We are using the resources of three planets, this is not sustainable. Some call it three planet syndrome, withought a couple of spare planets to use we will have to learn to get by with just this one.
When we run out of oil, and other scarce resources, where will we get more from? We changed from coal heating to gas and electric. We changed from gas lighting as there was a better alternative, electricity. What will replace oil? Coal and gas reserves are larger than oil, but cannot easily be used as a fuel for road transport.
Scarce resources are a growing problem, many wars have been fought over them, and I expect more to be. Most people see Iraq as a war over Oil, as there isn't any other obvious explanation. The USA saw a chance to break the OPEC stranglehold by controlling a major player, corporations saw a chance to make lots of money so backed Bush.
If you think about it, WW2 was over resources, the Germans and Japanese wanted more than they could easily get so invaded countries with large reserves, Russia and China respectively. The rest followed because of this. WW1 is a similar story, Germany wanted to knock out France quickly then defeat Russia. Their haste to keep to a timetable caused atrocities in Belgium, and helped persuade the UK and USA to join in and eventually defeat them after being bogged down in the trenches. Why did the Argentinians want the Falklands?
Looked at from this viewpoint, most wars are about resources. Now resources have become even more scarce, wars in the future may be fought over water, uranium, copper as well as oil.
