In the 1930’s, 25% of US population was in agriculture, and many of those were poor, small share-croppers. One or two bad crops due to a dust-bowl meant they were bankrupt - and the Okies were quickly on the way to California and the NW.
The US population now involved in farming is between 1-2%. We’ve already turned the desert into huge population centers.
The notion of another “dust bowl migration” is a nonsense idea.
I think he is talking about all the people in California who will have to move as no water to drink.
Stop confusing people with facts and logic!