There are droughts and droughts. Some suspect a 150 years drought led to the collapse of Maya civilization.
> Our results show rather modest rainfall reductions between times when the Classic Maya Civilization flourished and its collapse -- between AD 800-950. These reductions amount to only 25 to 40 per cent in annual rainfall. But they were large enough for evaporation to become dominant over rainfall, and open water availability was rapidly reduced. The data suggest that the main cause was a decrease in summer storm activity
> Studies of] Yucatecan lake sediment cores ... provide unambiguous evidence for a severe 200-year drought from AD 800 to 1000 ... the most severe in the last 7,000 years ... precisely at the time of the Maya Collapse.
The drought could get much worse than disrupting home irrigation. Depending on how bad it gets, the price of water could rise and force people out, leaving them with no choice but to leave. I don't know what that would look like or how it would affect households already economically strained with limited capacity to move, but I doubt it will be a good situation.
The disruption to California's ability to produce food will also affect people outside of the state, raising prices.
There's probably water around to import if the price is right if it came to that, so I think it just becomes a question of market forces and how the drought will impact California's economy and the country. I don't think many people are going to die of thirst, although that is a real possibility for immigrants who cross the border illegally who may encounter less water because of the drought.
> I don't think many people are going to die of thirst
Remember 80% of California's water goes to agriculture. More water is used to grow almonds than for all of residential irrigation. There are far more non-farmers than farmers; I expect the next step will be to cut back more on agricultural uses.
In a few generations we may look back and wonder why we were flooding fields half a foot deep with increasing scarce water to grow rice in an extremely dry climate. Especially when rice grows perfectly well in areas of the world that actually, you know, get rain all year round.
Another thing history might teach is that when critical resources like food and water are so poorly and corruptly managed that the result is famine and drought, millions of people can die. I suppose we're going to call that disruptive innovation?
