It is not an optimistic scenario. As the Copenhagen climate change conference moves to its conclusion and the 192 participating nations set out their negotiating stalls, there seems slim prospect of a global agreement. Nobody wants to be blamed for failure. But everybody went there with "red threads," a package of minimum demands that, they said, must be met if they were to approve of a deal.

China's position has been pivotal to the three-dimensional chess of these negotiations. It is perceived as ally and competitor both. This is no surprise, given the size of the country's economy, the pace of its economic growth, its expanding energy needs and its rising share of global greenhouse gas (GHG) emissions. There was never any doubt that without full Chinese involvement Copenhagen would not be a success.

Politics is at play here, including the politics of the US Congress. Todd Stern, US special envoy for climate change, signaled to the press even before reaching the conference venue that his delegation would be putting pressure on China. He said that he did not envision public funds going to China, declaring: "We would intend to direct our public funds to the neediest countries."

China's Vice-Foreign Minister He Yafei said he was shocked by Stern's remarks. China was not asking for money, he said, a position he underlined in other briefings during the conference. "Beijing set to drop funding demand" was the headline in the Financial Times last Monday. But maybe Stern already knew that and his tough talking was intended more for the ears of Washington lawmakers than Copenhagen negotiators!

Negotiations in Copenhagen have progressed on two tracks. The first is the Kyoto Protocol, which sets binding targets on developed countries for reducing their carbon dioxide (CO2) emissions up to 2012, but no targets for the developing economies (which include China). The US is not a signatory to the Kyoto Protocol and refuses to accept binding targets. The second track is the UN Framework Convention on Climate Change, parent of the protocol, in which the US is participating.

An initiative by the Danish presidency to combine the two agreements triggered a walkout by the African delegations at the start of the second week, because they feared that any binding targets beyond 2012 would be scrapped. They were reassured by the Danish presidency that long-term targets would indeed be set.

China has insisted that the Kyoto Protocol is the way ahead, as does the European Union (EU), which has already committed itself to binding emission limits, reducing by 30 percent by 2020, but only if other countries (especially the US) take on similar commitments.

The Europeans continue to push the faster developing countries such as China and India to set their own emission targets, but both continue to argue against any firm figures for controlling emissions because of the need to maintain economic growth and raise living standards of their people.

There was, however, a qualified welcome when Beijing announced targets for reducing its carbon intensity (the amount of carbon emitted per unit of GDP) by 40-45 percent on 2005 levels by 2020. It was seen as evidence that Beijing wanted the Copenhagen talks to succeed. Nonetheless, it implies a steady increase in China's CO2 emissions until they peak sometime between 2030 and 2040, and external verification of progress promises to be a difficult feature of any final settlement.

China's association with the group of 77 developing countries (G77) has been a feature of Copenhagen. It seems that the Chinese delegation has organized press conferences on behalf of the G77, without participating in them, although it supports the demand of the poorer countries that 1 percent of GDP of the developed world should be allocated to developing countries up to 2020 - equivalent to about $600 billion - in recognition of the fact that it is the developed world that is responsible for current levels of CO2 in the atmosphere.

Agreeing on how much funding poorer countries should get to help them deal with climate change remains a major issue. When EU leaders met in Brussels on Dec 11, they said the EU would transfer about $10 billion over the next three years. The offer got a cool reception among the developing countries, both because it was regarded as inadequate and for fear that it simply repackaged development aid that had already been allocated under earlier programs. There is general agreement on the need for technology transfer to help poorer countries to face the challenge.

Just how serious the outlook could be for some countries has been demonstrated by the discussions over global temperature targets, which form the basis of the CO2 emission limits. Island states such as the Maldives and Tuvalu have been demanding a settlement in Copenhagen itself, which would limit global temperature rise to not more than 1.5C - a position supported by the G77. Anything higher, they believe, and they would be submerged by rising sea levels.

The EU target is to keep the global temperature increase to 2C. That seems the likely outcome of any global agreement, too. Anything below that would require even more drastic emission cuts by everyone, including China and India.

The vital importance of the world's forests in mitigating global warming has been widely recognized in Copenhagen. It was demonstrated by China's recent announcement of a massive expansion of its forests and by general support for REDD (reducing emissions from deforestation and degradation), a global initiative to protect and expand the world's forests, which was expected to form part of any Copenhagen agreement.

Deforestation causes about 16 percent of the CO2 emissions. The EU is pressing for binding targets, which would bring down the level of deforestation by half by 2020 and end it by 2030, whereas countries such as Brazil prefer a voluntary agreement. Before the Copenhagen conference began, US President Barack Obama lent strong support to a Brazilian-Norwegian proposal for protecting the Amazon rainforest.

So the scientific basis underpinning the political process in Copenhagen evidently has gotten stronger by the day. The question for world leaders as they gather for the last day of Copenhagen talks is how the burdens of achieving a low-carbon world should be shared.

Most of the developed countries accept that they should take the biggest immediate cuts, but they have to convince their electorates of the need for action if they want their legislatures to approve of any global agreement. The EU has the institutions to do this, but it is a special challenge for the US, where a skeptical Congress may be difficult to convince. No matter what the outcome in Copenhagen is, Obama will have a huge political challenge ahead.

As we head into the final day of negotiations, it is clear that the battle lines are clearly drawn - and the biggest story for many will be the proactive and constructive role that China has played at the conference. By taking this approach, not only has China avoided much of the criticism it might have been exposed to, but also it has also shown itself to be a leading driver of positive change on one of the most important issues facing the world.

It seems unlikely that all the outstanding issues will be resolved in the next 24 hours. But then, given the importance and the complexity of the topic at hand, perhaps the expectation that the world would be able to come to a binding agreement in a matter of a few weeks was unrealistic to begin with. The real test of the world's political leaders will be their ability to sustain the momentum built in Copenhagen through the complex and technical discussions that will follow.

The author is an advisor to Fleishman-Hillard in Brussels. A former journalist, he was also a member of the Cabinet of European Commissioner Sir Leon Brittan.