Decomposition Analysis of the Carbon Footprint of Primary Metals

Abstract

This study investigates how different technological and socioeconomic drivers have impacted the carbon footprint of primary metals. It analyzes the historical evidence from 1995 to 2018 using new metal production, energy use, and greenhouse gas (GHG) emission extensions made for the multiregional input–output model EXIOBASE. A combination of established input–output methods (index decomposition analysis, hypothetical extraction method, and footprint analysis) is used to dissect the drivers of the change in the upstream emissions occurring due to the production of metals demanded by other (downstream) economic activities. On a global level, GHG emissions from metal production have increased at a similar pace as the GDP but have decreased in high-income countries in the most recent 6 year period studied. This absolute decoupling in industrialized countries is mainly driven by reduced metal consumption intensity and improved energy efficiency. However, in emerging economies increasing metal consumption intensity and affluency have driven up emissions, more than offsetting any reductions due to improved energy efficiency.

Material and Carbon Footprints of Machinery Capital

“…In this study, we use a broader definition of the machinery and equipment sector to include a wider range of industrial products. Employing the footprint calculation on the EXIOBASE platform, 34 we assess environmental flows, covering GHG emissions, material extraction, and primary metal use 35 from machinery production. These flows feed into stock assessments through dynamic material flow analysis, using survival curve and depreciation methods, respectively, to measure the footprint embodied in machinery stock across regions over time.…”

“…41 The IRP/WU material extraction data track gross material flows such as ores. Furthermore, given that metals often appear in ores at a lower grade, mingled with numerous nonmetals, we modeled primary metal use 35 which was obtained from the British Geological Survey. 42 It represents the actual amount of usable metal extracted from the ore. We allocate material extraction and metal use to sectors following a one-to-one exercise 34 in the EEIOA extension matrices.…”

Linking hypothetical extraction, the accumulation of production factors, and the addition of value

“…DSB's approach inspired subsequent environmentally focused studies (Guerra and Sancho, 2010;Wang et al, 2013;Zhang et al, 2019). HEM was used to quantify the carbon footprints of materials and metals contribution to the carbon footprint of products and consumption baskets (Hertwich, 2021;Rasul and Hertwich, 2023). A similar analysis, focusing on a wider basket of resources, had previously been conducted by Cabernard, Pfister, and Hellweg (CPH) and was used by the Global Resources Outlook of the International Resource Panel (Cabernard et al, 2019;Oberle et al, 2019).…”