China’s President Xi Jinping has called for “win-win co-operation” with the US on his first state visit to Washington.
Speaking on the White House lawn, he said the relationship with the US “must adapt to the changing times”.
He was welcomed by President Barack Obama, who said the two nations “had an unmatched ability to shape the course of the world” if they worked together.
Mr Xi is later expected to make a landmark pledge on climate change and on curbing harmful emissions.
The Chinese and US presidents held informal talks at the White House on Thursday, where they discussed Iran’s nuclear programme. Mr Xi’s visit has been overshadowed by an ongoing row over cyber security. Speaking at a welcome event on the White House lawn on Friday, both the US and Chinese leaders emphasised the benefits of closer co-operation.
Mr Obama said the US wanted to see the “rise of a China that is stable, prosperous and peaceful”.
Mr Xi meanwhile said the two countries had “no choice but to seek win-win co-operation”, and called for building “a new model of major country relations”.
A White House official told reporters that Mr Xi would announce on Friday plans to launch a national carbon emissions trading scheme in 2017.
The “cap-and-trade” scheme would see Chinese companies charged to emit pollutants beyond a certain level.
China would also make a “very substantial financial commitment” to developing nations to help them move to low-polluting technologies, the Associated Press news agency quoted the official as saying.
The expected Chinese announcement follows on from a joint US-China climate pledge in late 2014.
Then, Mr Obama set a new goal of reducing US levels by between 26%-28% by 2025, compared with 2005 levels. China did not set a specific target, but said emissions would peak by 2030.