Exactly how much impact does the food we eat have on environmental outcomes and what difference would following a vegan diet make compared to consuming a high meat, or even low meat diet? We linked dietary reports to a dataset containing information on the environmental impact of 57,000 foods.
Crucially, the dataset factored in how and where a food is produced – carrots grown in a greenhouse in Spain will have a different impact from those grown in a field in the UK, for instance.
This builds on past studies, which tend to assume for example that all types of bread or all steak or all lasagna has the same environmental impact.
By incorporating more detail and nuance, we were able to show with more certainty that different diets have different environmental impacts.
We found that even the least sustainable vegan diet was still more environmentally-friendly than the most sustainable meat eater’s diet.
In other words, accounting for region of origin and methods of food production does not obscure the differences in the environmental impacts between diet groups.
Unsurprisingly, diets containing more animal-based foods had higher environmental impacts.
Per unit of food consumed, meat and dairy has anywhere from three to 100 times the environmental impact of plant-based foods.
Vegans in our study had just 25% of the dietary impact of high meat-eaters in terms of greenhouse gas emissions, for instance.
That’s because meat uses more land, which means more deforestation and less carbon stored in trees.
Compared to the high meat-eaters, vegans also had just 25% of the dietary impact for land use, 46% for water use, 27% for water pollution and 34% for biodiversity.
Even low meat diets had only about 70% of the impact across most environmental measures of high meat diets.
In the UK, meat eating declined over the decade to 2018, but in order to meet environmental targets the National Food Strategy and the UK’s Climate Change Committee recommend an additional 30%-35% reduction.
Our study and others are continuing to solidify evidence that the food system is having a massive global environmental and health impact which could be reduced by a transition towards more plant-based diets.