During US President Barack Obama's first state visit to China, of the subjects for discussion, climate change is set to top the agenda along with the global economy and the North Korea nuclear issue. The meeting between President Hu Jintao and President Obama is seen as crucial to the world effort to build a consensus on a new global climate pact.

The Kyoto Protocol expires in 2012, and next month the United Nations will hold a conference in Copenhagen to discuss a new agreement. It will be virtually impossible to agree a new treaty, unless China and the United States, who are together responsible for 40 percent of world carbon dioxide emissions, reach agreement. As Washington senator Maria Cantwell said, "a deal between the world's two biggest CO2 polluters would also help build global confidence in the efforts to curb global warming."

For years, suspicion between China and U.S. has bedeviled progress towards a new international climate change treaty. Both countries have refused to commit to action, waiting for the other to take the first step. The U.S. has been unwilling to agree targets until China commits itself to acting on its emissions. China, for its part, insists the U.S. act first as it has made a far greater contribution to the crisis, by spewing out more than three times as much carbon dioxide as China over the past two centuries. The visit of President Obama provides an unprecedented opportunity to break the deadlock.

At the fourth meeting of the US-China Strategic Economic Dialogue (SED) held in Annapolis, Maryland last year, the U.S. and China signed a Ten Year Energy and Environment Cooperation Framework that sets goals and lays out concrete steps to be taken. The framework covers electricity, clean water, clean transportation, clean air and the conservation of forest and wetland ecosystems, and should lay a solid foundation for future US-China cooperation.

In February 2009, a visit by US Secretary of State Hillary Clinton to China opened a new chapter in environmental cooperation between world's two largest greenhouse gas emitters. She reviewed mistakes made by U.S. and Europe during their industrialization and development, and urged China not to repeat the same mistakes, calling instead for a US-China partnership in fighting global warming. China and the U.S. have agreed to build "an important partnership" to develop clean energy technologies and speed up their transition to low-carbon economies. Following Clinton's visit, the House Speaker Nancy Pelosi, Finance Minister Timothy Geithner, Commerce Minister Gary Locke, Energy Secretary Steven Chu and other senior American officials visited China one after another, setting US-China energy and environmental cooperation as their priority.

The US special envoy for climate change Todd Stern visited China in June. During his visit, China and the U.S. agreed to strengthen cooperation on clean energy. At the same time, he pointed out that China and the United States have "common-but-differentiated responsibilities" when it comes to actions to prevent climate change. Stern agreed that developing countries do not need to make the same emissions reductions as developed nations. But he added that China's current cuts were insufficient. It pointed to remaining underlining tension between the two countries.

There have been other steps forward. In July, China and the U.S. signed a "Memorandum of Understanding to Enhance Cooperation in Climate Change, Energy, and the Environment." In the same month, China and the U.S. announced the establishment of a Sino-US Joint Research Center on clean energy, a significant symbolic step on the road to broader cooperation. The top priorities of the center include energy-saving buildings and clean energy automobiles. In October, the Brookings and China Institute of Strategy and Management sponsored a clean-energy forum, which was attended by nearly 200 leading experts from both countries. It provided an important platform for researchers, corporations and others to devise new ways for China and the U.S. to work together to reduce greenhouse gas emissions.

All the positive achievements have paved the way for future China-US cooperation on energy and climate change. President Obama has proclaimed many times that "the U.S. should shoulder its responsibilities to tackle global warming", and pledged to reverse the resistance of his predecessor George W. Bush to action on climate change. In his speech at the Summit on Climate Change at the United Nations in September, he promised US investment in alternative forms of clean and renewable energy, such as wind and solar power, and to reduce carbon pollution, as well as endorsing important climate legislation in the US Congress. He said, "We understand the gravity of the climate threat. We are determined to act. And we will meet our responsibility to future generations."

President Hu Jintao also expounded China's position on this issue and the measures to be taken by China. He announced plans to cut emissions significantly by 2020, and to vigorously develop renewable and nuclear energy. In recent years, China has moved swiftly to adopt clean energy, and has emerged as one of the world's leaders in wind, water, solar and nuclear power. But China needs western technology to make further advances. As He Yafei, vice foreign minister of China, said at a press conference, "The climate change issue is related to human survival and development, to which both countries attach great importance. China and the U.S. have great room for cooperation on the front of climate change." In the future, we are bound to see more and more China-US cooperation in the development of new technology, tariff reduction on clean-energy related goods and services, as well as technology transfer.

After his inauguration, Obama pledged to promote a positive, cooperative and comprehensive Sino-US relationship. The issue of climate change provides a precious opportunity for the two countries to work together, remove suspicion and fulfill Obama's goal. The future close and sustained collaboration between the two countries will build a strong foundation for future Sino-American cooperation on other strategic challenges facing both nations in the 21st century.

As some high-ranking officials in the US government predict, during Obama's visit to Beijing, the U.S. and China are likely to sign a new bilateral agreement to combat climate change. The Chinese ambassador to the U.S. said, "Co-operation between our two countries on energy and environmental issues will enable China to respond to energy and climate change issues more effectively, while at the same time offering enormous business opportunities and considerable returns to American investors." Closer coordination will lead to a win-win result. An effective response to climate change by the international community depends on the full engagement and leadership of the United States and China. Only in this way can we expect to see a successful treaty in Copenhagen next month.