By comparing the grocery shopping of people in the US to recommended dietary guidelines, researchers found that reducing overconsumption could cut carbon emissions by a similar amount as going vegetarian
3 November 2021
Cutting snacks and pre-prepared meals from your diet may have as big an effect on your carbon footprint as going vegetarian, at least if you live in the US.
Hua Cai at Purdue University in Indiana and her colleagues analysed the grocery shopping of over 57,000 demographically representative people in the US for the entire year of 2010. The data was provided by marketing firm Nielsen, which asked participants to record every item they bought using a handheld scanner. The team chose 2010 to avoid the impact of the rise of food delivery service apps, which may skew people away from grocery shopping.
The researchers grouped the purchases into 83 food categories such as milk, sweets and ready meals. The team calculated how much carbon was required on average to produce a kilogram of each item, but did not include emissions from packaging and transporting of the product. “This is too variable to calculate effectively,” says Cai.
They then looked at how a household’s average grocery shop compared with the recommended US dietary guidelines, and found that if people in the US reduced their diets to the recommended levels it would lead to a 31 per cent cut in total CO2 emissions.
“That’s the equivalent of 45 million kilograms of carbon dioxide a year,” says Cai. “We believe that reducing overconsumption will achieve similar carbon reduction benefits as compared to big structural diet changes – like going vegetarian.” Previous research suggests going vegetarian cuts your diet’s carbon footprint by 20 to 60 per cent.
The team found in particular that sweets, ready-made meals and soft drinks had an oversized impact on their participant’s carbon footprint, because they were bought in such vast quantities.
They say that if everyone in the US cut ready-made meals by 10 per cent it would reduce yearly CO2 emissions by 1.2 million kilograms. The effect would be even larger when taking into consideration the CO2 emissions involved in packaging, says Cai.
The researchers also found that those living in a single or two-person household bought far more food than they actually needed, leading to unnecessary emissions. “Such households buy bigger quantities because it’s usually cheaper in the supermarket to do so,” says Cai. “But products like spinach and bread go off quickly and so this leads to food waste.” She says supermarkets need to be encouraged to produce food items that come in smaller and cheaper packages.
Lorraine Whitmarsh at the University of Bath, UK says this study points to the various ways in which household carbon footprints can be cut. “One of the take-homes of this study is that there are various ways of cutting our food carbon footprint including wasting less food, cutting snacks and changing diet – and these often bring wider benefits to health and our wallets,” she says.
Journal reference: Environmental Science & Technology, DOI: 10.1021/acs.est.1c02658
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