A beef burger or a chocolate bar – which will do more harm to the environment? You probably think you know the answer. One comes from a bloated, methane-belching cow, a leading cause of climate change; the other is a fairly harmless – and delicious – snack. Alas, it’s not quite that simple.
Experts say chocolate is a leading cause of deforestation, due to the need to cut down tropical forests to plant cocoa. The ‘highest-impact’ chocolate might actually be worse for the environment than lower-impact beef, says Anya Doherty, CEO of Foodsteps, an environmental consultancy, and former food researcher at the University of Cambridge. "No one’s going to like me for saying that," she admits.
The issue of carbon ‘foodprints’ – how much CO2 is emitted in the production, transportation, and preparation of various foods – is front and centre at this week’s Cop26 climate summit in Glasgow. On Tuesday, it emerged that restaurants inside the conference centre are printing carbon estimates on their menus, alongside each item’s price.
So a Scottish beef burger will pump a staggering 3.9 kilograms of CO2 into the atmosphere, according to one menu, while a kale and vegetable pasta will emit just 0.3kg.
In order to reach the goals defined in the Paris Agreement in 2015, we may have to limit our foodprint to no more than 0.5kg of CO2 emissions per meal. However, the conference’s speciality dish of haggis, neeps and tatties – essentially, spiced offal with turnip and potatoes – is marked as having a carbon-emissions estimate equivalent to 3.4kg of CO2, around seven times the target foodprint required to satisfy the Paris climate accords.
The markers are causing no end of confusion among delegates. Cop26 was recently forced to backtrack after having wrongly labelled a plant-based croissant as more carbon-heavy than a bacon sandwich (the calculation was based on a normal croissant, they said).
Amid the hoo-ha, France’s eco minister Barbara Pompili even suggested it was time for her country to eat fewer croissants. "A croissant is so good but it is fat and it’s not the best carbon footprint," she explained to the BBC at the summit.
Despite the confusion, "carbon menus" are continuing to attract a great deal of interest, with calls to make them compulsory in restaurants across the UK. But sustainability experts have in fact been looking for years at how we can measure the carbon output of our food, which is responsible for about a quarter of global greenhouse gas emissions. Some of their results proved surprising.
It’s 7am. You stumble bleary eyed into your kitchen. In this age of climate anxiety, you might assume a bacon-and-sausage fry-up is off the cards. Fortunately, it’s not quite that simple. It’s certainly true that meat, in general, is responsible for more carbon than plant-based options. Meat and dairy alone are responsible for about a seventh of global greenhouse gas emissions – as much as cars, lorries and aeroplanes put together.
But that distinction masks a world of complications, says Doherty. The meat in your sausage can have a high or low carbon impact, depending mostly on what the animal was fed. Soy, a common feed, for example, is responsible for deforestation. "We don’t have a great transparency at the moment; it’s a really complicated supply chain," says Doherty. Your fry-up is also likely to involve beans, which get the thumbs up from climate experts. Along with lentils, they have among the lowest carbon impact of any food type.
Lentils and beans are the top recommendation of nutritionist Dr Alona Pulde, adviser at Lifesum and author of the ‘Forks over Knives’ veg-based diet plan, who says they "help to replete their soil, reduce the need for fertilisers, and decrease greenhouse gas emissions".
But it’s better to swap your fry-up for porridge, or another oat-based food. Oats, seeds and nuts are responsible for a low amount of carbon. Your breakfast may also involve tea or coffee. It varies, but in some parts of the world - particularly Latin America - coffee is linked to deforestation, which means more carbon in the atmosphere. So it’s good to research the origin of your coffee beans. Now it’s time to top up your beverage with milk. Dairy is among the least environmentally friendly food groups, so it’s advisable to choose a non-dairy option such as oat milk. Almond milk, on the other hand, is not as virtuous as many vegans think, because it requires an enormous amount of water to grow.
It’s afternoon, and you opt for a sandwich. But beware: bread is much more carbon-intense than many people think, according to a 2017 University of Sheffield study, largely because of the use of ammonium nitrate fertiliser used to grow wheat.
And which sandwich to pick? Something like tuna and sweetcorn is a good idea, say experts. Research has found that wild fish such as tuna, anchovies, sardines, and herring have a much lower carbon footprint than a meat like chicken. If you’re feeling flash, a mollusc-based lunch, containing oysters, scallops, or clams, would also be a solid choice.
Your eyes drift over to the prawn cocktail baguette. Be careful. In parts of Asia, fellers are cutting down swathes of mangrove forest to make space for huge prawn farms, a practice that is causing increasing concern. In contrast, prawns caught wild in the North Sea are much less harmful, at least in terms of carbon. So before eating prawns, educate yourself.
If you’re feeling healthy, you may opt for a fruit salad. The important thing is to buy locally if you can, and in season – as Lancaster University’s Prof Mike Berners-Lee explains in his book How Bad Are Bananas? The Carbon Footprint of Everything.
You might think a thick steak is off the menu for any eco-conscious eater. But once again, it’s a little more complicated. As a broad rule, chicken is less carbon-heavy than beef and lamb, partly because the stomachs of cows and sheep contain a bacteria to help them digest grass – the same bacteria that makes them emit methane through flatulence.
But it depends massively on how and where the animal is reared. Is the animal reared on deforested land, or on land that was previously unused? Is the animal fed a sustainable diet – including grasses, and crops that would otherwise go to waste – or a diet of ground-up meat and fish? For potatoes and other vegetables, the greenhouse gas impact depends on how far the vegetable had to travel to reach your plate. As with fruit, it’s a good idea to buy vegetables in-season.
After polishing off the remnants of your main course, it’s finally time for dessert. Perhaps a cheese board? But choose carefully. The highest-impact cheeses - like cheddar and mozzarella - may well have a more severe carbon impact than a lamb chop, because they require 10 pounds of milk to make one pound of cheese. Low-fat cheeses like feta are safer options.
Doherty and other experts think we need a "full accounting exercise" to work out exactly how much carbon is bound up in our food chains. "It’s about looking at the whole system," she says. "Nothing in life is black and white."