Yesterday's unexpected agreement at the climate summit in Montreal is the biggest breakthrough yet in combating global warming, and it came because the global community stood up to President George Bush and called his bluff, as this newspaper has consistently urged. For the first time, all the countries of the world - including developing ones and even a kicking and screaming United States - have formally committed themselves to working out measures to tackle climate change. Even better, the countries that already subscribe to the Kyoto Protocol (all the industrialised ones apart from the US and Australia) have agreed to negotiate deeper cuts in their own pollution emissions over the next three years. Yesterday Margaret Beckett, the Secretary of State for the Environment, described the agreement as "a bigger breakthrough than Kyoto". She should know. Just 10 days ago, after The Independent on Sunday told her this should be the outcome, she accused us of "living in cloud-cuckoo land".
Britain deserves much credit. Tony Blair's courageous decision to make climate change one of the main planks of Britain's presidencies of the EU and the G8 group of industrialised countries helped mobilise public opinion around the world. As did the constant, alarming volleys of reports of melting glaciers and ice-caps, record-breaking hurricanes, growing deserts and threats to the Gulf Stream. Mrs Beckett herself, who burst into tears when agreement was reached, has been as tireless in her determination as leader of the EU delegation as she has been on the issue over the past years. And the Canadian government, which chaired the conference, showed great skill and commitment in pulling off agreement in the midst of an election campaign. But there is also a crucial lesson for Mr Blair. The United States did everything in its power to sabotage the negotiations. It even walked out, at one stage, in an attempt to stop a "dialogue" over future measures with developing countries including India and China, a particularly breathtaking piece of cynicism, since the reason that George Bush gave for pulling out of the protocol in the first place was that the Third World was not participating.
But the US had to back down because it was isolated at home and abroad: not one nation agreed to join it in blocking agreement in Montreal, and US public opinion was outraged. Much the same happened at the Gleneagles G8 summit this summer, when again the President faced isolation. Yet Mr Blair almost snatched defeat out of the jaws of victory over the past months by trimming his position, and even announcing he was "changing his thinking", in an apparent attempt to please Mr Bush. This time he - and his successors - must learn.
In the negotiations to come over the size of the cuts in carbon emissions that can be achieved, it ought to be understood that ultimately the US will move only when it faces a united front. As Mr Blair is fond of saying in other contexts, appeasement is no way to deal with bullies. The effect on domestic US opinion of their country being isolated in the world was the final push needed.
Of course, it is early days for the Montreal agreement but, for now, let us all seize the moment and unhesitatingly welcome one of the most hopeful days in the planet's recent history.