中文摘要：

本文以中国1997年和2007年的投入产出表为基础,核算了CO2排放强度的变化。结果表明,中国1997年CO排放总量为381788.56万t,强度为5.04t/万元。2007年CO2排放总量为775346.15万t,强度为4.23t/万元。10年间,CO2排放强度降低近20%。在此基础上进一步构建结构分解分析模型,将促使CO2排放强度降低的因素分解为4种效应,即能源效率因素、能源结构因素、产业结构效应和经济增长方式效应。计量结果表明,部门单位产出能源消费强度变化和部门能源消费结构变化是造成CO2排放强度下降的因素,其中以前者的影响最为显著。而产业结构变化和经济增长方式变化是促使CO2排放强度上升的因素,并且前者的影响更为显著。因此,未来要实现2020年CO2排放强度比2005年下降40%～45%的目标,必须调整产业结构,改变经济增长方式,以充分挖掘经济增长结构和方式转变的节能减排潜力。

英文摘要：

As one of largest emitters of CO_2, China is taking active measures to promote low-carbon economy. The Chinese government has set forth the goal of reducing CO_2 emissions per unit of gross domestic product （GDP） by 40 to 45% in 2020 with reference to 2005. Unraveling the reasons of decreases in CO_2 emissions intensity in the past years would be helpful for achieving the goal in the future. The authors used input-output tables of 1997 and 2007 to calculate CO2 emissions intensity change. Results show that the total CO_2 emissions were 3817885.6 and 7753461.5 thousand tons, and the CO2 emissions intensity was 5.04 ton/ten thousand Yuan and 4.23 ton/ten thousand Yuan in 1997 and 2007, respectively. During the ten years, the CO2 emissions intensity has declined by 20%. Then, we used a structural decomposition analysis model to measure the effects of CO_2 emissions intensity reduction of four factors, involving energy efficiency, energy structure, industry structure, and economy growth mode. Results show that the contribution values of energy efficiency, energy structure, industry structure, and economy growth mode were -3.4780, -0.0001, 2.2199, and 0.4455 ton/ten thousand Yuan during the period 1997-2007, respectively. The contribution ratios of the factors were 427.95%, 0.01%, -273.14%, and -54.81%, respectively, during the study period. Therefore, changes in energy efficiency and energy structure are the major drivers of promoting decreases in CO2 emissions intensity; and the effect of the former is more distinct than the latter. On the other hand, the industry structure and economy growth mode are the major drivers for increasing CO2 emissions intensity; and the effect of the former is more distinct than the latter. It is suggested that continued efforts need to be made to adjust industry structure and change economy growth modes so as to achieve the goal of cutting CO_2 emissions per unit of GDP by 40 to 45% in 2020 from 2005. It can also be concluded that decrease in CO2 emission intensity depends largely