To general surprise, the world's largest country has revealed itself as also one of the nimblest. Speaking to the United Nations, Hu Jintao, China's president, said his country would reduce its carbon intensity – the amount of CO2 it emits for each dollar of economic output. After months of rich and poor countries digging themselves deeper into their respective trenches, Mr Hu may just be leading the world out of the standoff.

With the Kyoto agreement ticking towards expiry, talks on a new treaty have stumbled on seemingly incompatible demands. Greenhouse gas emissions increasingly come from poor countries – China just surpassed the US as the greatest CO2 emitter. The developed world insists on their participation in a global climate deal (none more stubbornly than the US, where China's non-participation became an excuse for not ratifying Kyoto).

For their part, developing countries – India most stridently – have resisted binding pledges on emissions, pointing out that rich countries put most of the CO2 into the atmosphere – a good point, but one that undermines any global deal if taken to mean that now-industrialised countries must shoulder the entire burden of emissions control.