Yesterday's star-studded Live 8 concerts and mass demonstrations - epitomised by Geldof - have catalysed the huge public demand for action to relieve African poverty. Despite the cynics - and the experience of the huge march against the Iraq war - such expressions of public opinion put pressure on leaders who do not want to act and, even more crucially, create political space for those who do. The remarkable steps forward in increasing aid and debt relief for Africa - including from the Bush administration - owe much to the head of steam generated by the former Boomtown Rat and his fellow campaigner, Bono.
Tony Blair, however, has done even more. He has shown real courage in choosing to make these issues the focus of the summit, over other, easier options - and extraordinary determination in pressing forward with them. It would have been easy, for example, for him to have rested on the progress made over Africa and gone easy on global warming - or even traded one off against the other. Instead, he has continued to push for a breakthrough on climate change as well, despite entrenched opposition from President Bush. As the President continued to refuse to budge, France and Germany argued that it would be better not to reach agreement with him at any cost and instead that it should be made clear he was isolated, in a minority of one. Pointedly, Britain refused to rule this out, as the Prime Minister personally became increasingly irritated. Last night, it appeared that this approach might be paying off. Faced with a stand-off at a meeting negotiating the Gleneagles communiqué, the Americans blinked first, accepting that global warming presents a problem; that collective action is needed to deal with it; and even that there might be merit in the Kyoto Protocol.
It is only a start. The new text has now to go back to Washington and the other capitals for approval; it remains to be seen whether President Bush - who, with Vice-President Dick Cheney, is the most hawkish member of his administration on global warming - will accept it. Even if he does, Gleneagles will mark only the first faltering step back to sanity on the state of the world's climate.
But the lesson is clear. Bending over backwards to appease President Bush in the hope that he might make some concessions in return has proved to be an abject failure. The United States has only moved when faced with a united and determined front from the rest of the world. For the truth is that the President cannot afford to be isolated abroad, because he is coming under increasing pressure on global warming at home, as the remarkable article by Arnold Schwarzenegger on the page opposite demonstrates. Other top Republican governors, the Senate and the public are increasingly demanding a change of course, reacting against the President's very intransigence. Mr Blair has done well to create the conditions where some progress has been possible, but he - and the rest of the world - should not stop there. They should now make common cause with Governor Schwarzenegger and like-minded Americans to keep the squeeze on Mr Bush, and force him finally to act against what the Prime Minister has correctly identified as "long term, the single most important issue that we face as a global community".