Countries have been continuously fighting over territories especially those who have oil deposits. They fight for the ownership of it even though it is very far away from them and won't let other country to take over them. Like, you already have resources in your country to begin with so, why do you still want to take other's territories? Just for the things that you can get from it? And after maximizing the things that you can get from it you will leave them afterwards? World War III is really possible if there are countries that will still be continuously greedy of other country's territories.
Perhaps it is all about the cost of extraction. In some countries, it cost as less as $2 per barrel to extract crude oil. But in countries such as the United States and Venezuela, the cost can be as high as $60 per barrel.
It seems to me that Despite the fact that the reserves of carbohydrates on the planet are decreasing, it really can begin today because of energy resources. Perhaps in order to avoid the 3rd world war because of the energy potential of other countries for which they will fight, it is possible that in order to start mastering other possibilities and alternative sources of energy. Perhaps this is the very chance to save the world and people.