U.S. experts Thursday welcomed China's new goals to reduce the intensity of carbon dioxide emissions per unit of GDP in 2020 by 40 to 45 percent compared with the level of 2005.

"This new goal represents an important commitment by China to continue its aggressive existing energy conservation and renewable energy policies beyond its current five-year plan and sends a strong signal to the international community that it wants to be a constructive player at the UN Climate Conference in Copenhagen, which starts in less than two weeks," said Julian L. Wong, senior policy analyst at the Center for American Progress.

According to Wong, this reinforced China's pledge last week at the meeting between Chinese President Hu Jintao and his U.S counterpart Barack Obama to the "full transparency" of its mitigation actions and to "stand behind these commitments."

"China has showed a willingness to raise clean energy targets this year when it strengthened its wind energy and solar energy goals for 2020," Wong explained.

Jonathan Lash, president of the World Resources Institute (WRI), also spoke positively of the decision made by the Chinese government on Thursday.

"As we head towards Copenhagen, the world's two largest emitters have stepped up to the plate at the highest political level," he said. "This shows that international engagement on climate change can produce real results."

With the announcement by U.S. President Barack Obama on Wednesday that he would call for a U.S. emission-reduction target of 17 percent below 2005 levels in 2020, nearly all industrialized countries and major emerging economies have now announced emissions goals or major action plans on climate.

"Carbon intensity is the emissions produced per unit of economic output, and China's fast-growing economy means that absolute emissions in China will rise during this period," Lash said.

"However, China's goal is in line with what the International Energy Agency thinks is needed to keep global greenhouse gas (GHG) concentrations on a path that gives the world a chance of keeping global warming under 2 degrees Celsius, averting the worst impacts of climate change."

He pointed out that to meet the target, China appeared committed to implement ambitious energy-efficiency and fuel-switching policies.