When you look at the history of human technical achievement, it's a story of harnessing more and more energy. I don't think reducing energy use is any kind of solution and making energy more expressive is just going to greatly diminish the services we can provide and limit who we can provide them to. Viewed another way, solving global warming would be easy if we had a near infinite supply of extremely cheap energy. The most important thing we could do for the human race would be to invent 10x cheaper energy with 10x lower externalities.