India's greenhouse gas (GHG) emissions will grow four-fold in the next two decades if the economy expands by an average 8 per cent a year during this period, says a government-funded study by five different organisations.

India's per-capita emissions are estimated to rise to 2.1 tonnes by 2020 and 3.5 tonnes by 2030, the report released on Wednesday said. But still it remains below the global average for 2005.

The report, India's GHG emissions profile, was released jointly by Montek Singh Ahluwalia, deputy chairman of the Planning Commission, and environment minister Jairam Ramesh.

"It's not a do-nothing strategy," Ramesh told reporters, adding that the per-capita principle is the only internationally recognised measure of equity.

''Four out of the five studies show that even two decades from now, India's per capita greenhouse gas emissions would be well below the global average 25 years earlier,'' Ramesh said.

According to the United Nations Development Programme, India's per capita emission of GHG is 1.2 tonnes, while it is 15 tonnes for the UK and 20 tonnes for the US.

For long, India has been batting for equity in global climate change talks. In a Confederation of Indian Industry meet in April 2008, Shyam Saran, prime minister's then special envoy, said the global climate change negotiations should be based on the simple principle, ''the polluter pays'' (See: India for equity in global climate change negotiations: Shyam Saran).

The present report shows that India's energy use efficiency has been improving over the years, as the energy intensity of GDP has reduced from 0.30 kgoe (kg of oil equivalent) per dollar of GDP in 1980 to 0.16 kgoe per dollar of GDP in 2004.

Ahluwalia said the estimates are not projections that will reflect commitment in international negotiations.

''It is only to give a sense of what is our growth strategy and energy use in terms of emissions,'' he said.

The country will use the estimate, the first measure of emissions by the ministry of environment and forests, to support its position in the global climate talks in Copenhagen in December.

India has refused to accept mandatory emission cuts such as the ones imposed on some developed countries.

The estimates are based on assumptions on GDP growth rates, penetration of clean energy technologies, and improvements in energy efficiency.

Of the five studies, three were conducted by the National Council of Applied Economic Research and Jadavpur University, one by The Energy Research Institute and the ministry, and one by the ministry and Integrated Research and Action for Development.

The report, released prior to the UN climate meet in Copenhagen by the year end is seen as an official stand to be taken by the country during the summit.

"The structure of the economy, policy and regulatory regime and energy endowment together ensure that India's growth over the next two decades, while rapid, would remain inherently sustainable," the report said.

Developed nations now emit more than half of global greenhouse gas.

However, they say developing states must agree to emissions curbs as part of a broader climate pact.

In July, India, along with South Africa and 35 other like-minded countries have submitted a proposal calling for Annex-I parties (developed countries) to agree to at least 40 per cent emission reduction commitment by 2020 as compared to their 1990 levels under the Kyoto Protocol (See: India, other countries want developed world to agree to 40 per cent emission reduction by 2020).

According to a study by the German renewable energy industry institute IWR said India's carbon dioxide emissions alone were 1.4 billion tonnes in 2008, or about 1.3 tonnes per-capita.

China's carbon dioxide emissions in 2008 were 6.8 billion tones, while for the US it was 6.37 billion tonnes.