China must cut emissions sooner if the planet is to avoid climate “chaos”, US climate envoy John Kerry has warned, telling the Financial Times that he was keen to speak to Beijing about a possible carbon border tax. Limiting global warming to 1.5C will be a “pipe dream” if China waited as late as 2030 for the peak of its emissions, he said in an interview after a major policy speech in London on Tuesday. “We’ve got to deal with reality here, that is the baseline truth we’re talking about,” he said.

Kerry, who has criss-crossed the world to promote President Joe Biden’s climate agenda, in his speech singled out China and said it would be ‘impossible” to limit warming to 1.5C unless the planet’s biggest emitter changed its targets. The 1.5C target is enshrined in the 2015 Paris climate accord.

Co-operation between the US and China on climate was “the only way to break free from the world’s current mutual suicide pact”, he told his audience at the city’s Kew Gardens. Kerry will call on countries to cut emissions further at the G20 environment ministers meeting held in Naples, Italy on Thursday.

With US-China relations at a low, co-operation on climate issues is one of the few areas where the two broadly align, making Kerry’s pointed remarks unusual.

The carbon border tax, a policy that is gaining traction among SenateDemocrats in Washington, is an issue that could divide the US and China.

After the EU published its proposal for a carbon border adjustment mechanism last week — which would impose a levy on imports of steel, cement and fertilizer from countries without carbon pricing — the US is considering whether to follow suit.

“We’ve talked with France, Netherlands and the EU very closely,” Kerry said, referring to the carbon border adjustment mechanism.

“We’ve agreed to consult — we’ve not said we’re supportive of definitely putting one into place,” he added. “That’s something I really want to talk to China and other countries about.”

Addressing an audience gathered in a sweltering conservatory during a London heatwave, Kerry joked: “Although we came here to talk about the greenhouse, we did not mean to put you in a greenhouse