Leading article: Three degrees is at least one too many

It is fittingly ominous that 2010, year of the next big climate change conference, has been the hottest in recorded history. The heat rises inexorably yet the world dithers and looks away. None of the excitement that surrounded the opening stages of the climate summit at Copenhagen last year looks like materialising this November at Cancún in Mexico.

Developing and developed countries continue to trade blame over what went wrong at the last summit. There are few signs of sleeves being rolled up in serious preparation for the kind of binding agreements that might, at this near-midnight hour, contain average global rises in temperatures to around 2C – the maximum manageable. The lack of fervour is deeply worrying. When so little was achieved at Copenhagen under the expectant eyes of millions, what hope for Cancún if the surrounding mood is already one of apathy?

This week, the climate change secretary, Chris Huhne, travels to Berlin to try and forge a common European approach on what might be achieved at the summit before it opens. We must hope he succeeds in his goal, which is to persuade the European Union to unite round a new, ambitious pledge; to raise levels of cuts in CO2 emissions by 2020 from the 20 per cent already agreed to 30 per cent. An EU agreement of this sort would not, on its own, prevent the world from drifting towards what the overwhelming majority of scientists agree is a looming catastrophe. We need a global deal for that, including China and India. But it would inject some much-needed adrenaline into a movement that has lost much of its former momentum and optimism.

The failure to agree on binding commitments at Copenhagen was a moment of deep disappointment for the environmental movement. The faint but plausible hope that the world might unite against a common threat faded rapidly. Tragically, in Denmark, the poorer south proved unable to divest itself of a suspicion that climate change was an idée fixe of the rich north, and that Western calls for emissions cuts were an artfully packaged suggestion that they should remain undeveloped for eternity.

The result was not the binding agreements that almost all experts believed essential but looser pledges to meet voluntarily undertaken targets. And as we report today, those voluntary cuts, even if executed to the letter, which looks unlikely, are not enough. To slow the rise in warming to within 2C, the various voluntary targets would collectively need to stack up to an overall cut in global emissions of at least 25 per cent – preferably much more. Instead, analysis of the pledges shows they would cut global emissions by between only 11 and 19 per cent.

The differential is crucial. The consequence of a gap that big is that world emissions of CO2 will continue to increase rapidly, nudging the global rise in average temperatures over this century up from 2C to well over 3C. One degree more might not sound much, especially to us living in the cool north. But massive regional variations in warming – strongest in parts of the globe that are hot already – mean that significant parts of the world would become totally uninhabitable through desertification, while much land elsewhere would disappear under seawater as a result of the melting of the poles.

Whether these dismal predictions have a substantive effect on the delegates of the 200 or so nations meeting in Mexico this winter remains to be seen. They ought to. Meanwhile, it is possible that if some richer industrialised countries raise the bar by agreeing tougher commitments on emissions – as Mr Huhne wants us in Europe to do – at least some developing countries that said "no" to an agreement in Copenhagen might be sufficiently impressed to come on board. It would be a start.