With oil running out, we could very well be heading for a world war within 20 years. Here is a very simple example of something that could happen even within the next 2-5 years.
Pakistan collapses and becomes a failed state like Somalia is now. The country is already in trouble, terrorist bombings and political assassinations are all too common at the moment. Should the government collapse then the military would have a very hard time trying to take control over such a vast country. Islamic terrorists would just need to take control over a few military bases and suddenly they have a nuke they can fire into India.
India invades Pakistan in an attempt to take control of the nuclear arsenal in that country. Western nations might decide to help them, although many would opt out rather than face the possibility of a nuclear strike on their country.
China gets nervous, they would see this as an aggressive move by India right on their border. They decide to use this as an excuse to extend their sphere of influence over Asia. Fear in Taiwan and Japan grows. China begins to focus on central Asia due to its material resources such as oil in Kazakhstan. Russia feels threatened, it invades several former USSR nations in order to "protect" them. The EU (many of whose member states were formerly under Russian occupation) feels massively threatened by this move and forms a strong military alliance in case of an invasion.
Meanwhile, Iran builds THE BOMB. Israel launches a strike on Iran to destroy their nuclear facilities. In response, several Arab nations band together and war between this alliance and Israel is inevitable. Again.
Four or five major hot-spots, numerous nuclear powers, billions of lives in the balance. The worst part is that it is a domino effect; if just one of these events occurs it could trigger all the others. Are humans stupid enough to let all of this happen?
Of course we are.
Personally, I'm thinking of moving to South America. Does anybody know any reason why war might spread to that continent?