How are the energy requirements for keeping the lights on, providing heat, cooling, transportation and a myriad of assists to human life going to be provided/available without or with significantly less use of fossil fuels? IMO, H. Sapiens is on the proverbial "Horns of a Delema" vis-a-vie the use of less fossil fuels or the continued rate of use of such. i.e.: We're Damned if We Do and We're Damned if We Don't". Ref. "The Ends of The World" by Peter Brannen and "World Dynamics" by Jay Forrester. P.S.: Nuclear fusion may be a short term answer, but long term "what do we do with the radioactive spent fuel"?