US envoy John Kerry is heading to Shanghai to woo China in advance of a climate summit President Joe Biden is hosting next week.
After a major diplomatic row at the UN, both sides hope to co-operate over plans to drastically cut emissions.
The US wants China to cease building coal-fired power stations and to stop financing coal ventures abroad.
China wants the US to give more cash to developing countries to obtain clean technology and adapt to climate change.
It also wants Washington to announce deep cuts in emissions.
Speaking to CNN, Mr Kerry said China’s co-operation was “absolutely critical” to battle the climate crisis.
He is hoping to salvage the superpower relationship to allow progress at President Biden’s virtual summit on 22 and 23 April.
Scientists warn that without an agreement between the world’s great polluters there’s little chance of averting dangerous climate change.
Bernice Lee, a China expert at the UK think tank Chatham House, said: “This is good news. At least they’re talking in the run-up to the summit. There will be big issues for both sides to resolve. But they must be resolved.”
Neither party has formally declared its climate masterplan to the UN, and each is struggling to coax more concessions from the other.