BALI, Indonesia — President Biden and President Xi Jinping of China agreed on Monday to restart talks between their countries as part of international climate negotiations, a breakthrough in the effort to avert catastrophic global warming.
Talks between China and the United States over climate had been frozen for months, amid rising tensions between the two countries over trade, Taiwan and a host of security issues. China suspended all cooperation with the United States, including around climate change, in August as retaliation for Speaker Nancy Pelosi’s trip to Taiwan.
But the leaders of the world’s two biggest economies — and the two biggest sources of fossil fuel emissions that are warming the planet — met for more than three hours on Monday afternoon ahead of the Group of 20 summit in Bali, Indonesia, and emerged to say their representatives would return to the negotiating table.
The announcement reverberated nearly 6,000 miles away in Sharm el Sheikh, Egypt, where delegates and activists at the United Nations climate conference, known as COP27, were hoping for news that could spur more aggressive climate action from countries around the world.
“This is good news for the climate talks and for climate action,” said Nathaniel Keohane, the president of the Center for Climate and Energy Solutions, an environmental group based in Washington.
Thousands of diplomats and activists in Egypt were hyper-focused on Mr. Biden’s Bali meeting with Mr. Xi.
“A lot is at stake,” said Li Shuo, a Beijing-based policy adviser for Greenpeace, an environmental group. He said the United States and China needed to send a signal that the existential threat to humanity posed by climate change was worth putting aside their differences.
Mr. Biden seemed to push Mr. Xi on climate cooperation in his opening remarks in Bali before the bilateral meeting at the Chinese delegation’s hotel.
“The world expects, I believe, China and the United States to play key roles in addressing global challenges, from climate changes to food insecurity, and to — for us to be able to work together,” Mr. Biden said. “The United States stands ready to do just that — work with you — if that’s what you desire.”
After the meeting, the White House released a statement saying the two leaders “agreed to empower key senior officials to maintain communication and deepen constructive efforts” on climate change and other issues.
John Kerry, Mr. Biden’s climate envoy, and his counterpart, Xie Zhenhua, have had no formal negotiations in Sharm el Sheikh, where delegates representing nearly 200 countries are struggling with the question of whether industrialized countries should compensate developing nations for loss and damage from climate disasters.
The two men, who have known each other for 20 years, have met casually at least seven times at COP27, an administration official said. They have been seen speaking together in public — at one point, Mr. Xie affectionately clasped Mr. Kerry’s arm — and Mr. Kerry has been spotted walking into the Chinese delegation’s office.
The renewed talks come at a pivotal moment in the fight to limit global warming. Negotiators representing nearly 200 countries at the talks in Egypt are struggling to find common ground between rich and poor nations.
“Countries like to hide between the U.S. and China and say, ‘The two biggest polluters aren’t working together, aren’t doing much, so why should we?’” said Bernice Lee, a climate policy expert at Chatham House, a policy institute in Britain. When they come together around ambition, she said, it removes that argument.
The discussions also come as countries compete to dominate the industries that will help the world pivot from fossil fuels.
The United States is poised to compete aggressively with China when it comes to the green economy following a landmark climate law signed by Mr. Biden this summer that will pump $370 billion into renewable energy and electric vehicles. When Mr. Biden appeared at the climate talks in Egypt on Friday, he said the funding would clear the way for American innovation that would drive down the cost of solar, wind and other renewable energy.
The United States and China are the two largest emitters of greenhouse gases, which have already warmed the planet an average of 1.1 degrees Celsius, or 2.7 degrees Fahrenheit, compared with preindustrial levels. If temperature rise passes 1.5 degrees, scientists warn, the likelihood of catastrophic climate impact significantly increases.
Previous deals between the United States and China helped pave the way for the 2015 Paris Agreement, which was the first global warming pact in which both developed and developing nations pledged to cut greenhouse gases.
“Can we imagine meeting 1.5 without the United States and China talking to each other for the rest of this decade?” Mr. Li said. “I can’t see that.”
But it remains unclear how renewed cooperation between Washington and Beijing might translate into concrete agreements at COP27, which began on Nov. 6 and is scheduled to end on Nov. 18.
The two countries are at odds on several fronts.
The United States wants negotiators at COP27 to reaffirm a commitment to keep warming to 1.5 degrees Celsius but China is resisting because that would require it to commit to deeper emissions cuts.
The single largest issue facing negotiators in Egypt is whether to create a fund to help poor countries cope with the loss and damage from continuing climate disasters — like the devastating floods in Pakistan and Nigeria, or the need to relocate island communities because of rising sea levels.
The Biden administration is resisting the creation of a new fund, in part because it is unlikely to secure any money from Congress, and also because the administration does not want to be held liable for skyrocketing global disaster costs.
Mr. Kerry has also said that China should contribute to any new pot of money that might be created, given its large and growing contribution to the global warming. That has not gone over well with China, which is clinging to its status in the U.N. climate body as a developing country and not an industrialized nation.
“It is not the obligation of China to provide financial support” under the U.N. climate rules, Mr. Xie said on Wednesday. Beijing is prepared to spend money to help poorer countries, he said, but only through separate channels.
“Both countries are under pressure at the COP to mobilize more climate finance for poor countries,” said Kelly Sims Gallagher, a professor at the Fletcher School at Tufts University. She said she hoped that will be the focus when Mr. Kerry and Mr. Xie sit down for substantive discussions.