@albertcardona I think the booking thing could be private, there are many private airline ticket booking portals. Rome2rio.com is a start.

The tax needs to be global, I think just Europe won't work because it would create a competitive disadvantage. So maybe a G20 initiative, similar to the global corporate tax. I don't like the G20, because it has no democratic legitimacy, but I don't see another way of introducing this.

Interesting fact: A while ago UBS argued for a CO2 tax, saying it's the most efficient mechanism to curb emissions