Today’s livestock industry is resource-intensive and detrimental to the environment; it causes considerable damage to ecosystems, biodiversity and ecological resilience [1,2].
In 1990, global meat production amounted to 229 million tonnes. This number is expected to rise to 465 million tonnes by 2050 . In developed countries, animal products are believed to be an essential part of a balanced diet. In developing countries, these products are considered a luxury although growing in demand . Meat production has tripled in the past 40 years. It now grows faster than the world population and world meat consumption . The growth of the middle class in some regions will be accompanied by a consumption increase in animal products .
As there is such a large demand for meat, the current system dictates that more crops need to be grown for meat production. Horrigan et al. (2009) assert that “Human and food insecurity are currently problems not of resource scarcity but of insufficient political will or moral imperative to change the way food is allocated.” [2, p 453]. There are more than 820 million people in the world who do not eat enough yet a third of global crops are fed to animals [6,7].
Forty-three percent of the planet’s ice- and desert-free land is dedicated to agriculture. The land used for livestock represents 70 to 75% of agricultural land with the majority used to grow feed and the rest as grazing land [2,5]. Of world production of barley, rye, millet, oats and maize, 57% is fed to animals . One kilo of beef requires 7kg of grain . How is this efficient when 7kg of grain would feed many more people than 1kg of beef does? A parallel observation is made when looking at different water footprints: 1kg of vegetables requires 322 litres of water while 1kg of beef needs 15,415 litres . 92% of all freshwater is used for agriculture, of which almost one-third is used for livestock production .
Despite the substantial resources allocated to meat production, the resulting nutritive value is minimal. Meat and dairy provide humans with only 37% of their protein requirements and 18% of their calories . Taking population growth and resource scarcity into consideration, this system is unsustainable.
Animal agriculture has a considerable impact on the environment. Its greenhouse gas emissions are estimated at 18% of global GHG emissions. This is due to low feed-conversion efficiencies, ruminant emissions, transportation of feed crops across long distances to reach animals, manure being shipped for spreading on fields, processing the meat and getting it onto the consumer’s plate [8,11]. Agriculture alone is responsible for more than 80% of worldwide deforestation . Livestock production’s portion of that is 81% with 67% caused by growing feed .
Animal-based produce makes no environmental sense as it degrades the environment, no social sense as it cannot feed everyone. From an economic point of view, if an ‘efficient’ allocation of resources is one that allocates resources among different products according to individual preferences and available budget  then the livestock industry seems to only benefit a minority and thereby does not maximise social welfare. The obsession with cost-minimisation and profit-maximisation has led to the concentration of global agricultural activity to few factory farms. Farms are now very large in size and production capacity but small in number .
As there are more resource-efficient diets , why is meat still being produced? The answer lies with an ever-increasing demand for meat. If we apply a sustainable scale to the growing demand for meat, this system simply cannot be perpetuated. This relates to the contradiction inherent in our economic system’s addiction to the notion of unlimited growth on a planet with finite resources. We are overproducing and overconsuming in a finite global ecosystem .
A shift away from emissions-intensive livestock products is a viable solution. Instead of indirectly feeding crops to humans, the agricultural system needs to better allocate resources toward direct human nutrition. In this way, more people are fed and environmental degradation caused by livestock agriculture is reduced. An apparent solution is a move towards more plant-based diets . Global adoption of plant-based diets would reduce resource land use by 76% and would almost halve (49%) yearly food-related GHG emissions . This consumption change is also proven to have positive impacts on human health. Plant-based diets present lower rates of chronic diseases such as cardiovascular disease, cancer and diabetes than meat-based diets . This dietary change would reduce the pressure on the environment, improve human health and feed more people; that is, if food is subsequently distributed fairly. Shifting towards plant-based diets calls for changes in many areas such as education, governmental action and in agricultural practices.
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 Horrigan, L., Lawrence, R.S., Walker, P. 2002. How Sustainable Agriculture Can Address the Environmental and Human Health Harms of Industrial Agriculture. Environmental Health Perspectives. 110(5) pp. 445-456.
 Steinfeld, H., Gerber P., Wassenaar, T., Castel, V., Rosales, M. & Haan, C. 2006. Livestock's Long Shadow: Environmental Issues and Options. Food and Agriculture Organization of the United Nations.
 Springman et al. 2018. Options for keeping the food system within environmental limits. Nature. 562 pp. 519-525
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 World Food Program. 2018. Zero Hunger. Available at: http://www1.wfp.org/zero-hunger [Accessed 9 November 2018]
 Van der Zee, B. 2018. What is the true cost of eating meat? The Guardian
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 Heinrich Böll Foundation. 2014. Meat atlas: facts and figures about the animals we eat. Heinrich Böll Foundation.
 Gerbens-Leenes, P.W., Mekonnen, M.M. and Hoekstra, A.Y. 2013. The water footprint of poultry, pork and beef: A comparative study in different countries and production systems. Water Resources and Industry. 1, pp.25-36.
 Monbiot, G. 2018. The best way to save the planet? Drop meat and dairy. The Guardian. Available at: https://www.theguardian.com/commentisfree/2018/jun/08/save-planet-meat-dairy-livestock-food-free-range-steak [Accessed 5 November 2018]
 Thornton, P.K. 2010. Livestock production: recent trends, future prospects. Philosophical Transactions of the Royal Society B. 365. pp.2853-2867.
 Wageningen University and Research Centre. 2012. Agriculture is the direct driver for worldwide deforestation. Science Daily. Available at: www.sciencedaily.com/releases/2012/09/120925091608.htm [Accessed 12 November 2018]
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 Poore, J. 2018. We label fridges to show their environmental impact-why not food? The Guardian. Available at: https://www.theguardian.com/environment/2018/oct/10/we-label-fridges-to-show-their-environmental-impact-why-not-food [Accessed: 8th November 2018]