Shared socio-economic pathways and their implications for global materials use

The global economy relies on a continuous and ever-growing throughput of biomass, fossil fuels, metal ores and non-metallic minerals to build, maintain and fuel the infrastructure of cities and industrial systems. The amount of materials required year by year depends on population levels, the use of technologies in production systems, investment into public infrastructure, and the lifestyle choices and consumption behaviours of households. The level of global material use has important consequences for environmental pressures and impacts of socioeconomic activities. Using materials more efficiently has positive implications for the economy and allows for reduced pressure on climate change, biodiversity loss, resource supply systems and waste management. The Shared Socioeconomic Pathways (SSPs) structure assumptions of future population growth, economic activity and urbanisation into five core narratives and allow for greater comparability of scenario assumptions and assessments of future natural resource requirements and pollution levels. In this study we explore the future of global material use across the five SSPs using economic modelling with industry sector, country detail and technology extensions and provide a summary of global material demand scenarios. The challenge faced to reduce global material flows is determined by the material requirements of different levels of population, global economic growth, the potential to improve material intensity of production systems, and consumer behaviour. Under the scenarios, global material flows vary between 134 billion tonnes for SSP1 and 282 billion tonnes for SSP5 by 2060. A middle of the road SSP2 scenario projects material demand of 176 billion tonnes by 2060, which is twice the level of 2017's global material use. Despite yearly average improvements in material efficiency of 0.8% between 2015 and 2060, our results demonstrate the level of ambition that is required to curb the increasing pressures on natural resource supply systems and their environmentally detrimental consequences. This study presents five alternative baseline scenarios which assume a continuation of historical trends in the way in which production, consumption and material use are interacting. Efforts to reduce global demand of primary materials need be stepped up to manage the global economy within planetary boundaries. This can be modelled by introducing ambitious policy settings which was, however, not the purpose of this study.