When 195 nations clinched the Paris Agreement in December, it was heralded by some as a monumental achievement—the beginning of a process that would roll back the poisonous fruit of humankind's shortsightedness. Others viewed it as too little, too late. As officials converge this week on the United Nations for the signing ceremony, ominous reports in the four months since the deal have buttressed the doubters: Global warming may hit geological within decades. NASA is projecting that 2016 will break the annual heat record for the third year running; Greenland's ice sheet is experiencing springtime melt weeks earlier than average; and much of West Antarctica is...
