The most intensive round of negotiations in the history of climate change were under way here last night following a dramatic intervention by the US Vice-President, Mr Al Gore, calling for more flexibility from his own country's delegation at the Kyoto summit.
Most of the hard bargaining is among the EU, Japan and the US, with other countries left on the margins, at least for the moment, and the aim is to produce a package which could form the basis for a legally-binding protocol to reduce greenhouse gas emissions.
The speculation in the corridors last night was that this would involve a flat-rate cut of between 5 and 7 per cent - way below the EU's target - but without the various loopholes which would destroy the credibility of such a deal in the eyes of environmentalists.
The deal taking shape is likely to defer detailed consideration of issues such as greenhouse gas emissions trading and the use of forests as carbon "sinks" as well as "joint implementation" of reduction targets by industrialised and developing countries acting together.
One of the most crucial issues to be decided is whether at least some of the bigger developing countries, such as China, will agree to make "voluntary" commitments to limit the growth of their emissions. This is regarded as crucial to achieving US acceptance of a deal.
"There is real movement towards agreement," said Mr John Prescott, Britain's Deputy Prime Minister, although he conceded that it would not be easy. "We stand at the crossroads of failure or success, but the political will exists to reach an agreement," he declared.
At a news conference later before flying back to Washington, Mr Gore indicated that the US would apply its own pressure as the negotiations continued, with President Clinton and himself "hard at work behind the scenes".
Without naming names, he said they would be "telephoning presidents and prime ministers and asking them to deal with positions that their negotiating teams [in Kyoto] are taking when we believe that they're not helpful".
The latest, somewhat feverish, negotiations were given real impetus when Mr Gore departed from his carefully-crafted script at yesterday's plenary session to reveal that he and President Clinton had been "burning up the phone lines" to share new ideas on the issue.
After speaking with Mr Clinton just beforehand, Mr Gore said he was "instructing our delegation right now to show increased negotiating flexibility" on a plan involving "realistic" targets and timetables as well as "meaningful" participation by key developing countries.
This last-minute announcement by the US Vice-President took fossil fuel lobbyists by surprise. A spokesman for their principal vehicle, the Global Climate Coalition (GCC), said: "It disturbs us greatly because it seems to clear the way for the US to make increased commitments."
The GCC was angered by Mr Gore's attack on those who sought to "obfuscate and obstruct" the climate change talks by arguing that there was "really no problem at all", saying they were like the tobacco companies which used to insist that smoking did no harm.
The Vice-President made no attempt to deny that climate change represents a serious threat - quite the contrary. "Our fundamental challenge now," he said, "is to find out whether and how we can change the behaviours that are causing the problem."
Each of the 160 nations represented in Kyoto brought their own perspectives to the table, Mr Gore said.
Ironically, the US Vice-President was preceded in the running order by President Kinza Clodumar of the Republic of Nauru, a small island state in the South Pacific which - as he said solemnly - is "in the front line of the global climate catastrophe".
The Polynesian leader said his low-lying country, already deeply scarred by colonial phosphate mining, could be devastated by "a flood of biblical proportions" and, if it was wiped off the map, it would be "cultural genocide . . . an unspeakable crime against humanity".
Mr Gore's contribution drew a very mixed reaction. US environmental groups were generally positive, suggesting that it would help to "break the diplomatic ice" in Kyoto, where December temperatures are unseasonably high and there are still red leaves on the maple trees.
The Vice-President's call for flexibility in the US position "represents a real breakthrough", according to the Union of Concerned Scientists.
But there were sceptics, too. The World Wildlife Fund said it was ironic that the Scottish highlands, which so inspired W.H. Murray - the mountaineer quoted by Mr Gore at the end of his speech - were among the wild areas of the world most threatened by climate change.
Greenpeace International praised Mr Gore for his rhetoric, but said he had failed to move the US position forward. It also distributed small bottles of Antarctic meltwater with a penguin logo: "Al Gore, Cut the hot air or the penguin gets it, [signed] Greenpeace."