Estimating Raw Material Equivalents on a Macro-Level: Comparison of Multi-Regional Input–Output Analysis and Hybrid LCI-IO

Abstract

The mass of material consumed by a population has become a useful proxy for measuring environmental pressure. The "raw material equivalents" (RME) metric of material consumption addresses the issue of including the full supply chain (including imports) when calculating national or product level material impacts. The RME calculation suffers from data availability, however, as quantitative data on production practices along the full supply chain (in different regions) is required. Hence, the RME is currently being estimated by three main approaches: (1) assuming domestic technology in foreign economies, (2) utilizing region-specific life-cycle inventories (in a hybrid framework), and (3) utilizing multi-regional input-output (MRIO) analysis to explicitly cover all regions of the supply chain. While the first approach has been shown to give inaccurate results, this paper focuses on the benefits and costs of the latter two approaches. We analyze results from two key (MRIO and hybrid) projects modeling raw material equivalents, adjusting the models in a stepwise manner in order to quantify the effects of individual conceptual elements. We attempt to isolate the MRIO gap, which denotes the quantitative impact of calculating the RME of imports by an MRIO approach instead of the hybrid model, focusing on the RME of EU external trade imports. While, the models give quantitatively similar results, differences become more pronounced when tracking more detailed material flows. We assess the advantages and disadvantages of the two approaches and look forward to ways to further harmonize data and approaches.

Impacts Embodied in Global Trade Flows

“…Some studies have begun comparing the results obtained from different models, fi nding reasonable agreement as well as signifi cant discrepancies for certain indictors (e.g. Peters et al 2012 for CO 2 emissions and Schoer et al 2013 for raw materials).…”

“…Kastner et al ( 2014b ) fi nd contradictory results for China 's trade in embodied cropland when using physical instead of monetary input-output data. And Schoer et al ( 2013 ) explore the differences of employing life cycle inventory data versus MRIO modelling for raw material equivalents embodied in EU27 imports.…”

Measuring telecouplings in the global land system: A review and comparative evaluation of land footprint accounting methods

“…Beyond that, there exist further options for hybrid accounting, not yet applied to land footprint calculations. For example, several material footprint studies integrate detailed statistics in mass units into monetary IOTs, thereby creating mixed-unit IOTs (Buyny et al, 2009;Schoer et al, 2012;Schoer et al, 2013).…”

“…Results are significantly correlated with per capita income (R 2 = 0.665), indicating that the rice footprint of wealthier countries increases when flows are allocated according to monetary values as opposed to a mass-based allocation, while for low-income countries footprints are lower when using economic allocation. Quality and related price differences between rice imports to high-income and low-income countries can be assumed to cause these differences, a discrepancy which is discussed extensively by Schoer et al (2013).…”

“…This is relevant for the attribution of land to joint products such as oil and cake from soybeans, but also for unprocessed crop commodities in cases where prices of domestically used and internationally traded crops differ (Schoer et al, 2013). Other advantages include the detailed country-level geographical coverage, and the availability of data for long time series with timely and regular updates.…”