Improving The Completeness Of Product Carbon Footprints Using A Global Link Input-Output Model: The Case Of Japan

This paper is concerned with the main activities of Japan's 'Disclosure of CO2 emissions' programme, aimed at illustrating the CO2 emissions associated with consumer products as a 'carbon footprint' (CF). Although the current, provisional guidelines for calculating product carbon footprints specify that only the bottom-up approach is to be used for this purpose, this paper presents useful applications of input-output analysis that can improve the reliability of the method considerably, by taking full advantage of the strengths of input-output analysis. To this end, we first estimated the global carbon footprint (GCF) of food and consumables in Japan, using a global link input-output (GLIO) model comprising 804 economic sectors in Japan and 230 foreign countries and regions. By visualizing the GCF on a world map, the global distribution (including Middle East and African countries) of the induced CO2 emissions of each of the Japanese sectors were identified. To investigate the scope for reducing the data collection burden for CF practitioners, GCFs were compared with CFs obtained using a single-region input-output model. This showed that there are certain commodity groups with a CF equating to 70% to over 90% of the corresponding GCF, even if the imported goods used for producing a Japanese domestic product are considered environmentally equivalent to their domestically produced counterparts. Furthermore, it was identified which data should preferably be collected by the bottom-up approach to secure CO2 emissions coverage greater than a certain predefined level and keep data and labour costs at a minimum.