Good old climate change.
http://news.yahoo.com/s/ap/20070527/ap_on_sc/g8_climate_change_12;_ylt=Ag6Bxj42h_hHlqdVxuwCUE2EDvIINice to know that when the next G8 conference comes around that the folks whose houses get blown down in Kansas and Florida (and other states too) will still be exempt from doing anything about it. (this is odd, as the US managed to cut it's CO2 emmissions last year, and could probably continue doing so, with just a little restraint.)
It's been more than ten years since I got on a plane and took a holiday anywhere outside of the English countryside. When it becomes much much more expensive (as it will) fewer folk will afford the luxury of travel. Don't buy that holiday home in Siberia (or Rio), folks, because you won't be able to afford to get to it in fifteen years time.
The era of cheap travel is almost over.
The taxes on air travel are going to (at least) triple in the next ten years. But perhaps not in America.