Carbon Dioxide Emissions from Japanese Passenger Cars up to 2020: Projection Using Modified Lapeyres Decomposition Techniques

Abstract

Index decomposition methods have been widely used for quantitative identification of historical trends in factors related to changes in objective variables when examining environmental and energy issues; however, index decomposition methods have been rarely used for projecting carbon dioxide (CO₂) emissions. A method, called Modified Laspeyres Index method for Projection (PMLI method), was developed for projecting CO₂ emissions from car travel using index decomposition techniques. CO₂ emissions from Japanese passenger cars up to 2020 were then projected by using this method. The CO₂ emissions in 2020 will decrease to the 1990 level on the basis of the trends in factors observed over the period 2001 to 2005. Decreases in travel distance per passenger car in use and improvement of actual road fuel efficiency per average car weight will primarily induce these decreases. The PMLI method could be utilized in the construction of scenarios for reducing CO₂ emissions from car travel.