China has set a positive tone for global deal to cap carbon emissions

China for years led the developing world's resistance to mandatory caps on carbon emissions, arguing that it was the rich world's responsibility to take the lead in addressing a problem it was instrumental in creating through its own development. Unless climate-change sceptics are right, and despite the hypocrisy of the West, it is an argument that is ultimately unsustainable, especially for the country that is now the world's biggest carbon emitter.

That is implicit in China's pledge to ensure emissions peak in 2030, as part of a climate pact it signed with the United States last November. Official thinking on how this target was to be achieved remained unclear. Comments by the mainland's top meteorologist, Zheng Guoguang, in the Study Times, a publication of the Central Party School, throw some light on it.

He said well-off provinces in the east of the country should set mandatory targets for carbon emissions as soon as possible. This is the first time China has said it might set binding targets for some parts of the country.

Zheng said compliance with targets should weigh in evaluation reviews of local officials. He also said western provinces undergoing more economic development should keep emissions relatively low if they did not want to come under pressure to bring them down later.

This is consistent with a suggestion by Wang Yi of the China Academy of Sciences, an adviser to China's climate negotiating team, that Beijing should set a mandatory carbon emissions cap of 10 billion tonnes for 2020, compared with an estimated 7.25 billion tonnes in 2010, and assign responsibility to regions according to their development status.

China has previously set a target to cut carbon intensity - emissions per unit of economic growth - by 45 per cent by 2020 from 2005 levels.

The new line is to be welcomed. It sets a positive tone for negotiations to forge a new global deal on tackling climate change, due to be concluded in Paris in December.