US-China joint climate action back on track, hours ahead of Xi-Biden meeting in San Francisco

China and the United States pledged to renew climate cooperation and step up joint action to combat global warming just hours ahead of a high-stakes leadership summit, fuelling hopes that the rival superpowers could still work together to tackle global challenges.

In identical statements issued separately on Wednesday, the two countries agreed to relaunch a working group on climate cooperation, "pursue efforts to triple renewable energy capacity globally by 2030" and "accelerate the substitution for coal, oil and gas generation".

The world's top two carbon emitters also agreed to include methane in their respective 2035 emission-cutting plans - the first time China has made such a pledge - and work together to control other non-carbon dioxide greenhouse gas emissions, as well as curb forest loss and plastic pollution.

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The statements follow four days of talks last week between China's special climate envoy Xie Zhenhua and his US counterpart John Kerry at the Sunnylands estate in California.

Climate experts have welcomed the agreements, despite the absence of any pledge from China to phase out dirty coal or the building of new coal power plants.

Li Shuo, incoming director of the China Climate Hub at the Asia Society, said renewed US-China cooperation was "very important" both for bilateral ties and the COP28 United Nations climate talks in Dubai opening later this month.

"The Sunnylands statement is a timely effort to align the US and China ahead of COP28. It underscores the need for engagement between the two largest emitters of the world, a precondition for meaningful global progress," he said.

The release of the details was carefully timed, coming just as President Xi Jinping arrived in San Francisco ahead of a meeting with President Joe Biden for their first in-person talks in a year. As such, the limited progress on the climate front was not surprising, Li noted.

"It reopens a lot of environmental communication and it shows again that re-establishing engagement and dialogue between the US and China is very important," he said.

"But at the same time, we need to note that we have not seen any breakthroughs on some of the very core and substantive issues, such as COP28, energy transition and coal. I think this is largely in line with expectations, that under the current challenging political situation between China and the US, any climate outcome will only be 'floor setting', not 'tone setting' or ground breaking."