HANGZHOU, China — President Obamaand President Xi Jinping of China formally committed the world’s two largest economies to the Paris climate agreement here on Saturday, cementing their partnership on climate change and offering a rare display of harmony in a relationship that has become increasingly discordant.
On multiple fronts, like computer hacking and maritime security, ties between China and the United States have frayed during the seven and a half years of Mr. Obama’s presidency. The friction has worsened since the ascension of Mr. Xi as a powerful nationalist leader in 2013.
Yet the fact that he and Mr. Obama could set aside those tensions to work together yet again on a joint plan to reduce greenhouse gases attests to the pragmatic personal rapport they have built, as well as to the complexity of the broader United States-China relationship, a tangle of competing and congruent interests.
At a ceremony in this picturesque lakefront city, the two leaders hailed the adoption of the Paris agreement as a critical step toward bringing it into force worldwide. Together, China and the United States generate nearly 40 percent of the world’s emissions, not far from the threshold of 55 percent required for the global pact to take effect.
“Despite our differences on other issues, we hope our willingness to work together on this issue will inspire further ambition and further action around the world,” Mr. Obama declared.
Mr. Xi praised the Paris agreement as a milestone, adding, “It was under Chinese leadership that much of this progress was made.”