Beijing, China (BBN)-China and the US have unveiled new targets to cut greenhouse gas emissions, as the leaders of the two countries met for talks in Beijing.
US President Barack Obama said the move was "historic", as he set a new goal of reducing US levels between 26%-28% by 2025, compared with 2005 levels, reports BBC.
China did not set a specific target, but said emissions would peak by 2030.
It is the first time China, the world's biggest polluter, has set an approximate date for emissions to peak.
The news came during a state visit by Obama to Beijing, which followed a major Asian regional summit.
The two countries together produce about 45% of the world's carbon dioxide.
The unexpected announcement could be boost efforts to secure a global deal on reducing emissions after 2020, to be finalised next year in Paris.
'SLOW, PEAK THEN REVERSE'
The new goal from the US is up from a previous target to cut emissions by 17% by 2020.
In September, China told a United Nations summit on climate change that it would soon set a peak for carbon emissions and that it would make its economy more carbon efficient by 2020.
China's carbon emissions are still increasing as it builds new coal plants to generate electricity and support its rapidly growing economy.
Obama called Wednesday's agreement "historic" and said the US would work with China to "slow, peak and then reverse the course of China's carbon emissions".
Republican leaders in the US reacted strongly to what they called an "unrealistic plan" proposed by Obama.
"This unrealistic plan, that the President would dump on his successor, would ensure higher utility rates and far fewer jobs," Senate Republican Leader Mitch McConnell said.
The UN has previously warned that the impact of global warming is likely to be "severe, pervasive and irreversible", and would lead to problems including sea level rise, greater risk of flooding and changes to crop yields.
BBN/SS-12Nov14-10:30am (BST)