To TGV or not to TGV. That is the question, at least when considering whether to take the environmentally friendlier option to Spain. It is (almost always) much greener to catch a train than hop on a plane. The stats are clear. At its very worst, the overall climate impact of flying can be over 80 times worse than taking a train, if the non-CO₂ effects of air travel (such as NOx and water vapour) are included. Planes emit, on average, 4.84 times more greenhouse gas emissions than trains,