Developing methodology to evaluate decoupling economic growth from environmental impacts of materials use in Japan

Resource Productivity (GDP/Resource consumption or input in case of national level) has been recognised as one of most important indicators to evaluate resource efficiency policies. However, Resource Productivity and Material... [ view full abstract ]

Resource Productivity (GDP/Resource consumption or input in case of national level) has been recognised as one of most important indicators to evaluate resource efficiency policies. However, Resource Productivity and Material Flow indicators have been discussed with regards to concerns on underestimating the impact of materials with a large environmental impact on a small production scale. In this study, referring to Van del voet.et al (2003), we estimate the time-series environmental impact of material use from 1990 to 2010.

We firstly identify 212 materials as target materials in four categories (fossil resources, non-metallic minerals, metals and biomass) to evaluate in this study. This study explores data availability of national level statistics on production, LCI database and I-O table; the lifecycle of each material to avoid double counting of impacts; representativeness and comprehensiveness of a resource category; and improving logicality of selection to identify target materials. Secondly, this study uses the LCI database IDEA v2 and Input-Output table to obtain per unit upstream (process related to production) environmental impacts of each target material (E_{unit_up}) as well as downstream (processes after use) environmental impacts of each target material (E_down), making sure to make adjustments for double counting. We also apply an iterative allocation process based on monetary Input-output coefficients of non-targeted materials process emissions for estimating E_down. This study accounts for the environmental impacts of the process, taking place in Japan, covering the lifecycle of target materials from extraction to waste management. Thirdly, we compile production/shipment data of target materials (years 1990-2010), depending on availability. Lastly, the environmental impacts of each target material is calculated as the sum of the upstream impact (E_up ), obtained by the multiplying the unitary impact taken from LCI (E_{unit_up} ) with the amount of the target material not used in the supply chain of other target materials (X), and the downstream impact (E_down). The total environmental impacts of our 212 targeted materials is then simply derived by adding up the resource specific impacts of each target material. Compared to the decreasing trends of domestic material consumption (DMC) in Japan, the total environmental impact shows a stagnant trend except for some decline due to economic crisis of 2008. Results in the reference years 1990, 2000 and 2010 show that the total environmental impacts of the 212 target materials added up to about JPY 6.38 trillion, JPY 6.52 trillion and JPY 5.96 trillion, respectively. 58 % of the impact in 2010 was found to be associated with the top 10 materials. The top 10 materials of estimated resource specific impact in 2010 are natural gas which shows the highest impact followed by gasoline, electrolytic copper, brown rice, heavy fuel oil C, light oil, rolls of newsprint, painted printing paper and raw milk.

 In addition, this study preliminarily estimates the eco-efficiency (GDP/ total environmental impact of material use (JPY/JPY)) in 1990-2010. We found that eco-efficiency is on an increasing trend, which shows impact decoupling.