Sergio Serra: Without a doubt, China's measures to cut emissions are very significant. Its goal was to reduce emissions per unit of GDP 40-45 percent from 2005 levels by 2020. We have been closely watching China's moves and admired its serious efforts in several areas, including the use of renewable energies and afforestation, as well as technological research in cleaner coal burning. Since it is one of the major developing countries, China also has an important role to play in the climate negotiaitons.

Alf Wills: China is emerging as a political and economic leader among developing countries, and the country has taken a leadership role in a very constructive and positive manner. Like South Africa, China has called for a legally binding agreement in the future, and has also made ambitious voluntary commitments to emission reduction.

So China is not just paying lip service, but also backing up the pledges with solid actions. I hope the leadership shown by China is going to help bring the United States into the multilateral process in a much more constructive manner.

Jake Schmidt: China has impressed me with bold moves to cut emissions and reduce local air pollution. We noticed a surge in clean energy investments, which will significantly improve the energy mix of the country. The challenge for China is how it can keep those positive steps and maintain the green momentum in the long term.

In the negotiations, China has showed great willingness to be creative and clearly signaled that it wants a positive outcome in Cancun. That is the kind of spirit that we need when going into negotiations. As a key element of the talks, China has to show confidence in the climate architecture that we are building.

China is taking remarkable steps on the green path, and has enjoyed domestic benefits for its economy. But it has not received the international recognition that it ultimately deserves. Greater transparency in climate actions will allow the country better recognition for its vigorous efforts.

In your opinion, what is the biggest reason climate negotiations have stalled in recent years?

Abdullah Al-Saidi: Mistrust is the biggest barrier impeding the negotiating process. After all, the global problem of climate change requires a global solution. So all countries should voice their opinions and find common ground on key issues.

The emission reduction pledges of the industrialized world fall short of what is needed to prevent catastrophic global warming. So fears are growing that the Earth is heading for a disaster, with melting ice glaciers and submerged cities in countries like Yemen.

Due to their production model and way of life, industrialized nations were the biggest cause for global warming. Given the seriousness of the situation, it is urgent for them to shoulder the historical responsibility and help steer humanity toward a sustainable future.

Meanwhile, some developed countries are trying to impose strict MRV (measurable, reportable and verifiable) standards on the voluntary emission reduction efforts of developing countries. This is unacceptable to the G77 and China. We must make a distinction between the MRV that is helpful in curbing climate change and using the MRV to interfere with domestic affairs of other countries.

Sergio Serra: The environment of climate negotiations has not been favorable since the world suffered the sweeping financial crisis that distracted attention of the countries. On top of that came the debt contagion in Europe. More disturbing, though, is the fact that the U.S. Senate has failed to enact a comprehensive climate and energy bill.

We have to deal with those negative factors and bring the negotiation back to the fast track. I believe Cancun will mark a step forward and help rebuild confidence for a greener world.

How is your country cooperating with China to combat climate change?

Sergio Serra: We have many opportunities to join hands in protecting the Earth. Actually, much cooperation is already underway, including technology exchange and knowledge sharing. A good example is that the two countries have jointly built a series of Earth resource satellites that effectively helped monitor deforestation in the Amazon region.

Alf Wills: Leveraging advantages of their own in different areas, South Africa and China are beefing up cooperation in green businesses. For example, China has raced ahead of others in solar panel and wind power energy, and many Chinese manufacturers of solar water heaters have gained a market foothold in South Africa.

On the other hand, South Africa leads the globe with its carbon capture and storage (CCS) technology. South African Coal, Oil and Gas Corp., the world's first and biggest producer of fuels from coal, has teamed up with Chinese companies to build CCS projects for cleaner coal businesses.

(Reporting from Cancun)