Drastic reductions in energy use aren't going to happen so perhaps the focus should be on reducing costs for cleaner sources. And I'm not talking government subsidies that don't actually reduce overall costs. I'm talking about finding ways to build and run the sources cheaper. Fossil fuel use won't be effectively reduced until the supplies are eliminated or the price for the alternatives become cheaper for everyone without the use of subsidies.
Drastic reductions in energy use aren't going to happen ....
Then I think we're fucked. I don't think there's any practical way to simply swap our astronomical fossil-fuel energy expenditure with renewables.
Not at the current costs. That's why I said the cost of renewables needs to be brought down to below the cost of fossil fuels. Humans can be creative and inventive beings, maybe someone (not a politician) can create some sort of incentive to help bring it out.
I think we need everything: to drastically reduce our energy use, decimate the fossil fuel industry, large scale carbon capture techniques, and geoengineering. Honestly I don't see it happening.