Researchers trained an algorithm to estimate the environmental impact of 57,000 products sold in the UK and Ireland to help consumers make eco-friendly choices
8 August 2022
Avoid the supermarket aisles piled with cheese, quiches and pies. That’s the message of an analysis that found they fare worst for nutritional quality and environmental impacts among thousands of food and drink products sold in the UK. And if your priority is curbing carbon emissions and water use, avoid the meat and fish shelves too.
So far, most studies assessing the environmental footprint of food have focused on the impact of agricultural commodities such as beef or soya, rather than the lasagnes, tofu and other products that shoppers often buy. Where research has focused on consumer products, it has usually been for a small number of them.
In a bid to bridge the gap, Michael Clark at the University of Oxford and his colleagues analysed more than 57,000 food and drink products sold in the UK and Ireland. The team took the ingredients data from eight retailers, including major supermarkets Tesco and Sainsbury’s.
However, precise figures on how much of each ingredient is in each product were only available for around a tenth of them. To estimate the rest, Clark and his colleagues trained an algorithm on the known products and used it to predict the composition of the unknown ones, helped by the fact that UK regulations mean ingredients must be listed in descending order of quantity. Finally, the team linked all the ingredients to an existing database of environmental impacts, including emissions, land use and water stress.
The results may come as no surprise: meat, fish and cheese products had the highest environmental impact. Desserts, pastries and savoury pies came next. Fruit, vegetables, bread and sugary beverages had the lowest burden. For the most part, there was an overlap between low environmental impact and good nutrition, a further analysis showed.
Clark concedes that none of this is mind-blowing, given what we already knew from past research. “The major advance is not that beef has high impacts, fish has high impacts, cheese has high impacts. It’s the fact that you can start getting these impact estimates for products that people are purchasing, which then has a lot of knock-on implications,” he says.
One of those is eco labels, which a growing body of evidence shows can steer consumers to make greener choices. However, retailers have struggled in the past with the scale of the challenge. In 2012, Tesco stopped trying to add carbon labels to all its products because it would take centuries to assess them all at the rate it was managing.
Clark’s approach points the way to doing such labelling at scale. He is thinking about how to eventually turn the data into an app that could be used either by shoppers or by retailers wanting to reduce their environmental impact. “We’ve made that information available in a way that means people can start making informed decisions,” he adds.
The main limitation of the new research is that it doesn’t account for different sources of the same ingredients, such as beef produced in the UK or imported. For example, according to the UK Climate Change Committee, UK beef emissions are 14 per cent lower than the European Union average.
“The paper provides a lot of value by making the environmental impacts of foods more tangible and applicable for consumers,” says Hannah Ritchie at Our World in Data. “Previous studies mostly focus on the impacts of broad food categories – such as maize, wheat or legumes.” She thinks the study is a step towards eco labels in supermarkets.
Journal reference: PNAS, DOI: 10.1073/pnas.2120584119
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