3 rules substantially reduce aviation emissions without removing strategic travel. The 4-hour rule requires the train where the journey takes less than 4 hours (Paris-Lyon, Brussels, London, Bordeaux): flying saves no door-to-door time and emits 10 to 20 times more. The annual carbon allowance per employee encourages responsibility without prohibiting travel: once the allowance is exhausted, meetings are by video. Video meetings by default then eliminate a large share of travel. For journeys of 4 to 8 hours, the night train avoids flying and a hotel night.
Read the source article: Flight carbon footprint: the figures by destination