World's largest polluter decouples economic growth from growth in greenhouse gas emissions in new plan. Prime Minister Wen Jiabao will take part in the Copenhagen climate conference.

China announced plans Thursday to cut its carbon emissions by up to 45 percent as measured against its economic output – a target aimed at keeping its surging growth while still reining in pollution.

According to the State Council announcement, China pledges to cut carbon intensity – carbon dioxide emissions per unit of gross domestic product – by 40 to 45 percent by 2020, compared with 2005 levels.

The goal does not mean that China will cut its total carbon emissions by 2020. Given the expected growth in its economy, its global warming emissions should increase over the next decade – but at a much slower pace than if China had made no changes.

China is the world's largest emitter of greenhouse gases believed to cause global warning.

India, the world's fifth-biggest greenhouse gas emitter, has proposed a similar policy to link emissions to growth in gross domestic product.

China's State Council said the improvements would come through better research and development, clean coal technology, advanced nuclear energy and better transportation systems. Tax laws and regulations will also be changed to encourage energy efficiency.

China announced earlier that Premier Wen Jiabao will take part in the Copenhagen conference.

Despite setting a target on carbon emissions, China is not expected to accept an international treaty that sets a binding target for it.

Yu Jie, head of policy and research programs for The Climate Group China, a non-governmental group, describes China's 45 percent target as "quite aggressive".

Leader of WWF Global Climate Initiative, Kim Carstensen, says that "a 40-45 percent reduction in China's carbon intensity from business as usual projections is far from trivial."

"Given the size of China's economy, the decoupling of China's economic growth from growth in emissions is one of the most important factors that will determine whether the world can get on course to keep temperature rise below two degrees Celsius," says Carstensen.

UN climate chief Yvo de Boer says in a comment that "the US commitment to specific, mid-term emission cut targets and China's commitment to specific action on energy efficiency can unlock two of the last doors to a comprehensive agreement" in Copenhagen.