Beijing is enveloped in heavy smog on Jan. 10, 2013. [File photo/Chinanews.com]

Greenhouse gas emissions in China in 2011 increased to their highest level since data began being collected by network stations in 1990, according to China's first Greenhouse Gas Bulletin.

The bulletin, released by the China Meteorological Administration (CMA) on Monday, showed carbon dioxide levels measured at 392.2 parts per million at Waliguan station in Qinghai Province. This was a peak since the station began operating in 1990.

The figures, revealed in Shenyang, capital of northeast China's Liaoning Province, are also slightly higher than the global averages in all greenhouse gas components including atmospheric carbon dioxide, methane and nitrous oxide.

The bulletin indicates a sign of the government's improving transparency in facing environmental issues, said Duan Yihong, head of the China Meteorological Academy of Sciences.

According to Duan, data on greenhouse gas levels in 2012 can be expected soon, as the government is determined to publish the bulletin annually.

He said greenhouse gas emissions, which are a cause of the persistent smog currently enveloping the north of China, are mainly produced through burning of fossil fuel and biomass.

"In addition to industrial emissions, automobile exhausts and coal burning for winter heating are two major contributors to the suffocating smog," he said.

The bulletin showed that the annual averaged greenhouse gas emissions observed by three regional stations set up in northeast China's Heilongjiang Province, Beijing and eastern Zhejiang Province are all higher than figures collected at the Waliguan station in sparsely populated Qinghai.

The bulletin was based on data collected by seven atmospheric background stations established and operated by the CMA. Four of the stations have been listed in the World Meteorological Organization's Global Atmosphere Watch Program directory.