China's carbon emissions could peak in 2021 under certain conditions, an expert on the Chinese economy said Wednesday.

Zhang Jianhua, head of research at China's central bank, made the remark at the Low Carbon Economy and Financial Innovation Forum held by the Institute of Finance and Banking of Chinese Academy of Social Science and the World Wildlife Fund (WWF) in Beijing.

Zhang said China's carbon emissions could peak at 8-9 billion tons in 2021 at the earliest only if the country maintains an average annual GDP growth of 8 percent until 2020 and thereafter eases down to 6 percent. The target is also based on the premise that use of fossil fuel drops by 0.3 percent annually, and energy consumption per unit of GDP falls by 5 percent annually, up from the 4 percent goal set by the government for the 11th Five-year Plan Period (2006-2010).

If the GDP expands on average by 9 percent annually in the decade to come, before falling to 6 percent, the emissions peak would be delayed to 2034, when the country's carbon emissions would reach 9.8 billion tons, Zhang said.

However, he said, it is still too early for China to give a compulsory emissions reduction target, as requested by some developed countries.

"All my guesses regarding the carbon emission peak are conditional, as the country, like other developing countries, still has other development goals to balance. I just want to illustrate with those assumptions that developing low-carbon economy is an urgent issue for China," said Zhang.

Zhang said developing a low-carbon economy was an opportunity for China to change its economic growth model by restructuring its energy mix and taking carbon costs into account in its macro economic development.

The Chinese government is making great efforts to reduce carbon emissions, he said.

In early June, Premier Wen Jiabao said that China would put in place carbon emissions reduction targets in future national development programs.

The State Council has also ordered provincial and local governments include climate change initiatives in their economic and social development policies. But the development of a low-carbon economy requires technological, capital and institutional support, said Zhang.

He suggested the establishment of an active carbon trading market where the government sets emission reduction goals for companies and allows them to trade carbon 'credits.'

An effective carbon trading mechanism would also create an opportunity for financial institutions to develop products to meet the funding needs of companies developing low-carbon technologies, Zhang said.