Oil
I think that we all want to believe that there is no long term problem with our oil supply.
However, there is a long list of books and talking heads coming out about the "end of oil". Add to our problems of the USD and inflation, the growth of China and India it seems inevitable that the price of fuel will double or triple over the next 5 to ten years.
One book that I read claimed that we will have oil above $200 a barrel in 2010. It also claimed that in 2008 we would reach $100. So far its predictions are right on.
As pilots our entire profession is dependent upon a free flowing supply of fuel. Demand in the airlines swings wildly with the price of tickets. In ten years from now we most likely will have a much different and smaller industry than we do today.
SkyHigh