California Gov. Jerry Brown, right, delivers his speech flanked by the head of the pontifical academy of Science, Bishop Marcelo Sanchez Sorondo, during a conference on Modern Slavery and Climate Change in the Casina Pio IV the Vatican, Wednesday, July 22, 2015. Dozens of environmentally friendly mayors from around the world are meeting at the Vatican this week to bask in the star power of eco-Pope Francis and commit to reducing global warming and helping the urban poor deal with its effects.
California Gov. Jerry Brown, right, delivers his speech flanked by the head of the pontifical academy of Science, Bishop Marcelo Sanchez Sorondo, during a conference on Modern Slavery and Climate Change in the Casina Pio IV the Vatican, Wednesday, July 22, 2015. Dozens of environmentally friendly mayors from around the world are meeting at the Vatican this week to bask in the star power of eco-Pope Francis and commit to reducing global warming and helping the urban poor deal with its effects. Alessandra Tarantino AP
California Gov. Jerry Brown, right, delivers his speech flanked by the head of the pontifical academy of Science, Bishop Marcelo Sanchez Sorondo, during a conference on Modern Slavery and Climate Change in the Casina Pio IV the Vatican, Wednesday, July 22, 2015. Dozens of environmentally friendly mayors from around the world are meeting at the Vatican this week to bask in the star power of eco-Pope Francis and commit to reducing global warming and helping the urban poor deal with its effects. Alessandra Tarantino AP