Cooperation is "the single best chance that we have" to save the planet, President Obama said Saturday 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 UN Secretary-General Ban Ki-moon, the AP reports. The papers certified the US and China have taken the necessary steps to join the Paris accord that set nation-by-nation targets for cutting carbon emissions.
"This is not a fight that any one country, no matter how powerful, can take alone," Obama said of the pact. "Some day we may see this as the moment that we finally decided to save our planet." Xi, speaking through a translator, said he hoped the announcement would spur more countries to take action. "Our response to climate change bears on the future of our people and the wellbeing of mankind," he said. The announcement means the accord could take force by the end of the year, a faster than anticipated timeline. The ceremony occurred shortly after Obama arrived in the scenic Chinese city of Hangzhou for the annual G20 summit of industrialized and emerging economies. (Read more climate change stories.)