“If China sticks with its current plant and does not peak its emissions until 2030, then the entire rest of the world must go to zero by 2040 or even 2035,” he warned.
“There is simply no alternative because without sufficient reduction by China, the goal of 1.5C is essentially impossible. China’s partnership and leadership on this issue of extraordinary international consequence is essential.”
Mr Kerry said he was convinced that China could outperform the targets it had set itself and that despite their diplomatic differences, the US was keen to co-operate.
He also said all other major economies would have to step up, with more ambitious targets and plans for the next decade.
Mr Kerry’s comments come as new research shows that G20 countries are continuing to support fossil fuels in ways that are incompatible with the goals of the Paris agreement.
According to Bloomberg’s Climate Policy Factbook, G20 nations collectively cut fossil fuel funding by 10% from 2015 to 2019. However, eight countries, including the US, Canada and Australia increased their financial support for oil, coal and gas in this period.
Last week, Mr Kerry travelled to Moscow where both sides agreed that the climate issue is one of common interest. President Putin said that Moscow “attaches great importance” to achieving the goals of the Paris climate agreement.
In May, Mr Kerry was criticised by some scientists for rejecting the idea that Americans would have to change their consumption habits, for example, eating less meat.