These are the points I would have made if I had more time. I believe in man made climate change but these sort of studies make it easy for those who don't to point and laugh. The idea that there will be no progress in energy production in 200 years is such a silly assumption it means that this study can only be used for scaring the incredulous.
If I were to point to the fact that vinyl record sales are the fastest growing segment of music purchases and concluded that they would eventually overtake downloads the slashdot crowd would shout down my faulty reasoning pretty quickly. But because this study is about climate change the faulty assumptions get a free pass.