The major challenge, if not an outright hazard, to the industrialized nations of the world in the next thirty years is not going to be global climate change. Oh, that is surely going to be a very significant issue. But my bet is on the depletion of cheap energy sources, primarily oil, but perhaps also coal and hydroelectric as well. Our entire economic infrastructure is based on the existence of very cheap, readily available energy on which our entire economic engine is based. If you make energy into a very high priced, relatively scarce commodity that causes conflict between regions, states, or countries, and you have the makings of a global upheaval.
I, for one, do not want to see wars being overtly fought for control of oilfields. We are getting rather close to that scenario right now in Iraq. If we have regional conflicts that are exclusively about who gets the oil, then there will be some major-league players that will become involved. China, Russia, Japan and Europe are not about to sit still and let the United States gain control of foreign oil fields in the Middle East, Africa or South America. The U.S. could find itself at odds with countries that we now think of as allies. If it became a free-for-all, where each country was out to solely protect its own interests, then there could be a war that has never been seen before. It would not be the Red Team vs. the Blue Team. It could possibly be a war on many fronts involving many different nations, none aligned with any of the others.
If I were president, I would make finding some energy alternatives a national priority. It should be on the order of a 21st Century Manhattan Project. If we, as a global society, are to maintain any sort of structured civilization, we need to do something about this problem in the next twenty years.