When and where during the worlds? Travel arrangments etc.

not really, flying london > NYC is the same per passenger as driving a volvo estate around the world.

Depends on the statistic, you can prove it either way... the skew is average capacity vs full capacity. But you're right, averaging out a few sources seems to put the train at ~50kg CO₂ vs the plane at ~200kg CO₂ for London to Berlin (my bad).