Vegetarians against climate change

ResearchBlogging.orgA member of the audience at one of my climate change slide shows asked me why I hadn't mentioned the benefits of switching to vegetarianism when it comes to things we can do to lower our carbon footprint. I replied that I thought eating less meat will be as much as consequence of our actions as a way to change them.

It's not that I disagreed with the premise that meat production consumes too much energy and water, resources that could be better used to grow more plants. That's inarguable. It's just that I see enormous resistance among North Americans and Europeans to the idea of voluntarily eating less meat, more resistance even than to giving up the personal automobile. Sooner I later, it will just make no sense to waste resources raising cows, I reckoned, and society will reduce its meat production because it has to as the world heads toward 9 billion people.

But the scientific calculations behind the argument in favor of giving up meat are become hard to ignore. There's a new paper in the journal Climate Change: "Climate benefits of changing diet" by Elke Stehfest and colleagues at the Netherlands Environmental Assessment Agency and Wageningen University Research that comes to some dramatic conclusions.

I strongly suspect at least some of the authors are vegetarians, what with language like:

Dietary changes may not only be attractive from a climate perspective, the impacts they might have on human health and life expectancy are also of great interest from a public health perspective.

But I don't know and don't much care. What's important is the rigor of the analysis. And the paper seems to take a comprehensive look at the issues involved. Stehfest et al write that the net decrease in land required for agriculture if we mostly eliminate livestock from the industry means that there will be a lots of land reverting to forests and other carbon sinks, sinks that will go a long way toward keeping greenhouse-gas concentrations down to 450 ppm of CO2e.

[Some believe that won't be low enough and that we need to be closer to 350 ppm, but whatever the ultimate target, it would be foolish to ignore any strategy that could help us get us to wherever we need to go.]

They sketch out four possible pathways to effect the kind of change they suspect is necessary. There's the No Ruminant (basically four-legged) Meat, No Meat, No Animal Products scenarios and Healthy Diet (some meat, more fish, etc) scenarios. It's not immediately obvious which will produce the best result, as replacing milk with plant proteins, for example, leads to an increase in cropland, rather than a reduction. But:

The largest reduction of greenhouse gas emissions by product category is caused by the substitution of ruminant meat, with a large terrestrial net CO2 sink of about 30 GtC over the whole period compared to a net source of 34 GtC in the reference case

There are plenty of opportunities to bias the calculations in one direction or another. Stehfest et al are up front about the uncertainties involved when trying to generate scenarios that makes sense. They write, for example, that

The pace at which natural vegetation recovers on abandoned agricultural land is another important uncertainty. As described above, the time needed for reaching maximum net primary production ranges from 2 years for grasslands to 20 years for boreal forest (van Minnen et al. 2000). In a sensitivity run, this recovery time was increased by a factor of 2. A further important uncertainty is the effect that drastic demand changes may have on the agricultural system. In the variants, we had assumed that crop yields are identical to those in the reference case. However, a decreasing demand and a subsequent decrease in land prices is likely to slow down the improvement of agricultural technology and crop yields. And even more directly, the abandonment of vast areas of pasture and cropland for feed production may lead to extensification of the remaining agriculture.

The real Achilles heel of this kind of research, research that addresses the relative financial cost of mitigation as well as the physical consequences of particular strategies, is that predicting effects on human actions is pretty well impossible to do to any degree of confidence. As the authors admit, "we have ignored possible socio-economic implications such as the effect of health changes on GDP and population numbers."

Getting back to my original approach to the chicken-or-egg question of the relationship between meat and climate change, here's one last excerpt, this time from the paper's closing discussion:

An interesting question is what kind of potential strategies could lead to lower consumption of meat, eggs and milk. While some authors have recently suggested reducing meat consumption via a special tax, others stress that no large changes can be expected through price mechanisms.... Nevertheless, the benefits of dietary change to both health and climate mitigation and the feasibility of low stabilization targets as shown here are important enough to put this issue on the political agenda.

Food for thought, indeed.
Elke Stehfest, Lex Bouwman, Detlef P. Vuuren, Michel G. J. Elzen, Bas Eickhout, Pavel Kabat (2009). Climate benefits of changing diet Climatic Change DOI: 10.1007/s10584-008-9534-6


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The big question with this is how you efficiently recycle nutrients in a zero-input, closed-cycle system of agriculture without livestock. There is also the small point that many of those ruminants are grazing land that isn't much use for other forms of agriculture (at least, not without massive and unsustainable inputs of water and macro-nutrients), or are eating feeds derived from waste streams.

Less meat, I have no problem with, but I'm not sure that the total elimination of livestock is a good idea.

While I wouldn't argue with the eat-less-meat crowd's central premise, another at-least-as-important set of numbers which needs to be run involves the potential reduction of climate harm from slowing and reversing human population growth worldwide.

By Pierce R. Butler (not verified) on 11 Feb 2009 #permalink

Does 'replacing ruminants' mean eating more chicken? Pigs are not ruminants either, correct?

This is very interesting. As a very occasional meat eater, I doubt I would miss it that much (especially if pork was still an option), but I seem to be the exception rather than the rule.

After listening to those radio programs that were posted, I wondered, "If algae is that much more productive for biofuels, can it be that much more productive for food production?"

By foolfodder (not verified) on 11 Feb 2009 #permalink

Does 'replacing ruminants' mean eating more chicken? Pigs are not ruminants either, correct?

Correct. There is another consideration - the amount of feed it takes to produce one pound/kilogram of meat: Cattle>>pigs>chickens>vegetarian fish. This means that much less agricultural land is necessary to produce feed for chickens than cattle, but any calculation that includes land use will have to take into account that cattle and sheep can be effectively pastured, but not pigs or chicken.

By natural cynic (not verified) on 11 Feb 2009 #permalink


'Apocalyptic climate predictions' mislead the public, say experts

Met Office scientists fear distorted climate change claims could undermine efforts to tackle carbon emissions

"Stehfest et al write that the net decrease in land required for agriculture if we mostly eliminate livestock from the industry means that there will be a lots of land reverting to forests and other carbon sinks"

I guess that depends on where it is, and what the state of the economy is. The US has been losing agricultural land for decades, and continues to do so, and much of it is used to build new housing developments. A lot of the suburban mcmansion subdivisions built during the recent bubble were built on land purchased from former farms. Though I suppose if cornfields in Iowa and Nebraska now used for feed-crops become essentially surplus, I don't know what will go there.

Sooner I later, it will just make no sense to waste resources raising cows, I reckoned, and society will reduce its meat production because it has to as the world heads toward 9 billion people.

Not without some sort of mechanism to make it happen. As we saw last year, the wealthy can continue to eat meat while the price of crops goes through the roof.

I personally feel that the joys of cooking and eating would be severely diminished without any meat at all, never mind dairy. Although I do agree it would be well to consume animal products at a lower rate that the current average American diet, I hope that in the future (assuming we have one) we can figure out a way to include meat and dairy on our menus.

I agree that we would be at least as well off including the human population explosion as a relevant topic, which I have read was taken of the table of international discussions.

Often I feel there is a moral imperative underlying the vegan and vegetarian arguments that we must all conform to save the planet from climate change. I heard this argument from a friend and had to point out with some amusement that she has possessed her entire life at least one horse for pleasure riding. The question to ask these types is, should we also ban all pets? No more kitties and dogs? Watch them get all huffy puffy.

Also, where I live in NJ even the suburbs are overrun with deer. They are destroying the ecosystem of the woods by consuming any saplings that sprout. We should get rid of them before we deny people beef, but that doesn't go over so well either.

It would seem possible to close the loop on meat production. By that I mean that the digestion of animal waste products in digestors will produce methane for energy production, and produce high quality nitrogen fertilizer which is used to grow the grain which feeds the cattle, pigs, and chickens. The electricity can run the process and the surplus be sold back to the grid. In theory there should be little need for fossil fuels to be injected into the loop, so the entire process will be carbon neutral. This is already being done in Pennsylvania on some dairy farms, but needs a subsidy to get the digestors built and installed. Venture capital will provide the funds, with the payback from selling the excess power.

By Joe in PA (not verified) on 11 Feb 2009 #permalink

Thank you Joe! That's what I'm thinking. There can be a way. My chickens and peacocks, and dog and cats and parrot, all thank you for this perspective!


I have to admit that I'm more than a little leery of Al Gore. I think his efforts to erase the medieval warm period and the little ice age from AIT suggests he is a man willing to exaggerate when necessary to win people over to his side. He also greatly exaggerated the issue of polar bear drownings. My understanding is that he quoted a study that cited only four polar bears drowning under some unusual storm conditions. Finally, implications that the Aral Sea's current condition is the result of global warming is a complete lie. If there is such a strong case for AGW, why does he feel the need to stretch the truth in order to get the public's attention?


P.S. We can discuss his "Do As I Say, Not As I Do" lifestyle next time :-)

Doesn't anything that extends human life actually make climate change worse? ;-)


I don't quite understand completely the resistance to reducing, or better still "eliminating" meat consumption. It is clearly the easiest and quickest way to accomplish a reduction in methane/greenhouse gasses. Halting the toxic wastes generated from "leather" production alone would be a large benefit to the health of the planet.

Someone mentioned the (dreaded) thought of cooking without meat/dairy products - actually, vegan cooking and vegan foods are just as wonderful, given a chance. The personal health benefits should be motivation enough... let alone the good that it does for the planet & yes, even the lowly animals. Go Vegan

The big question with this is how you efficiently recycle nutrients in a zero-input, closed-cycle system of agriculture without livestock.

Well, there are livestock. They live in cities, and the nutrients that go through 'em get treated and fushed out to sea. As soils get depleted, sooner or later someone is going to have to come up with a plan for putting urban sewerage back on the farms.

Here on Oz, we are starting to come to terms with drinking water extracted from sewerage. Living on a continent that's 2/3rs desert helps overcome the "ick" factor. I wonder if the process leaves easily-transportable, nutrient-rich solids?

These people are a disaster for the environmentalist movement because they're piggybacking their obnoxious agenda onto the important issue of climate change.

The energy cost of cattle is a distraction from the fact that our system is based on fossil fuels as an energy source. That is the root cause of the energy expense of cattle. Cattle could be used as an energy source harvesting solar energy if they're raised on farms by grazing. The problem is we feed our cows corn in huge lots. No longer is manure from cows used as fertilizer for crops, instead it's now a problem, a waste byproduct of feedlots. Instead we get nitrogen into our crops from fertilizer made by the energy intensive Haber process.

Meat itself isn't the problem, it's the structure of our entire food supply being based on corn and the Haber process.

Oh and I would rather die than eat vegan. De gustibus non est disputandum. Please keep your food religion to yourselves. That diet is not healthy, nor compatible with everyone's needs wants culture or ethics. .

I take objection to MarkH's comments on the farming system. I don't like factory farms, but I do admit that they are vastly more efficent than pasturing, in terms of using less land, and recycling almost everything - if 'waste' doesn't get made in fertilizer, it becomes feed or gets burnt to make electricity.

They are still less efficient for making food than is eating the crops directly.

As to the health factors:
The US food and drug authority states that a vegetarian diet is appropriate for all stages of the life span. The nutrition textbook which the university of canberra proscribes states that vegetarianism tends to be healthier than a meat-containing diet, as it is lower fat, higher fibre, higher in many vitamins and minerals, and less calorie dense, therefore less likely to contribute to obeisity. (for reference, this book is called Understanding Nutrition, 10th ed., by Whitney, E., and Rolfes, S.R.).

A vegan diet is also easily adequate, and depending on which study you cite, considered slightly more or slightly less healthy than a vegetarian one. You do need to supplement Vitamin B12 (easily grown on a petrie dish). Before you say "oh, need to supplement, eh? see you do need meat", please note, that all B12 comes from bacteria - its just that meat is frequently contaminated with it. So is human poo - see page 1 of the paper at this link:…

It describes how in the '50s Sheila Callender cured people of B12 deficiency with a solution purified from their poo. now we grow the B12 on agar plates, and can take it as tablets - much more palatable. But bacteria are the only source of this vitamin.

Finally, taste. I am vegetarian, but most of my friends/family are not, and they happily eat my cooking, and visit my favourite restaurant with me (Kingsland, Dickson, A.C.T.,and 100% vegan). In short, if you didn't like the vegetarian/vegan food you've eaten, Mr MarkH, it wasn't a reflection on its vegetarianness. Everybody has foods they don't like, and most of us have made the discovery that a any particular ingredient is much nicer when it's cooked properly. Almost everything can be prepared in such a way that it tastes nice. If you need some help, Heidi, of 101 cookbooks may provide it.

If you'd like/need further help/advice ask your local veg*n society

Happy, Healthy, eating

I also disagree with MarkH. For a start there are problems with farming other than the energy cost, the land usage for instance. I don't even consider the animal rights side of the issue, I have no problem whatsoever with the purely ethical aspect of killing animals for food, so I don't think I'm trying to push an 'obnoxious agenda'.

Mostly, though, it seems from his comment that he knows our current system of meat farming is damaging the environment, but refuses to act on it because taking up a reduced-meat or meat-free diet would somehow 'distract' from whatever efforts he's making to completely overhaul the agricultural energy supply system. I think this kind of flawed logic could be used on almost anything that asks us to give up something we enjoy in order to decrease our impact on the environment. The energy cost of driving everywhere could be seen as a distraction from the fact that we still use fossil fuels to power our cars.

I think the real problem here is that there are so many different factors to consider. It seems almost certain that cutting down on meat would decrease your impact on the environment. But what about animals grazing on otherwise useless land? What about local meat versus foreign vegetables? What's the impact of eating dairy and eggs? When their this many variables to consider you can justify almost any position, so nine times out of ten selfishness wins out and we believe what we want to believe.

By chemniste (not verified) on 14 Feb 2009 #permalink

Oh yeah, and 'food religion'? Seriously Mark? Kind of taking a page from the creationists book there.

By chemniste (not verified) on 14 Feb 2009 #permalink

all for keeping the food chains short. outstanding.

By sami-jaine (not verified) on 15 Feb 2009 #permalink

MarkH. Vegetarians have a demonstrated commitment to caring
about pain and suffering ... look at Peter Singer's 1991
edition of Animal Liberation where concern for global
warming and the environment gets its own chapter. So I'd
say its the other way round, its the environmental movement
with no track record in caring about pain and
suffering (human or otherwise) who has suddenly discovered
compassion. Environmentalists, in general,
care about an animal only if it is
rare and endangered ... otherwise you can snare it, trap it
poison it, shoot it, club it, burn it or eat it and they
are silent. But as soon as its numbers
drop to some magical point ... then they suddenly start
to care.

By Geoff Russell (not verified) on 03 May 2009 #permalink