Have you ever wondered about the climate change impacts of a single meal?
Food production significantly affects climate change, so let’s consider how adding ingredients to an existing recipe can affect the relevant greenhouse gas emissions. The recipe in this instance (for four people) is Harissa Bean Tagine, from The Kind Cook. 
In its original form, based primarily on emissions intensity figures from the Food and Agriculture Organization of the United Nations (FAO), the recipe’s ingredients are estimated to produce 2.3 kg of carbon dioxide-equivalent greenhouse gases.
The chart below shows the revised emissions after adding 250 grams (just over half a pound) of various ingredients and adjusting the FAO’s figures to allow for a 20-year time horizon in assessing the impact of methane and nitrous oxide.   [Footnote]
Two global average figures are shown for beef; grass-fed and “mixed-fed”. Beef from grass-fed cows is far more emissions intensive than beef from mixed feeding systems, involving grain and grass. No cows are fed grain exclusively for their entire lives, as they have not evolved to consume it and would not survive. “Grain-fed” cows are usually “finished” on grain for up to 120 days prior to slaughter, and the chart refers to the meat as “mixed-fed”.
For Oceania, the FAO only provided an overall figure, combining grass-fed and mixed-fed systems. Australia and New Zealand are the major beef-producing nations within Oceania. In 2013, Australia produced around 2.5 million tonnes of beef, with New Zealand’s output equivalent to less than a quarter of that figure.  Excluding beef from the dairy herd, New Zealand’s relative output may be significantly lower than indicated by those figures.
The emissions intensity figures for beef are for specialised beef, excluding meat from dairy cows, whose emissions are also attributed to dairy products.
The figures for fish and tofu are from a 2014 study by Oxford University. As processing accounts for a relatively small portion of a product’s emissions, the figure for tofu is based on the results for soy. 
Figure 1: “Harissa Bean Tagine” – kg of greenhouse gas emissions with the addition of new ingredients
What about pork, chicken and fish?
There are two key reason for the relatively low emissions from pork, chicken and fish, although it should be noted that emissions relating to any type of food can vary widely, depending on the methods and conditions involved.
Firstly, the animals involved are not ruminants, and therefore do not produce methane to the same extent as, say, cows and sheep. Methane is a potent greenhouse gas.
Secondly, unlike cows and sheep, they do not graze on pasture as part of the production process. That means that a relatively small land area has been cleared for products derived from them. Deforestation, regular burning of savanna to promote new grass and prevent forest from regenerating, and grazing on natural pasture, emit carbon dioxide and other greenhouse gases.
Unfortunately, even the emissions figures for beef and lamb do not include foregone sequestration. That is, they do not allow for the fact that current atmospheric carbon concentrations are far higher than they would have been if forest and other wooded vegetation had been retained, removing carbon from the atmosphere.
What many of us assume to be natural landscapes may be very different to what existed before livestock (the major cause of clearing) and other pressures were introduced. The problem is highlighted in the following words from Australia’s Commonwealth Scientific and Industrial Organisation :
“It was once possible to walk from Melbourne to Sydney through almost continuous woodland cover, but now much of it is gone and the remaining patches are small and highly disturbed.”
A major contributor to deforestation in the Amazon and Cerrado regions of South America is conversion of forest and other wooded vegetation to soy bean plantations. Most of the world’s soy is fed to livestock, including nearly 500 million pigs in China, in an inherently and grossly inefficient system of producing nutrition for the world’s human population.  
Those inefficiencies are a key factor in other critical environmental problems involved in producing food from animals, resulting in the over-use of resources (such as land, fertiliser, pesticides and fossil fuels), the creation of waste, and the destruction of oceanic ecosystems far in excess of what would occur if our nutrition was derived directly from plants.
Adequacy of Alternative Diets
“It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes. A vegetarian diet is defined as one that does not include meat (including fowl) or seafood, or products containing those foods.”
As the extent of fortification of foods with nutrients such as vitamin B12 and vitamin D varies by country, it is important to review the adequacy of your diet based on local conditions.
“Most adults are unlikely to obtain more than 5%-10% of their vitamin D requirement from dietary sources. The main source of vitamin D for people residing in Australia and New Zealand is exposure to sunlight.”
The vitamin B12 found in certain animal-based food products is produced by soil microbes that live in symbiotic relationships with plant roots, and which find their way into the animals’ digestive tracts. Such bacteria are also found in humans’ digestive tracts, but too far along to be readily absorbed for nutritional purposes. 
Vitamin B12 is not synthesised by plants, nor is it generally found on vegetables in our modern sanitised lifestyle. However, B12 supplements are readily produced from bacteria, to be ingested directly or incorporated in various other food products. That is a far more natural approach than: (a) destroying rainforests and other natural environs; and (b) operating livestock production systems; purely for animal food products.
The Oxford Dictionary defines the word “natural” to mean: “Existing in or derived from nature; not made or caused by humankind”. On the basis of that definition, no livestock production systems could be described as “natural”. Even so-called “free range” systems involve factors such as selective and intense breeding programs, premature death, and often mutilation, such as ear-notching and castration.
To encourage dietary practices that have the most beneficial impact on climate change, governments need to introduce policies that establish pricing signals incorporating the environmental costs of different products. With such policies, beef and certain other products would become luxury items, with reductions in demand, production and the resultant environmental impacts.
If you would like more information about using a 20-year time horizon for assessing greenhouse gas emissions, please see my page GWP Explained.
None of the information contained in this article is intended to represent nutritional, dietary, medical, health or similar advice.
Recipe for Harrisa Bean Tagine from The Kind Cook
Harissa is a hot paste from Tunisia (North Africa), made from chilli, herbs and spices. Traditionally cooked in a tagine, this dish can also be done by gently cooking on your stove top. Choose good quality chopped tomatoes and go easy on the harissa paste if you are not great with chilli.
This is such a simple, uncomplicated, warming, economical and nourishing dish. Loads of fresh herbs lift its earthy notes.
Oil for cooking
1 large brown onion, peeled and finely diced
4 cloves of garlic, peeled and minced
2 x 400 gram cans chopped tomatoes
1 – 1.5 teaspoons of harissa paste
2 teaspoons of pure maple syrup
2 cans cannellini beans, rinsed well and drained
1 cup of fresh parsley, washed well and roughly chopped
1 bunch of fresh coriander, washed well, stems finely diced, leaves roughly chopped
1/2 teaspoon salt/cracked black pepper
#optional – 1 teaspoon of dried chilli
Heat a small amount of oil in a large pan. Alternatively just use a little water and sauté the onion until softened. Add the garlic and cook on a gentle heat for another minute or two.
Add the crushed chopped tomatoes, harissa paste and maple syrup. Stir to combine and simmer gently for 10 minutes.
Add the beans. Stir through the parsley and coriander. Bring everything to the boil.
Check the seasoning. Add some chilli flakes if you want more heat.
Serving suggestion: This is lovely served with cous cous, steamed maple carrots, loads of salad dressed in fresh lime juice and olive oil. Fresh bread to mop up all the juices is also a great accompaniment.
Yields: 4 small serves
Time: Takes about 30 minutes.
Notes: Harissa paste is available in well stocked delis.
I often also add a generous handful of good quality Kalamata olives to this dish, when I add the beans.
If you have left overs, this is delicious on toast the next day.
 The Kind Cook, http://thekindcook.com/; http://thekindcook.com/harissa-bean-tagine/ (Used with permission.) Also: https://www.facebook.com/thekindcook; http://twitter.com/TheKindCook; http://pinterest.com/thekindcook/; http://instagram.com/thekindcook/
 Food and Agriculture Organization of the United Nations, “Tackling climate change through livestock: A global assessment of emissions and mitigation opportunities”, Nov 2013, http://www.fao.org/ag/againfo/resources/en/publications/tackling_climate_change/index.htm; http://www.fao.org/docrep/018/i3437e/i3437e.pdf
 Food and Agriculture Organization of the United Nations, “Greenhouse gas emissions from ruminant supply chains: A global life cycle assessment”, Nov 2013, http://www.fao.org/ag/againfo/resources/en/publications/tackling_climate_change/index.htm; http://www.fao.org/docrep/018/i3461e/i3461e.pdf
 FAOSTAT, Livestock Primary, 2013, http://faostat.fao.org/site/569/DesktopDefault.aspx?PageID=569#ancor, accessed 27 June, 2015 (Actual numbers: Australia 2,480,458 tonnes; New Zealand 572,628 tonnes)
 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, http://link.springer.com/article/10.1007%2Fs10584-014-1169-1
 Lindenmayer, D. and Burgman, M., “Practical Conservation Biology” (2005, CSIRO Publishing), p. 235, http://www.publish.csiro.au/onborrowedtime/docs/PCB_Ch09.pdf and http://www.publish.csiro.au/pid/5034.htm
 FAOSTAT, Live Animals, 2012, http://faostat.fao.org/site/573/DesktopDefault.aspx?PageID=573#ancor, accessed 12 May, 2014. (Actual number: 471,875,000 of a global population of 966,170,968)
 Brown, L.R., “Full Planet, Empty Plates: The New Geopolitics of Food Scarcity, Chapter 9, China and the Soybean Challenge”, Earth Policy Institute, 6 November, 2013, http://www.earthpolicy.org/books/fpep/fpepch9
 Craig, W.J., Mangels, A.R., American Dietetic Association, “Position of the American Dietetic Association: vegetarian diets.”, J Am Diet Assoc. 2009 Jul;109(7):1266-82, http://www.ncbi.nlm.nih.gov/pubmed/19562864
 Nowson, C.A., McGrath, J.J., Ebeling, P.R., Haikerwal, A., Daly, R.M., Sanders, K.M., Seibel, M.J. and Mason, R.S., “Vitamin D and health in adults in Australia and New Zealand: a position statement”, Med J Aust 2012; 196 (11): 686-687, doi: 10.5694/mja11.10301, https://www.mja.com.au/journal/2012/196/11/vitamin-d-and-health-adults-australia-and-new-zealand-position-statement
 Trafton, A., “MIT biologists solve vitamin puzzle”, MIT News, 21 March, 2007, http://newsoffice.mit.edu/2007/b12 and McDougall, J., “Vitamin B12 Deficiency—the Meat-eaters’ Last Stand”, McDougall Newsletter, Vol. 6, No. 11, Nov, 2007, https://www.drmcdougall.com/misc/2007nl/nov/b12.htm