Check out this clip of Bill McKibben, the author and climate activist who led the successful effort to kill the Keystone XL Pipeline – via a spell in the clink – on last night's Colbert Report. His big message was that the proposed 1,700-mile tube, which would bring oil from the Canadian tar sands all the way to the Gulf of Mexico, might not be dead after all. Republicans have made the project a top priority and Big Oil is pushing hard to get construction approved. That would be a disaster, says McKibben; the tar sands contain the second-largest pool of carbon in the world after Saudi Arabia, and knowing what we now know about climate change, we'd be crazy to do anything other than leave it in the ground. He calls on Colbert Nation to sign his petition opposing the pipeline at 350.org.