With or without global warming (and warming will likely worsen things) the state has built extreme vulnerability to rare, but inevitable meteorological monstrosities
The weight of humanity on California's sliding and sinking landscape. My sister's family being evacuated from their home in the Santa Barbara area in the 2017 Thomas fire burn scar. That is where all the mudslides in Montecito occurred in early 2018.
We don't need to worry about any of this because there is a solution. The Yellowstone Super Volcano. Once the Yellowstone volcano goes off so much ash will fall on California that it will raise the ground level sufficiently to prevent serious flooding. I knew you'd want to know this good news right away. :-).