Researchers at the Research Institute for Humanity and Nature in Kyoto, lead by Associate Professor Keiichiro Kanemoto, analyzed the carbon footprints of the diets of 60,000 households across Japan's 47 prefectures.
Using a life-cycle approach which details food supply chains, they found that meat consumption was relatively constant per household - and yet carbon footprints were not. Meat consumption could only explain less than 10% of the difference in carbon footprints.
Instead, the researchers found that alcohol and confectionery consumption in higher carbon footprint households were 2-3 times that of consumption in low carbon footprint households. These higher carbon households also consumed more restaurant food, more vegetables and more fish: but it was the amount of alcohol and confectionery consumption ‘that really stood out’.
The researchers agree that eating meat is more environmentally damaging than other foods - beef production emits 20 times more greenhouse gases than bean production for the same amount of protein - and meat and dairy consumption still accounts for around 30% of household carbon footprints. But cutting down on luxury items could be an easy way to reduce carbon footprints, write the authors in their study.
"Because household wealth is correlated with higher food-related carbon footprints, income- or wealth-based policies, such as luxury tax on food, measures to prevent food waste, better consumer labeling, or carbon offset schemes, could help reduce excessive consumption or mitigate the dietary carbon footprint of wealthy households.
"Finally, as it is not widely known or discussed that alcohol, confectionery, and restaurants meals in fact substantially differentiate high-carbon footprint households, simply communicating this message could provide surprising and helpful information to households seeking to reduce their dietary carbon footprint."
Regional differences are important
Japan has the world’s longest lifespan; and its population is one of the oldest in the world. As other countries follow this trend and move towards ageing populations, Japan’s policies in diet and energy efficiency could become a model for other nations.
Dr. Christian Reynolds, a co-author of the study who is based at the Institute of Sustainable Food at the University of Sheffield, Sheffield, England, says that regional differences in diet and food supply chains need to be taken into account when looking at food sustainability policy.
"Due to wealth, culture, and farming practices, different regions in a country consume food differently. Japan alone has prefectures with more than 10 million people and others with fewer than one million," said Dr. Reynolds. "These regional and income differences in food consumption are also found in the UK, Europe, Australia, and the USA.
“This evidence from Japan demonstrates that research can help us to identify what to focus on. The same patterns of dietary change in terms of sugar, alcohol and dining out need to be considered in the UK, Australia, the US and Europe."
The research is published in One Earth