A duration of six days, two documents, three major knots, some sparkles in negotiations, and the place is China -- these might be all, if no more, about the upcoming UN climate talks in Tianjin.

On Oct. 4-9, two special working groups under the United Nations Framework Convention on Climate Change (UNFCCC) and its Kyoto Protocol respectively, each involving negotiators from more than 190 parties, will meet side by side to seek consensus and narrow their gaps, mainly on two draft documents.

There is not a duel between the two working groups. They will work on two tracks, or in a duel-track way, to push forward the UN climate talks to combat global warming.

Negotiators in Tianjin talks, like in other working group meetings, have two primary tasks. One is to narrow their differences and make a 70-page negotiating text under the UNFCCC "slimmer" to submit to the Cancun Conference scheduled for Nov. 29-Dec. 10 this year in Mexico.

Another task is that negotiators need to focus on a draft proposal and prepare a better document under the Kyoto Protocol for the Cancun Conference to facilitate the Conference to reach agreement on more points under the Kyoto Protocol and push ahead the process.

However, analysts believe that neither track is easy to move on due to three major obstacles, or knots which are difficult to be unbuckled.

First, the United States refused to return to the Kyoto Protocol. The world's top developed country refused to sign the revised Kyoto Protocol in Bonn in 2001 and pulled out, asking for a lower emissions target among others.

"Friends of the Earth", an international environmental organization, said in a recent statement that criticism on the United States may rise in the Tianjin climate talks.

"Lack of climate legislation in the U.S. may lead to less tolerance for U.S. efforts to torpedo Kyoto Protocol," it said.

"The U.S. remains the only wealthy country that has not ratified the Kyoto Protocol, the only international instrument related to climate change that contains legally binding emission reduction targets," it noted.

In the past, some countries might tolerate the United States' stance to leave or try to act against the Kyoto Protocol, because they believed that tolerance is the only way to let the United States return, analysts said. But now their tolerance is decreasing.

Secondly, unreasonable requirements that press big developing countries, such as China, India, Brazil and South Africa, to reduce emissions also will undermine the smooth proceeding of the talks, as it was an alternative way in which the developed countries shift their responsibility.

Some developed countries even sought to monitor the voluntary emissions reduction process in these developing countries, triggering intensive controversy in the talks.

The third obstacle lies in the transfer of technology and funds, while the key problem in the transfer of technology is the intellectual property right.

Currently, the negotiating progress nearly stalled on the technology transfer issue. As for funds, its sources, management and distribution remain quite uncertain.

Despite the three major obstacles, some sparkles, or positive scenarios, may appear in the talks.

For example, at the Copenhagen Conference last year, developed countries said that they will offer additional 30 billion U.S. dollars each year from 2010 to 2012 to help developing countries tackle climate change.

A high-level UN team reportedly is lobbying around the developed countries for funds. At a recent meeting in New York, UNFCCC head Chiristiana Figueres said that 28 billion U.S. dollars has so far been collected this year, very close to this year's target.

However, the developing countries doubted it. They believed that some of the funds collected came from the aid originally offered by developed countries and were just "pasted with a climate label" . Whether developing countries will accept the practice is still a problem.

The Ad Hoc Working Group on Further Commitments for Annex I Parties (AWG-KP) will convene their 14th session here since it was established in December 2005 under the Kyoto Protocol to discuss a draft proposal by its chair.

Meanwhile, the Ad Hoc Working Group on Long-term Cooperative Action (AWG-LCA) will convene their 12th session since it was launched in 2007 under the UNFCCC to focus on a negotiating text prepared by its secretariat.

This is the first time for China to host such UN climate change negotiations.

The Tianjin negotiation is an event held by the United Nations and China just plays a role as the host country, said Li Gao, a senior negotiator from China's National Development and Reform Commission.

It is wrong to believe that China may exert more influences over the talks as the talks are held in China, Li said.

The talks are a multilateral process and what progress will be made in the talks depends on the negotiators from the participating parties, Li added.