On the final weekend of November, 2015, marches will occur around the world, with participants demanding urgent and effective action on climate change. The organisers of the Australian marches, like so-called world leaders who will meet at the Paris climate summit, are focusing almost exclusively on the impact of fossil fuels. In doing so, they are overlooking or ignoring another critical contributor to climate change, animal agriculture.

This post is a recap of some of the key issues, along with some new information.

What is the problem?

Producing animal-based foods affects the environment in dramatic ways. Here are some examples of prominent organisations and individuals sounding the alarm over many years:

“[Animal food products] place undue demand on land, water, and other resources required for intensive food production, which makes the typical Western diet not only undesirable from the standpoint of health but also environmentally unsustainable.” The Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (2002)

“[Livestock production] is one of the major causes of the world’s most pressing environmental problems, including global warming, land degradation, air and water pollution, and loss of biodiversity.” The Food and Agriculture Organization of the United Nations (FAO, 2006)

“[A new UNEP report] calls for a significant shift in diets away from animal based proteins towards more vegetable-based foods in order to dramatically reduce pressures on the environment” . . . “. . . substantial reduction of impacts would only be possible with a substantial worldwide diet change, away from animal products.” United Nations Environment Programme (2010)

“Please eat less meat; meat is a very carbon intensive commodity.” Former head of the IPCC, Rajendra Pachauri (2010)

Livestock’s climate change impacts arise from many inter-related factors, such as its inherent inefficiency as a food source; the massive scale of the industry; land clearing far beyond what would otherwise be required to satisfy our nutritional requirements; greenhouse gases such as carbon dioxide, methane and nitrous oxide; and other warming agents such as black carbon.

Livestock’s impacts are understated

The adverse climate change impact of livestock production is understated in most 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. The findings were reinforced in a subsequent peer-reviewed journal article, which had two co-authors in common with the BZE paper.

Some key contributors

Methane (CH4) is produced in the digestive system of ruminant animals, such as cows and sheep. In Australia, measured over a 20-year time horizon, methane from livestock produces more warming than all our coal-fired power stations combined. That’s in a country with amongst the highest per capita emissions in the world due to our heavy reliance on coal.

The 20-year time horizon (including its associated “global warming potential”) is critical in terms of potential climate change tipping points, with potentially catastrophic and irreversible consequences. [See footnote.]

Although methane is a critical problem (including methane from livestock-related savanna burning), so are livestock-related carbon dioxide (CO2) emissions, resulting from the clearing of forest and other vegetation. The carbon locked in cleared vegetation is released as CO2. We are hit twice, as once the vegetation is gone, 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 livestock production. A large portion of the remainder has been severely degraded by livestock grazing, with significant loss of soil carbon.

According to the World Resources Institute, overgrazing is the largest single cause of land degradation, world-wide. Much of the degradation occurs in the semi-arid areas. Cattle are heavy animals with hard hooves, big appetites, and a digestive system that produces large quantities of manure. Turned loose on fragile, semi-arid environments, they can soon devastate a landscape that has not evolved to cope with them.

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

Two warming agents generally omitted from official figures, and prominent in animal agriculture, are tropospheric ozone and black carbon. They remain in the atmosphere for a short period, but have a significant impact.

The impact of chicken, pig and dairy consumption

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 while continuing to destroy the Amazon rainforest and occupy previously cleared land in order to grow soy beans (and graze cattle).

A significant proportion of those soy beans are fed to billions of chickens and pigs in a grossly inefficient process. Cows in the dairy industry are also major recipients.

Seafood’s impacts

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).

The oceans cover 71 percent of our planet’s surface. 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 recent paper in Nature Climate Change has helped to highlight some of impact. 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.

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.

Will we grasp a golden opportunity?

A 2009 study by the PBL Netherlands Environmental Assessment Agency estimated that a global transition to a completely animal free diet would reduce climate change mitigation costs by around 80 per cent. A meat-free diet would reduce them by 70 per cent.

Will we grasp the opportunity that those figures represent, or continue to effectively ignore the issue?

The failure of prominent environmental groups

Prominent organisations, such as Australian Youth Climate Coalition (AYCC), Australian Conservation Foundation (ACF), the Greens political party in Australia, and 350.org, have failed to campaign meaningfully, if at all, on the livestock issue.

ACF advocates consumption of “grass fed as opposed to grain fed meat”, seemingly unaware that the emissions intensity of grass-fed is far higher than that of the grain-fed alternative (with both being on a different paradigm to plant-based foods). Bill McKibben of 350.org has made similar claims, with neither citing evidence for their position to my knowledge. Despite what they may wish to believe, the natural way is not always best in every respect.

AYCC describes itself as “a real force to be reckoned with”, but has failed miserably on this topic.

Hopefully, those groups and others will add the livestock issue to their campaigning efforts, helping to inform their supporters and significantly enhancing their effectiveness.

Social Justice

Environmental groups in Australia are using the catch-cry “Climate justice, climate peace” in the weeks before the Paris climate summit. It may have merit, but to the extent campaigners consume animal-based foods, they ignore the injustice of livestock production.

For example, researchers from the University of Minnesota have estimated that we would have the capacity to feed another 4 billion people with a general transition to a plant-based diet. That would enable us to resolve the current crisis that exists in the form of nearly 800 million people who are chronically under-nourished.

Of course, with livestock’s massive climate change impacts, ignoring the issue flies directly in the face of the message of climate justice and peace intended to be conveyed by the campaigners.

Personal choice?

Many people argue that food consumption is a matter of personal choice, and that their choices should not be challenged by others. However, we can no longer regard food choices as strictly personal when their impacts have far-reaching, adverse consequences.

Governments could assist with information campaigns, and by creating pricing mechanisms that ensure the environmental cost of consumption is allowed for in the price paid by the end-user, thereby reducing demand for high emissions intensity products, along with the resultant supply.


The road to Paris may have been difficult so far, but the way forward, with potential tipping points and runaway climate change, could be very ugly indeed. It is time to wake up, face the ultimate inconvenient truth, and take all necessary steps in an effort to avoid catastrophe.


Paul Mahony (also on Twitter, Facebook, Scribd, Slideshare, New Matilda, Rabble and Viva la Vegan)


For more on the “global warming potential” of different greenhouse gases, see GWP explained.

Even in the absence of clear tipping points, climate feedback mechanisms create accelerating, non-linear changes, which are potentially irreversible.


Food and Agriculture Organization of the United Nations and World Health Organization, “Human Vitamin and Mineral Requirements: Report of a joint FAO/WHO expert consultation Bangkok, Thailand”, 2001, pp. 14, ftp://ftp.fao.org/docrep/fao/004/y2809e/y2809e00.pdf and http://www.fao.org/docrep/004/Y2809E/y2809e08.htm

The Food and Agriculture Organization of the United Nations, “Livestock impacts on the environment”, Spotlight 2006, November 2006

United Nations Environment Program “Energy & Agriculture Top Resource Panel’s Priority List for Sustainable 21st Century”, 2 June 2010, http://www.unep.org/wed/2010/english/media/EnergyAgric.asp

Agence France-Presse, “Lifestyle changes can curb climate change: IPCC chief”, 15 January, 2010, http://afp.google.com/article/ALeqM5iIVBkZpOUA9Hz3Xc2u-61mDlrw0Q

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, http://bze.org.au/landuse

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 7, Issue 3, September 2015, pp.11-27. Article: Print (Spiral Bound). Published Online: August 17, 2015, http://ijc.cgpublisher.com/product/pub.185/prod.269

Mahony, P., “The Electric Cow”, Terrastendo, 27th May, 2014, https://terrastendo.net/2014/05/27/the-electric-cow/

Russell, G., “Bulbs, bags, and Kelly’s bush: defining ‘green’ in Australia”, 19 Mar 2010 (p. 10) (http://hec-forum.anu.edu.au/archive/presentations_archive/2010/geoffrussell-hec-talk.pdf), 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

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

Mahony, P., “Chickens, pigs and the Amazon tipping point”, Terrastendo, 5th October, 2015, https://terrastendo.net/2015/10/05/chickens-pigs-and-the-amazon-tipping-point/

National Oceanic and Atmospheric Administration, “Ocean” (undated), http://www.noaa.gov/ocean.html

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, http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2763.html

Macreadie, P., Ritchie, E., Hays, G., Connolly, R., Atwood, T.B., “Ocean predators can help reset our planet’s thermostat”, The Conversation, 29th September, 2015, https://theconversation.com/ocean-predators-can-help-reset-our-planets-thermostat-47937

Stehfest, E, Bouwman, L, van Vuuren, DP, den Elzen, MGJ, Eickhout, B and Kabat, P, “Climate benefits of changing diet” Climatic Change, Volume 95, Numbers 1-2 (2009), 83-102, DOI: 10.1007/s10584-008-9534-6 (Also http://www.springerlink.com/content/053gx71816jq2648/)

Australian Conservation Foundation, “Meat Free Week: eat less, care more, feel good”, 17th March, 2014, http://www.acfonline.org.au/news-media/news-features/meat-free-week-eat-less-care-more-feel-good

Mahony, P., “The real elephant in AYCC’s climate change room”, Terrastendo, 5th September, 2013, https://terrastendo.net/2013/09/05/the-real-elephant-in-ayccs-climate-change-room/

Mahony, P. “Do the math: There are too many cows!”, Terrastendo, 26th July, 2013, https://terrastendo.net/2013/07/26/do-the-math-there-are-too-many-cows/

Harper, L.A., Denmead, O.T., Freney, J.R., and Byers, F.M., Journal of Animal Science, June, 1999, “Direct measurements of methane emissions from grazing and feedlot cattle”, J ANIM SCI, 1999, 77:1392-1401, http://www.ncbi.nlm.nih.gov/pubmed/10375217; http://www.journalofanimalscience.org/content/77/6/1392.full.pdf

Eshel, G., “Grass-fed beef packs a punch to environment”, Reuters Environment Forum, 8 Apr 2010, http://blogs.reuters.com/environment/2010/04/08/grass-fed-beef-packs-a-punch-to-environment/

Food and Agriculture Organization of the United Nations, “The State of Food Insecurity in the World 2014”, http://www.fao.org/publications/sofi/2014/en/


Paris Climate Change Conference 2015 Photo © Delstudio | Dreamstime.com