Where I live, we have plenty of water and the amount will increase as the Earth warms, based upon current theories. But, there is a limit to how much water is treated and the local government refuse to invest in additional treatment. So we have water shortages here even though our lakes and rivers are filled and in some cases a bit overfilled.
Eventually people in the Southwest will have to move, along with people in the South. And people think migrations are bad now, wait a few decades.
The discussion around climate change and breakdown of current climate cycles is always about what's survivable for our current environment and biosphere with humans in it...
I think it's also hard for people to grasp the stepwise process for this breakdown, at least from my personal experience I feel most are ignorant about the cycle of increasing social strife across the globe that will happen, a cycle of ever-increasing misery spreading across societies, eroding civil structures, etc.