Mayor Jean-Francois Parenteau, left, of Montreal, Quebec, speaks with Mayor Jim Brainard, of Carmel, Ind., following a clean energy panel discussion during the Boston Climate Summit in Boston, Thursday, June 7, 2018. About two dozen mayors and city leaders were attending the event, billed as a chance to explore ways to reduce greenhouse gas emissions and prepare for the challenges posed by climate change. (AP Photo/Charles Krupa)