Classifying CO2 emissions from the viewpoint of LCA by reflecting the influence of regional activities

Abstract

After COP3 a lot of countries and even their local governments are struggling to reduce CO2 emissions. However, the way to define CO2 emissions is not consistently standardized. In this study we calculate CO2 emissions in two ways: apparent and responsible emissions. Apparent CO2 emissions are caused by the domestic industrial activities and they include CO2 embodied in exports. Responsible CO2 emissions are attributed to domestic final demand and they include CO2 embodied in imports. We classify domestic production into that of Tokyo and that of the other regions, and calculate regional CO2 emissions by the above two ways. From the viewpoint of LCA (LifeCycle Assessment), we utilized the regional input-output table for the database. Apparent and Responsible CO2 emissions of Tokyo are 17 Mt-C and 32Mt-C, respectively. Because the amount of CO2 results in such different values, standardizing the way to define CO2 emissions is a critical problem for deciding the goal of CO2 reduction. Concerning the emissions in each sector, power generation and transport have the largest reduction potential in industrial sectors. Making the life of buildings longer is the most effective measures from the consumers viewpoint.