Decoupled ore and scrap trade networks constrain low-carbon metal supply

Global supply chains for critical metals such as aluminium and copper are increasingly exposed to sustainability and geopolitical risks under the pressure of energy transition. In this paper we compare primary (ore) and secondary (scrap) trade networks for the United States, European Union and China using multilayer network analysis. We focus on the years 2010-2023, a period that captures intensified demand for the two metals. Results identify a marked structural decoupling: around 40% of scrap-trading countries do not participate in ore trade. Further, while about 50% of ore trade links overlap with scrap networks, only some 10–15% of scrap connections overlap with ore trade. Despite strong alignment in trading partners, volumes of scrap and ore trade diverge substantially. The observed differences indicate that the two commodity streams use partly distinct international trading relationships. Major economies may compete for ore suppliers but remain interdependent in scrap trade, revealing a bifurcated system with uneven resilience. Strengthening integration between primary and secondary supply chains is therefore critical for achieving sustainable critical metal supply for the low-carbon energy transition and establishing resource-efficient metal systems.