Study finds 1.4 Gt discrepancy between national and provincial data sets for greenhouse gas emissions in China
A study lead by researchers from the Institute of Applied Ecology, Chinese Academy of Sciences has found a 1.4-gigatonne gap between CO2 emissions calculated on the basis of the two publicly available official energy data sets from China: one national, the other provincial. (The provincial aggregation is the higher figure.) The gap, noted the researchers in their open-access paper in Nature Climate Change, is equivalent to Japan’s annual CO2 emissions, the world’s fourth largest emitter, with 5% of the global total.
Differences in reported coal consumption in coal washing and manufacturing are the main contributors to the discrepancy in official energy statistics, they found.
These discrepancies have a number of important implications. The large deviation of China’s CO2 emissions can significantly skew the global total, resulting in an incorrect understanding and modelling of the global carbon cycle, and thus hampering the ability of many climate models to produce trustworthy and accurate predictions.
The sad fact is that Chinese energy and emission data as primary input to the models will add extra uncertainty in modelling simulations of predicting future climatic change. Such an uncertainty of CO2 emissions also brings challenges in allocating responsibilities and setting emission targets during international negotiations for post-Kyoto to achieve global emission reductions. Moreover, China is planning a domestic emission cap-and-trade mechanism between different provinces, which requires an effective measuring, reporting and verification system at both the provincial and national level. Therefore, it is of critical importance to reform the present statistical system with special attention to coal statistics in small-scale manufacturing and coal washing to derive better estimates for energy consumption and the corresponding CO2 emission.
Using remote-sensing data is another effective tool to reduce the statistical gap and monitor and verify CO2 emissions. CO2 emissions, in turn, depend on reliable energy consumption data and appropriate understanding of emission factors. Increasing the qualified statistical labour forces and their on-site surveys would help the national and regional statistical offices to improve and update the fuel combustion factors they have been using since 1990. The information provided by the Chinese Energy Statistics Yearbook should include important factors such as quality of coal, oxidation rates and so on. More bottom-up research is required to fully understand the variation of these factors within and between provinces and over time.—Guan et al.
Dabo Guan, Zhu Liu, Yong Geng, Sören Lindner & Klaus Hubacek (2012) The gigatonne gap in China’s carbon dioxide inventories. Nature Climate Change doi: 10.1038/nclimate1560