Comparative Analysis on Japan's CO2 Emission Computation - Gaps between Japanese GHG Inventory Report and IEA Statistics and Their Factor Decomposition

Being used as Japan's energy-originated carbon dioxide emission data are estimates by two agencies. They are the greenhouse gas inventory report by the Ministry of the Environment and the CO2 Emissions from Fuel Combustion by the International Energy Agency. Under the U.N. Framework Convention on Climate Change and the Kyoto Protocol, the GHG inventory report specifying GHG emission and absorption data is submitted by the Japanese government to the UNFCCC Secretariat. The IEA uses Japan-submitted energy consumption data for estimating CO2 emissions based on the IPCC (Intergovernmental Panel on Climate Change) guidelines as revised in 1996. But the two CO2 emission estimates do not match each other. The IEA's sector-by-sector estimates are largely different from those in the Japanese GHG inventory report. GHG emission data are used for a wide range of areas as the first commitment period under the Kyoto Protocol begins. However, emission data users have little recognized gaps between the Japanese government and IEA data. The data are in a state of contradiction. In order to allow GHG emission data to be used properly for many analyses with right recognitions, the reporter would like to compile the gaps between the Japanese government and IEA data from a statistical viewpoint.