What would happen if everyone went vegan?

What would happen if every person on Earth adopted a vegan diet – without milk, meat, honey, or any other animal-sourced food? It’s a (very) hypothetical question, but environmental writer Paul Allen argues that it's more relevant than ever.

Cows standing in a misty field

The idea of everyone adopting a vegan diet might sound extreme, but in the last decade, the number of people in the UK following a plant-based diet has risen 340%. There are now over 0.5 million British vegans – with around 20% of 16 to 24-year-olds in the UK following a vegetarian or vegan diet.

You can see this growing interest in veganism all around us. From the explosion of dairy-free milk alternatives on supermarket shelves and the growing number of celebrity advocates like Liam Hemsworth and Natalie Portman, to movies like Cowspiracy and Simon Amstell’s futuristic vegan comedy Carnage. What was recently a radical lifestyle choice is slowly moving into the mainstream.

For scientists, policymakers and economists, the idea of a vegan future is especially interesting – and one of the biggest reasons is the environment.

Going green?

Your fridge might seem an unlikely setting for the fight against global warming, but did you know that food is responsible for over one quarter of all greenhouse gas emissions? What’s more, meat and dairy make up the vast majority of that carbon footprint.

The UN says that farmed livestock accounts for 14.5% of all manmade greenhouse gas emissions (with cow burps a surprisingly big culprit). To put that into perspective, the BBC reported that this is roughly equivalent to the exhaust emissions of every car, train, ship and aircraft on the planet.

If we all went vegan, the world’s food-related emissions would drop by 70% by 2050 according to a recent report on food and climate in the journal Proceedings of National Academy of Sciences (PNAS). The study’s authors from Oxford University put the economic value of these emissions savings at around £440 billion.

Healthy living

Being vegan doesn’t necessarily mean you’re eating healthily. You can chow down on junk food – and miss out on vital nutrients – whether you eat meat or not. For example, vegan diets are naturally low in calcium, vitamin D, iron, vitamin B12, zinc and omega-3 fatty acids. If you are following a vegan diet it is important to include protein from foods such as nuts, seeds, beans and pulses. Of particular note are lentils, chickpeas, tofu and soya versions of milk and yogurt. Other good sources include cashew, pistachios, flaxseed, chia and pumpkin seeds, buckwheat and quinoa.

At the same time, some vegan products contain a lot of coconut oil, for example, which is high in saturated fat. That said, it’s easy to get the right food balance as a vegan, but you need to be aware of what you’re eating – good advice for omnivores and herbivores alike.

We know that Western diets are linked to many health problems including heart disease, diabetes and obesity. In 2015, the World Health Organisation went so far as to categorise processed meat as “carcinogenic”, along with asbestos, alcohol and arsenic.

With fewer cases of lower coronary heart disease, strokes, type 2 diabetes and some cancers, its researchers report that a global vegan diet would also result in 8.1 million fewer deaths per year worldwide. This would have projected cost savings of “$700–1,000 billion per year on healthcare, unpaid care and lost working days”.

Make hunger history 

Would a vegan future make food poverty history? If it’s about freeing up space and resources for growing food, there’s some evidence to back that up.

A meat-eater’s diet requires 17 times more land, 14 times more water and 10 times more energy than a vegetarian’s, according to research published by The American Journal of Clinical Nutrition. This is principally because we use a large proportion of the world’s land for growing crops to feed livestock, rather than humans. (Of the world’s approximately five billion hectares of agricultural land, 68% is used for livestock.)

This squeeze on resources is only set to intensify. In 50 years’ time, the UN predicts there will be 10.5 billion people on the planet (the current world population is around 7 billion). To feed us all, it says, we will need to grow food more sustainably. Dr Walt Willett, professor of medicine at Harvard University, says we could eliminate the worst cases of world hunger today with about 40 million tonnes of food – yet 760 million tonnes is fed to animals on farms every year.

One of the counter-arguments against this vegan solution is that some grazing land simply isn’t suitable for growing crops. That’s certainly true, but there’s actually a bigger problem with eradicating world hunger. Right now, we already produce more than 1½ times the amount of food needed to feed everyone on the planet. It just doesn’t get to everyone in need.

In other words, having enough to eat is as much about politics and big business as dietary choices – so there’s nothing to say that hunger would be a thing of the past in a vegan world.

Culture shock

It should also be remembered that we've been farming and eating livestock for around 10,000 years. Our diet isn’t just the food on our plate – it shapes everything from our jobs and trade to our religious and cultural identities. Today, the global meat and dairy industries provide work for millions of people in often very poor communities around the world.                            

Where would all the animals go?

If we no longer bred farm animals, what would happen? Would they go extinct? Would they overrun the planet?

Billions of farm animals would no longer be destined for our dinner plates and if we couldn’t return them to the wild, they might be slaughtered, abandoned, or taken care of in sanctuaries. Or, more realistically, farmers might slow down breeding as demand for meat falls.

Farm animals are bred far more intensively than they reproduce in the wild – so any “cows take over the world” scenarios are a little far-fetched. As with all wildlife, any returned animal numbers would fluctuate and reach a balance, depending on predators and available resources in the wild.

It’s worth noting that not all animals could simply “go free”. Some farm breeds, such as broiler chickens, are now so far removed from their ancestors that they couldn’t survive in the wild. Others, like pigs and sheep, could feasibly return to woodlands and grazing pastures and find their own natural population levels. On top of that, even if we stopped eating animals, our destruction of wild habitats would still reduce their numbers. With nature, it’s always a question of balance.

Paul Allen is author of The Ethical Careers Guide and founder of tone of voice agency Lark

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7th Oct, 2019
There is also the fact that a lot more processed food would need to be produced…man made. Plus a lot more supplements would have to be taken to ensure health for everyone: eg, vitamin B12 which CANNOT be sourced anywhere except animal products, (in case anyone comes up with a plant based idea of B12 they have to know that it is B12 analogues (and inactive) that are in plant foods and our bodies cannot use them. They also block the body's B12 receptors stopping any active B12 from being used. Cutting out full food groups from a diet will have a knock on effect somewhere. Even the Vegan society tells vegans this. Seems to me that if a person's diet cannot give that person everything that their body needs in order to regain healthy, then the diet is faulty.
Guy's picture
22nd Sep, 2019
I just don't understand the logic or rationality in this. Go vegan because cows burp, and contribute so much to climate change? That doesn't make sense. Would you also suggest we stop wearing clothes because our synthetic clothes will poison the oceans and landfill for thousands of years? Going vegan means no animal products in your life, not just no ungulates. There are plenty of sources of good healthy nutrition from animal products that do not contribute to global warming. Pigs, rabbits, fish, duck and chicken are just a few meats that can be reared sustainably without contributing to climate change. Cattle and sheep too if they are farmed correctly. This is a good argument for stopping modern methods of factory feedlot farming of cattle but this has nothing to do with whether or not we should eat meat. In fact Traditional mixed rotational farming is good for the environment. It creates a sustainable bio-diverse ecosystem, it is good for the animals, and best of all it helps reduce carbon in the atmosphere. Farms run on these lines can be carbon neutral or even carbon negative. And this would be a major source of carbon capture since we seem to have such a problem reducing burning fossil fuels, which is the overwhelming main caise of climate change. Going vegan would create even more environmental problems not to mention health problems. There is a good reason why Humans have never gravitated towards a vegan diet and there is no vegan culture anywhere in the world.
26th Jul, 2019
"Do the best you can until you know better. Then when you know better, do better.” -Maya Angelou Now we know better (thanks to our extensive information sharing) let's do better. A world where sensory pleasure dictates what's right and what's wrong remains a pretty scary world.
Guy's picture
22nd Sep, 2019
Sensory pleasure has nothing to do with it, Benedict, It is all about nutritional needs and eating what the Land provides through geographical variance.
Lesley Beagley's picture
Lesley Beagley
11th May, 2019
So there are lots of concerns about what would happen to all the animals, the "health" of z vegan diet, the net emissions once additional farm equipment is factored in etc but the bit that caught my eye was: "8.1 million fewer deaths per year" Sounds great, but in a world that is already overpopulated, we would suddenly be increasing that population exponentially every year...and putting more and more demands on food production, land space, sources of energy etc. We are already producing more babies by artificial intervention and saving more and more lives through medical breakthroughs....controversial I realise, but perhaps we need a few "unhealthy" practices (and I dont personally consider eating meat and animal produce in *sensible* amounts to be unhealthy) to control the population a bit??
Emma LaCour's picture
Emma LaCour
24th Apr, 2019
Ok so you all are talking about how animals wouldn't be able to over-populate fast enough to "take over the world", but there are many things that vegetarians do not know. And wouldn't you be telling scientists that there theory's are wrong for a healthy diet? Because a healthy diet has 1/2 vegetables and fruit, 1/4 grain food, and 1/4 protein. So wouldn't you technically be telling scientists that there theory's are wrong?
Yvette Addy
1st Mar, 2019
Ok so human farts and excrement would not replace the methane gases in the atmosphere as though they don't add to it already 7.7 billion people in the world and counting so give me an answer what would change you would still need the fertilizer and not to mention the trackters to sew and harvest said food. None of the poorer countries would actually benefit from it with the corruption at the heads of their governments so poverty would not change at all. and animals such as pigs would become a problem if their numbers are not controlled as would most wild game animals you would have a pest problem that would eat the crops you grow so hmmmm I think if you are going to kill an animal then you should not waste the life and put the meat and hide to use. but i dont believe in making the animal suffer before it goes.
Cascade Delrivo's picture
Cascade Delrivo
19th Jan, 2019
About veganism The way i see it.we are all on this earth,we allhave different roles.1life only.we are carnivores.the cows,pigs,chickens have no life without us
27th Sep, 2018
I would miss seeing beautifully cared for sheep and cattle in the landscape. The thought of these poor animals being forced to hunt around for food, to be bereft of care when they get injured and to die a slow painful death if they get old seems crueller than the current situation. By all means campaign for better standards of care, but think things through. If all of us stopped using leather goods, what would the environmental impact be with the increased demand for plastics and man made fibres? We are carnivores, it's a fact, lets learn to deal with it sensibly.
Homer J. Simpson's picture
Homer J. Simpson
9th May, 2019
Awww. We wouldn't want nature to work exactly how it's supposed to right? We want to keep making inbred sheep and cows that are given no space to live right? Because that's what beauty is. Why would there be an increase in demand for leather? If anything it would go down- because people wouldn't like the thought of it. Yeah, instead of leather shoes, ill make plastic ones. Man-made fibers arent bad, pal.


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