Despite being generally cynical of events such as the recent meeting in Paris there were three things he hadn't anticipated: “one, the science has become clearer and clearer. Scientists are now practically begging we do something because of the danger of continued green-house gas emissions. We simply are on a very terrifying path. The science is in and it is frightening. Two, I never imagined that the two biggest emitters, China and the United States, would get together and say, "We have to do something about climate change." That's huge. But the third thing, that is the absolute game changer, was Pope Francis' encyclical. It is the most incredible piece of literature. I weep when I read it. He puts everything together; He doesn't fragment everything, he doesn't say, "Oh well, hunger and poverty, that's as issue for Oxfam, and social justice, that's an issue for Amnesty International, and the environment, that's an issue for the Suzuki Foundation." All of it is in a single package: we're now confronting a moral issue about the way we live on this planet. We've spent all our time being a focused on two relationships-human relationship with God and human relationships with other human beings. But the third one is a human relationship to the rest of creation."
You can read or download the encyclical at http://m.vatican.va/content/francescomobile/en/encyclicals/documents/papa-francesco_20150524_enciclica-laudato-si.html