This is a bit of an absurd discussion, and, sorry, but to say
I can't "afford" to take the train so I am going to take the bus ... and what people label as "
luxury" in this context ... mind boggling. Sorry, but the question one ought to ask: Do I really need to travel and do I need to travel so far? And the honest answer in most cases would be: NO. Leisure travel is the luxury, not the mode of transport for leisure travel. And most obviously: the more people travel for leisure and the farther they travel for leisure the worse for the use of non-replaceable resources and of the lasting effect of burning them.
Short-haul flights have a higher CO2 footprint per passenger and km than medium and long distance flights, due to the proportionally higher fuel consumption at start and landing. There are efforts to ban them, not very successfully so far. France has made a first step: Domestic flights are now no longer allowed when an alternative of a train or bus connection of two and a half hours or less exists for the same distance.
There are thousands of "calculators". Just for amusement, as I saw this on the BBC website, below is one that covers London to Madrid. Note: As to CO2 emissions alone, bus is worse than long-haul flight according to these results but not coach???
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