Some of my Swedish classmates have already stopped flying - they only travel to places that can be reached by train. My kids' schools (private international school and public high school) in Denmark has a policy of sustainable school trips. Their class trips have been Berlin and Prague - I know another high school kids went to Barcelona by bus. I found it absolutely stupid - spending 2 days each way to drive to Prague. You can't beat flying when you want to get to places quick.

My son sent me a picture of the black exhaust from the ferry he was on - ferries are really bad in CO2 emission too.

CO2 emission is not the only thing that is killing our planet earth but it is the easiest to advertise.