-flight to avoid contrails while also not disrupting passengers' comfort. A pilot would need to spot these in "sufficient time for an aircraft to adapt gracefully", he adds. But Prof Voigt does not believe this is necessarily a problem. She thinks flight comfort could improve as flight paths would avoid some of the sky's water vapour areas - which both form contrails and cause bumpy turbulence.

Raimund Zopp, former pilot and co-founder of Austrian flight services software company, Flightkeys, is working on contrail visualisations to programme into flight plan technology.

The company plans to include contrail avoidance in their airline customers' flight plan trajectories by As a former pilot, Mr Zopp says that from a flight procedure perspective, adding this information would be easy.

Any action on climate change that doesn't relate directly to cutting emissions is lower down the priority list for governments and industry, because CO2 is the most important greenhouse gas for most sectors.

Yet unlike other sectors, aviation also has very significant non-CO2 impacts. Dr Stettler believes that people have hesitated to reduce contrails by diverting flights because of fears it would be completely unfeasible - that all flights might have to be changed or it would hugely increase fuel consumption.

This latest research shows this is not the case. Dr Jarlath Molloy, senior environmental affairs manager at the air traffic service provider, NATS, agrees that up until now, there has been a lack of focus on non-CO2 problems from the entire industry. Yet from an operational perspective, tackling contrails is "just one extra element the aircraft would have to compute", he says, and it could even be managed in a similar way to how authorities already orchestrate groups of flights to avoid big winter storms.

The Department for Transport says it is "currently considering" a range of responses to its Jet Zero consultation on how to "make the sector cleaner and greener", and that this strategy "will aim to address" aviation's non-CO2 impact.