Geoffrey Lean: A duck could be a good weapon against climate change, Tony

I worry about your tendency to let George Bush off the hook

An open letter to Tony Blair

Dear Tony,

May I suggest the single most important thing you could do this weekend in response to the terrifying new UN report predicting devastating climate change?

Go out and buy a yellow plastic duck. It could be your most persuasive weapon in dealing with your old buddy and comrade in arms, George Bush. I'll explain about the duck later, if I may. Let me first say - though we have, heaven knows, been at loggerheads enough in the past - how much I agree with you on many points.

I know we agree that 2007 is the make-or-break year. Unless key world leaders start to lay down the outlines of a new agreement - preferably including a commitment to reduce emissions of carbon dioxide by 30 per cent by 2020 - the creaky international negotiating machinery simply will not be able to produce a working new treaty by the time the current arrangements under the Kyoto protocol run out in 2012.

I know, too, that you and Angela Merkel, are putting together a coalition of world leaders to put pressure on Mr Bush and try to forge the outlines of an agreement at the G8 summit in June.

You have continued since I wrote, meeting President Lula of Brazil and President Calderon of Mexico, and having yet another go at persuading President Bush on the phone. I'm not sure, though, that one top-level meeting will be enough - and would commend the proposal of Achim Steiner and Yvo de Boer, the new heads of the UN Environment Programme and the UN climate treaty, to follow it with a special summit on global warming.

We are agreed too that the report by the Intergovernmental Panel on Climate Change effectively ends any debate there ever was on whether human activities are heating up the world.

Yet, alarming as it is, the report almost certainly downplays the seriousness of our predicament. The panel is a cautious body, operating by consensus. Its last report, in 2001, underestimated the rises in sea levels and temperature that have actually since taken place. The new one is under authoritative attack for, among other things, underplaying the melting of Antarctica.

So the question is, how to persuade George Bush to move far enough, fast enough. As you privately accept, he missed a golden opportunity to change course in his State of the Union address last month. He admitted, through gritted teeth, that climate change presented "a serious challenge" but failed to do anything effective to tackle it. Yet he is becoming isolated at home as well as abroad. A whole series of bills mandating action has been introduced. Even business leaders and evangelical Christians are urging radical steps.

I know you have had a hand in these developments. But I worry about your tendency to let George Bush off the hook. You did it again in Davos when you hailed his damp squib in the State of the Union speech as a "quantum leap" forward. He has only ever moved when up against the wall.

Now, back to the duck. A year ago, at a conference in Montreal, even starting negotiations on an agreement seemed stillborn when the US opposed any compromise, on the ground that if "it looked like a duck, it was still duck". Suddenly yellow plastic ducks appeared all over the conference, popping out of briefcases, sitting on desks, peeping out of pockets. Isolated and ridiculed, the US scrambled into line. So buy that duck. Put it on your desk. And whenever you are tempted to appease George, look it in the eye.

Yours, Geoff