Keisuke Nansai is Head of the International Material Cycles Section, Centre for Material Cycles and Waste Management Research, National Institute for Environmental Studies, Japan. His expertise includes environmental input-output analysis.

Keisuke Nansai (南齋 規介) is Head of the International Material Cycles Section at the Centre for Material Cycles and Waste Management Research of National Institute for Environmental Studies. He is an adjunct professor at the Graduate School of Environmental Studies at Nagoya University in Japan and a visiting professor at the Faculty of Science at the University of Sydney in Australia. He is a council member of the International Society of Industrial Ecology and a board member of its Environmentally-Extended Input-Output chapter, as well as a council member of the Institute of Life Cycle Assessment, Japan. He is an editorial board member both of Economic Systems Research and Journal of Economic Structure.

He has been specializing in environmental systems analyses based on life-cycle thinking, and applying an input-output analysis, life-cycle analysis, material flow analysis and network analysis to environmental and social assessments of technologies, human life style, and policies. He is a developer of 3EID, the Japanese environmental input-output database that has been widely used for carbon footprint analysis in Japan. His present research interests includes the nexus of planetary health and resource productivity, resource criticality of technologies for climate change mitigation/adaptation, and future global material flows under carbon budget.