Day Zero, Capetown.

[Wyrd of Gawd]

It's still nice and chilly for the mammoths across large swathes of the globe, the earth getting warmer was not enough, on it;s own, to off them.  They had help.  We're super helpful like that.  

The same is most likely true about human beings.  Drastic climate change would inconvenience us, greatly, but it;s only with a little bit of help from our friends that we'd manage to off ourselves when it happens.  The residents of Cape Town have been negatively impacted by climate change, but as noted in the story they're getting helped along by their neighbors..who continue to be wasteful.  In the event that the area became uninhabitable..well, they have legs, sure..the problem is that the other guys  have guns and don't like immigrants.

Well, Cape Town is next to the ocean and engineers do know how to build desalination plants so maybe they should get busy and bang out six or twelve.  And neighborhoods can put in their own water from air machines if they are so inclined.  There are multiple solutions to the problem if people really want to do something about it.

http://ec2-34-230-69-62.compute-1.amazon...generator/

http://ec2-34-230-69-62.compute-1.amazon...-from-air/

https://www.treehugger.com/clean-technol...r-air.html

https://www.popsci.com/technology/articl...-water-air

http://www.instructables.com/id/DIY-Atmo...Generator/