And rulers? Rulers? Are you fucking kidding me?
But from a completely detached and amoral (and not intending to use that word in a judgemental way) point of view, sure, you are totally correct.
Well the issue is, if it's adapt or die, a pretty fucking huge number of people will end up dying. Yes, with the earth being warmer, perhaps the net amount of usable land would increase. But if said usable land is in a different location than the current usable land there might be a few, you know, issues in picking up the entire agricultural infrastructure of the world and relocating it. Especially when you take into account things like national borders which countries tend to be a little touchy about.
So yeah, sure, we'll adapt, it won't be the end of humanity. But the transition is going to suck.
Personally, while I find the moral/philosophical teachings most important, I also like a bit of abstraction too. That said, it's not really essential to my belief system and I'm happy to acknowledge that, objectively speaking, it's a little silly.
Of course, the thing about Buddhism is that it "works" even if you do away with all the supernaturalist elements - the Buddha's teachings about suffering etc., applied to a single lifetime, are quite useful (in my opinion, that is)