Post written by R. Cretney.
You are what you eat – or so the
common saying goes. But as a global community are we what we eat? The issue of
how our personal dietary choices effects social and environmental issues has
long been a contentious issue. Considering the recent critique of the
undesirable impacts of quinoa’s popularity on poverty in Bolivia, it is
understandable that many are left confused over what is the best choice,
socially and environmentally. While the increase of organic, fair trade
products has eased the social conscience of some, the issue of greenhouse
gases, and in particular meat consumption, has proved a more tricky issue to
deal with.
Some advocate that a world dominated
by vegans and vegetarians is the only possible way to sustain the human
population on a planet with finite resources. But what does the science say to
support this?
Let us start with the issue of meat.
As is quite well known, particularly in New Zealand, ruminant animals release
Methane and Nitrous Oxide into the environment. These greenhouse gases (GHGs)
contribute to our emissions profile as a country and as individuals. But is the
complete elimination of meat and dairy products from our diets necessary?
A paper by Jennie MacDiarmid and others
released in 2012 suggests otherwise.
In this paper, the authors look at the optimum diet that maintains ideal
standards of nutrition while maximising the possible GHG reductions in the
United Kingdom. Food such as most vegetables, fruits and grains were considered
low greenhouse gas emitters, certain fruits and vegetables, eggs, chicken,
dairy products, nuts and sweet foods were considered moderate greenhouse gas
emitters while red meat, turkey, cheese, pork and fish were considered high
greenhouse gas emitters.
This backs up what many have argued,
that red meat contributes significantly to our carbon footprints. But the issue
is far from clear cut – the MacDiarmid (2012) article suggests that actually
the most nutritious yet low GHG diet includes red meat but in smaller
quantities than is currently consumed. Another recently released study by
Darmon and others in the American Journal of Clinical Nutrition also suggested
that moderation was key. This research studied the entire life cycle of the food
and took into account all GHGs produced except those resulting from transport
from the store to the home. The authors found that overall the emissions for
meat products were 15 times that of fruit and vegetables. However, when taking
into account the amount of energy in kilocalories that the food provided, meat
products only emitted 3 times the GHGs as a comparable amount of energy derived
from fruit and vegetables.
Darmon’s paper has been criticised by
some proponents of vegetarianism who pointed out that most vegetarians do not
eat the large quantity of vegetables that were used to compare emissions to a
small portion of meat. Instead they argue that because they eat less vegetables
than the nine pounds used, their carbon footprint is lower than the study
suggests. Regardless, Darmon’s research is still useful, especially in
combination with the MacDiarmid paper as both studies look into the
increasingly grey area of the impact of our food choices on climate change.
Here are some New Zealand figures
that compare the GHG per kilogram of meat or milk solids as food for thought.
The studies referred to before deal largely with European food production systems.
As Saunders and MacDonald (2011) note, several types of meat production in New
Zealand, such as lamb, are produced with much less emissions than those
produced in Europe. This information shows that unlike the MacDiarmid study,
New Zealand poultry and pork are actually low emitters (as opposed to moderate
emitters in Europe) while sources of red meat are still high emitters. To put
this data in context, a flight from Wellington to Auckland would release
approximately 67.1kg of Co2 per passenger. The source of this data is the
latest New Zealand legislation for emissions trading and the Air New Zealand
carbon calculator.
Type of food
|
Kilograms of Co2 e/per
kg at slaughter
(See Climate
Change (Agricultural Sector) Amendment Regulations 2012 Legislation)
|
Sheep, Beef and
Goat
|
12.7kg
|
Milk solids
|
8.5kg
|
Poultry
|
0.20kg
|
Deer
|
21.0kg
|
Pork
|
1.76kg
|
While we may not be able to expect the
entire world to become strict vegetarians, in the long run, a shift towards
less red meat intensive diets could encourage a reduction in GHG emissions
while acknowledging the importance of consuming meat for many economies and
cultures. In the meantime there are less GHG intensive farming options to
explore such as the adoption of more efficient farm management techniques.
These options can be explored by farmers in New Zealand who will be able to
market their products to those wishing to remain meat eaters while watching
their carbon footprint (Clark et al 2011).
Clark, H.; F. M. Kelliher and C Pinares-Patino. 2011.
"Reducing CH4 Emissions From Grazing Ruminants in New Zealand: Challenges
and Opportunities", Asian-Australian
Journal of Animal Science, 24:2, pp. 295-302.
Vieux, F., Darmon, N., Touazi, D., & Soler, L. G. (2012). Greenhouse gas emissions of self-selected individual diets in France: Changing the diet structure or consuming less?. Ecological Economics, 75, 91-101.
Macdiarmid, J. I., Kyle, J., Horgan, G. W., Loe, J., Fyfe, C., Johnstone, A., & McNeill, G. (2012). Sustainable diets for the future: can we contribute to reducing greenhouse gas emissions by eating a healthy diet?. The American journal of clinical nutrition, 96(3), 632-639.
Saunders, C., McDonald, H., Driver, T. 2011. “Enhancing
Value for New Zealand Farmers by
Improving the Value Chain”, Agribusiness
and Economics Research Unit Report No. 324.
