I did the research on bear deaths in CA a couple of years ago. There have been three:
1. Grizzly attack in the 1870s
2. Asian Brown bear attack at the San Diego Zoo
3. Captive Movie Grizzly near Big Bear

I didn't know in my heart that Black Bears were really not a threat until I actually encountered one (in West Virginia). I didn't need to do anything to get the bear to retreat other than to walk in its general direction.

the black bear's flee and climb instinct, especially around humans, is the main reason it is still found in California today. The grizzly's more aggressive nature is also the reason it is not found in California today.