Changes in Japan's food consumption footprints under human depopulation

What is it about?

Does a shrinking population consume less? We investigate this question by examining Japan's food consumption between 2008 and 2022. We calculated the land, water and greenhouse-gas emissions required to produce food for Japanese households, including environmental pressures generated in other countries through imported food. W found that despite Japan’s population declining by about 4%, its total food-related environmental footprints did not fall over the period under investigation. Indeed, the impact per person increased by between 21% and 30%. Growing affluence and changes in diet, particularly greater consumption of ultra-processed foods and animal products, more than cancelled out the potential savings from having fewer people. Together, these foods produced most of Japan’s food-related land, water and emissions footprints. Our research also reveals how international trade can conceal environmental damage. By 2022, approximately 90% of the land and 88.5% of the water required to supply Japanese food consumption came from overseas, particularly the Asia-Pacific region, the United States and Australia. Japan therefore consumes food at home while much of the associated pressure on land and water occurs elsewhere. Our main conclusion is that population decline alone will not make food consumption sustainable. Environmental improvements will also require less resource-intensive diets, reduced food waste, stronger domestic food production and more transparent and responsible international supply chains.

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Photo by Rafael Hoyos Weht on Unsplash

Photo by Rafael Hoyos Weht on Unsplash

Why is it important?

Our research addresses a widely held but largely untested assumption: that fewer people will consume less, leading to less environmental damage. Japan provides an unusually valuable test because it combines sustained population decline with high incomes, changing diets and extensive dependence on imported food. The study is timely because many countries are approaching demographic conditions resembling those already present in Japan, such as China and South Korea in East Asia, as well as many European countries. The important question is not whether population decline will occur, since the Japanese population is now under sustained decline and other countries are following, but how consumption and environmental pressures will change as a result. What makes the research distinctive is that it follows the environmental consequences of Japanese food consumption through global supply chains. Conventional national statistics can make a country appear more sustainable when it reduces domestic farming or production. But if it replaces domestic production with imports, much of the environmental pressure has been moved elsewhere. By counting the land, water and emissions embodied in imported food, our study provides a more complete account of Japan’s environmental impact. For specialists and policymakers, the findings show that population size cannot serve as a reliable proxy for environmental pressure. Consumption per person, dietary composition, income and trade relationships can outweigh demographic change. Food, demographic, agricultural and environmental policies must therefore be considered together. For general readers, the research demonstrates that everyday consumption, particularly in richer countries, connects people to distant environments. A product bought in Japan may depend on land in Australia, water in the Asia-Pacific region and processing or distribution within Japan. Environmental responsibility consequently belongs not only to producing countries but also to the affluent societies and consumers whose demands organize these supply chains. The research changes the central question from “Will population decline reduce environmental damage?” to “How should societies change so that population decline can contribute to sustainability?”

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