Those questions are over our heads, of course. I've heard that thanks to international regulations the depletion of the ozone layer may be stopped before it gets too bad. Global warming, including rising sea levels and many drastic climate changes is another matter. The U.S. in particular seems to be doing everything possible to bring it on quickly, by burning fossil fuels for frivolous purposes, such as to enjoy imaginary power and adventure in SUVs in the suburbs.
It's extremely hard to know how well people will be able to cope with the huge environmental changes we are creating. For one thing, we don't know exactly how big those changes will be. Will the globe heat by 4°F? 20°F? The models aren't yet quite accurate enough to say for sure. Will the Gulf Stream shut down abruptly? We don't know. How clever will people be in somehow coping with these disasters? Again, we don't know.
I suspect that actual extinction of our species is quite unlikely, however, because our ancestors showed great adaptability in living in all sorts of environments with minimal technology. In some ways the lives of hunter-gatherers are pretty good, so perhaps the worst-case scenario wouldn't be all that bad for the small number of survivors.
(republished on 07/12/06)