Leonello Calvetti / mikroman6 / WIRED

Environmentally-speaking, the world is not in a great place right now. The amount of carbon dioxide in the atmosphere – one of the main contributors to climate change – is continuing to rise past levels last seen millions of years ago. This, combined with other greenhouse gases, has triggered extreme weather events across the globe. Seven of the ten hottest years on record took place in the last decade.

Things are looking bad on land too. In August the International Panel on Climate Change released a report warning of the effect that agriculture and other human activity is having on soil, which is a major carbon sink alongside forests and the oceans. Deforestation, land degradation and agriculture are all having a devastating impact on land, the report argued.


So what can we do about it? Going vegan is often touted as the most impactful thing you can do to minimise your environmental impact – more than cutting down on flights or switching to a renewable energy supplier. Here’s how much swapping meat for veg really helps the planet.

We currently eat way too much meat

At last count, in 2016, there were approximately 540,000 vegans in the UK – which amounts to about 0.82 per cent of the entire population. And according to polling agency YouGov a further 14 per cent of the country consider themselves flexitarians, opting to only eat meat occasionally rather than shunning animal products altogether.

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Despite this, data from the National Diet and Nutrition Survey – a government-backed investigation into the UK’s eating habits – suggests that there’s been little change in the average total meat intake between 2008 and 2017. While the intake of red and processed meat has declined slightly – especially among young boys – on the whole UK meat consumption didn’t decline.

So what are we eating? A 2015 report by the Department of Environment, Food and Rural Affairs is the most recent guide to exactly how much meat we’re eating. On average, people in the UK eat around 929 grams of meat each week, and a further 146 grams of fish. Nearly a quarter of that weekly meat intake is made up of poultry, while beef and veal is the next most popular category – we chomp our way through an average of 102 grams of beef every week, without factoring in ready meals or heavily processed beef.


It’s worth noting that other sources tell a slightly different story. The Agricultural and Horticultural Development Board estimates that the average UK meat consumption was 79 kilograms per person in 2016 – or about 1.5kg per week. But whatever way you cut it, we’re definitely eating a lot of meat. In 2014, the global average meat consumption was just 43kg per person with some countries – such as Nigeria, Tanzania and Ethiopia – consuming closer to 10kg of meat per person per year.

We’re not lagging behind when it comes to guzzling through other animal products either. In a week, the average UK citizen chomps through about 1.8kg of milk and cream, 112g of cheese and 42g of butter.

All those animal products have a sizeable environmental footprint

The problem with eating all this meat is that animal products – and beef in particular – have an outsized impact on the planet. A study of 40,000 farms in 119 countries published in the journal Science found that although livestock provide just 18 per cent of the calories we eat globally, farming them uses 83 per cent of all farmland. Unlike plants, when you calculate livestock’s environmental impact you also have to take into account all the crops grown to feed animals. According to the UN’s Food and Agriculture Organization (FAO) an estimated 33 per cent of all croplands are used to grow livestock feed.

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So how does this tally with what’s on our plates? It’s notoriously tricky to get a precise measure on the amount of greenhouse gases released in meat production as the environmental impact shifts depending on how the animals are reared. Grass-fed beef, for example, uses 15 to 20 times as much land and produces more greenhouse gases than cattle reared in industrial feedlots.


But if we map our best estimates onto what we know about UK diets, we can start to figure out the real environmental cost of animal products. For every gram of protein, beef production releases 221.6g of carbon dioxide equivalents (CO2e) into the atmosphere. Meat production produces lots of different greenhouse gases, including methane and nitrous oxide, so using CO2e is an easy way of expressing all those greenhouses gases in terms of carbon dioxide alone.

Anyway, back to our plates. Multiply the carbon footprint of beef by the average weekly intake and you find that the average UK adult’s beef habit alone produces just under six kilograms of CO2e per week – although that’s probably on the low end of things and doesn’t include processed beef in ready meals. According to some estimates, 100 grams of beef could produce as much as 25kg of CO2e or as little as five kilograms.

Beef and lamb have by far the biggest environmental footprint of any of the major animal products. Next worst is pork, which produces 36g of CO2e per gram of protein – just 16 per cent as much as beef. Then we’ve got dairy, at 35g of CO2e, poultry at 32g and eggs at 24g. If you add up all of these, that means that the average British diet produces around 21.2kg CO2e every week in animal products alone, excluding fish. Over a year that adds up to about 1.1 tonnes of CO2e – a little more than one return London-New York flight or around 2,600 miles driven in an average petrol car.

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But it’s not just carbon dioxide

Rearing livestock doesn’t just produce a lot of greenhouse gases – it has other impacts on the environment too. Every kilogram of beef produced requires around 15,400 litres of water, according to a report from UNESCO’s Institute for Water Education. In total, almost a third of the world’s freshwater usage goes into animal products. This is mainly due to the vast quantities of crops needed to feed animals.

Beef is way out in front in terms of its water use. Lamb consumes 8,763 litres per kilogram while pigs and chickens consume 6,000 and 4,300 litres respectively. Vegetables, on the other hand, require just over 300 litres per kilogram while cereal crops require 1,600 litres. Water pollution from animal waste and fertilisers can also end up choking lakes of oxygen, poisoning fish and degrading water supplies.

Cattle ranching is also a major driver of deforestation. According to the FAO, during the 1990s 94,000 square kilometres a year of forest were destroyed mostly to crow crops and for grazing livestock. Many of the fires that have devastated the Amazon rainforest this year were set by ranchers attempting to clear the forest for cattle grazing.

How do animal products compare to other foods?

Even if you end up opting to cut animal products out of your diet altogether, you’ll have to replace those missing calories with something. Pulses – which includes beans lentils and peas – produce just 0.58g of CO2e per gram of protein. That’s just 0.26 per cent of the greenhouse gas output of beef. One hundred grams of tofu protein produce between one and four kilograms of CO2e.

And, of course, it’s all a sliding scale. Chicken has a slightly higher greenhouse gas footprint than pork, which has a lower impact than lamb, which is less damaging than beef. If you can’t face cutting out animal products altogether, then switching from higher-impact foods to more sustainable ones can still have a significant impact. The moral glow might not be quite as bright, but at least you’re still doing your bit to cut down your personal environmental footprint.

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