The difficult relationship between the world’s two largest carbon emitters has somewhat thawed over the issue of global heating, with both sides indicating they see it as a shared menace set aside from other tensions around trade or the status of Taiwan. The US and China are “alarmed” by the state of “one of the greatest challenges of our time” and will work to resolve it despite other differences, as the countries’ joint statement on Tuesday put it.

The breakthrough has been welcomed by climate experts who point out that little can be done to stem the unfolding climate crisis without strong action from both China and the US, which together are responsible for nearly 40 percent of the world’s greenhouse gas emissions. Climate talks have been on hold for more than a year but are set to be on the agenda, among more contentious issues, as Joe Biden meets his Chinese counterpart, Xi Jinping, in California on Wednesday.

Much of the groundwork for this has been conducted through months of talks between John Kerry, the US president’s climate envoy, and Xie Zhenhua, China’s top climate negotiator. The duo met at the sprawling Sunnylands estate near Los Angeles last week and this laid the groundwork for an announcement punctuated with promising highlights.

The two superpowers will work to “triple renewable energy capacity globally by 2030”, the statement outlines, which will “accelerate” the replacement of oil, coal and gas with cleaner sources, such as solar and wind.

The duo will strive to “halt and reverse” forest loss by 2030 and, importantly, China will set reduction targets for all of its greenhouse gas emissions, not just the carbon dioxide addressed in its current plan. China is a major emitter of methane, a potent greenhouse gas released by mining and agriculture that is up to 80 times more powerful in heating the planet, over the short term, than CO2.

“Methane has been notably absent from China’s previous commitment under the Paris agreement,” said David Waskow, international climate director of the World Resources Institute. “This announcement is a major step because China is the world’s largest methane emitter and serious actions to curb this gas is essential for slowing global warming in the near term.”

The US and China have agreed that the next round of climate pledges, set to be put forward by countries in 2025, will include planned emissions cuts across all of China’s economy, an improvement on the country’s current promise, which seeks to peak carbon pollution prior to 2030 but does not set out by how much it will slash emissions.

The joint plan also is notable in what it lacks, however. There are no specific emissions cuts laid out in this generic framework, nor is there any firm commitment to phase out fossil fuels, which is a major priority for activists and some countries at the UN’s climate summit, known as Cop28, starting in Dubai in two weeks’ time.

“It is disappointing that the two nations said nothing about the need to rapidly transition away from fossil fuels this decade,” said Waskow. A recent UN report warned countries are pushing ahead fossil fuel projects at a rate incompatible with avoiding climate breakdown.

The US has wanted China to do more to wind down its heavy use of coal, the dirtiest of fossil fuels, amid complaints by members of the US Congress that China, now the world’s biggest carbon emitter, isn’t doing enough to curb its permitting of new coal plants, which continue to proliferate alongside a boom in clean energy projects.

China, meanwhile, is believed to think the US, the world’s largest historical emitter, should accelerate its own emissions cuts — US oil and gas production is set to break records this year — and is wary of the US’s volatile political situation around the climate crisis. Donald Trump, the likely Republican nominee for next year’s presidential election, has vowed to reverse Biden’s climate agenda and spur a glut of new oil and gas drilling.

The joint statement, therefore, should be seen as a “very important” re-establishment of dialogue between China and the US, according to Li Shao, director of the China Climate Hub at the Asia Society, but one that still sits in the context of broader unease between the two countries.

Talks were frozen last year after Nancy Pelosi, then House speaker, traveled to Taiwan, a move seen as an outrageous provocation by Beijing. This was followed by an incident earlier this year when a US fighter jet shot down a Chinese spy balloon that had floated across a large swathe of US territory.

The statement “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”, Li said. Much more will need to be done at Cop28, taking place in what is almost certain to be the hottest year ever recorded, to make up the ground needed.