Increased carbon footprint of materials production driven by rise in investments

摘要

The production of materials is an important source of greenhouse gas emissions. To reduce emissions, policies aim to enhance material efficiency and the circular economy, but our understanding of the dynamics of material-related greenhouse gas emissions is limited. Here, I quantify the greenhouse gas emissions from material production and the carbon footprint of materials in industries that are the first users of materials, and in final consumption, using a multiregional input-output model of the global economy and the hypothetical extraction method. From 1995 to 2015, greenhouse gas emissions from just material production increased by 120%, with 11 billion tons of CO2-equivalent emitted in 2015. As a proportion of global emissions, material production rose from 15 to 23%. China accounted for 75% of the growth. In terms of the first use of materials, two-fifths of the carbon footprint of materials is attributed to construction, and two-fifths to the manufacturing of machinery, vehicles and other durable products. Overall, the replacement of existing or formation of new capital stocks now accounts for 60% of material-related emissions. Policies that address the rapidly growing capital stocks in emerging economies therefore offer the best prospect for emission reductions from material efficiency.