Evaluating mineral resource boundaries for application in absolute environmental sustainability assessment

Environmental sustainability assessments use absolute boundaries, also known as carrying capacities, to interpret the environmental performance of products and technologies in a broader, planetary perspective. Several absolute boundaries have been made operational for natural systems, including for climate change impacts and use of land. However, absolute boundaries for our use of mineral resources lag behind. This gap means that while mineral resource accounting is common in life cycle assessments (LCA) or environmental footprinting, it is seldom considered in absolute environmental sustainability assessment (AESA). We aim to enrich the discussion on the relevance of considering absolute boundaries for mineral resources by 1) reviewing current boundary definition proposals, 2) classifying the proposed boundaries, 3) comparing them based on a common metric, and 4) evaluating them using a consistent set of criteria. Our analysis reveals that the currently proposed boundaries for mineral resource use are very diverse and lack the maturity required for reliable use in AESA.