Water. As I’ve said for many years.
The world is facing an imminent water crisis, with demand expected to outstrip the supply of fresh water by 40 percent by the end of this decade, experts have said on the eve of a crucial UN water summit.
I’ll use the US as an example, though this going to effect almost all countries, some much worse than others, and it will cause a number of wars. Candidates include all nations along the Nile River, and all nations around the Himalayan plateau, among many others. The US may threaten war with Canada to get Canada’s water resources and may invade if Canada is recalcitrant. The Great Lakes will be a great problem.


