Methane emissions in China 2007

In contrast to the ever-increasing focus on China's CO2 emissions, little attention has been given to its CH4 emissions, the second largest greenhouse gas. Presented in this paper is a comprehensive assessment of the CH4 emissions in Mainland China by source and region based on the latest statistical data and research literatures available. The total CH4 emission in China 2007 is estimated as 38.6 Tg, one and a half times of that in USA. Even by the lower IPCC global warming potential (GWP) factor of 25, it corresponds to 964.1 Mt CO2-eq, in magnitude up to one seventh of China's CO2 emission and greater than the nationwide gross CO2 emissions in Australia, Canada, and Germany in 2007. As the leading emission source, energy activities are responsible for 45.3% of the total emission, agricultural activities contribute a comparable share of 40.9%, followed by waste management of 13.8%. Among all the 11 major emission sources, coal mining (38.3% of the total), enteric fermentation (21.4%) and rice cultivation (14.4%) essentially shape the CH4 emission profile for China, quite different from that for USA which is characterized by prominent emissions from enteric fermentation, municipal solid waste landfill and natural gas leakage. The Western and Central areas contribute 70.9% of the total nationwide emission and Shanxi is the largest regional CH4 emitter with an amount of 4.6 Tg. The five regions of Xizang (Tibet), Shanxi, Qinghai, Ningxia, and Guizhou are identified with the largest emissions per-capita and emission intensities. In contrast to the focused areas of CO2 emission reduction mainly in the energy-intensive eastern regions, the mitigation potential of CH4 emissions in the western and central regions is huge by integrating emission quantity and structure with emission per-capita and emission intensity at the regional level. Corresponding policy-making implications for CH4 emission mitigation in China are addressed.