“We should eat less
meat in order to save the planet”, has almost become a dogma. There is no doubt
that industrial animal production is harmful for animals and nature. But the
framing of the path to a sustainable agriculture system in terms of how many
grams of potatoes, wheat and meat per day we should eat is to start in the
wrong end of the stick. Instead we should focus our interest into the
transition to a sustainable and regenerative food and agriculture system. Such a system would exclude or substantially reduce those foods which
are wasteful regardless if those are eggs from caged hens or asparagus flown
from one side of the globe to the other. With the right design animals, especially
ruminants such as cattle, sheep and goats, can be companions in this transition
rather than a problem.
The article Options for keeping the food system within
environmental limits published in Nature 10 October 2018 has the following key messages according to the lead
author, Marco Springmann:
- Climate change cannot be sufficiently mitigated without dietary changes towards more plant-based diets. Adopting more plant-based “flexitarian” diets globally could reduce the greenhouse gas emissions of the food system by more than half, and also reduce other environmental impacts, such as those from fertilizer application and the use of cropland and freshwater, by a tenth to a quarter.
- In addition to dietary changes, improving management practices and technologies in agriculture is required to limit pressures on agricultural land, freshwater extraction, and fertilizer use.
- Finally, halving food loss and waste is needed for keeping the food system within environmental limits.
Not surprising, media
featured the ”eat less meat” message strongly. But, what does the article
really tell us? The article is building scenarios to 2050. That is a nice
method to visualize possible implications of trends and possible options. However, the food system is a very dynamic
socio-ecological system where changes in one place will trigger a cascade of
changes in other places. “Small” details such as the invention of the shipping
container, a bird flu pandemic, antibiotic resistant bacteria, or a populist
president in the White house can have enormous impact, even on people’s diets.
It should be very clear that scenario building is not predicting the future.
The results are determined by the data put into
the model and the assumptions made, and will not prove anything else than what
is already determined by those, therefore it is essential that the assumptions are clearly expressed and
communicated together with the results. The choice of assumptions, the model
and the data put into the scenarios have some major flaws as follows (first the
main points of criticism, which are expanded upon later).
- The assumption for
economic growth doesn’t seem very realistic. The projection for land use is to
no extent based on a historical trend and disregard the enormous increase in
productivity in the farm sector.
- Their own data show
that livestock products don’t have a disproportionally big environmental impact
on four of the five impact categories compared with their contribution to human
nutrition, but their conclusions are implying the opposite.
- The allocation of
all environmental impact associated with livestock to meat and milk omits that
livestock has many other functions.
- When calculating greenhouse gas emissions,
Springmann et al do that only based on methane and nitrous oxide emissions,
thus excluding carbon dioxide, the greenhouse gas with the biggest impact of
them all. This systematically misrepresent livestock and in particular
ruminants.
- The expression of
methane emissions as carbon dioxide equivalents can be questioned, especially
when used for making scenarios for many decades.
- There is no mention
of the enormous variations and uncertainties regarding nitrous oxide emissions,
which potentially have a huge impact on the results.
- The research is supposedly
for the food system, but the results and comparisons between diets are about
agriculture raw materials. There are massive emissions in the rest of the food
chain which thus are neglected. Again, this systematically misrepresent
livestock, and in particular ruminants.
Projections and assumptions
The article assumes
that population will grow with 50 % and global income grow three times.
Considering the strong link between GDP and the minor decoupling of growth from
greenhouse gas emissions that can be observed, one could argue that we are
doomed with such projection regardless if we fix the food system or not.
The researchers also
assume that the demand for crop land will increase by a whopping 67 percent. Looking
back, that assumption seems unsubstantiated. The gross output of global
agriculture grew from 3,760 calories per capita to 5,740 calories per capita
between 1960 and 2012 while the population more than doubled and consumption of
animal products increased a lot. But during the same period global crop land
just increased by around 15 percent. The authors don’t give any convincing
explanation for this mismatch between their projection and historical trends.
Misrepresentation of animal products impact
This is not so much an
error of the research, but an error with the conclusions as they are
communicated by the lead author (see above). According to their own figures the
proportion of livestock’s impact for the five categories are (2010):
Greenhouse gas
emissions 72%
Cropland use 23 %
Bluewater use 10%
Nitrogen application
20%
Phosphorus application
20%
Animal products
contributes 18 percent of all calories, 40 percent of all protein and 45
percent of all dietary fats (FAOSTAT). The environmental burden of livestock
products is therefore not disproportionally
high with the exception of greenhouse gases (see more below). Considering that protein and dietary
fats are more limiting factors in the food system than calories or kilos are, one
could clearly argue the opposite.
Livestock’s multiple functions are ignored
While it is true that
in most developed countries the purpose of livestock keeping has, largely, been
reduced to the production of meat and milk, that is not a fair representation
of the real value of livestock. Increasingly, other functions of livestock are
recognized, such as maintaining bio-diversity, circulation of nutrients, use of
wastes, carbon sequestration etc. In many cultures where livestock keeping is
still a way of life the main purpose of livestock can be for draught power,
transport, insurance and savings and for
cultural and religious reasons. In some cultures livestock provides housing
(yurts, and manure/clay adobe) in others they are a source of cooking fuel.
Livestock also provide clothing, shoes and leather. It is arrogant and culturally
insensitive to brand animals primarily as commodities (do that to dogs or
horses and see which reactions you get in the Sweden, UK or the USA!). If other functions and values of livestock
are recognized, the costs and impacts of livestock also needs to be distributed
across those categories instead of being seen as a result of diets.
Calculation of greenhouse gas emissions biased
against ruminants
The authors base their
calculation of greenhouse gas emissions only
on methane and nitrous oxide, thus leaving carbon dioxide out of the equation.
They don’t provide a reasonable explanation for why they do like that. The
reason is probably how the IPCC classify emissions. Most people would assume
that for agriculture, emission data would include pumping of water for
irrigation and the production of artificial fertilizers, but they don’t.
Production of artificial fertilizers is booked under “industry” and if you use
an electric pump irrigation power falls under “power generation”. As a matter
of fact not even the fuel for tractors or dryers or any other fuel used in a
farm is booked under “agriculture” in the IPCC methodology. Essentially there
are no CO2 emissions
at all as a result of farming according to this methodology. But of course
there is in real life. Lifecycle analysis will include those emissions under
agriculture, and they tell quite a different story. For most crop production
systems, CO2
emissions are much bigger than methane and nitrous oxide emissions. A recent study of Chinese agriculture shows that it is only in paddy rice
production that methane and nitrous oxide emissions exceed CO2 emissions. In most cropping
systems, nitrogen fertilizer production was the main source of greenhouse gas
emissions. Research from Australia shows that 65 % of the greenhouse gas emissions
caused by the growing of vegetables comes from electricity for irrigation,
cooling, washing etc.
By excluding CO2 from the calculations the proportional contribution of ruminants to greenhouse gas emissions
is grossly exaggerated. This can be seen in the values used in the calculations in the article
(which are find in the extended data table 3). For beef, the authors use the
figure 32 kg carbon dioxide equivalents (CO2e) per kg while for vegetables the
figure is just 0.06 kg CO2e per kg. But lifecycle analyses of vegetable production
mostly end up with 1 kg or more, twenty times the value used in this research. If vegetables are grown in heated
greenhouses or air-freighted the emissions will be up to 100 times higher.
Also for the other crops values are much lower than the results of LCAs,
e.g. wheat in the study has 0.23 kg CO2e GHG intensity, while LCA analysis
normally will rate it 0,5 kg to 1 kg. Intensive livestock systems based on
cultivated crops, e.g. poultry and pigs,
are also assigned proportionally very low emissions due to the methodology
chosen. The researchers use 1.41 kg CO2e per kg of poultry, while the FAO estimates the global average to around 6 kg CO2e per kg.
The effects of methane emissions are
misrepresented
The authors mechanistically
express methane emissions as carbon dioxide equivalents. While this is common
and follows an established standard, it is not appropriate in general and in
particular not for such a long period of time. In the article New use of global warming potentials to compare cumulative and
short-lived climate pollutants in Nature Climate Change, Myles Allen (one of the authors of various IPCC-reports)
and colleagues demonstrate how the calculations for expressing methane in
carbon dioxide equivalents misrepresent the real impact on climate. For
short-lived greenhouse gases the comparison with carbon dioxide based on a
pulse of emissions of both gases (which is the basis for the recalculation to
carbon dioxide equivalent emissions) gives a reasonably correct result only in
a time span of a few decades. In the longer term, the more correct comparison
is between a pulse of carbon dioxide and a constant rate of methane
emissions. Constant methane emissions do not cause any increase in global
temperatures after a few decades, while constant carbon dioxide emissions lead
to cumulative increases for thousands of years. The article should have based
its calculations on the actual impact on global temperature (which is the real
planetary boundary) instead of taking the detour via carbon dioxide
equivalents.
Huge uncertainties regarding nitrous oxide
The data used in the
calculations are based on fixed emission of methane and nitrous oxide per kg
product. For methane the main problem is described above, but for nitrous oxide
the problem is that the values used are so uncertain. Lifecycle analysis and
the IPCC use emissions factors which are calculated as if there were linear
relationship between the amount of manure applied and nitrous oxide emissions
and the use of chemical nitrogen (N) fertilizer and the emissions. But research
show that there is no such linear function, and in most cases low N-intensity
leads to much less emissions per kg N than high N-intensity. Through the use of
constant emission factors, nitrous oxide emissions for extensive production
(e.g. pastured ruminants, or low yielding grain cropping) are grossly exaggerated,
while emissions from intensive production such as industrial pork or poultry
production or conventional vegetable farming are underestimated. How dubious the emission factors are
best shown that when New Zealand recalculated its nitrous emissions based on
actual measurements instead of the IPCC emissions factors, nitrous oxide
emissions from its big dairy sector was reduced with 60 %. The uncertainties in the
calculation of nitrous oxide emissions from soils puts into question if the
kind of detailed calculations made by the authors is meaningful at all. In any
case it would have been reasonable to declare and discuss the huge
uncertainties regarding nitrous oxide emission, following good research
practice.
Agriculture raw material vs food on the plate
The article talks
about the “food system”, but ultimately, apart from the food waste, the article
is about the agriculture production of raw materials. The rest of the food
chain, however, has many impacts, use of water, effluents and emissions. In
developed countries the greenhouse gas emissions post farm gate may well equal
those at the farm gate. Those emissions are caused by transport, food
processing, storage, cooling and cooking. There is no reason to believe that
livestock products are overrepresented here. This means that if you are to
replace meat products with more vegetables, fruits, vegetable oil and legumes,
which is what the article suggests, there will be no big potential for savings
in the post farm stage. By omitting the
impact of post farm emissions, the relative impact of meat in general and
ruminant meat in particular, for the emissions of the food system, is
exaggerated.
Summing up – quite a different picture emerge
According to the article,
emissions from animal products cause 77 % of the “food-related” greenhouse gas
emissions. However, that is the projection for 2050. If we take the figure for
2010 they cause 72%. But is this really correct?
If we add CO2 emissions in
agriculture and emissions in the rest of the food chain we increase total
emissions with 100-200 %. This is in line with global estimates by Vermeulen et al 2012. An assessment of the emissions in
the EU food chain by Camanzi et al, concluded that CH4 and N20
contribute less than half of total emissions in the whole chain and that
emissions post-farm are much higher than previously estimated. If we assume,
rather conservatively, that emissions of CO2 from agriculture and all greenhouse gases post farm
gate corresponds to 150 % of the methane and nitrous oxide emissions from
agriculture, around 40 % of the total emissions can be attributed to livestock
(with all the reservations stated above) – coincidentally the same proportion
as their contribution to global protein supply. If we skip animal products
altogether the net “saving” of emissions will not be that high as livestock
products have to be replaced by other products. The net saving will depend on
which products that will replace animal products, but it likely to be in the
range of 20%. It will be higher if animal products are replaced by pulses, root
crops and grains, and lower if animal products are replaced by exotic fruits, soft
vegetables and processed foods, i.e. the kind of non-animal foods that
dominates in developed countries.
By phasing out fossil
fuels, including its use for fertilizers and global transports but with no
change in global diets, total emissions would be reduced by more than 50 % of
the current emissions, according to my back-of-the-envelope calculations. It is
strange that scenarios for our future food system don’t include the phasing out
of fossil fuels, as that would have a huge impact.
As little as we can predict
the real outcome of a phase-out of animals from the food system can we predict
the outcome of a total de-carbonization. Food and agriculture are very dynamic
systems where you can’t change just one thing. In reality, phasing out fossil
fuels would also change diets a lot, as it would change both availability and
relative prices of food. Poultry and pork would become much more expensive.
Pasture raised animals would be less costly. Global competition in foods would
be much less intensive and prices will go up, which would stimulate local
production and it would reduce waste etc. Use of artificial fertilizers would
fall dramatically. They could still be produced with non-fossil fuel processes,
but they would be considerably more expensive, which in turn would reduce
nitrous oxide emissions considerably.
Conclusion
The assumptions and
limitations of the article Options for
keeping the food system within environmental limits give it a very strong
bias against ruminants. The conclusions of the article as communicated by the
lead author are not supported by their own research.
I have no problem with
”eating less meat” as such. But it is the wrong entry point for an intelligent
analysis of our food system. Increase in meat consumption is primarily caused
by a massive overproduction of staple crops driven by the use of artificial
fertilizers and pesticides. Those cheap staple crops form the basis for the
industrialization of meat production and a production model where animals have
been separated from the land and the land has been put into monocultures. That
kind of livestock system is wasteful and unethical, and “we” should not eat its
products – at all. But livestock which is properly integrated into an
ecologically sound agriculture system is not wasteful. It can clearly increase
productivity of the whole system, it can vitalize the soil and sequester carbon
at the same time. Even the last IPCC report concludes that: “Overall, there is high agreement that
farm strategies that integrate mixed crop - livestock systems can improve farm productivity
and have positive sustainability outcomes.”
1.3 billion people depend on
livestock for their
livelihoods and some 200 million are agro-pastoralists. In arid and semi-arid lands,
mountainous areas, non-arable land and natural rangelands, pastoralism is the
only possible production system that allows to transform non-edible plants and
marginal lands into nutritious food (meat and milk). These lands cannot be used
in any other way for human consumption if not grazed by animals. Many of the
pastoralists consume very high levels of animal products.
The environmental impact of the food chain is
too high. The main driver of destruction is the globalized fossil fuel economy
and industrial agriculture of plants and animals. Once we redesign agriculture
into sustainable and regenerative systems where land, people and food are
“re-coupled”, diets will be diverse and adapted to the local ecological
conditions, population densities, etc. The notion of some kind of globally
averaged diet is flawed. The share of animal products in peoples’ diets will
vary from very high to very low depending on the conditions, in the same way it
has always done.