Look at the travel route below on the previous post.
The distance by train is 2358 km
the distance by air is 1155 km
average co2 emissions from train is 47 g Co2 per passenger per kilometer
average co2 emissions from plane is 238 g
Sum up and you find that going by train is around 1/3 of the emissions compared to flying on this distance. But the personal price is almost two full days of traveling and two nights of completely impossible sleeping conditions. Any suggestions?