climate change can be dealt with
Implying that humans do somethings to make the climate like it was in 1900: No, probably not. The Earth goes on, but maybe without us. I think the things that can wipe out humanity are all man made. Climate change may precipitate one or the other, but we don't actually die from climate change.
One of the most likely is a synthetic virus that kills every body who is Black, or Yellow, or White. Some people seem to think everything would be peachy if we could just kill xxxx*. Of course, once you have an xxxx specific virus it's just a small tweak to make it kill other races.
* Where xxxx represents the race of your choice.