Can eating less meat really tackle climate change?

by Mike Berners-Lee

Visiting Researcher, Lancaster Environment Centre, Lancaster University

With the food system accounting for up to a third of global greenhouse gas emissions, anything that reduces its impact will make a big difference to the climate.

It is a system riddled with inefficiencies and waste. Humans don’t simply eat food straight out of the ground, of course. It’s harvested, stored, processed – or fed to animals who are in turn slaughtered and processed – and finally packaged and delivered. Each of these stages uses energy, which means emissions.

In very rough terms, the world grows about 6,000 calories per person a day in edible crop harvest. That is about three times the 2,000 calories a day that end up getting to be eaten by humans. This would be enough to feed everyone if we shared it round perfectly, which we don’t, so some people go hungry while others eat more than is good for them.

So what happens to the massive 4,000 calories per day gap between field and fork and what has this got to do with going vegetarian or even vegan?

Here, again in rough numbers, is how the missing calories can be accounted for:

About 900 are agricultural waste, much of which is simply left in the ground. Supply exceeds demand or the crop is deemed not able meet customer standards.

About 500 go to biofuels. This is not necessarily a bad thing, but it is something we need to keep a very close eye on if we are ever to achieve a low-carbon world. If free market forces were allowed to do their thing we could see a huge shift from food crops to more profitable fuels, at the expense of nutrition in poorer countries.

Around 600 calories are then lost in post-harvest waste. This is mainly an issue in developing countries and is inherently solvable, at face value, through the provision of such things as sealed containers to keep food dry.

Where do the calories go? A simple map of the food system. Adapted from 'The Burning Question'p163, Mike Berners-Lee & Duncan Clark (2013), Author provided

So far in the story from field to plate there is still a plentiful 4,000 calories per day left for feeding people. Around 1,700 of these are fed to animals. The animal diet is further supplemented with a substantial amount of grass, some but not all of which is grown on land that could alternatively be used to grow yet more human food.

Animals – some more than others – add an intrinsic inefficiency into the food chain, using up energy for such things as walking around and keeping warm (per kilo of meat, poultry do a lot less of less of this through their lives than cows, making chicken a significantly more efficient energy source than beef). A mere 500 calories per person per day come back out of the animal food system as meat and dairy foods. So the inefficiency of our meat and dairy diet leads to a loss of 1,200 calories per person per day, excluding any grassland that could be used for edible plant crops. And meat consumption is rising fast in developing countries.

To finish off the story, around 800 calories are lost to processing, distribution and household waste, of which the biggest element is household waste in developed countries – the homes of most of the people reading this are included here. Inadequate sharing of the remaining 2,000 that humans actually eat means that some people end up obese while others are hungry.

Seen in this way, the world food system looks to be brimming with opportunities for improvement. If we can get organised – which of course is not at all easy – we ought to be able to use new technologies and deploy best practices to increase yields, as well as cutting out most of the 2,300 calories that are wasted. Even with a rising population – and even with climate change adversely affecting land fertility in some areas – we ought to be able to feed everyone while improving biodiversity and increasing the biofuel output somewhat.

A carbon footprint hierarchy of meats at UK check-outs: deforestation costs Brazilian beef, all cows and sheep ruminate, whereas chickens make relatively efficient food converters. 'The Burning Question', Mike Berners-Lee & Duncan Clark (2013), Author provided

Our animal intake puts a huge and growing pressure on the food and land system. If the world went vegan overnight we might be able to feed several billion more people and double biofuel production, even without tackling waste or improving yields.

We need to be asking how plants can become more aspirational foods than cows. But if we are still going to eat meat, stick to chicken which has only about one-tenth of the carbon footprint per kilo of Brazilian beef. This is partly because a chicken is a more energy-efficient meat producer, partly because chickens don’t ruminate, or chew the cud (which emits methane, roughly doubling the footprint of a cow) and partly because chicken farms are less strongly associated with deforestation.

Our studies of the footprint of UK dietary choice have shown that going vegetarian might cut the greenhouse gas footprint by 25%. However the same reduction can also be made through modest actions split across what for most UK people are the three most important things you can do to cut your food carbon: reduce meat, switch type of meat and, of course, cut waste.

This article was originally published on The Conversation. Read the original article.

Mike Berners-Lee is an expert in greenhouse gas footprinting and organisation development. He is also the co-author of The Burning Question and author of How Bad Are Bananas? The carbon footprint of everything.

He is Director and Principal Consultant at Small World Consulting developing research and understanding around climate change and enabling businesses, public organisations, communities and individuals to manage their impact on the environment.

Browse articles by author

More Essays

Added 12.06.2018
Extract: “Nothing is beautiful except what is true,” Cézanne once said, “and only true things should be loved.” As the philosopher Jacques Derrida put it: “The truth in painting is signed Cézanne.” Perhaps it is this above all else that makes him the indispensible painter for our times, this era of so-called ‘post-truth.’ For Cézanne “painting was truth telling or it was nothing.” That is what it meant to paint from nature, to be primitive, to be free from all affectation, to be like those “first men who engraved their dreams of the hunt on the vaults of caves…” This is why we need to look and look again at Cézanne. And it is perhaps best that he has come to the National Gallery, to D.C., but a stone’s throw away from where truth is daily made a mockery of, and lies are proffered with breathtaking ease.
Added 06.06.2018
Extracts from the article: "Johnson and Johnson recently announced that it was halting a clinical trial for a new Alzheimer’s drug after safety issues emerged. This latest failure adds to the dozens of large, costly clinical trials that have shown no effect in treating this devastating disease. The growing list of failures should give us pause for thought – have we got the causes of Alzheimer’s all wrong?".............."Another option is to look at the risk factors for developing Alzheimer’s. One of these is type 2 diabetes." ............"Testing these [diabetes] drugs in animal models of another neurodegenerative disorder, Parkinson’s disease, also showed impressive effects, ............These new theories bring a fresh view on how these diseases develop and increase the likelihood of developing a drug treatment that makes a difference. To see any protective effect in the brain in a clinical trial is completely new, and it supports the new theory that Alzheimer’s and Parkinson’s disease are caused, at least in part, by a lack of growth factor activity in the brain. These new theories bring a fresh view on how these diseases develop and increase the likelihood of developing a drug treatment that makes a difference."
Added 01.06.2018
Extract from the article: "The most common defense of truth is the pragmatic one – namely, that truth works; that true beliefs are more likely to get the job done than those that are not true. The pragmatic account of the value of truth is not wrong, but at the same time it is not enough. Truth is not valuable for solely instrumental or extrinsic reasons. Truth has intrinsic value as well. When we reduce the value of truth to instrumentality, it is a very short step to saying that we just want beliefs that work for us, regardless of whether they are true or not."
Added 14.05.2018
During the first century of modern art, Paris was a magnet for ambitious artists from all over Europe. Remarkably, the current exhibition at Paris’ Petit Palais tells us that “Between 1789 and 1914, over a thousand Dutch artists traveled to France.” Prominent among these were Ary Scheffer, Johan Jongkind, Jacob Maris, Kees van Dongen. But of course most prominent were Vincent van Gogh and Piet Mondrian.
Added 10.05.2018
The Jewish Museum in New York City is currently presenting the work of Chaim Soutine (1893-1943), featuring just over thirty paintings by one of the most distinctive and significant artists of the early twentieth century. Focusing on still life paintings, of which he was a master, "Chaim Soutine: Flesh" includes his vigorous depictions of various slaughtered animals - of beef carcasses, hanging fowl, and game. These are dynamic works of great boldness and intensity, and taken together they constitute a sustained and profoundly sensuous interrogation of the flesh, of carnality - of blood, skin and sinew.
Added 08.05.2018
The impact of air pollution on human health is well-documented. We know that exposure to high levels of air pollutants raises the risk of respiratory infections, heart disease, stroke, lung cancer as well as dementia and Alzheimer’s disease. But there is growing evidence to suggest that air pollution does not just affect our health – it affects our behaviour too.
Added 05.05.2018

The May bank holiday is intimately linked to labour history and to struggles over time spent at work. In the US, May Day has its origins in the fight for an eight-hour work day at the end of the 19th century.

Added 01.05.2018
Quote from the article: "Who is talking about how globalized the world was between 1880 and 1914 -- until war broke out and fascists subsequently determined the course of history -- and the parallels between then and now? Globalization always had a down side, and was never meant to last forever -- but the gurus chose not to talk about it. It is always just a question of time until economic nationalism reappears, but the gurus have done a poor job of addressing the nexus between economics and politics, and its impact on business, which is the real story."
Added 29.04.2018
"......if we did manage to stop the kind of ageing caused by senescent cells using telomerase activation, we could start devoting all our efforts into tackling these additional ageing processes. There’s every reason to be optimistic that we may soon live much longer, healthier lives than we do today."
Added 29.04.2018
Many countries have introduced a sugar tax in order to improve the health of their citizens. As a result, food and drink companies are changing their products to include low and zero-calorie sweeteners instead of sugar. However, there is growing evidence that sweeteners may have health consequences of their own. New research from the US, presented at the annual Experimental Biology conference in San Diego, found a link with consuming artificial sweeteners and changes in blood markers linked with an increased risk of obesity and type 2 diabetes in rats. Does this mean we need to ditch sweeteners as well as sugar?
Added 25.04.2018
Female doctors show more empathy than male doctors. They ask their patients more questions, including questions about emotions and feelings, and they spend more time talking to patients than their male colleagues do. Some have suggested that this might make women better doctors. It may also take a terrible toll on their mental health.
Added 25.04.2018
The English-born Thomas Cole (1801-1848) is arguably America's first great landscape painter - the founder of the Hudson River School, the painter who brought a romantic sensibility to the American landscape, and sought to preserve the rapidly disappearing scenery with panoramas that invoke the divinity in nature. The Metropolitan Museum of Art's "Thomas Cole: Atlantic Crossings" is an astounding exhibition featuring a painter of extraordinary power and vision, underscoring his environmentalism and the deep sense of loss that pervades many works as he reflects on deforestation, the intrusion of the railroad, and the vanishing beauty of the untrammeled wilderness.
Added 23.04.2018
Quantitative evidence from three independent sources — auction prices, textbook illustrations, and counts of paintings included in retrospective exhibitions — all pointed to the fact that some important modern artists made their greatest work late in their careers — Cézanne, for example, in his 60s, and Kandinsky and Rothko in their 50s. But the same evidence indicated that other important artists produced their greatest work very early — Picasso, Johns, and Stella, for example, all in their 20s. Why was this was the case: why did great artists do their best work at such different stages of their careers? I couldn’t answer this question until I understood what makes an artist’s work his or her best.
Added 19.04.2018

People of all ages are at risk from diseases brought on by loneliness, new data has revealed.

Added 09.04.2018

I was a senior university student in Baghdad, Iraq. It was March 2003, and over the past few months, my classmates had whispered to each other about the possibility of a US-led invasion and the likelihood that 35 years of dictatorship and tyranny could be brought to an end.

Added 26.03.2018
In 1815, 69-year old Francisco de Goya painted a small self-portrait. Today it hangs in Madrid’s majestic Prado Museum. Next to it are the two enormous paintings of the uprising of May, 1808, in which Madrid’s citizens had been slaughtered by Napoleon’s troops, that Goya had painted in 1814 for King Ferdinand VII, to be hung in Madrid’s Royal Palace. One of these, of the execution of Spanish civilians by a French firing squad, is now among the most famous images in the history of Western art.
Added 15.03.2018

Soon after I enrolled as a graduate student at Cambridge University in 1964, I encountered a fellow student, two years ahead of me in his studies, who was unsteady on his feet and spoke with great difficulty. This was Stephen Hawking.

Added 03.03.2018

A lack of essential nutrients is known to contribute to the onset of poor mental health in people suffering from anxiety and depression, bipolar disorder, schizophrenia and

Added 27.02.2018

Mindfulness is big business, worth in excess of US$1.0 billion in the US alone and linked – somewhat paradoxically – to an expanding range of must have products.