If you think heat will make it uninhabitable, then look to the Middle East to see people live where it's much hotter and drier. So far not a mad rush to live above the Arctic Circle.
There's plenty of water in Tucson. Ever notice not a lot of lakes here? That's because our water is banked underground here. If there ever was a problem, Agriculture uses more than 90% and they would be cut back first. There is a current threat to this water supply as PFAS from firefighting foam is approaching the aquifer.
"That’s enough to serve the city’s customers for more than 200 years, Tucson Water says."
From this article, https://tucson.com/news/local/tucsons-water-supply-can-survive-worst-case-cap-cuts-city-official-says/article_4054bc28-2e32-547e-9b71-4627e81c40e9.html
The SW monsoon acts like clockwork here. Every June heat builds thru out the SW. So much this year that a record heat dome moved across the Pac NW setting records. This record dome caused a counter flow underneath of moist air to give us our wet monsoon.
Those who believe climate is linear will learn by studying Sea Surface Temperatures that the ocean's surface will always warm and then cool. These processes guarantee that the ocean's heat will always fluctuate. SSTs get too hot = clouds and rain = cooling.