WASHINGTON/BEIJING - When President Barack Obama sits down with his Chinese counterpart next week to talk climate change, it is highly unlikely they will craft a definitive plan to tackle global warming.
But the summit between the world's two biggest spewers of carbon dioxide will probably set the tone for next month's U.N. climate talks in Copenhagen.
Any progress in bridging the North-South climate divide would help lift the shroud of pessimism enveloping Copenhagen and Obama told Reuters this week he was optimistic of progress.
Conversely, a failure to advance, or any sign the big two could conspire to effectively let each other off the hook in Denmark, would probably condemn the talks to failure.
Everyone is very pessimistic about Copenhagen, so there's a need for a positive signal from China and the United States, said Zhang Haibin, a professor of environmental diplomacy at Peking University.
A joint statement that both countries are willing to cooperate and will not abandon this process would help lift hopes for Copenhagen. Without it, Copenhagen looks even bleaker, and the subsequent negotiations would also be damaged.
The United States has emitted more carbon into the atmosphere than any country on earth but China has since taken up the mantle as top producer of the gases blamed for warming the Earth's atmosphere. Together, they account for 40 percent of the world's greenhouse gas emissions.
So there can be little progress without cooperation between the two countries at the December 7-18 meeting in Copenhagen that is designed to succeed the Kyoto climate protocol.
You are not only talking about the two greatest emitters but the two emitters that are iconic of the whole divide between developed and developing countries, said Julian L. Wong, Senior Policy Analyst at the Center for American Progress in Washington.
Wong thinks the international climate talks are far too complicated for Obama and President Hu Jintao to hammer out a definitive agreement on climate change when they meet next week.
But the two sides are expected to make announcements showing how they are engaging on renewable energy projects and research into things like electric cars and capturing carbon at power plants for storage underground. The two leaders will pledge greater cooperation on climate but specifics of any bilateral plan might be sparse.
There will also be discussion of how to achieve some sort of agreement in Copenhagen -- something to boost global confidence -- but no major breakthroughs, said Wang Ke, a professor at Renmin University in Beijing
Obama told Reuters in an interview prior to the trip that it was key the two countries reach a framework agreement other nations could buy into.
I remain optimistic that between now and Copenhagen that we can arrive at that framework, he said, adding he would travel to Denmark next month if he saw a chance of progress.
Jennifer Morgan, director of the World Resources Institute Climate and Energy Program, said the two leaders need to show they want to go to Copenhagen to seal the deal.
The signal President Obama and Hu Jintao sends is very vital for hopefully inspiring others to come to Copenhagen with a high level of ambition, she told a journalists' briefing.
But both leaders will also be constrained by domestic issues and policies.
Obama must be careful not to preempt Congress, or risk a backlash.
The Senate needs to feel like it's beginning to tackle climate change itself, not because Obama boxed them in after visiting Beijing, said Michael Levi, a director at the Council on Foreign Relations.
A sweeping climate bill that would seek to reduce U.S. emissions is struggling through the congressional maze in Washington and it faces opposition across the political divide on concerns about costs for industry. But the Chinese could help Obama if they recognize Obama's domestic constraints.
Any progress on the part of the Chinese in accepting the political reality in the U.S. Congress would be very important, said Levi.
For its part, China is making strides embracing renewable energy and has pledged to reduce its emissions intensity -- the amount of emissions from each unit of economic output -- by a notable margin.
But China is resisting pressure from the United States and other developed countries to agree to a specific emissions targets.
Developed countries must lead the way with transforming their unsustainable production and lifestyle, and lead the way with deep cuts to greenhouse gas emissions, Xie Zhenhua, minister in charge of the National Development and Reform Commission, told a meeting in Beijing, according to an official Chinese climate news website.
As a responsible country, we will continue enhancing efforts to save energy and reduce emissions, but we will also resolutely oppose any effort to impose unreasonable demands on us, he said.
(Additional reporting by Timothy Gardner in Washington; Editing by Simon Denyer and Vicki Allen)