Humanity currently extracts almost 70 billion tons of materials per year. During the last century global materials extraction and use have increased by one order of magnitude. Growth accelerated in the last decade, when materials extraction grew with the global economy at an annual rate of 3.6%. For sustainable development it is of key importance to understand the spatial and temporal dynamics of global material use and the underlying drivers. This paper explores changes in global material use during the last century from a systemic perspective based on the concept of socio-economic metabolism.
In recent years socio-economic (or, more narrowly termed industrial) metabolism became a prominent concept in sustainability science as many global sustainability problems are directly associated with humanities growing demand for raw materials and their transformation into wastes and emissions after processing and use. Material Flow Analysis (MFA) is one of the approaches available to study social metabolism. It provides data and headline indicators for resource use in national economies and is widely used in science and by policy makers.
This paper presents results from a global material flow analysis and explores long term the development of global material extraction and use. It shows that in particular the period after WWII was characterized by a rapid expansion of resource use, driven by both population and economic growth. Within this period a shift from the dominance of renewable biomass towards mineral and fossil materials, which now account for 70% of all used materials, was observed. Overall, material use increased at a slower pace than the global economy, but faster than world population. As a consequence, material intensity (i.e. the amount of materials required per unit of GDP) declined throughout the 20th century, while materials use per capita doubled. The use of materials is by no means equally distributed around the globe. Per capita material use varies by a factor of 20 across countries. At the turn of the millennium, 15% of the global population living in industrialized countries were using half of all mineral and fossil resources; in contrast, the least developed countries, inhabiting 11% of global population, appropriated only 1% of these strategically important materials. In recent years, however, the emerging economies gained significance as drivers for physical growth. So far there is no evidence that growth of global materials use is slowing down. The paper discusses the implications of the results from the material flow analysis for sustainable development.