On Thursday, the pope will publish a blunt encyclical, somewhere between a policy paper and an edict, calling for the world's richest polluters to step up and finance projects to help poorer nations avoid following in their path. He'll also blast climate change deniers, and the nefarious role of "economic powers" that undermine carbon-cutting efforts. How much impact will the encyclical have? And is it Francis' role to get involved?
