In case you missed it (because we nearly did!) In July, Google quietly altered the way it calculates the environmental impact of flights.  

Previously their carbon footprints included all the extra stuff a plane pumps out, known as the ‘carbon dioxide equivalents’, these measurements include the contrails of nitrous oxides and water vapour, which trap further heat in the atmosphere when emitted at high altitude.  

But now, Google are provisionally removing the effects of contrails from their estimations, in an