Leading article: The chance for a cleaner world

It would be good if President Bush joined the trip; even better, perhaps, if he could be left behind on a convenient iceberg. For he and his cronies are stopping the world from tackling what Tony Blair recognises to be the most important single issue facing the world. George Bush is increasingly isolated even at home. Public opinion has swung against his refusal to act; 190 US cities and nine states are taking measures to fight the climate change; and even the Senate - often cited as obstructive - voted this summer for "mandatory action" to combat it.

Mr Blair has done well to highlight the issue, and to make it a focus of his presidency of the G8. He has worked hard to get the rival camps of the US and of leading developing countries such as China and India engaged in seeking a solution, and has made some progress. But in recent weeks he has come close to ruining it all by flip-flopping on the issue like a beached flatfish, alternatively supporting a new treaty to succeed the Kyoto Protocol, and apparently rejecting it. Yesterday - after environmentalists rounded on him earlier in the week - in an article in The Independent backing new targets to cut pollution, he finally got back "on message". He should stay there, for his leadership is badly needed.

As Mr Blair rightly points out, new clean technologies are needed if the world is to cut the pollution that causes climate change. But they will not develop in the desperately short time that is left to us if governments fail to provide incentives or to set binding targets for cutting emissions. The Montreal meeting is a vital part of this. At the very least, it must provide a clear commitment to the principle of a new treaty when Kyoto runs out in 2012. Otherwise even the glacially slow progress now being made will grind to a halt.