Droughts happen in the southwest.
You are trying to blame climate change for a cycle that has been going on for 100,000 of years. The American southwest has a long history of a natural cycle of periods of high rain mixed with times of drought that has driven a following cycle of rising and falling populations.
All of the major cities in the American southwest were developed based on water allocation models built on data obtained during those good rainfall years. Politicians have been slow to admit this failure in planning in large part because they would lose power if the truth came out.
Can you imagine the political shift in this nation if millions of people moved away from the droughts and relocated to where the water is? What do you think would happen if people were told that they could no longer drill deeper for water and that they already have data indicating the underground water sources will dry up in 30 years?
What would happen is people would move. States like Wisconsin and Michigan would again be political heavy weights while California, Arizona and Texas would become political lower population lightweights like Montana and North Dakota.