Aircraft could be diverted hundreds of kilometres to avoid creating artificial clouds, providing climate benefits.

These clouds, called contrails, can form when planes fly through very cold and humid atmospheric regions, and can contribute to global warming. Emma Irvine and her colleagues at the University of Reading, UK, modelled the maximum extra distance that different-sized aircraft could travel to avoid these contrail-forming regions, without the additional emissions from fuel offsetting the benefits.

In some modelling scenarios, small aircraft could add ten times the length of the avoided contrail to their flight distances, whereas very large jets could add three times their contrail length. Re-routing many flights to travel 100 km further could provide climate benefits, if this avoided contrail formation as a result.

Environ. Res. Lett. 9, 064021 (2014)