We’ve all heard the animal welfare arguments for going vegetarian, but in recent years there has also been a lot of talk about the environmental benefits.

So what would happen if the whole world suddenly decided to give up meat? How much difference would it really make? And would it all be positive?

Energy intensive

One of the most frequently mentioned environmental costs of eating meat is the CO2 involved in producing it. Compared to fruit and vegetables, the amount of CO2 released by the production of meat is remarkably high.

According to Scientific American, producing half a pound (226g) of potatoes emits the same as driving a small car 0.17 miles (0.2km). Half a pound of beef emits as much as driving the same car 9.8 miles (12.7 km).

Image: Scientific American

A global switch to diets that rely less on meat and more on fruit and vegetables could reduce greenhouse gas emissions by two thirds, according to research from the Oxford Martin School at Oxford University.

The study estimated both the health and climate change impacts of moving towards more plant-based diets for all major regions of the world.

Healthier planet, healthier population

Researchers looked into the environmental and healthcare benefits that would be felt by 2050 in three scenarios.

The first looked at the world’s population following global guidelines on healthy eating (HGD), the second at the world becoming vegetarian (VGT) and the third, vegan (VGN).

Image: Oxford Martin School, University of Oxford

They found significant environmental benefits in the form of lower CO2 emissions as well as significant healthcare benefits in terms of lower premature deaths and lower healthcare costs.

The large variables indicated on the chart stem from the unknown cost of carbon emissions and healthcare in 2050.

“What we eat greatly influences our personal health and the global environment,” says Dr Marco Springmann of the Oxford Martin Programme on the Future of Food, who led the study.

Water use

The amount of water needed to produce meat is another major environmental cost. On this chart only butter (another animal product) and nuts can match the thirst of animals raised for meat.

What about the people?

So is it all good news? Are there any losers in this scenario?

“There are over 3.5 billion domestic ruminants on earth, and tens of billions of chickens produced and killed each year for food,” Ben Phalan, who researches the balance between food demand and biodiversity at the University of Cambridge, told the BBC. “We’d be talking about a huge amount of economic disruption.”

While retraining and government subsidies could help many former livestock-related employees, significant unemployment and social upheaval would be inevitable, especially in rural communities.

And parts of the world which currently support livestock would be able to support crops instead.

“Without livestock, life in certain environments would likely become impossible for some people,” Ben Phalan says. That especially includes nomadic groups such as the Mongols and Berbers who, stripped of their livestock, would have to settle permanently in cities or towns – likely losing their cultural identity in the process.”

It is likely that the world’s poor would lose most from no longer having nutrient-dense meat in their diet. Animal products contain more nutrients per calorie than plants such as grains and rice. “Going vegetarian globally could create a health crisis in the developing world, because where would the micronutrients come from?” Tim Benton, a food security expert at the University of Leeds, told the BBC.

There would also be a huge impact on almost all cultures worldwide which centre important traditions round the consumption of meat.

Is there an environmental cost?

Some experts have also highlighted that ending meat consumption would not be all good news for the planet, either.

The BBC reports that in the past, when parts of the Sahel, an area south of the Sahara in Africa, have been converted from livestock pasture to croplands, the result was desertification.

In addition, areas which currently rely on grazing livestock to keep natural reforestation at bay could become less biodiverse and even more dangerous. And if those currently making a living farming animals in rural areas can no longer do so, the inevitable growth of urban areas would also have a negative impact.

The reality

Of course, the world is not about to give up meat. In fact, with the growth of the middle class in countries like India and China, more meat is being consumed than ever before.

There is, though, clearly much to be learned from imagining a meat-free world which could help tackle aspects of man-made climate change.

The key, as parents around the world have been telling their children for millennia, is moderation.