Indeed. To American ears, it's really not significant, other than in the "open up vast swaths of Northern farmland to much greater diversity of crops" sense.

The skepticism most commonly found in the US, based on my anecdotal evidence, is not toward whether AGW is happening, but rather why anyone ought to care. Some even consider it a good thing.

Tell people "large parts of mexico may become uninhabitable"

I'm pretty sure the people who prefer to ignore climate change would not consider this their problem.

But probably consider "rampant immigration" as relevant. Unless they're up for genocide, which they quite frankly probably are, it is their problem. Genocide or not.

Yes that's correct.