Climate change activists have an influential new ally who could bring along more than a billion followers. This week the Vatican held a summit on how environmental crises hurt the poor. A top Vatican official and point person for Pope Francis announced at the summit that increasing use of fossil fuels is disrupting Earth on an "almost unfathomable scale" and cautioned that a "full conversion" of hearts and minds is needed if global warming is to be conquered. The summit is widely seen as a lead-in to the Pope's upcoming encyclical framing the fight against global warming as a moral responsibility -- a first of its kind. Activists hope the Catholic Church will inject the largely secular climate change movement with a spiritual infusion. However, It could put the Pope and the church at odds with conservatives -- Catholics included, some of whom deny the existence of global warming and believe religion has no place in this political battle.