Leading article: The battle to come

The old argument over climate change is over. Few doubt any longer that our world is heating up, and that it is primarily a result of man-made carbon dioxide emissions. The evidence is now overpowering. Last year was the warmest on record in Britain. Globally, it was the sixth hottest. Even those who live in temperate climes can sense the planet is getting warmer.

Elsewhere the signs are less subtle. Scientists revealed an unprecedented ice retreat in the Arctic last summer. By 2060 there could be no summer sea ice there at all. We learned only last week from Canadian scientists that the Ayles ice shelf - a chunk of ice measuring 41-square miles - has broken free. Meanwhile, drought in the Horn of Africa has been particularly intense in recent years.

There has been another significant boost for those advocating swift action to curtail climate change. Sir Nicholas Stern's Treasury report two months ago has helped to discredit the argument that action to stop climate change will be prohibitively expensive. Thanks to his analysis, we now know that it will cost us far more if we do nothing. We are beginning to recognise the dire consequences of this warming of the earth. Rising sea levels, higher temperatures, drought, desertification, increasingly powerful storms and changes in rainfall patterns will make much of the planet uninhabitable within the lifetime of our children.

But despite this growing acceptance of the uncomfortable truth, little has been done about it. The international meeting last year in Nairobi to establish a successor to the Kyoto Protocol achieved nothing. Nor is there any sign that the Bush Administration is going to sign up to serious action to curb emissions. With the US, the world's largest economy and polluter still dragging its feet, developing nations are feeling little compulsion to reduce emissions themselves. And our own Government, has recoiled from the type of radical emission-cutting measures at home that would set an example to the rest of the world.

This has to be the year of action. There are some encouraging signs. Angela Merkel has pledged to make energy one of the key themes of Germany's Presidency of the G8 this year. But there is little time. Jim Hansen of the Nasa Goddard Institute for Space Studies, and one of the world's foremost experts on climate, believes we have less than a decade to significantly cut back emissions. Scientists are deeply concerned by mounting evidence of "positive feedback" in the warming process. It could all be happening much more quickly than we expected.

The argument has been won, but unless this new consensus produces the kind of leadership necessary to curtail climate change it will prove a hollow victory indeed.