I think there's a small but non-trivial chance that, in the next 3 or 4 decades, global weather will become so erratic and severe that we'll lose a good 90% of

I think there's a small but non-trivial chance that, in the next 3 or 4 decades, global weather will become so erratic and severe that we'll lose a good 90% of our ability to grow food, world wide. That would end our civilization. It would, obviously, be a long, slow, agonizing, random and exceedingly chaotic process. Hopefully that's not what will happen.