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Which dietary change for reducing food’s environmental impact


New evidence highlights the importance of dietary change in reducing food’s environmental impact

A recent study by Poore et al gathered a wealth of information from a wide range of food producers across the globe on their practices and the associated environmental impacts. The data set covers approximately 38,700 farms in 119 countries, and 40 products representing approximately 90% of global protein and calorie intake. Environmental indicators examined included land use, freshwater use, greenhouse gases emissions (GHGe), acidifying and eutrophying emissions.

According to this recent research, meat, aquaculture, eggs and dairy use approximately 83% of the world’s farmland and contribute 56 to 58% of food’s different emissions, despite providing only 37% of our protein and 18% of our calories. Even the environmental impact of the lowest impact animal products can markedly exceed those of vegetable substitutes. While the authors suggest introducing mitigation strategies to producers with particularly high environmental impacts, they note there are limits on how far producers can lower these impacts. To bring about the greatest environmental benefit, they emphasise dietary change is required, in particular a reduction in total animal production.

The authors calculated by excluding animal products, and introducing new vegetable proteins, food’s land use would reduce by 76%, GHGe by 49%, acidification by 50%, eutrophication by 49% and scarcity-weighted freshwater withdrawal by 19% compared to a 2010 reference year.

This is supported by another recent study, published in the journal Nature, which suggests switching to a more plant-based diet is a key step towards feeding 10 billion people sustainably by 2050. This study is the first to quantify how food production and consumption affects the planet’s boundaries, a term which describes a safe operating system beyond which Earth’s vital systems could become unstable.

For this study, the researchers gathered country-specific data to examine the global environmental impact of food production, both now and in the future. The five environmental indicators and related planetary boundaries measured included GHGe related to climate change; cropland use related to land-system change; fresh water use; and nitrogen and phosphorous application related to biogeochemical flows. They found that without concerted action the environmental effects of the food system could increase by 50 to 90% by 2050 as a result of a growing population and a rise in consumption of Western style diets. These levels are beyond the planet boundaries being measured.

They then analysed various options for reducing these environmental impacts and recommended three areas for action; adopting a more plant-based, flexitarian diet that reduces meat and dairy intake; cutting food loss and waste in half and improvements in farming practices.

The researchers estimated that switching to a healthier, more plant-based diet could reduce food related GHGe by more than a half, and reduce the use of fertiliser, cropland and freshwater by between 6 to 22%. Recommendations to achieve this include aligning national dietary guidelines with the current evidence on healthy eating and the environmental impacts of diets.

  • Poore J, Nemecek T. Reducing food’s environmental impacts through producers and consumers. Science 2018;360:987-92.
  • Springmann M, Clark M, Mason-D’Croz D et al. Options for keeping the food system within environmental limits. Nature 2018


- Lynne Garton

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