René Kleijn (PhD) is an Industrial Ecologist, working as an associate professor at the Department of Industrial Ecology of the Institute of Environmental Sciences (CML), Leiden University. He is the scientific lead of the Leiden-Delft-Erasmus Circular Industries Hub. The focal point of his research is the systematic analysis of sustainability issues using tools like Life Cycle Assessment, Substance and Material Flow Analysis and Environmentally Extended Input Output analysis. His current work relates to the development of more dynamic and comprehensive tools that can be used to study the effects of large-scale transitions i.e. Life Cycle Sustainability Analysis (LCSA). He applied these different tools in many domains including chemical industry, energy systems and recycling technologies. In recent years, he studied the material constraints of new technologies, material scarcity in general and the resilience of material supply chains. His research resulted in over 50 peer reviewed scientific journal papers as well as many research reports, conference papers, columns and media appearances. He has over 20 years of experience in scientific research and education and was involved in over 15 large European research projects.