CANCUN, MEXICO - China is certainly making serious efforts to deal with carbon emissions, US Special Envoy for Climate Change Todd Stern said Wednesday, adding he has "enormous respect" for what China is doing domestically.

Stern told reporters that he knew China is doing a great deal with respect to increasing energy efficiency, renewable energy and so forth after visiting factories, the Tianjin Climate Center and various places in China in October.

"We know that there are more to be done (in China)," said Stern at the sideline of the ongoing United Nations climate change conference.

In November 2009, China promised to reduce carbon dioxide emissions per unit of gross domestic product by 40 to 45 percent by 2020 from 2005 levels, while increase the share of non-fossil fuels in primary energy consumption to around 15 percent by 2020.

During the 11th Five-Year Plan (2005-2010) period, China's investment in energy-saving and emission-reduction projects reached about two trillion yuan ($300 billion), more than 200 billion yuan of which came from the Chinese government, according to China's National Development and Reform Commission.

Stern said even with all the good work China is doing, its emissions are still enormously high. However, "China is certainly making serious efforts to deal with it," Stern said.

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The official said the United States and China have very good channels of communications and he "absolutely" hopes the US and China can cooperate together on climate change.

"I think there will be a lot of cooperation in the future and it needs to be," he told reporters.

The UN climate change conference, running from Nov 29 to Dec 10 in the Mexican resort of Cancun, aims at finding solutions to global climate change. Attendees include some 25,000 government officials, businessmen as well as members of nongovernmental organizations and research institutions from almost 200 countries.