Mohamed Nasheed is the president of the Maldives, a group of low-lying islands in the Indian Ocean that will be among the first to vanish as the sea-level rises in a warming world. That's why he is so outspoken in challenging the current negotiating position of the developing countries.

"When I started hearing about this climate change issue, I started hearing developing countries say 'we have a right to emit carbon because we have to develop,' " he told the BBC recently. "It is true, we need to develop; but equating development to carbon emissions I thought was quite silly."

That is heresy, for the standard position of the group of developing countries (G77) is that since the rich countries caused the problem, they must make the emissions cuts that would stop it. And they really did cause the problem: It was 200 years of burning fossil fuels that made them rich, and they are responsible for 80 percent of the greenhouse gases of human origin that are now in the atmosphere.

But if only the rich countries cut their emissions, while the rapidly developing countries (which have three times as many people) let their emissions grow at the current rate, the planet will probably topple into runaway warming by mid-century.

The numbers are brutally simple. Since the industrial revolution began around 1800, the concentration of carbon dioxide in the atmosphere has risen from 280 parts per million to 390 ppm. The point of no return is 450 ppm. After some delay, that will raise the average global temperature by 2 C.

We only have 60 ppm to go, and the newly industrializing countries are growing so fast that we are collectively adding between 2 and 3 ppm per year. At that rate, we'll reach the point of no return in 20 to 30 years.

What happens then is that the warming we have already caused triggers natural processes, like the melting of the permafrost and the warming of the oceans, that dump even more carbon dioxide into the air, causing even faster warming. Even if we later cut our own emissions to zero, the permafrost will go on melting, the oceans will continue to warm — and we may be into runaway warming.

Almost every government on Earth has formally committed to holding the warming below 2 C. They have not, however, committed to any process that will actually achieve that goal — which is why they keep coming back to the conference table despite all the past failures.

Why don't all the governments act? Because the developing countries refuse to accept limits on their emissions for fear that they wouldn't be able to go on growing their economies. They also resent the fact that the past emissions of the rich countries have brought us all so close to 450 ppm. Whereas the rich countries ignore the history and demand similar cuts from all countries, rich and poor.

Nasheed is abandoning the old common front of all developing countries because, while it may serve the short-term interest of the rapidly industrializing countries in the G77, it is not in the interest of poorer, slower-growing countries like the Maldives at all.

At least 30 countries in the G77 privately share Nasheed's view: the impending split was already visible even at last year's Copenhagen conference. Moreover, he argues, the current negotiating position of the G77 is silly even for the bigger, richer members of the group.

"There is new technology," Nasheed argues. "Fossil fuel is obsolete, it's yesterday's technology; so we [aim to] come up with a development strategy that's low carbon."

If China, India, Brazil and the other big, fast-developing countries believed that they could go on growing their economies without growing their emissions, he says, then they'd also be willing to sign up to binding limits on emissions.

"They have to rapidly increase their investments in renewable energy," he says, "and I think they are doing that. Once they've done it, they're going to say 'right, we need a legally binding agreement.' " It's fast becoming true: China is already the world's largest exporter of solar panels, and India is the leading exporter of wind turbines. But there is one remaining problem.

Wind turbines, solar panels and the like tend to be more expensive than cheap and dirty coal-fired power stations. If the developing countries choose the more expensive option, who pays the difference? The old rich countries who landed them in this dilemma, of course.

People in the rich countries don't even understand that history, so they are still a long way from accepting that deal. It won't happen at Cancun, and it may be years before it does. Maybe too many years.