US, China formally enter landmark climate deal

President Barack Obama on Saturday said cooperation was "the single best chance that we have" to save the planet as he stood with China's President Xi Jinping to formally enter their two nations into last year's Paris climate change agreement.At a ceremony on the sidelines of a global economic summit, Obama and Xi, representing the world's two biggest carbon emitters, delivered documents to U.N. Secretary-General Ban Ki-moon.The papers certified the U.S. and China have taken the necessary steps