I'm not sure that there is a two class system by design. That is certainly true for desert societies, but come cultures are MUCH more complex than two. Even Marx's comrades were three classes, also in Brave New World.
I'm for distributed sustainable energy budgets for high tech cultures. That means your energy budget depends on the climate you find yourself in, and is somewhat outside of your control. Cheap fossil fuels are nice for a time, but their regeneration cycle is too long to be sustainable over the long term.
However, every inch of this planet has plenty of ambient energy lying around, just not necessarily in a usable form. Getting it into a usable form is NOT a one-size-fits-all mass produced solution, and can't be. Anybody who says, just end the use of fossil fuels tomorrow, has not looked at the cost. I'm blessed in the Pacific Northwest with four major sustainable sources of energy at different times of the year, and with the new batteries, we can do even better.
As for climate change- there really are only two sustainable strategies- adapt and use the changes in weather to generate usable electricity, grow more food, store excess carbon in our graves. Or try to fight with outlandish ideas like eliminating fossil fuels, putting powdered aluminum in orbit to throw energy away, or the stupid carbon tax that will never work anyway.
My money is that cultures and species that adapt instead of trying to fight, will win out in the long run. I place that bet due to the history of this planet- when conditions change, species that adapt to the new conditions live, everybody else goes extinct.