The UN climate talks have advanced into the stage of "substantive negotiations" after some progress was made during the just ended session here, said Su Wei, head of the Chinese delegation.

In a recent exclusive interview, Su told Xinhua that the Bonn session from Aug. 2 to 6 saw participants discuss the negotiating drafts line by line and put forward new proposals, which marked an important step toward a final treaty.

"Although the text went longer during debates and contained some disputed points, it did reflect a party-driven process, which could be viewed as a significant progress since the adoption of the Bali Road Map," he said.

The Bali agreement, reached in late 2007 in Bali, Indonesia, is aimed at finalizing a legally-binding international treaty on tackling climate challenges in the long term.

In the next session, to be held in Tianjin, China, in early October, parties would try to streamline the Bonn text and find more common grounds, before they head for the climate summit in Cancun, Mexico, later this year, said Su. ' "In this substantive phase of negotiations, parties need to show their sincerity and make necessary compromises from the perspective of combating a common challenge faced by the mankind," added the Chinese chief negotiator.

Commenting on the Cancun conference, Su said that the world needs to be ready for two scenarios.

"On the one hand, we have good wishes, and are ready to make constructive efforts with hopes that the meeting can complete the mission left by the Copenhagen summit in 2009," which ended without a binding agreement as the Bali Road Map requested but a political deal, Su said.

"On the other hand, if the Cancun session could not fulfill the task set by the Bali Road Map, all parties would have to gain as much progress as possible and thus lay a solid foundation for the 2011 summit in South Africa," he added.

However, "a series of extreme weather events around the globe this year have given us firsthand experiences of destructive climate change, and the urgency is mounting for concrete moves to handle it," Su said.

The glooming picture requires the international community to quicken the pace of climate talks and put words into deeds without any delay, he added.

As to China's efforts, Su said that China hosting the October session before the Cancun summit reflects the country's "sincere attitude" and great attention to promoting the UN climate negotiation process.

"The Chinese government hopes that the Tianjin gathering can help advance the talks in the right direction, and China will continue to make its own contributions to addressing climate change," he said.