From a recent study by the National Center for Atmospheric Research, a map of expected drought conditions across the planet, 2030-2039. The map assumes a moderate level of greenhouse gas emissions, per climate models used in the 2007 Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Click on the image below for full resolution.
A drought index of -4 is considered extreme. More on the study from Joe Romm of the Center for American Progress.
1) Much of the U.S. is under extreme drought conditions.
2) Much of Canada is not.
I expect that the United States will annex all of Canada by 2050. I'm not joking. We will need Canada's farm land, and its food, as well as the more temperate conditions.
Given the level of economic distress implied by the above map, and by peak oil, importing Canadian food will not be enough. The U.S. government and a desperate U.S. population will want direct control over Canada's food supply. Millions of impoverished, heat-stricken Americans will also want free access to temperate Canadian lands. Canadian immigration restrictions won't allow that, so the U.S. government will undoubtedly remove those restrictions, by removing Canada's existence as an independent nation-state. The only question is whether Canadian territory will be incorporated directly into the Union as new states or instead be administered as a conquered area under emergency rule.
The U.S. military of the 2020s and 30s won't be the same global colossus we see today, given the decline in energy supplies. But I expect it will continue to exist, with numbers and cohesion sufficient to take Canada. And also strength enough to lock out millions of refugees fleeing the extreme drought zones of Mexico and Central America. The people of those countries will be forcibly confined in their uninhabitable homelands, I expect, by the military forces of the United States. U.S. military power will serve the same function as Stalin's armies in the 1930s, which enforced deliberate, genocidal starvation in the Ukraine.
Looking at the map above, it's easy enough to project the same grim events in other parts of the world. In the age of energy decline and climate disintegration, politics and international relations will depend crucially on the ability to wield effective military force. I don't like that conclusion, but I don't really see any way to escape from it.
If I'm wrong about this, though, then somebody would have to come up with a different, more persuasive scenario covering, for example, U.S.-Canadian relations in the 2030s. Given that the levels of drought on the above map are a near certainty, how might the geopolitics of North America evolve in a relatively benign way? Hundreds of millions of Americans suddenly deciding to live with a lot less water doesn't seem likely. Nor does a drought-stricken United States seem likely to open its borders to the virtually inevitable waves of refugees from the south. Nor does a United States suffering from drought unprecedented in modern history seem likely to settle for some clunky, European Union style of peaceful integration with its bountiful, temperate neighbor to the north.
No. The age of climate and energy collapse will be the age of war. And government of the warlords, by the warlords, and for the warlords.