Sustainable food choices

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Excluding meat from our diet is not enough on its own to benefit the climate. Eating a lot of cheese or simply eating a lot of everything also leads to high greenhouse gas emissions.

As part of the “Zero Carbon Britain” project the Centre for Alternative Technology (CAT) has compared 13 diets for their effects on health, greenhouse gas emissions and land use. They experimented with different degrees of excluding meat and dairy products, and examined what happens if we eat more than we need, including more junk food. In addition to examining the current average diet of the whole population they also looked at the poorest tenth. They also investigated the importance of reducing food waste, choosing locally grown produce and reducing energy consumption for cooking and storage in relation to changes in diet.

Being vegetarian is often cited as a positive thing when it comes to reducing greenhouse gas emissions. The reason behind this is the high emissions related to meat production, in particular meat from ruminants. This theory was shown to be correct in the sense that all diets in the study that excluded meat resulted in lower emissions than the current average diet. But a vegetarian diet high in dairy products, especially cheese, can actually have a higher carbon footprint than some more health- and climate-conscious meat diets. In the end it turns out that a balanced vegan diet (excluding meat and dairy products) is the most climate-friendly option of all. 

Of special interest for everyone who feels that excluding all meat and dairy is a bit too radical, is the so-called carbon minimiser diet. This involves reducing the consumption of animal products, but not excluding them completely. Instead low-emission alternatives are chosen: yogurt and milk instead of cheese, chicken and pork instead of red meat. In this way, omnivores¹  can also contribute to significant reductions in greenhouse gas emissions.

CAT also investigated a so-called junk food vegan diet, in which a large proportion of all calories comes from foods with a high fat and sugar content. It turns out that this leads to slightly higher greenhouse gas emissions than the more healthy vegan diet, but still lower than all the other diets examined. It thus undermines the belief that there is an absolute correlation between eating healthy and eating climate friendly. However when the current average diet is compared to a diet designed in accordance with nutritional recommendations, the latter is also preferable from a climate perspective. Eating too much is also inadvisable – not only from a health perspective. When the intake of food increases, emissions increase subsequently. Overeating is common. If Brits started to eat according to national dietary recommendations (in terms of calories) emissions would go down by 15 per cent.

The report also examines the impact of different diets on land use. In this case there is a much clearer connection with meat consumption. Diets that entail high meat consumption use more land than diets with low or zero meat consumption. Supplying the entire British population with food today requires 230,000 square kilometres of land globally. In comparison the total agricultural land area in the UK is just 180,000 square kilometres. The area needed could be reduced to less than 100,000 square kilometres with diets that are low in meat or exclude it entirely. 

But just looking at the total area of land use is oversimplifying the issue. All land cannot be used for the same purposes. It is worth noting that more than half of the land used in the UK for current food production is grassland. This may be land that is unsuitable for growing food crops. A more likely alternative land use would be growing biofuels.  

When discussing the environmental impact of food production, reduced waste is often put forward as an attractive measure since it has the potential to save money for both producers and consumers. A halving of food waste at all stages was shown to reduce emissions by 13–25 per cent, and land use by about 16 per cent, which makes it an important but less significant measure than shifting diet. 

Another often-mentioned measure to reduce environmental impact is to buy locally produced food.  The 13 original diets that were examined included both local and imported food. The authors of the study chose to compare two extremes, one where as much as possible is shifted to UK produce and another where all food products are imported from outside of Europe. When this is done with the current average diet, greenhouse gas emissions increase by 23 per cent under the all-imported scenario, while eating as much domestic produce as possible would reduce emissions by nine per cent. It is worth noting that with the current average diet it is not possible for everyone to make this shift – there is simply not enough land. 

The report also discusses the potential for other food-related behavioural change, such as reducing energy use during cooking and storage, walking or cycling instead of taking the car to the grocery store, or reducing packaging. However the potential is considered marginal compared to the other measures examined, although there might be other benefits for health and the environment. 

Kajsa Lindqvist

People, Plate and Planet – The impact of dietary choices on health, greenhouse gas emissions and land use. Report by The Centre for Alternative Technology.

¹ An omnivore is someone who eats food of both animal and plant origin

Table: The impact of dietary choices and behaviours on greenhouse gas emissions and land use.