Content uploaded by Mike Joy
Author content
All content in this area was uploaded by Mike Joy on Jun 19, 2017
Content may be subject to copyright.
Our deadly nitrogen addiction
Humanity is facing an unprecedented dilemma – how to feed a burgeoning population while still
maintaining the life supporting capacity of the planet. The predicament becomes more intractable as
human population and appetites grow, resources decline, and the ability of the earth’s ecosystems
and atmosphere to absorb pollution diminishes.
A scientific breakthrough made a hundred years ago is at the heart of the problems. It allowed
humans to exploit ancient energy to enhance plant growth, but, sadly it turns out the process
threatens the very life supporting capacity of the planet. The breakthrough was the Haber-Bosch
process1 which enabled the use of fossil energy, stored over millennia, to transform ubiquitous
atmospheric nitrogen into a form that plants can use. The resulting product - nitrogen fertiliser
enabled the ‘green revolution’ a massive increase in food production. For most of history nature
fixed atmospheric nitrogen mainly through leguminous plants, blue-green algae and lightening. But
now using fossil energy, the flux of anthropogenic nitrogen into the atmosphere, soils and water has
increased ten-fold over all natural sources1.
An indication of the importance of synthetic nitrogen is that it has allowed the current human
population to reach double the 3.5 billion that could have been be sustained without it. Since the
discovery world population growth and the increase in nitrogen fertiliser production have been in
sync2. Now we are on track to reach a world population of more than nine billion by 20503, three
times what could have been supported without synthetic nitrogen.
Overdose?
Like a wonder drug that only later you discover has terrible side effects, it is becoming increasingly
obvious that the Haber-Bosch process opened up a Pandora’s Box of problems that now threaten
the very existence of humankind. By exploiting energy built-up over millennia, in a single century we
have radically altered the ecological balance of agricultural systems. The distortion then triggered a
proliferation of livestock so that the synthetically enhanced food system is now responsible for more
than a quarter of all anthropogenic greenhouse gas (GHG) emissions, is the dominant driver of
deforestation and biodiversity loss and is a major user and polluter of water resources4. Nitrogen is
not the only fossil derived part of the problem, oil is another culprit. On top of the nitrogen footprint
our industrial food production system now uses over 10 calories of oil energy to plough, plant,
1 On 13 October 1908, Fritz Haber filed his patent on the "synthesis of ammonia from its elements" for which
he was later awarded the 1918 Nobel Prize in Chemistry.
fertilise, harvest, transport, refine, package, store/refrigerate, and deliver 1 calorie of food to be
eaten by humans5.
A graphic example of the human food domination of the planet enabled primarily by synthetic
nitrogen and fossil fuel derived energy is that in the last 100 years the biomass of domestic animals
on the planet quadrupled. By the beginning of this century ninety-eight percent of the total biomass
of terrestrial mammals on the planet was humans and the animals that feed them, leaving only two
percent as wild animals6.
Despite the intensification of agriculture, mainly through fossil energy (nitrogen and oil) we still have
nearly a billion people suffering from inadequate and insecure diets, while another 2.1 billion people
have become obese or overweight due to a move to highly processed foods high in refined sugar,
refined fats, oils and meats7. Thus an important first step to feed the world without destroying it
must be to address this inequality, stop food waste but that alone will not be enough.
A one-off bonanza
It’s not just the environmental impacts of the artificial nitrogen driven intensification that threatens
the future of humankind, but also the fact that the very fossil fuels that drove the inherently
unsustainable population growth are dwindling. Demand for nitrogen fertiliser is expected to
continue to increase by 4 percent annually8 but easily obtained gas is declining, so this production
will increasingly rely on fracked wells for gas. Fracked gas has many environmental issues and is very
inefficient compared to conventional wells. For example, fracked gas wells leak 40 to 60 percent
more methane9. Also, as fossil gas supplies diminish, their extraction becomes more energy
intensive. The energy return on investment for gas is declining so at some point we inevitably must
face the disastrous dilemma that we have a population many times higher than can be nourished
without fossil energy10.
Leaky systems
One of the main reasons synthetic nitrogen fertiliser has so many impacts is that most of it doesn’t
end up where it was intended. Only around 17 percent of the amount applied as fertiliser makes it
into crops or animal products consumed by humans11. The rest is lost to the environment where
mostly it does harm. The bulk of the reactive nitrogen2 leaks into aquatic systems where it does
2 Reactive nitrogen is a term used for a variety of nitrogen compounds that support growth directly or
indirectly Representative species include the gases nitrogen oxides (NOx), ammonia (NH3), nitrous oxide
(N2O), as well as the anion nitrate (NO3
−)
damage mainly through accelerated eutrophication. Accelerated eutrophication is simply an
unnatural excess of nutrients that often drives algal blooms which have many impacts, often the
worst being a reduction of available oxygen in water killing aquatic life. This eutrophication,
primarily from agricultural sources has contributed to the many eutrophic lakes and rivers but it
doesn’t end there, the rest makes it to oceans. Theses nutrients in oceans have created over 400
oceanic dead zones worldwide, primarily concentrated in Europe, eastern and southern US, and
Southeast Asia. In total, these dead zones cover a total area of 245,000 square kilometres, similar to
the total land area of New Zealand. Part of the inefficiency of nitrogen fertiliser is that livestock are
wasteful in their conversion. For example in the European Union livestock consume around 85
percent of the 14 million tonnes of nitrogen in crops harvested or imported into the EU but only 15
percent goes to feed humans directly12.
Another example of the leakage is nitrogen fertiliser loss to the atmosphere - the IPCC estimated
that for every 100 kg of nitrate fertiliser applied to soil, one kg ends up in the atmosphere as nitrous
oxide (N2O)3, a gas 300 times more potent a GHG than CO2 and N20 is the most ozone-depleting gas.
This creation of nitrous oxide can be seen in a 17 percent increase since the pre-industrial era from
below 270 ppb in the atmosphere to more than 320 ppb now13.
An expensive addiction
While nitrogen fertiliser undoubtedly increases production, the negative impacts including the costs
to clean up and costs to human health are huge. These expenses are known as externalities because
they are not paid by industry rather they are left for others to pay. For example EU farmers add 11
million tonnes of reactive nitrogen in fertiliser annually giving them a direct benefit of €20 – €80
billion when long-term gains are included. However, the cost to society of excess nitrogen for the
EU was estimated to be between €70 billion and €320 billion per year. These costs were based on
estimates of the price of damage to human health, ecosystems and biodiversity loss14. Thus, the
costs far outweigh the value that nitrogen fertilisers add.
In New Zealand the ratio of nitrogen costs to gains is likely to be similar – put simply, they constitute
a net loss for society. One facet of the environmental costs of nitrogen pollution of freshwaters in
New Zealand can be quantified by what it costs to remove it from waterways like lakes and this
highlights the extent of the externalising to society of industry incurred costs. Trials in Lake Rotorua
showed it cost a minimum of $250 to remove 1 kg of nitrogen from the lake15, whereas to not use a
3 This IPCC estimate is thought to be an underestimate by a factor of 2 or more http://www.nine-
esf.org/node/360/ENA-Book.html
kilogram of nitrogen fertiliser on farm would mean a loss of revenue for the farmer of around $616.
Another example of the costs of nitrogen pollution; the Bay of Plenty Regional Council is currently
paying farmers to de-intensify their farming in the lake catchment order to stop 100 tonnes of
reactive nitrogen entering the lake. One hundred tonnes is the amount that has been estimated
that must be reduced to stop the lake clarity declining17. The regional council have a $40 million tax
and ratepayer clean-up fund for the lake and so are paying polluters $400 for every kilogram of
nitrogen they currently leach, paying them to not leach it in the Lake Rotorua catchment.
Planetary boundaries
All these impacts add up to major reductions in the life supporting capacity of the planet. In an
attempt to quantify the limits, analysis has been done by the Stockholm Institute into planetary
boundaries to find the tipping points that must not be exceeded for humankind to continue to
exist18. Their analysis revealed that of the ten boundaries identified, three; biodiversity, the nitrogen
cycle and climate change have been drastically surpassed. The nitrogen cycle is already more than
three times the safe limit; biodiversity loss is more than ten times the limit and with CO2 at 400 ppm
in the atmosphere climate change is well past the 350 ppm CO2 boundary.
Livestock a big chunk of GHG emissions
The global food system, boosted by synthetic nitrogen, is responsible for more than a quarter of all
human induced GHG emissions19. Livestock are responsible for around 15 percent of all
anthropogenic GHG emissions, 37 percent of all anthropogenic methane emissions, and 65 percent
of all nitrous oxide emissions20. Within the livestock sector almost half of the emissions are in the
form of methane (CH4); the remaining part is almost equally shared between nitrous oxide (N2O) and
carbon dioxide (CO2). Of the livestock production emissions, the majority are from beef (41 percent)
and cattle milk (20 percent). Breaking down the livestock emissions further, ruminants are far and
away the biggest problem, responsible for about 12 percent of all anthropogenic greenhouse gas
(GHG) emissions21,22. In 2011 the estimated 3.6 billion domestic ruminants23 on the planet were
responsible for more than 80 percent of the total livestock-related GHG emissions24.
Livestock impacts the story just gets worse
While livestock provide a third of the dietary protein for humans especially in developing countries
they have massive environmental footprint over and above the considerable climate change
implications25,26. Globally livestock are responsible for an estimated 55 percent of the sedimentation
of waterways through accelerated erosion, 37 percent of pesticide use, 50 percent of all antibiotic
use, and 64 percent of ammonia loss and a third of the anthropogenic loads of nitrogen and
phosphorus to freshwater resources27. Livestock are also very inefficient at energy conversion; they
consume 77 million tonnes of human edible protein contained in feedstuff that could potentially be
used for human nutrition, whereas they supply only 58 million tonnes of protein in food products for
humans28.
Livestock and landuse
Of all human land uses, livestock occupies the largest share, around 70 percent of all agricultural
land and one third of the land surface of the planet. Around 20 – 30 percent of the global ice free
area total is used for grazing, and around a third of cultivated land area is used for their feed and
forage29, and expansion of livestock is a major driver of land-use conversion30. Between 1980 and
2000, 83 percent of agricultural land expansion in the tropics occurred at the expense of forests, and
livestock were a major contributor31.
Benefits of livestock
Clearly livestock numbers now threaten the very life supporting capacity of the planet. But at
sustainable densities they also have ecological benefits. For example, livestock create human food
from inedible sources, they can conserve grassland ecosystems, and they help recycle nutrients and
can provide many social benefits32.
How do we feed the world sustainably?
All the evidence is clear that the ability of the planet to provide enough food for the extra 80 million
mouths to feed every year is likely to decline. Two fatal trajectories are converging and if they meet
humankind will pass a crucial threshold into a bleak future. The first trajectory is the declining
amount and quality of available land, declining fossil fuel availability to make nitrogen fertiliser,
declining water quality, and declining wild fisheries. The second trajectory is increasing human
population, increasing animal products in diets and increasing food wastage. Climate change is
speeding up the convergence of the two trajectories, so we are fast running out of options. Given
that one major driver pushing us over the planetary boundaries is our current food system,
especially the livestock sector then for humankind to continue the solution must be to radically
change the way we live and what we eat.
Techno fixes?
While there are undoubtedly technological and efficiency gains to be made through precision
agriculture and irrigation and there are great potential for reductions in food waste as mitigation
options33, most of the agricultural GHG emissions are intrinsic to the current livestock centred
agricultural system. Furthermore, as population and diets increase exponentially the small gains are
negated by a net increase in production volume and associated impacts. Also, because most
methane emissions come from ruminants and nitrous oxide emissions from fertilizers then they can
only be addressed by reducing the animal component of food particularly ruminants34.
Dietary choice solutions - reducing livestock consumption a win-win
Human health
Reducing meat consumption can have many positive effects for the environment and human health.
High levels of meat consumption in developed countries are strongly correlated with rates of
diseases such as obesity, diabetes some cancers and heart disease35. Reducing meat and replacing it
with high protein plant foods is associated with significant health benefits36. A recent study revealed
that if global diets reduced their reliance on meat it could lead to healthcare-related savings and
avoid climate damages of $1.5 trillion by 2050. Additionally it would lead to a reduction of mortality
of 6 – 10 percent and reduction of 29 – 70 percent of GHG emissions. A recent global study found
that adopting diets in line with global dietary guidelines could avoid 5.1 million human deaths per
year by 205037. Even greater benefits could come from vegetarian diets (avoiding 7.3 million deaths)
and vegan diets (avoiding 8.1 million deaths, and billions of animal deaths). Approximately half of
the avoided deaths would come from a reduction of red meat consumption, with the other half due
to a combination of increased fruit and vegetable intake and a reduction in calories, leading to fewer
people being overweight or obese.
Nitrogen footprint studies clearly reveal the differences in impacts with different diets. For example
the per capita N footprint in the United States is 41 kg N/yr whereas in the Netherlands it is 25 kg
N/yr. These differences are mainly a result of the more meat oriented US diet compared to the more
dairy, eggs and fish diet in the Netherlands.
Another human health issue that could be addressed by reducing livestock consumption is antibiotic
resistance. The widespread preventive use of antibiotics in industrial animal production systems has
exacerbated the problem of bacterial resistance to antibiotics with half of all antibiotics produced
used in agriculture38. This represents a significant health risk for humans39 confronted with
pathogens that have accumulated resistance to virtually all existing antibiotics40. The World Health
Organisation have stated that: “without urgent action we are heading for a post-antibiotic era, in
which common infections and minor injuries can once again kill”
Eutrophication and water-use
Dietary choices can hugely influence environmental impacts of food. For example, red meat has the
highest eutrophication potential of foods, followed by dairy products, chicken/eggs and then fish.
The cereal and carbohydrate (cereal/carbs) food group is identified to have the lowest nutrient
footprint among all food sub-groups. Producing, processing, transporting, and packaging 1kg of red
meat generates on average 150g nitrogen-equivalent emissions, whereas to supply 1kg cereal/carbs
results in around 2.6g nitrogen equivalent emissions41.
Depending on the system, livestock can use copious amounts of water. Mostly it goes to irrigate
crops. There have been many estimates of litres per kilogram of protein but most agree that at least
8 times more water is used per kg for a meat diet than that needed for a vegetarian diet42. Livestock
systems also in many cases limit the quality of available water through eutrophication resulting from
their farming.
Land area
Another limitation to feeding the world’s population is the availability of land to grow food. Many
studies have shown much less land is required if protein goes directly to humans rather than via
animals. As an example a comprehensive study of the area of land required to feed humans over a
range of diets in the USA revealed that a vegetarian diet used on average one eighth of the area
needed for a current omnivorous diet43. But livestock farming can take place on land not suitable for
crop production so making comparisons is difficult.
Tax to pay for impacts and drive diet change?
One way to achieve dietary change is to use specific taxes; in a tax study researchers found that beef
would have to be 40 percent more expensive globally to pay for the climate damage caused by its
production. They found that the price of milk and other meats would need to increase by up to 20
percent, and the price of vegetable oils would also increase significantly. The researchers estimated
that such price increases would result in around 10 percent lower consumption of the food items
that are high in GHG emissions44.
Climate change : the ultimate threat
Of the three planetary boundary overshoots, undoubtedly the most pressing is climate change. The
World Health Organisation says it is now the biggest threat to human health45. Lord Stern following
up on his 2006 review on the economics of climate change46 recently said that he had
underestimated the risks; as the planet and the atmosphere seem to be absorbing less carbon than
we expected, emissions are rising strongly and that we are on track for an average temperature rise
of four degrees47. This catastrophe will inevitably also have major impacts on the ability of the
planet to provide enough food for the total human population.
The hottest year on record for New Zealand, and the world was 201648. This was also the first year
that all the global monitoring sites exceeded 400ppm CO2 and this marks the highest point that CO2
has been in the last 3 million years. The last time CO2 was this high, sea levels were 10 – 20m higher
than now49. To try and keep global temperatures at a liveable temperature we have a budget of
GHG emissions we must not exceed. If we do nothing, at current emission rates we will have used
up the emission budget to limit temperature rise to 2oC budget50 in 20 years and four or five years
for limit to 1.5oC. The message is clear we must act now. There is no time to spare.
The New Zealand situation
Synthetic nitrogen is applied as urea in New Zealand and its use has increased dramatically over the
last few decades. Its importation mainly from the Middle East steadily increased from 58 tonnes in
1990 to more than 600,000 tonnes in 201651 and approximately another third (260,000 tonnes) is
produced in the country from Taranaki gas fields52. This increase in nitrogen fertiliser use has been
matched by livestock intensification illustrated by a 460 percent increase in dairy exports between
1990 and 201053. The impacts of this intensification in New Zealand on the environment are
becoming more and more obvious. Almost daily in summertime there are new stories of rivers, lakes
and groundwater becoming undrinkable and unswimmable54. Freshwater monitoring shows quality
and quantity impacts in all intensively livestock farmed areas55 and freshwater pollution events are
exacerbated by climate change with predicted drying on the east coast and more extreme rainfall
events.
Most of the media coverage around climate change has been focused on CO2 emissions, with
transport and energy receiving the biggest coverage. This is an odd situation given that the non CO2
emissions are proportionally more than the entire global transport system56. Non-CO2 GHG
emissions contribute about one-third of total anthropogenic CO2 equivalent emissions and 35-45
percent of climate forcing resulting from those emissions57.
In New Zealand the climate change implications of livestock receive little publicity and despite the
obvious climatic changes already occurring. So far the only response from government is to look for
technological fixes for methane emission from ruminants. Rather than pushing for reductions in
livestock numbers the Ministry for Primary industries is predicting growth in livestock numbers and
production58, and the government is calling for and funding growth in animal agriculture with its
Primary Growth Partnerships59. So despite ample evidence of the impacts of livestock on
freshwaters and the climate there is little sign of any limitation or reduction in the numbers of
livestock from government central or local. In addition, despite the impacts of climate change
becoming more obvious agriculture has been left out of the emissions trading scheme.
The only significant sign of recognition of the issues of livestock farming has come from New Zealand
biggest farmer the State-Owned Enterprise Landcorp, who recently announced they would stop
using imported palm kernel expeller and become carbon neutral in decade60.
There are many examples from studies in other parts of the world showing that more people can be
fed from the same land area and with significantly lowered environmental and health impacts when
livestock numbers are reduced. While undoubtedly there are areas of New Zealand where livestock
and forestry are the only options, there are large lowland areas where more diverse farming systems
not dominated by livestock could see a much more sustainable outcome. A switch away from
livestock and synthetic nitrogen would mean that we could feed more people a more healthy diet,
and not destroy waterways and increase the chances of having a liveable atmosphere. While New
Zealand may be relatively immune to many global crises, climate change is not one of them.
Conclusions
There is clear evidence that if we continue on our present path then GHG emissions from food and
agriculture will dramatically increase, with a predicted 80 percent increase by mid-century, due to
population growth and dietary changes moving toward animal-based foods that are more emissions-
intensive61. If we do nothing by 2050, food related GHG emissions could account for up to half of the
total emissions 62. We have ignored non-CO2 emissions for too long now and the biggest component
of those emissions is from livestock particularly ruminants. It’s simply a ‘them or us’ choice, if we
don’t drastically reduce livestock from diets, as we reduce other GHG emissions we have no future.
1 UNEP and WHRC. 2007. Reactive Nitrogen in the Environment: Too Much or Too Little of a Good Thing. Paris.
2 Erisman, J. W., M. A. Sutton, J. Galloway, Z. Klimont, and W. Winiwarter. 2008. How a century of ammonia
synthesis changed the world. Nature Geoscience 1:636-639.
3 https://esa.un.org/unpd/wpp/publications/Files/WPP2015_DataBooklet.pdf accessed 04/02/2017
4 Vermeulen, S. J., B. M. Campbell, and J. S. I. Ingram. 2012. Climate Change and Food Systems. Pages 195-+ in
A. Gadgil and D. M. Liverman, editors. Annual Review of Environment and Resources, Vol 37.; Steinfeld, H. et
al. Livestock's Long Shadow (FAO, 2006). Tubiello, F. N. et al. (2012) Agriculture, Forestry and Other Land
Use Emissions by Sources and Removals by Sinks: 1990_2011 Analysis (FAO Statistical Division).
5 Neff, R. A., C. L. Parker, F. L. Kirschenmann, J. Tinch, and R. S. Lawrence. 2011. Peak Oil, Food Systems, and
Public Health. American Journal of Public Health 101:1587-1597.
6 Smil, V. 2003. The Earth’s Biosphere: Evolution, Dynamics, and Change The MIT Press.
7 Tilman, D., and M. Clark. 2014. Global diets link environmental sustainability and human health. Nature
515:518.
8 FAO, "World fertiliser trends and outlook to 2018", 2015: http://www.fao.org/3/a-i4324e.pdf
9 Mark Fischetti,"Fracking would emit large quantities of greenhouse gases,", Scientific American, January
2012: http://www.scientificamerican.com/article/fracking-would-emit-methane/
10 Erisman, J. W., M. A. Sutton, J. Galloway, Z. Klimont, and W. Winiwarter. 2008. How a century of ammonia
synthesis changed the world. Nature Geoscience 1:636-639.
11 http://www.unep.org/pdf/dtie/Reactive_Nitrogen.pdf
12 Mark A. Sutton, Clare M. Howard, Jan Willem Erisman, Gilles Billen, Albert Bleeker, Peringe Grennfelt, Hans
van Grinsven, and B. Grizzetti. 2011. The European Nitrogen Assessment: Sources, Effects and Policy
Perspectives. Cambridge University Press.
13 Park, S., P. Croteau, K. A. Boering, D. M. Etheridge, D. Ferretti, P. J. Fraser, K. R. Kim, P. B. Krummel, R. L.
Langenfelds, T. D. van Ommen, L. P. Steele, and C. M. Trudinger. 2012. Trends and seasonal cycles in the
isotopic composition of nitrous oxide since 1940. Nature Geoscience 5:261-265.
14 Sutton, M. A., O. Oenema, J. W. Erisman, A. Leip, H. van Grinsven, and W. Winiwarter. 2011. Too much of a
good thing. Nature 472:159-161.
15 Foote, K. J., M. K. Joy, and R. G. Death. 2015. New Zealand Dairy Farming: Milking Our Environment for All
Its Worth. Environmental Management 56:709-720.
16 Joy, M. K. 2015. Polluted inheritance; New Zealand's freshwater crisis Bridget Williams Books, Wellington.
17http://www.nzherald.co.nz/rotorua-daily-post/news/article.cfm?c_id=1503438&objectid=11430926
retrieved 03/02/2017
18 Rockstrom, J., W. Steffen, K. Noone, A. Persson, F. S. Chapin, E. F. Lambin, T. M. Lenton, M. Scheffer, C.
Folke, H. J. Schellnhuber, B. Nykvist, C. A. de Wit, T. Hughes, S. van der Leeuw, H. Rodhe, S. Sorlin, P. K.
Snyder, R. Costanza, U. Svedin, M. Falkenmark, L. Karlberg, R. W. Corell, V. J. Fabry, J. Hansen, B. Walker, D.
Liverman, K. Richardson, P. Crutzen, and J. A. Foley. 2009. A safe operating space for humanity. Nature
461:472-475.
19 Vermeulen, S. J., B. M. Campbell, and J. S. I. Ingram. 2012. Climate Change and Food Systems. Pages 195-+
in A. Gadgil and D. M. Liverman, editors. Annual Review of Environment and Resources, Vol 37.; Steinfeld, H.
et al. Livestock's Long Shadow (FAO, 2006). Tubiello, F. N. et al. (2012) Agriculture, Forestry and Other Land
Use Emissions by Sources and Removals by Sinks: 1990_2011 Analysis (FAO Statistical Division).
20 Gerber, P.J., Steinfeld, H., Henderson, B., Mottet, A., Opio, C., Dijkman, J., Falcucci, A. & Tempio, G. 2013.
Tackling climate change through livestock – A global assessment of emissions and mitigation opportunities.
Food and Agriculture Organization of the United Nations (FAO), Rome.
21 Westhoek H, et al. The Protein Puzzle. The Hague: PBL Netherlands Environmental Assessment Agency;
2011
22 Climate change mitigation through livestock system transitions. Proceedings of the National Academy of
Sciences of the United States of America 111:3709-3714
23 Ripple, W. J., P. Smith, H. Haberl, S. A. Montzka, C. McAlpine, and D. H. Boucher. 2014. COMMENTARY:
Ruminants, climate change and climate policy. Nature Climate Change 4:2-5.
24 Herrero, M., P. Havlik, H. Valin, A. Notenbaert, M. C. Rufino, P. K. Thornton, M. Bluemmel, F. Weiss, D.
Grace, and M. Obersteiner. 2013. Biomass use, production, feed efficiencies and greenhouse gas emissions
from global livestock systems. Proceedings of the National Academy of Sciences of the United States of
America 110:20888-20893.
25 Moll, H. A. J. 2005. Costs and benefits of livestock systems and the role of market and nonmarket
relationships (vol 32, pg 181, 2005). Agricultural Economics 33:130-130.
26 Herrero, M., P. K. Thornton, A. M. Notenbaert, S. Wood, S. Msangi, H. A. Freeman, D. Bossio, J. Dixon, M.
Peters, J. van de Steeg, J. Lynam, P. P. Rao, S. Macmillan, B. Gerard, J. McDermott, C. Sere, and M. Rosegrant.
2010. Smart Investments in Sustainable Food Production: Revisiting Mixed Crop-Livestock Systems. Science
327:822-825.
27 Steinfeld, H. 2006. Livestock's Long Shadow; environmental issues and options. Food and Agriculture
Organisation, Rome.
28 Steinfeld, H. 2006. Livestock's Long Shadow; environmental issues and options. Food and Agriculture
Organisation, Rome (page 270).
29 Janzen, H. H. 2011. What place for livestock on a re-greening earth? Animal Feed Science and Technology
166-67:783-796.
30 Geist, H. J., and E. F. Lambin. 2002. Proximate causes and underlying driving forces of tropical deforestation.
Bioscience 52:143-150.
31 Gibbs, H. K., A. S. Ruesch, F. Achard, M. K. Clayton, P. Holmgren, N. Ramankutty, and J. A. Foley. 2010.
Tropical forests were the primary sources of new agricultural land in the 1980s and 1990s. Proceedings of the
National Academy of Sciences of the United States of America 107:16732-16737.
32 Janzen, H. H. 2011. What place for livestock on a re-greening earth? Animal Feed Science and Technology
166-67:783-796.
33 Smith, P., D. Martino, Z. Cai, D. Gwary, H. Janzen, P. Kumar, B. McCarl, S. Ogle, F. O'Mara, C. Rice, B. Scholes,
O. Sirotenko, M. Howden, T. McAllister, G. Pan, V. Romanenkov, U. Schneider, S. Towprayoon, M.
Wattenbach, and J. Smith. 2008. Greenhouse gas mitigation in agriculture. Philosophical Transactions of the
Royal Society B-Biological Sciences 363:789-813; Climate change mitigation through livestock system
transitions. Proceedings of the National Academy of Sciences of the United States of America 111:3709-3714.
34 Golub, A. A., B. B. Henderson, T. W. Hertel, P. J. Gerber, S. K. Rose, and B. Sohngen. 2013. Global climate
policy impacts on livestock, land use, livelihoods, and food security. Proceedings of the National Academy of
Sciences of the United States of America 110:20894-20899.; Havlik, P., H. Valin, M. Herrero, M. Obersteiner,
E. Schmid, M. C. Rufino, A. Mosnier, P. K. Thornton, H. Bottcher, R. T. Conant, S. Frank, S. Fritz, S. Fuss, F.
Kraxner, and A. Notenbaert. 2014. Climate change mitigation through livestock system transitions.
Proceedings of the National Academy of Sciences of the United States of America 111:3709-3714.
35 Fraser, G. E. 2009. Vegetarian diets: what do we know of their effects on common chronic diseases? (vol 89,
pg. 1607, 2009). American Journal of Clinical Nutrition 90:248-248.
36 Craig, W. J., A. R. Mangels, and Ada. 2009. Position of the American Dietetic Association: Vegetarian Diets.
Journal of the American Dietetic Association 109:1266-1282.
37 Springmann, M., H. C. J. Godfray, M. Rayner, and P. Scarborough. 2016. Analysis and valuation of the health
and climate change co-benefits of dietary change. Proceedings of the National Academy of Sciences of the
United States of America 113:4146-4151.
38 Carlet, J., V. Jarlier, S. Harbarth, A. Voss, H. Goossens, D. Pittet, and I. rd World Healthcare-Associated. 2012.
Ready for a world without antibiotics? The Pensieres Antibiotic Resistance Call to Action. Antimicrobial
Resistance and Infection Control 1.
39 Carlet, J., V. Jarlier, S. Harbarth, A. Voss, H. Goossens, D. Pittet, and I. rd World Healthcare-Associated. 2012.
Ready for a world without antibiotics? The Pensieres Antibiotic Resistance Call to Action. Antimicrobial
Resistance and Infection Control 1.
40 Chowdhury, P. R., J. McKinnon, E. Wyrsch, J. M. Hammond, I. G. Charles, and S. P. Djordjevic. 2014. Genomic
interplay in bacterial communities: implications for growth promoting practices in animal husbandry.
Frontiers in Microbiology 5.
41 Xue, X., and A. E. Landis. 2010. Eutrophication Potential of Food Consumption Patterns. Environmental
Science & Technology 44:6450-6456.
42 Janzen, H. H. 2011. What place for livestock on a re-greening earth? Animal Feed Science and Technology
166-67:783-796.
43 Christian J. Peters , Jamie Picardy, Amelia F. Darrouzet-Nardi, Jennifer L. Wilkins, Timothy S. Griffin, and G.
W. Fick. 2016. Carrying capacity of U.S. agricultural land: Ten diet scenarios. Elementa 4:116.
44 Springmann, M., H. C. J. Godfray, M. Rayner, and P. Scarborough. 2016. Analysis and valuation of the health
and climate change co-benefits of dietary change. Proceedings of the National Academy of Sciences of the
United States of America 113:4146-4151.
45 WHO, 2016. Preventing disease through healthy environments: A global assessment of the burden of disease
from environmental risks. World Health Organization, Geneva.
46http://webarchive.nationalarchives.gov.uk/20130129110402/http://www.hmtreasury.gov.uk/d/CLOSED_SH
ORT_executive_summary.pdf
47http://webarchive.nationalarchives.gov.uk/20100407172811/http://www.hmtreasury.gov.uk/stern_review_
report.htm
48 https://www.nasa.gov/feature/goddard/2016/climate-trends-continue-to-break-records
49 Masson-Delmotte, V., M. Schulz, A. Abe-Ouchi, J. Beer, A. Ganopolski, J.F. González Rouco, E. Jansen, K.
Lambeck, J. Luterbacher, T. Naish, T. Osborn, B. Otto-Bliesner, T. Quinn, R. Ramesh, M. Rojas, X. Shao and A.
Timmermann, 2013: Information from Paleoclimate Archives. In: Climate Change 2013: The Physical Science
Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on
Climate Change [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.
50 Meinshausen, M., N. Meinshausen, W. Hare, S. C. B. Raper, K. Frieler, R. Knutti, D. J. Frame, and M. R. Allen.
2009. Greenhouse-gas emission targets for limiting global warming to 2 degrees C. Nature 458:1158-U1196.
51 http://www.stats.govt.nz/infoshare/ViewDataOptions.aspx?pxID=86f8384d-e307-4c7d-a8bd-d24ca109f49a
52 http://business.taranaki.info/casestudy_detail.php/id/50/from/229
53 Foote, K. J., M. K. Joy, and R. G. Death. 2015. New Zealand Dairy Farming: Milking Our Environment for All Its
Worth. Environmental Management 56:709-720.
54 Joy, M. K. 2015. Polluted inheritance; New Zealand's freshwater crisis; Bridget Williams Books, Wellington.
55 Parliamentary Commissioner for the Environment. 2013. Water quality in New Zealand: Land use and
nutrient pollution. http://www.pce.parliament.nz/media/1275/pce-water-quality-land-use-web-
amended.pdf
56 Steinfeld, H. 2006. Livestock's Long Shadow; environmental issues and options. Food and Agriculture
Organisation, Rome.
57 Montzka, S. A., E. J. Dlugokencky, and J. H. Butler. 2011. Non-CO2 greenhouse gases and climate change.
Nature 476:43-50.
58 www.mpi.govt.nz/document-vault/12630
59 https://www.horizons.govt.nz/HRC/media/Media/Accelerate%2025/Accelerate25-Prospects-Report-as-at-
January-2016.pdf?ext=.pdf
60 http://www.radionz.co.nz/news/rural/292144/nz's-largest-farmer-makes-climate-pledge
61 Popp, A., H. Lotze-Campen, and B. Bodirsky. 2010. Food consumption, diet shifts and associated non-CO2
greenhouse gases from agricultural production. Global Environmental Change-Human and Policy Dimensions
20:451-462.; Hedenus, F.,Wirsenius, S. & Johansson, D. J. A. (2014) The importance of reduced meat and
dairy consumption for meeting stringent climate change targets. Climatic Change 124, 79_91. Tilman, D., and
M. Clark. 2014. Global diets link environmental sustainability and human health. Nature 515:518-+.; Bajzelj,
B., K. S. Richards, J. M. Allwood, P. Smith, J. S. Dennis, E. Curmi, and C. A. Gilligan. 2014. Importance of food-
demand management for climate mitigation. Nature Climate Change 4:924-929.; Springmann, M., H. C. J.
Godfray, M. Rayner, and P. Scarborough. 2016. Analysis and valuation of the health and climate change co-
benefits of dietary change. Proceedings of the National Academy of Sciences of the United States of America
113:4146-4151.
62 Springmann, M., H. C. J. Godfray, M. Rayner, and P. Scarborough. 2016. Analysis and valuation of the health
and climate change co-benefits of dietary change. Proceedings of the National Academy of Sciences of the
United States of America 113:4146-4151.
