We are now facing a climate emergency. We will not overcome that emergency without a general move toward a plant-based diet.
Atmospheric concentrations of carbon dioxide (CO2) were stable at around 280 ppm during the 10,000 year period that encompassed the development of human civilisation prior to the start of the industrial revolution. In 1912, atmospheric CO2 concentrations exceeded 300 ppm for the first time in at least 2.1 million years. 
They are now around 391 ppm, an increase of 30% in 100 years.
Feedback mechanisms involving the Arctic sea ice, permafrost (frozen land) and other natural features are creating greenhouse gas emissions that are self-perpetuating and may continue to accelerate unless we draw sufficient volumes from the atmosphere to create some cooling from current levels.
We must cease burning fossil fuels to the maximum extent possible if we are to overcome climate change. However, we must also reforest massive tracts of land that have been cleared, and reduce emissions of non-CO2 forcing agents, such as methane, nitrous oxide, tropospheric ozone and black carbon. Animal agriculture is a critical component of all those factors.
Some recognition of animal agriculture’s impact can be seen here:
United Nations Environment Programme: 
"Impacts from agriculture are expected to increase substantially due to population growth increasing consumption of animal products. Unlike fossil fuels, it is difficult to look for alternatives: people have to eat. A substantial reduction of impacts would only be possible with a substantial worldwide diet change, away from animal products.""Animal products cause more damage than [producing] construction minerals such as sand or cement, plastics or metals. Biomass and crops for animals are as damaging as [burning] fossil fuels." (Professor Edgar Hertwich, lead author)
Food and Agriculture Organization of the United Nations and World Health Organization: 
“[Animal food products place] an 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.”
Henning Steinfeld, United Nations Food & Agriculture Organization, 2006: 
“Livestock are one of the most significant contributors to today’s most serious environmental problems. Urgent action is required to remedy the situation.”
Dr James Hansen, Director of Goddard Institute for Space Studies, NASA: 
“If you eat further down on the food chain rather than animals, which have produced many greenhouse gases, and used much energy in the process of growing that meat, you can actually make a bigger contribution in that way than just about anything. So that, in terms of individual action, is perhaps the best thing you can do.”
Dr Rajendra Pachauri, Chairman, Intergovernmental Panel on Climate Change: 
“Please eat less meat - meat is a very carbon intensive commodity.”
PBL Netherlands Environmental Assessment Agency: 
A study by the PBL Netherlands Environmental Assessment Agency reported that a global transition to a completely animal free diet is estimated to reduce climate change mitigation costs by around 80%. Removing just meat from the diet would reduce the costs by around 70%.
The report’s abstract states: “By using an integrated assessment model, we found a global food transition to less meat, or even a complete switch to plant-based protein food to have a dramatic effect on land use. Up to 2,700 Mha of pasture and 100 Mha of cropland could be abandoned, resulting in a large carbon uptake from regrowing vegetation. Additionally, methane and nitrous oxide emission would be reduced substantially.”
If we move away from animals as a food source, will we better able than now to feed the world’s population?
The answer is an emphatic “Yes”!
We would be far better equipped to feed all if we focussed on plant-based nutrition. Animal agriculture is unsustainable and inherently and grossly inefficient as a food source.
This can be demonstrated by the work of two teams of Austrian researchers, who have shown that humans in 2000 appropriated 23.8 percent of the planet’s net primary productivity or annual plant growth. Of that amount, around 30 percent was used for paper production, construction and the like. 58 percent was fed to livestock and supplied 17 percent of human-kind’s global food calories. Only 12 percent was consumed directly by humans, providing 83 percent of calories.
If an individual business were operating with the level of efficiency demonstrated by the Austrian teams’ work, it would almost certainly be closed or its methods radically overhauled. How is it that we allow these levels of inefficiency in such a massive and critically important operation?
The following image depicts the comparison.
Information reported by Dr David Pimentel, Cornell University, USA in 2003 also highlights the extent of the livestock industry’s inefficiency: 
- The US livestock population consumes more than 7 times as much grain as is consumed directly by the entire American population. (US Department of Agriculture, 2001. Agricultural statistics, Washington, DC)
- The amount of grain fed to US livestock is sufficient to feed about 840 million people who follow a plant-based diet. (Dr David Pimentel, Cornell University, “Livestock production and energy use”, Cleveland CJ, ed. Encyclopedia of energy (in press). (Cited 2003)
We now have more than one billion under-nourished people in the world. Quite apart from the horrendous environmental impacts of livestock production, the willingness of the wealthy to allow others to starve while plant production is channelled through livestock is morally repugnant.
Australia’s Food Production:
Using information from the Department of Agriculture Fisheries and Forestry’s (DAFF) "Australian food statistics 2010-11"  and the United States Department of Agriculture’s (USDA) "National Nutrient Database for Standard Reference" , it has been possible to calculate gross production figures for certain nutrients in Australia. Examples are depicted in the charts below. Others published in the DAFF paper referred to in the note below include: zinc; calcium; Vitamin B12; Omega 3; Vitamin C; magnesium; and potassium.
The charts include, for each specified nutrient, an indication of the percentages derived from animal and non-animal products.
They include products that are exported and/or used as livestock feed. The inclusion of the latter means there is some double-counting of nutrients. However, given animal agriculture’s relatively low output levels for most nutrients, the double-counting does not appear to be significant.
For beef, lamb and pig meat, the charts are based on 55% of the tonnage reported in DAFF’s Australian Food Statistics. That tonnage is based on carcass weight. This approach is in line with an estimate by the not-for-profit group Carbon Neutral that 55% of the carcass is used as meat. Carbon Neutral's aim is to measure, reduce and offset greenhouse gas emissions and implement re-vegetation projects. 
Comments on the relative value of nutrients derived from animal versus plant-based sources, in the context of animal agriculture’s climate change impact, will appear in a subsequent article.
The figures may seem surprising, but they help to highlight livestock's relative inefficiencies, as referred to earlier in this article.
1. Energy: Plant Products 91%; Animal products 9%
2. Protein: Plant Products 81%; Animal products 19%
3. Iron: Plant Products 97%; Animal products 3%
As we will not overcome climate change without a general move toward a plant-based diet (in addition to action on fossil fuels and non-CO2 climate forcing agents), it is imperative that resources are devoted to such a transition.
This article contains information that has been included in the author’s response to the Department of Agriculture, Fisheries and Forestry’s National Food Plan green paper. That response can be seen here: http://tinyurl.com/9caee37
It will also appear here at a later date: http://tinyurl.com/97mxbrp
In 2009, he prepared Vegetarian Victoria’s submission to the Victorian State Government in response to its Climate Change Green Paper. His question on animal agriculture and climate change finished second in polling for The Sunday Age’s 2011 "Climate Agenda", and prompted an article prior to the close of polling and another subsequently.
Paul has had over forty letters published in The Age and The Sunday Age since 2008. He is also contributing to the land use component of “ZCA 2020”, a joint project between Beyond Zero Emissions and The University of Melbourne. His work is also featured on the websites of BCCAG and LIVE.
 CO2now.org, http://co2now.org/Current-CO2/CO2-Now/the-climate-sheet.html
 Carus, F, “UN urges global move to meat and dairy-free diet”, The Guardian (Environment, Food), 2 June 2010, http://www.guardian.co.uk/environment/2010/jun/02/un-report-meat-free-diet
 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
 “Livestock a major threat to environment”, FAO Newsroom, 29 November, 2006, http://www.fao.org/newsroom/en/news/2006/1000448/index.html
 Russell, G, “Dietary Guidelines Committee ignores climate change”, 24 March 2012, http://bravenewclimate.com/2012/03/24/dietary-gc-ignores-cc/
 Anon., “Lifestyle changes can curb climate change: IPCC chief”, 16 January, 2008, http://www.abc.net.au/news/stories/2008/01/16/2139349.htm?section=world
 Elke Stehfest, Lex Bouwman, Detlef P. van Vuuren, Michel G. J. den Elzen, Bas Eickhout and Pavel Kabat, “Climate benefits of changing diet” Climatic Change, Volume 95, Numbers 1-2 (2009), 83-102, DOI: 10.1007/s10584-008-9534-6, http://www.springerlink.com/content/053gx71816jq2648/ and http://www.pbl.nl/en/publications/2009/Climate-benefits-of-changing-diet
 Pimentel, D. & Pimentel M. “Sustainability of meat-based and plant-based diets and the environment”, American Journal of Clinical Nutrition, Vol. 78, No. 3, 660S-663S, September 2003, http://www.ajcn.org/content/78/3/660S.full.pdf
 Dept of Agriculture, Fisheries and Forestry, “Australian Food Statistics 2010-11”, http://www.daff.gov.au/__data/assets/pdf_file/0015/2144103/aust-food-statistics-2011-1023july12.pdf
 USDA "National Nutrient Database for Standard Reference" via Nutrition Data at http://www.nutritiondata.com
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