please welcome michael shellenberger. [cheers and applause] thanks so much for coming on. >> thanks for having me. >> stephen: i know you are an environmentalist because you are not wearing a tie. >> yes. >> stephen: but you are radical because you are very well coifferd. >> thank you. >> stephen: you are president and cofounder of breakthrough institute coauthor of the book breakthrough which made a splash a couple years ago and a new e-book. what is your new idea for saving the environment? >> the big idea is we spent 20 years on global warming trying to make fossil fuels more expensive. that didn't work. there's an important shift that needs to be made to making clean energy safe. >> stephen: what is your idea clean coal? >> all the technologies. >> stephen: clean coax you are on board. >> if they can figure out a way to cheaply capt tiewrt coal it needs to be put on the list. >> stephen: clean cool. that takes care of all of it. you are not like a tree hugger kind of guy, right? >> i am sort of a tree hugger. >> steph