The decision by United States President Barack Obama to reschedule his appearance at the United Nations climate change summit in Copenhagen was warmly welcomed by Chinese experts as a sign that there is increasing momentum toward a new global treaty.

But experts also said China should not be greatly affected by the White House rescheduling. Premier Wen Jiabao is still expected to attend the conference though his schedule is still unknown.

Experts said the rescheduling will allow Obama more time to make important decisions on such issues as the transfer of capital and technology to developing countries before the end of the two-week conference, which begins today.

"Otherwise, his rescheduling is meaningless," said Pang Zhongying, professor on American Studies with Renmin University of China, to China Daily yesterday.

Obama abruptly changed his itinerary to be in the Danish capital of Copenhagen on the closing day of the climate meet on Dec 18. He had planned to be there at the outset.

Controversy brewed over Obama's plan in the midst of the summit to travel to Oslo, Norway, to collect his Nobel Peace Prize. His Oslo schedule remains unchanged.

Analysts said Wen is likely to appear during the second week of the UN talks, seen as the more critical stage of the conference.

"By sending Premier Wen to Copenhagen, China has already sent a clear message to the West," said Pang. "And that is, China has already pledged enough and the premier is there to tell the world how to deliver on the promises."

Some experts questioned the US' seriousness in mitigating global warming, saying Obama's readjusted schedule "can hardly guarantee stable climatic policies from US."

The Obama administration has been encouraged by recent announcements by China and India, two other major carbon emitters, to set targets to rein in emissions. It has also been influenced by growing consensus to raise cash to help developing nations cope with global warming, seen as a stumbling block to a new UN deal.

China announced it will cut carbon intensity by 40-45 percent by 2020 from 2005 levels, after the US pledged to reduce greenhouse gases emissions by 17 percent by 2020 from its 2005 base level.

The Danish government said more than 100 world leaders including Premier Wen, British Prime Minister Gordon Brown and French President Nicolas Sarkozy, have confirmed they will attend the conference, which Denmark hopes will help lay the foundation for a successor to the 1997 Kyoto Protocol on curbing global warming gases.

Danish Prime Minister Lars Lokke Rasmussen swiftly welcomed Obama's decision, saying his attendance was "an expression of the growing political momentum towards sealing an ambitious climate deal in Copenhagen."

In London, a spokesman for Brown said Obama's presence would give "huge impetus" to the negotiations.

Environmentalists welcomed Obama's move and called for him to shift his administration's target for cutting emissions.

"After a global outcry, President Obama has listened to the people and other world leaders; he has come to his senses and accepted the importance of this potentially historic meeting," said Martin Kaiser, Greenpeace International's political climate coordinator.

"Now that he has moved the date, he needs to move his targets and his financial contribution to be in line with what climate science demands," he said.

But some don't agree.

"Obama's decision has signaled that his administration is still dangling in regards to discussing climate change," said an environmentalist named Zhang, who heads a US environmental organization in Beijing.

"If a US president can't hold a stable schedule, my interpretation is that he is not serious in joining global efforts in tackling global warming and it is hard to expect stable policy outcomes back at home," Zhang said. "I have to assume they were getting feedback from other global leaders that people thought it was important that he be there at the end. And if you're moving in that direction, why come twice?"

Official comment from China on Obama's Friday decision was unavailable.