Cop26 president Alok Sharma has demanded more details from Beijing about how it will meet climate goals following two days of talks with Chinese officials.
The United Nations Cop26 climate summit, which will be held in Glasgow in November, aims to secure global net-zero emissions by the middle of the century.
But China has so far only committed to achieve carbon neutrality by 2060.
Mr Sharma said questions remained over how fast Beijing’s commitments would be put into action.
China’s role in tackling climate change will be vital due to the size of both its population and economy.
Mr Sharma met China’s special representative for climate change affairs, Xie Zhenhua, in Tianjin for talks described as robust but constructive by insiders.
The pair discussed President Xi Jinping’s commitments to achieve carbon neutrality by 2060, peak emissions before 2030 and reduce China’s use of coal.
Mr Sharma said: “I have had constructive discussions on my first visit to China in the Cop26 role, but time is running out to prevent a climate catastrophe, and so the discussions I have had here are nothing short of crucial.
“The commitments President Xi has made over the last year are welcome and China’s pledge to tackle climate change as a shared mission for humanity is encouraging.
“The question that remains is how fast they put these into action, along with other major emitters. I look forward to more detailed plans being published setting out how China’s targets will be met.
“The clock is running down fast and the next decade will be decisive. All countries need to pick up the pace on driving down emissions and safeguarding people and nature from the worst effects of climate change.”
During the visit Mr Sharma also discussed the detailed Covid measures that will be in place for the Glasgow summit in an effort to reassure the Chinese delegation.
It remains unclear whether President Xi will join other world leaders in Glasgow.
Officials have acknowledged that Cop26 will not be the end of the road in tackling climate change amid concerns that its goals will not all be met.
Mr Sharma also met other senior ministers virtually including Chinese vice premier Han Zheng, as well as the governor of the People’s Bank of China Yi Gang and business representatives.
His trip to China followed US climate envoy John Kerry’s visit to Tianjin earlier in September.
Mr Kerry told Mr Han in a virtual meeting that there was “no way” for the world to solve the climate crisis without China’s “full engagement and commitment”.