Re-estimating China's Sectoral Carbon Dioxide Emissions:Based on Product Technology Assumption
The carbon dioxide(CO2)emissions accounting based on the input-output method has attracted wide attention.However,scholars often confuse industrial emissions with product emissions due to the inconsistent classification of China's official energy data by industry and the input-output tables by product,leading to differences in the basic accounting data on sectoral emissions.To address this issue,this study innovatively proposes a method based on product technology assumption(PTA)to convert industrial emissions into product emissions with the input-output model,decomposes the calculating deviations of the energy consumption method(ECM)and the industry technology assumption method(ITA)from PTA,and reveals and analyzes the influencing factors.Compared with existing literature,this study makes the following contributions.First,it innovatively proposes a method to convert industrial emissions into product emissions based on PTA.This method overcomes the constraints of calculating China's official energy sectoral emissions,which rely on industry-based statistics.It avoids the emission calculation deviations caused by equating industrial emissions to product emissions in previous studies,thus improving the accuracy of sectoral emissions accounting in China.Second,it reveals and analyzes the main influencing factors that cause deviations in calculating Chinese sectoral emissions using the ECM and ITA methods from PTA.The study provides scholars with a reference for adopting appropriate emission accounting methods and improves the theoretical framework and methods for sectoral carbon emissions accounting in China.Third,it provides foundational data support for further empirical analysis of energy and emissions at the sectoral level,such as further examining China's embodied carbon emissions and assessing emission reduction policies.The results reveal that for pure sectors,the emissions calculated with PTA,ECM,and ITA are the same.It is the complex production correlation that determines whether there are deviations in calculating sectoral emissions using ECM,ITA,and PTA.Pure sectors achieve consistency between energy data by industry and the input-output tables by product due to the absence of secondary products.However,for mixed sectors with secondary products,there are significant accounting differences.The ECM and ITA underestimate CO2 emissions from high-emitting sectors and overestimate emissions from other sectors.Taking the major sectors as an example,on average,the emissions of high-emitting sectors,including non-metallic mineral products,smelting and pressing products of metals,and production and supply of electricity and heat,are underestimated by 56.08 MtCO2(2.6％)and 101.21 MtCO2(4.6％)under ECM and ITA,respectively.Additionally,the emissions of medium-emitting sectors tend to be overestimated by an average of 25.38 MtCO2(14.3％)and 31.04 MtCO2(17.5％)under ECM and ITA,respectively.These sectors encompass mining and washing products of coal and processing products of petroleum,coal and other fuels,and chemicals.Further analysis demonstrates that accounting deviations mainly depend on the product supply source in the national economy and emission disparities among production sectors.The ECM equates industrial emissions to product emissions.When high-emitting industries produce low-emitting products,emissions from high-emitting products produced by secondary industries in the PTA are changed into emissions from medium to low-emitting products produced by high-emitting sectors in the ECM.This leads to an underestimation of emissions from high-emitting sectors and an overestimation of emissions from medium to low-emitting sectors.On the other hand,ITA assumes that the emission intensity of primary and secondary products produced in the same industry is identical.It evenly distributes industrial emissions to sectors based on product proportions,resulting in an underestimation of emissions from high-emitting sectors and an overestimation of emissions from medium to low-emitting sectors.Moreover,lager emission disparity between primary and secondary products in an industry is larger,along with higher market share or product proportion of secondary products,resulting in more pronounced accounting differences between ECM and ITA.Based on the above conclusions,this study puts forward the following policy recommendations.First,when constructing sectoral CO2 emissions inventories based on input-output tables,attention should be paid to the data classification(industry or product).If discrepancies exist,the method proposed in this study can be employed to convert the data,ensuring consistency between energy statistics and the input-output data.Second,emissions reduction planning and policy measures at the product level need appropriate adjustments and optimization.For high-emitting sectors,as current emission reduction efforts may not be sufficient to achieve the sector's reduction targets,they should focus on promoting green transformation,optimizing the design of low-carbon development paths,and reasonably adjusting their emission constraints or intensity targets.For medium to low-emitting sectors,it is necessary to reassess their low-carbon development levels and the rationality of current emission reduction efforts and optimize their green transformation plans.Policymakers can consider adopting relatively moderate emission reduction measures and appropriately slow down the pace of emission reduction to reduce the costs for both sectors and the economy.Third,emphasis should be placed on utilizing input-output accounting as part of the framework for national economic accounting and strengthening the accounting and compilation of supply and use tables.
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