The fight against catastrophic global warming scored its greatest success to date yesterday, when negotiators from more than 180 nations unexpectedly agreed to develop far-reaching measures to combat climate change.
In the process, the delegates to the climate summit in Montreal dealt a humiliating blow to President George Bush's five-year attempt to destroy the Kyoto Protocol. The United States, which tried to sabotage the meeting at the last minute by walking out of the negotiations, was forced to join the agreement after failing to persuade a single nation to join it.
Many delegates - including Margaret Beckett, the UK's Secretary of State for the Environment - were openly in tears when agreement was finally reached yesterday morning after two successive all-night sessions and as many dramas and cliff-hangers as a second-rate soap opera.
Mrs Beckett told The Independent on Sunday that it represented an even greater breakthrough than the original agreement of the Kyoto Protocol almost exactly eight years ago. Environmentalists hailed the agreement - which exceeded the most optimistic expectations - as "historic".
The agreement marks the culmination of a remarkable year for the world's attempts to bring global warming under control before it is too late. Not much more than a year ago, the Kyoto Protocol had yet to come into force, many leading commentators were writing its obituary, and the US administration was blocking any attempts even to talk about future negotiations.
Then Russia - the key hold-out - ratified the protocol, enabling it to come into force in February, and Tony Blair made climate change one of the top priorities of Britain's presidencies of the EU and the G8 group of industrialised nations this year. At the G8 Gleneagles summit this summer President Bush had to agree to further talks.
Yesterday's agreement - far from burying the Kyoto Protocol as the US wanted - has confirmed it and extended it. The 39 nations governed by it - all the industrialised countries apart from the US and Australia - have agreed in principle to make deeper cuts in the pollution emissions causing climate change when their present clean-up commitments run out in 2012.
They have decided to agree the new cuts by 2008, far faster than expected.
Meanwhile the US has, against its will, had to agree to talks with both rich and developing countries to new measures that all nations can take on combating the threat. The resolution is vague and the talks are only "open and non-binding", but it is far more than the US wanted or most people expected.
The atmosphere at the Montreal meeting was far more determined to reach agreement than either the US or its bitterest critics had expected, following a year of constant, alarming evidence that climate change is happening far faster than scientists had predicted. These included a record hurricane season, record melting of sea ice and glaciers in the Arctic, and disturbing signs that the Gulf Stream - which makes Britain inhabitable - may be beginning to fail.
So when the US walked out, it failed to find any support, despite intensive lobbying of delegation after delegation, as the rest of the world resolved to go ahead without it.
At the same time, the Bush administration has come under enormous pressure at home with three-quarters of Americans now demanding action on climate change and nearly 200 cities and many states taking their own far-reaching measures to cut pollution. Bill Clinton also fatally undermined the US position by calling it "dead wrong".
Last night, Tony Juniper, a director of Friends of the Earth, called the deal "excellent". Phil Clapp, head of the US National Environmental Trust, said it was "absolutely extraordinary".