President Barack Obama on Tuesday said the U.S. and China have a “special responsibility to lead” efforts to curb carbon greenhouse gas emissions, as he sought to enlist nations around the globe in efforts to combat climate change. “There is one issue that will define the contours of this century more dramatically than any other,” Mr. Obama said at a United Nations climate summit in New York. “That is the urgent and growing threat of a changing climate.” Mr. Obama told delegates the U.S. is ready to lead in a new set of global climate-change negotiations but urged major economies—including emerging economies—to get on board. “Nobody gets a pass,” he said. In an afternoon address, Mr. Obama announced a set of limited measures Washington will take to address climate change abroad and to align […]