Anyone living in Britain will be familiar with the white contrails that aircraft produce as transatlantic flights cross the country. Some days they disappear in seconds, but on others, when the air is already full of moisture, they join together to form cirrus clouds which can linger for up to 18 hours. They make the sun hazy and prevent heat escaping back into space from the atmosphere, adding to climate warming.
Scientists from Imperial College London calculate that these contrails add as much again to heating the atmosphere as the carbon dioxide produced by the aircraft but have found a solution. By altering the altitude of aircraft flying into humid air up or down by 2,000ft (610 metres) to reach drier layers, the formation of contrails and the resultant warming is cut by 59%.
Even better, if the airlines used cleaner engines to produce less black carbon from their fuel, the vapour trails would rarely form at all. The ice crystals need the unburned specks of carbon as a base to form the contrails in the first place.
The two improvements combined would cut contrail heating by 90%. For an industry under increasing pressure because of its rising contribution to the climate crisis, getting rid of contrails would at least show willing.