Not important, but I want to briefly point out as a Grammar Nazi that you mean uninhabitable regions. Inhabitable and habitable mean the same and their opposites are uninhabitable and not habitable. This is one of those bizarre oddities of the English language.

Climate migration from South and Central America to North America has already started. If the US think they have an immigration problem right now, I can’t imagine how vicious immigration propaganda is going to get when that number goes up by an order of magnitude.