Global warming poses the great threat to the survival and development of human being and ecosystems. The excessive anthropic emissions of greenhouse gases (GHGs), mainly CO2, is one of the major causes of global warming. Cities are the dominant regions of human activity and fossil energy consumption Analysis of the status and composition of the CO2 emissions from fossil-fuel consumption in typical cities, and clarification of the dynamics and critical influencing factors of the CO2 emissions in different cities could provide an important scientific basis for mitigation action in urban areas.
In the consideration of the completeness and continuousness of fossil energy consumption data acquisition, this study chose 11 typical cities with different magnitude, economic development situation, energy and industrial structure in the 9 metropolitan areas of China, namely Beijing, Shanghai, Chongqing, Guangzhou,Urumqi, Tangshan, Hefei, Guiyang, Daqing, Hohhot and Harbin. With the IPCC recommended methods, Chinese emission factors and parameters, and fossil fuel consumption statistics, an estimate was made on the CO2 emissions from fossil fuel combustion in 11 typical cities from 2006 to 2015. The characters of fossil energy CO2 emissions, per capita CO2 emissions, CO2 emissions intensity, energy and industrial characters were examined. Through location quotient (LQ) and Nelson taxonomy, these 11 typical cities were grouped into four different function categories, i.e., comprehensive service industry cities, industrial cities, resource cities and constructive cities. Especially for the energy fossil CO2 emission characters of the industry sectors of the four function categories. Then the CO2 emissions from fossil energy consumption were decomposed by LMDI (Logarithmic Mean Divisia Index) method in the aspect of economic development, energy intensity, population magnitude, industrial structure and energy structure to quantitively analyze the influence of the dynamics of these factors among the cities.
The results indicated that, the total fossil energy consumption of 11 typical cities varies greatly. Shanghai and Tangshan consumed the most energy, Hefei and Guiyang consumed the least energy. Beijing and Guangzhou had the lowest average annual growth in energy consumption, which was at -3.0% and 0.89%, respectively. During the study period, energy intensity of all the 11 typical cities showed a downward trends, among which Guangzhou and Beijing had the largest declines, with a cumulative decline of 59.12% and 55.45%, respectively.
From 2006 to 2015, the highest increasing rate of the fossil energy consumption CO2 emission happened in Urumqi, Hefei and Chongqing, and the average annual increasing rate was 14.87%, 10.56% and 7.32%, respectively. While the CO2 emission showed decreasing trends in Beijing and Guangzhou, and the increasing rate was -0.12% and -11.82% respectively. The highest cumulative CO2 emissions from 2006 to 2015 appeared in Tangshan, Shanghai, Urumqi and Chongqing, accounting for 20.60%, 17.48%, 12.01% and 11.44% of the total emissions of the 11 cities,respectively. Among these four cities with largest fossil energy CO2 emission, Shanghai and Chongqing were categorized as industrial cities while Tangshan and Urumqi were categorized as resource cities. The cumulative CO2 emissions from 2006 to 2015 of the three cities categorized as comprehensive service industry cities, i.e.,Beijing, Guangzhou, and Hohhot, accounted for 8.65%, 7.95% and 6.62%, respectively, of the total cumulative CO2 emissions of the 11 cities. The percapita CO2 emissions were distinct among the 11 cities, but showed a spatial pattern similar to that the total CO2 emissions. The CO2 emissions intensity went down fast in Beijing, Shanghai, Guangzhou and Guiyang and slow in Chongqing, Harbin,Tangshan, Daqing, Hohhot and Hefei, but went up in Urumqi, the change of urban CO2 emission intensity was related to the growth of economy and CO2 emission.During the research period, the proportion of coal related CO2 emissions and the CO2 emissions ratio of industrial sectors in the total fossil energy CO2 emissions both decreased to below 50% in Beijing and Guangzhou. Emission from industry took the dominant position of the fossil energy CO2 emissions of all the 11 cities in long-term,and CO2 emissions of all the four categories of the cities were mainly from highly energy-consumed industry.
For all the cities, economic development was the main factor that lead to CO2 emissions growth; meanwhile, the change of energy intensity acted as the main driving factor of CO2 emissions reduction or constraint of emission increase.Population size increment made positive promotion effect to CO2 emissions in all the 11 typical cities, but the contribution to accumulated CO2 emissions was far less compared with economic development. The energy structure effect only inhibits the CO2 emissions of Beijing and Guangzhou, where coal’s proportion in fossil energy consumption was low and going down fast, At the same time, the evolution of industry structure could reduce CO2 emissions in Beijing, Shanghai, Guangzhou,Urumqi, Daqing and Guiyang, where the tertiary industry GDP increased faster than those of the second industry. Finally, CO2 mitigation measures for different categories of cities were also suggested based on the results of this study.