In California electricity is increasingly generated by renewables (~25% in 2016) with the goal of hitting 50% by 2030, which looks achievable. We actually have a surplus of renewables during the late afternoon that can cause power prices to go negative. Between this and conservation measures like insulation the impact of home energy use does not look that high. It's also getting better over time.
The big problem in California is transportation, which is still petroleum-based autos. You don't commute by car but many people do. Knocking that out is one of the best things you can do to combat global warming. For example my commute, which is about 50 miles generates between 60 and 80 pounds of C02 daily assuming 3-4 gallons. That's assuming a fuel-efficient car. (Fortunately I only do it a couple of days a week.) At some point the car will be electric but mass replacement of the fleet is still a long way off.
You could always cool of the way God intended, sweat your ass off. :)
Use a smaller heater, solar panels, LED globes etc.
I haven’t done any math on it, but it’s something I do worry about.