As the world's main CO2 emitters, both China and the United States have released their low-emissions target ahead of the meeting. It is an encouraging sign for the eventual formulation of a substantive agreement to fight global warming. Experts warn, however, that the negotiations that still lie ahead will be tough going.

China has announced it seeks to reduce the intensity of its carbon dioxide emissions per unit of GDP in 2020 by 40 to 45 percent, relative to the 2005 level. The target convincingly demonstrates that China can be counted on as a responsible member of the international community in the collective effort against climate change. At the same time, it encourages developed countries to raise their own emission cut targets.

The United States is pushing for another approach, with President Barack Obama pledging to cut greenhouse gases by 17 percent below 2005 levels by 2020.

But while the Obama administration has shown more willingness to fight global warming than its predecessor, that target still falls short of what scientists is required.

Liu Zhibo, Suntech Power Ltd. Co., said, "I think the pledge that both China and America have made shows they are responsible countries in terms of their efforts to curb global warming. Both nations have taken a big step toward ensuring the success of the conference."

But for these leaders, sealing a deal will not be easy.

As a whole, developed countries are offering only an 8 to 14 percent cut below 1990 levels by 2020. It is far below the target of 25 to 40 percent that scientists say is necessary to stabilize the climate.

Ding Yihui, china Meteorological Admin., said, "Developed countries insist they cannot accept a 25 to 40 percent reduction. However, many experts believe that the target, relative to the 1990 baseline, is critical."

Whether or not to maintain requirements of the Kyoto Protocol is another contentious issue.

The Kyoto Protocol was initially adopted in 1997. Its central principle was the recognition that rich nations have an obligation to compensate poorer nations for the costs incurred as a result of climate change.

At the current conference, rich and poor nations will argue over the legal structure of the post-Kyoto deal.

In addition, any agreement on how much industrialized countries should pay for poor nations' clean energy technology and other projects will be difficult to reach.

Many skeptics, therefore, feel that it is virtually impossible for the Copenhagen conference to produce an outcome that meets the demands of all parties. Nevertheless, regardless of the outcome, it will still be a historic turning point in humanity's fight against climate change.

(CCTV.com December 8, 2009)