And there are other alternatives in a resource crisis. Most notably, the fear with water is not that we will starve, but that one country will be forced to kill

And there are other alternatives in a resource crisis. Most notably, the fear with water is not that we will starve, but that one country will be forced to kill the users in another country over it. So a crisis forcing reduced usage is after he have examined/tried killing the other humans using the resource. Not a pleasant thought, but reality.