The senator’s comments mark a further sweetening of the mood music between the two nations that together account for almost half of the world’s greenhouse gas emissions, but this has yet to translate into concrete progress.
In their formal positions, the two sides remain far apart. China wants developed nations to make a 40% in emissions by 2020 from 1990 levels, far above the goal set by President Obama’s administration.
The United States wants China to set voluntary but verifiable goals to reduce its energy use and, in the longer term, to join richer nations in cutting overall emissions.
But Kerry said senior Chinese politicians had shown a willingness to compromise, particularly over the 40% target that he described as politically impossible in the US at present.
By sharing know-how and conducting joint research into renewable and energy-saving technology, he said China would realise that it can go beyond its current target of a 20% cut in energy intensity relative to economic growth.
The Chinese government has already tripled its target for wind power and will soon announce a $200bn investment in clean energy, Kerry said.
He quoted first vice-premier Li Keqiang as saying “Let’s do it” with regard to bilateral cooperation in the field.
Major sticking points remain over the question of which nations will pay and how much will be spent on measures to mitigate climate change and its impact. It is also far from certain that China will agree to the stringent verification process sought by the US.
How far each side is willing to compromise will be largely determined in June, when the chief US negotiator Todd Stern visits Beijing, US politicians consider new legislation to cut emissions and the United Nations hosts international talks in Bonn at which the first negotiating texts will be on the table.
US house speaker, Nancy Pelosi, said the possibility of a deal on the environment could transform relations between the world’s richest and most populous nations.
“I do see this opportunity for climate change to be … a game-changer,” she told students at the elite Tsinghua University. “The impact of climate change is a tremendous risk to the security and wellbeing of our countries.”
In a sign of shifting priorities, Pelosi has been noticeably quiet about China’s human rights record during this week’s visit. She was previously a vociferous critic of Beijing’s controls on the media, political activists, lawyers and religious groups.
Many doubt the two nations are being ambitious enough. If China sticks to its current energy efficiency goals and growth rate, the consultancy McKinsey estimates that its emissions will double by 2030.
“That will swamp everything that Europe and the US is willing to do,” said Charlie McElwee, a Shanghai-based environmental lawyer.