COPENHAGEN, Denmark — The Danish atomic scientist Niels Bohr once famously said: "Prediction is very difficult, especially about the future."
As the mammoth United Nations climate change conference staggered on to its finale in Bohr's hometown, delegates were daring to predict the shape of a deal that leaders might be able to sign on Friday.
The last few days have resembled a 192-hand poker game in which participating nations have bluffed, stone-faced and indulged in last-minute accusations of cheating. But with just one day left, the outline of a possible deal looked to be emerging.
However, instead of being the epoch-marking mother of all climate climate deals that many hoped for, the possible compromise appears to leave many issues open. Indeed, a Copenhagen agreement might require a whole new summit — likely in Mexico in 2010 — to hash out the more contentious details.
After two days of stalled talks, an announcement by U.S. Secretary of State Hillary Clinton injected new momentum into the negotiations Thursday. Clinton announced Washington's backing for an Afro-European plan to set up a $100 billion-a-year fund beginning in 2020 to help poor nations cope with the impact of global warming and develop clean energy.
"A hundred billion dollars a year is a lot of money. That’s a commitment that is very real and can have tangible effects," Clinton told reporters, although she stressed the money will only become available if there is an acceptable global deal on fighting climate change.
Details of where contributions for the fund will come from and how it will be managed will likely be put off until next year.
The U.S. is also expected to announce — perhaps when President Barack Obama joins the meeting Friday — that it will participate along with the European Union, Japan and other nations in a "fast-track" fund of at least $10 billion starting from next year to support poor countries most effected by climate change.
In another sign that the delegates were edging toward progress, European nations suggested they would agree to demands for a "two-track" approach that would bind developed nations to legal emissions targets in an extension of the 1997 Kyoto Protocol, which is due to run out in 2012.
New industrial powers such as China, India and Brazil would sign up to a less firm convention where they would set and police their own targets. Poorer nations insist that different a approach is needed to allow them to develop their economies and that it appropriately places the burden on the rich world for decades of pollution.
"The developed countries must adopt ambitious benchmarks for reducing emissions, that reflect their historic responsibilities," said Brazilian President Luiz Inacio Lula da Silva. "The maintenance of the Kyoto Protocol is an absolute necessity."
China stood by its rejection of international monitoring of its efforts, but Vice Foreign Minister He Yafei said Beijing could agree to "exchanges, dialogue and cooperation" that are "not intrusive" and respect Chinese sovereignty.
The United States, which has long rejected the Kyoto deal, would join the developing nations in the convention but with the stronger commitment to cut emissions in line with its target of 17 percent below 2005 levels in 2020.
Any final agreement is also expected to set a long-term target — likely 50 percent of 1990 levels by 2050 — with cuts of at least 80 percent for the most developed countries. It will also set a target limit for average global temperature rises, probably 2 degrees Celsius, although African and small island nations are calling for 1.5 degrees Celsius or lower to save them from climate disaster.
In another development, a leaked U.N. document reported by Britain's Guardian newspaper and distributed by Greenpeace points to concerns that even if nations follow through on their strongest pledges for emission cuts they may still fall short the target of keeping average temperature rises below the 2 degrees Celsius by the end of the century. The document warns temperatures could rise by 3 percent without further cuts.
Negotiations among lower-level officials continued Thursday on a draft framework agreement that can be presented to the summit on Friday.
Meanwhile a stream of world leaders took to the main floor to lay out their demands, requests and grievances. Among dozens of speakers on the summit's penultimate day were presidents of Israel, Iran, Brazil, Mexico, France and South Korea; prime ministers from Britain, Australia and Spain; and the Chancellor of Germany.
Many Western leaders called on China and other fast-developing nations to be bolder in their commitments to cut.
"Despite the considerable efforts by the industrialized nations, we cannot save the planet if the emerging nations ... don't make an effort on their part to put the brake on the increase of their emissions," said French President Nicolas Sarkozy. "Who would dare contest that?"
One key issue still to be decided is when the leaders will call a follow-up summit to fill in the details of the Copenhagen framework. The Mexico City meeting is scheduled for the end of 2010, but many are calling for it to be brought forward to July to avoid wasting more time.
Among the issues likely to be left until 2010 are the level and timetable of emission cuts for individual nations; methods for monitoring emission cuts; deciding how to raise the $100 billion in long-term funding for developing nations from public and private funding and establishing a mechanism for distributing the funds; and an agenda to review the decisions if they fail to have sufficient impact on rising temperatures in the years ahead.
Top officials were preparing to work late into the night to produce a text that leaders can approve on Friday.
"Time is running out for some of us, so it is imperative that we act now," said Anote Tong, president of Kiribati, one of the Pacific Island nations judged most at threat from rising sea levels. "If we cannot achieve our objective of legally binding agreement this week, then we must [have it] not later than the middle of next year."