Commercial aviation is one of the biggest CO2 emitters.
But point that out to all the travel obsessed millennials who want to brag about their Prius and their composet pile... and they tell you what an awful person you are. lol
A 4 hr train trip vs a flight is about a 1000x difference in CO output.
I don't travel much because it's one of the most environmentally destructive things any single average person can do. Not traveling is way more green than buying a Prius/EV. But it seems to be the #1 social status marker among the under 40 set. Esp among young women.