[gambiting]

While I can believe we can manage the heat somewhat, I do not believe we can manage the declining oxygen levels. I think it's actually made worse by the fact that the decline is so incredibly slow - coming up with a solution will always be something that can be left "for the next generation". And humans can survive at 20% oxygen. At 19%. At 18%. But after a certain point, you're just starting to feel like crap, but hey - just buy yourself some oxygen, right? Free market will solve that problem. If, of course, the free market still exists at that point. I am of course being sarcastic.

[gridlockd]

Why do you believe that? Tibetans, for instance, are already genetically adapted to high altitudes where ordinary people may have some health issues. Mountain climbers can adapt to lower effective oxygen levels in a relatively short amount of time.

Again, some of our ape ancestors evolved in a time with far lower oxygen levels. After that, oxygen levels rose higher, but they have been drifting downwards for millions of years since then.