Well said Rainbow, countries from the Eastern side of the world are getting wealthier and very powerful, it will not be long till tens of millions of people will want to explore.
I work for Newcastle University where alot of research is done on the impact of travelling by road rail and air. The models they use for predicted growth in all sectors is substantial. Which is why there is alot of panic about the effects on global warming (although i seriously doubt we have caused this)