Vegan Rising | The Environmental Destruction of Eating Animals
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The Environmental Destruction of Eating Animals

The Environmental Destruction of Eating Animals


Producing animal-based food products affects the environment in dramatic ways.

The impacts arise from many inter-related factors, such as the inherent inefficiency of animals as a food source; the massive scale of the farmed animal sector; land clearing far beyond what would otherwise be required; greenhouse gases such as carbon dioxide, methane and nitrous oxide; and other global warming agents such as tropospheric ozone and black carbon.


The adverse climate change impact of farmed animal production is generally understated in official figures, because relevant data is either omitted, classified under non-livestock headings, or included on the basis of conservative calculations.

Allowing for the relevant factors, the 2014 Land Use, Agriculture and Forestry discussion paper prepared by Australian climate change advocacy group, Beyond Zero Emissions in conjunction with Melbourne Sustainable Society Institute (University of Melbourne), indicated that animal agriculture was responsible for around 50 per cent of Australia’s greenhouse gas emissions. [1] That compares to the official figure of around 10 per cent. The findings were reinforced in a subsequent peer-reviewed journal article, which had two co-authors in common with the BZE paper. [2] [Footnote 1]

The researchers used a 20-year time horizon for determining the “global warming potential” (GWP) of the various greenhouse gases. The 20-year time horizon is critical in terms of potential climate change tipping points, with potentially catastrophic and irreversible consequences. [See Footnote 2.]

Using that approach, methane from farmed animal production in Australia generates more global warming than all our coal-fired power stations combined. [3] That’s in a country with amongst the highest per capita emissions in the world due to our heavy reliance on coal.

Figures 1(a) and (b) provide examples of greenhouse gas emissions intensity figures for individual products, based on findings of the UN Food and Agriculture Organization, adapted to include 20-year GWP figures: [4, 5, 6, 7]

Figure 1(a): Emissions intensity (kg CO2-e/kg protein) for beef, sheep meat and cow’s milk

Figure 1(b): Emissions intensity (kg CO2-e/kg protein) for other products

The figures for beef are conservative, as they include the dairy herd, for which a large portion of emissions are attributed to dairy products, rather than beef.

The figures vary significantly by location and production system, but the emissions intensity of animal-based foods is invariably a multiple of the plant-based alternative.


Although methane from ruminant animals is a critical problem, so are farmed animal-related carbon dioxide (CO2) emissions, resulting from the clearing of forest and other vegetation. The clearing causes the carbon that had been locked within the vegetation to be released as CO2. The problem is compounded by the fact that, once the vegetation has been removed, we no longer have the benefit of its ability to absorb carbon from the atmosphere.

In Australia, nearly a third of our non-arid and semi-arid land has been cleared for farmed animal production. [8] A large portion of the remainder has been severely degraded by grazing, with significant loss of soil carbon.

According to the World Resources Institute, overgrazing is the largest single cause of land degradation globally. [9]

Figure 2 demonstrates the extent of farmed animal grazing across Australia, the planet’s sixth largest country by land area. [10]

Figure 2: Australian Land Use 2010-11

Nitrous oxide (N2O) is also emitted in great quantities from animal manure and fertiliser used on animal feedcrops, along with farmed animal-related savanna burning. It is nearly 300 times as potent as CO2 as a greenhouse gas.

Two short-lived climate pollutants generally omitted from official figures, and prominent in animal agriculture, are tropospheric ozone and black carbon. Although they remain in the atmosphere for a short period, they have a significant impact.


Chickens and pigs are not ruminant animals belching significant amounts of methane (although methane and nitrous oxide are emitted from their excrement). However, we are sitting on a climate change precipice with no buffer for avoiding disaster, while continuing to destroy the Amazon rainforest (currently a carbon sink but rapidly becoming a carbon source) and occupy previously cleared land in order to grow soy beans (and graze cattle). 

Although soybean meal for farmed animal feed was once considered a by-product of soybean oil production, it is the requirement for farmed animal feed that now drives the international soybean trade. [11] The product is fed to billions of chickens, pigs and dairy cattle in a grossly and inherently inefficient and unsustainable process. Other forms of farmed animal feed contribute to the same problem elsewhere.

As a result, land clearing for egg, dairy, chicken meat and pig meat production is contributing to us passing critical climate change tipping points or thresholds with the potential to lead to runaway climate change. Such potential is not fully accounted for in the products’ emissions intensity figures, which (as demonstrated in Figure 1) are already multiples of those from non-animal products.


Like chickens and pigs, fish and other sea creatures do not belch methane, and they do not require us to destroy massive areas of rainforest for grazing (although they are fed soy meal in fish farms, with critical problems as referred to in the previous section).

The oceans cover 71 per cent of our planet’s surface. [12] They are home to complex ecosystems that are being disturbed by industrial and non-industrial (including recreational) fishing in ways that may profoundly affect our climate system.

A 2015 paper in Nature Climate Change has helped to highlight some of impact. [13] The problem arises largely from the fact that fishing disturbs food webs, changing the way ecosystems function, and altering the ecological balance of the oceans in dangerous ways. The paper focused on the phenomenon of “trophic downgrading”, the disproportionate loss of species high in the food chain, and its impact on vegetated coastal habitats consisting of seagrass meadows, mangroves and salt marshes.

The loss of predators such as large carnivorous fish, sharks, crabs, lobsters, seals and sea lions, and the corresponding population increase of herbivores and bioturbators (creatures who disturb ocean sediment, including certain crabs) causes loss of carbon from the vegetation and sediment.

Those habitats are estimated to store up to 25 billion tonnes of carbon, making them the most carbon-rich ecosystems in the world. They sequester carbon 40 times faster than tropical rainforests and contribute 50 per cent of the total carbon buried in ocean sediment.

Estimates of the areas affected are unavailable, but if only 1 per cent of vegetated coastal habitats were affected to a depth of 1 metre in a year, around 460 million tonnes of CO2 could be released. That is around the level of emissions from all motor vehicles in Britain, France and Spain combined, or a little under Australia’s current annual emissions. [14, 15]

Loss of ongoing carbon sequestration is the other problem. If sequestration capability was reduced by 20 per cent in only 10 per cent of vegetated coastal habitats, it would equate to a loss of forested area the size of Belgium.

These impacts only relate to vegetated coastal habitats, and do not allow for loss of predators on kelp forests, coral reefs or open oceans, or the direct impact on habitat of destructive fishing techniques such as trawling.


In terms of coral loss, environmental groups almost invariably focus on the impact of bleaching caused by rising seawater temperatures and increasing acidity, associated with global warming and climate change. However, on the Great Barrier Reef (by far the world’s largest coral reef), more than half of the coral loss had already occurred by 1985, fifteen years before the first major bleaching event, as demonstrated by Figure 3.

Figure 3: Great Barrier Reef coral cover

Dr Jon Brodie of the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University has reported that Crown-of-Thorns starfish (COTS) were probably the major cause of coral mortality in the period from 1960 to 1985. [16]

According to Brodie, it is now well established that the major COTS outbreaks since 1962 were most likely caused by nutrient enrichment associated with increased discharge of nitrogen and phosphorous from the land due to soil erosion and large scale fertiliser use. The nutrients promote phytoplankton growth suitable to COTS larvae.

Dr Glenn De’ath and fellow researchers from the Australian Institute of Marine Science (AIMS) and the University of Wollongong have estimated that COTS were responsible for 42 per cent of coral loss from 1985 to 2012, with the other causes being cyclones at 48 per cent and bleaching at 10 per cent. [17]

The Queensland Government’s 2013 and 2017 Scientific Consensus Statements and the related 2017 FAQs have confirmed that grazing lands have been major contributors to sediment and nutrient discharge. [18, 19, 20]

Sediment blocks the sun, smothers coral and promotes the excessive development of algae, making the coral less resilient than it would otherwise have been to the impacts of other stressors, such as warming and more acidic waters. Allowing for gully and hillslope erosion directly attributed to farmed animal grazing, along with the activity’s share of streambank erosion, grazing’s overall contribution to fine sediment in the reef’s waters appears to be around 70 per cent.

It is the dominant source of particulate nutrients, which are mostly deposited near river mouths. From there they can be broken down for years by bacteria into the most damaging form, dissolved inorganic nutrients. 

Figure 4 provides an example of gully erosion in northern Australia, initiated by cattle grazing and a major contributor to sediment loads.

Figure 4: Gully erosion on cattle property in northern Queensland

© Griffith University – Andrew Brooks

The Queensland government issues report cards which measure progress towards the Reef Water Quality Protection Plan’s goal and targets. The most recent report card, issued in October 2017 and showing the status as at June 2016, rated overall grazing management as “D”, indicating “poor”. [21] That result reflected 36 per cent of grazing lands being subject to best management practice systems.

It is estimated that expenditure ranging from $5.3 billion to $18.4 billion (most likely $7.8 billion) would be required to reduce sediment flow by 50 per cent, which is a target established under the Australian and Queensland governments’ Reef 2050 Long-Term Sustainability Plan. [22] 

In a rehabilitation pilot study by researchers from Griffith University, it was found that sediment run-off could be reduced by 75 per cent in two years. [23] The researchers have stated:

“. . . what is clear from these existing trials is that, given the scale of the alluvial gully sources in particular, the scope of this problem has grown way beyond being managed by individual farmers and graziers. These are a legacy of the past 100-150 years of land use . . . The benefits that will flow from the intensive, precisely targeted management of alluvial gullies are largely a public benefit for the downstream ecosystems and ultimately the Great Barrier Reef. In other words, this is a problem we have to tackle collectively . . .”

Much of the damage has already been done, but remediation efforts remain an essential aspect of strategies to limit further coral loss. As an example of such efforts, in 2016 the Queensland government purchased the 56,000 hectare Springvale cattle station on Cape York, with the intention of removing the cattle and rehabilitating the station’s stream and river banks and gullies. [24]


Professor Wayne Meyer is Professor of Natural Resource Science at the University of Adelaide and former Deputy Chief and Business Director for Commonwealth Scientific and Industrial Research Organisation (CSIRO) Land and Water. He has received the CSIRO Medal for Research Achievement for his research in irrigation water management.

Prof. Meyer has estimated that, to produce 1 kilogram of product, it takes between 50,000 and 100,000 litres of water for beef compared to between 715 and 750 litres for wheat and between 1,550 and 2,000 litres for rice. [25]

David and Marcia Pimentel of Cornell University have reported that producing 1 kilogram of animal protein requires about 100 times more water than producing 1 kilogram of grain protein. Their estimates for 1 kilogram of beef range from 100,000 litres (relating to grain and hay for production systems that include intensive feedlots) to more than 200,000 litres (relating to forage production on rangelands). [26]

Elsewhere, David Pimentel and co-authors have cited figures of 43,000 litres for intensive production including feedlots and 120,000 – 200,000 litres for open rangeland production. [27]

Professor Meyer’s figures were originally derived for intensive production using irrigated pastures. Seemingly consistent with the findings of David and Marcia Pimentel, he has subsequently suggested that if the same exercise were conducted on rain fed, extensive meat production, there may be even more water involved. The reason is that feed conversion is likely to be lower, energy expended in gathering dry matter (including grass) would be greater and soil evaporation losses may even be higher than in a system involving irrigated pasture. [28]

It then becomes a question of the optimum use of the water, taking into account potential alternative uses.

Prof. Meyer has pointed out that water used for irrigation has many alternative uses, including keeping it in the river systems, keeping riverine and wetland ecosystems healthy and providing water for urban and industrial uses. He has noted that alternatives for rain fed areas are more restricted, but could include provision of run-off in catchment areas, growing native vegetation for conservation purposes and or for groundwater recharge. He has said:

“Using this logic there is little value in arguing that meat production does not embody a lot of water. More rationally the discussion can be about the value we place on the genuine alternatives for the use of this water.”

In areas where crops for human consumption can be grown, there are high opportunity costs in meat production, with the water requirement of animal-based foods being many times that of non-animal options for any given level of nutritional output.

In non-cropping areas, the choice can be as simple as steak dinners versus natural ecosystems. Alternatives are available for steak dinners but not for natural ecosystems.

Prof. Arjen Hoekstra of the University of Twente in the Netherlands and Prof. Ashok Chapagain of the University of Free State, South Africa, have estimated that, in Australia, 17,112 litres of water are required to produce 1 kilogram of beef. [18] Although lower than other estimates referred to in this article, their estimate is still many times higher than estimates for vegetables and grains. [29]

Their figures for soy beans are 2,106 litres (Australia) and 1,789 (global average), and for paddy rice 1,022 litres (Australia) and 2,291 litres (global average).

Hoekstra and Chapagain are on the supervisory board of the Water Footprint Network, which is a non-profit foundation under Dutch law. The founding partners were: University of Twente, World Wildlife Fund, UNESCO-IHE Institute for Water Education, the Water Neutral Foundation, the World Business Council for Sustainable Development, the International Finance Corporation (part of the World Bank Group) and the Netherlands Water Partnership. [30]

In responding to queries regarding the differences between his figures and those of Prof. Meyer and Dr Pimentel, Prof Hoekstra has noted: [31]

“. . . all authors agree the water footprint of beef is larger than the water footprint of pork or chicken and much larger than the water footprint of grains”.

His global average figures for chicken meat and pig meat are more than double those of soy beans, while the multiple for beef is more than eight.


We will have no chance of overcoming critical environmental problems, including the existential threat of climate change, without a general transition away from animal-based foods. Essential efforts focusing on other contributing factors will be futile unless that issue is addressed. 

In view of animal-based food production’s tragic environmental consequences, why is the livestock sector effectively ignored by most prominent campaign groups?

Author: Paul Mahony

Paul Mahony is an environmental and animal rights campaigner based in Melbourne, Australia. He has presented to The Greens, Sustainable Living Festival, Australian Climate Action Summit, and numerous university, Rotary and Probus groups. His articles have also appeared on national and international websites, and his campaigning efforts were featured in the book “Guarding Eden” by Deborah Hart. His website is


  1. For more on the subject of percentage contributions, see the article “Livestock and climate: Do percentages matter?“.
  2. Even in the absence of clear tipping points, climate feedback mechanisms create accelerating, non-linear changes, which are potentially irreversible.


[1] Beyond Zero Emissions and Melbourne Sustainable Society Institute of The University of Melbourne, “Zero Carbon Australia – Land Use: Agriculture and Forestry – Discussion Paper”, October, 2014,

[2] Wedderburn-Bisshop, G., Longmire, A., Rickards, L., “Neglected Transformational Responses: Implications of Excluding Short Lived Emissions and Near Term Projections in Greenhouse Gas Accounting”, International Journal of Climate Change: Impacts and Responses, Volume 7Issue 3, September 2015, pp.11-27. Article: Print (Spiral Bound). Published Online: August 17, 2015,

[3] Mahony, P. “The low emissions diet: Eating for a safe climate” (2016), p. 8, utilising: Australian Government, Dept of the Environment, “National Inventory Report 2012 Volume 1”, Table 6.1 Agriculture sector CO2-e emissions, 2012, p. 257,; George Wilkenfeld & Associates Pty Ltd and Energy Strategies, National Greenhouse Gas Inventory 1990, 1995, 1999, End Use Allocation of Emissions Report to the Australian Greenhouse Office, 2003, Volume 1, Table 5.2, p. 83; and Australian Government, Dept of the Environment, “National Inventory Report 2012 Volume 1”, Table 3.1 Energy sector CO2-e emissions 2012, Item 1A.1, p. 48.

[4] Food and Agriculture Organization of the United Nations, Global Livestock Environmental Assessment Model (GLEAM) – Results,

[5] USDA National Nutrient Database for Standard Reference at via Nutrition Data at

[6] Scarborough, P., Appleby, P.N., Mizdrak, A., Briggs, A.D.M., Travis, R.C., Bradbury, K.E., & Key, T.J., “Dietary greenhouse gas emissions of meat-eaters, fish-eaters, vegetarians and vegans in the UK”, Climatic Change, DOI 10.1007/s10584-014-1169-1,

[7] Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: “Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group 1 to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change” , Table 8.7, p. 714 [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA,

[8] Russell, G., “Bulbs, bags, and Kelly’s bush: defining ‘green’ in Australia”, 19 Mar 2010 (p. 10) (, which utilised: Dept. of Sustainability, Environment, Water, Population and Communities, State of the Environment Report 2006, Indicator: LD-01 The proportion and area of native vegetation and changes over time, March 2009; and ABS, 4613.0 “Australia’s Environment: Issues and Trends”, Jan 2010; and ABS 1301.0 Australian Year Book 2008, since updated for 2009-10, 16.13 Area of crops

[9] Australian Bureau of Statistics, “Themes – Environment, Land and Soil, Agriculture”, citing World Resources Institute, World Resources, 1998-99: A Guide to the Global Environment, Washington, DC, 1998, p. 157, cited in “The Ethics of What We Eat” (2006), Singer, P & Mason, J, Text Publishing Company, p. 216

[10] Australian Government, Department of Agriculture and Water Resources, ABARES, National scale land use (based on Land Use of Australia 2010-11, Version 5, ABARES 2016), Last reviewed 5th March 2018,

[11] McFarlane, I. and O’Connor, E.A., “World soybean trade: growth and sustainability”, Modern Economy, 2014, 5, 580-588, Published Online May 2014 in SciRes, Table 1, p. 582,

[12] National Oceanic and Atmospheric Administration, “Ocean”

[13] Atwood, T.B., Connolly, R.M., Ritchie, E.G., Lovelock, C.E., Heithaus, M.R., Hays, G.C., Fourqurean, J.W., Macreadie, P.I., “Predators help protect carbon stocks in blue carbon ecosystems”, published online 28 September 2015,

[14] World Health Organization, “Number of registered vehicles. Data by country”

[15] Australian Government, Department of the Environment, “National Inventory Report 2013, Volume 1”, Table ES.01, p. x,

[16] Brodie, J., “Great Barrier Reef dying beneath its crown of thorns”, The Conversation, 16th April, 2012,

[17] De’ath, G., Katharina Fabricius, K.E., Sweatman, H., Puotinen, M., “The 27–year decline of coral cover on the Great Barrier Reef and its causes”, PNAS 2012 109 (44) 17995-17999; published ahead of print October 1, 2012, doi:10.1073/pnas.1208909109,

[18] Kroon, F., Turner, R., Smith, R., Warne, M., Hunter, H., Bartley, R., Wilkinson, S., Lewis, S., Waters, D., Caroll, C., 2013 “Scientific Consensus Statement: Sources of sediment, nutrients, pesticides and other pollutants in the Great Barrier Reef Catchment”, Ch. 4, p. 12, The State of Queensland, Reef Water Quality Protection Plan Secretariat, July, 2013,

[19] Bartley, R., Waters, D., Turner, R., Kroon, F., Wilkinson, S., Garzon-Garcia, A., Kuhnert, P., Lewis, S., Smith, R., Bainbridge, Z., Olley, J., Brooks, A., Burton, J., Brodie, J., Waterhouse, J., 2017. Scientific Consensus Statement 2017: A synthesis of the science of land-based water quality impacts on the Great Barrier Reef, Chapter 2: Sources of sediment, nutrients, pesticides and other pollutants to the Great Barrier Reef. State of Queensland, 2017,

[20] Frequently Asked Questions: Reef 2050 Water Quality Improvement Plan and 2017 Scientific Consensus Statement, State of Queensland, pp. 7 – 8,

[21] Queensland Government, Reef 2050 Reef Water Quality Improvement Plan, Report Card 2016 – Management Practices,

[22] Australian Government, Department of Environment and Energy, Reef 2050 Long-Term Sustainability Plan – Progress on Implementation Review by Great Barrier Reef Independent Review Group, February 2017, p. 50

[23] Brooks, A. and Olley, J., “Solution at hand for saving Great Barrier Reef”, Griffith News, 23 Nov 2015,

[24] Willacy, M., ABC News, “Great Barrier Reef: Queensland Government buys $7m cattle station in ‘unprecedented’ protection bid”, 28th June 2016,

[25] Meyer, W. 1997 “Water for Food – The Continuing Debate”,

[26] Pimentel, D & Pimentel, M, “Sustainability of meat-based and plant-based diets and the environment”, American Journal of Clinical Nutrition 2003; 78 (suppl): 660S-3S,

[27] Pimentel D, Berger B, Filiberto D, Newton M, Wolfe B, Karabinakis E, Clark S, Poon E, Abbett E, Nandaopal S. 2004. Water Resources, Agriculture, and the Environment. Ithaca (NY): New York State College of Agriculture and Life Sciences, Cornell University. Environmental Biology Report 04-1

[28] Meyer, W, “Water and meat producers”, Nov 2007 and updated Dec 2007 and Jun 2008

[29] Hoekstra, A.Y. & Chapagain, A.K. “Water footprints of nations: Water use by people as a function of their consumption pattern”, Water Resource Management, 2006, DO1 10.1007/s11269-006-9039-x (Tables 1 & 2),

[30] The Water Footprint Network,

[31] Hoekstra, A, Email correspondence 9 Sep, 2009


Adwo, “Free range Australian bull”, ID: 1043628112, Shutterstock

Brian Kinney, “Wonderful and beautiful underwater world with corals and tropical fish”, ID: 260385482, Shutterstock

Andrew Brooks, Griffith University, Gully erosion at Springvale Station, originally from “Research leads to Great Barrier Reef Rescue Purchase”, Griffith News, 23 June 2016 (Used with permission)

Love Bree Photography, Photo of the article’s author

Dan Gold – Unsplash, Article Cover Image

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