U.S. President Barack Obama and Chinese President Xi Jinping ratified the Paris global climate agreement on September 3 at the G20 summit in Hangzhou.
The city is hosting the Group of 20 summit of industrialized and emerging economies.
This marks Obama’s last trip to Asia as president.
At a ceremony on the sidelines of the summit, Obama and Xi, representing the world’s two biggest carbon emitters, hailed their new era of climate cooperation as the best chance for saving the planet.
The Paris deal will come into force after at least 55 countries ratify it. The nations that have joined must also produce at least 55 percent of global emissions.
The United States and China, in total, produce 38 percent of the world’s man-made carbon dioxide emissions.