Changes in Japan's food consumption footprints under human depopulation

Population growth debates often posit that depopulation would reduce ecological strains. We explore that premise through the case of Japan, where population decline coincides with rising affluence, dietary change, and growing dependence on food imports. Using environmentally-extended multi-regional input-output analysis, we examine changes in Japan's food-system footprints between 2008 and 2022 and apply decomposition analysis to identify key drivers. Our findings show that despite a shrinking population, absolute footprints remained stable, while per-capita shares increased by 21-30%, driven primarily by consumption of ultra-processed and animal-based foods, underpinned by affluence and dietary change. Most critically, Japan's ultra-globalized food system offshores around 90% of its virtual land and water demand, while 54% of embodied GHG emissions are sourced domestically. Hence, Japan's experience foreshadows a broader structural shift, whereby affluent societies generate disproportionately large per-capita environmental footprints. We emphasize the primacy of consumption and trade in shaping sustainability outcomes in the Anthropocene.