It's the moment the world has been waiting for.

India has committed to cutting its carbon intensity by 20-25% over the next ten years.  Environment Minister Jairam Ramesh announced this in Parliament on Thursday evening.  By doing so, it has become the fourth, and last, major polluter to volunteer a cut ahead of the Copenhagen climate change conference.

Carbon intensity refers to how much coal and carbon-based fuels like petrol and diesel are used to produce the country's Gross Domestic Product. India's per capita carbon intensity is 1.2 tonnes, compared to China's 5.3 tonnes, and America's whopping 21.2 tonnes.

India's promise to slash its carbon intensity by a fourth follows China's recent promise  of a 40% reduction. Significantly, what India and China have committed to is quite different from richer nations, which have offered to cutting actual carbon emissions.

Addressing concerns that carbon cuts will slow down growth, especially in the manufacturing sector, Ramesh said that new technologies will be embraced to ensure that's not the case.  India will "ensure 50% of new capacity is based on clean coal technology," said Ramesh.  He also said that he will legislate mandatory fuel efficiency standards by 2011.

Ramesh claimed that India is more vulnerable to climate change than any other country in the world, and needs to be worried about the effects of climate change for its own sake, and not because of external international pressure.

"India will go to Copenhagen meet on climate change with a positive frame of mind; we will be flexible. We want a comprehensive and equitable agreement from Copenhagen," he said.

However, the minister reiterated India's stated position that it will not accept legally-binding emission cuts.