What should an environmentally aware meat-eater avoid?
February 1, 2007 4:22 PM   Subscribe

We all know that the world's cattle herds pump a significant amount of methane into the atmosphere, contributing to global warming. Are other farmed animals better or worse for the environment, comparatively? Is eating red meat significantly worse for the planet than eating the same amount of poultry? Are there studies, numbers and league tables on this?

Because we're intelligent people we already know (or at least we've been told) that it takes ten kilos of grain to raise a kilo of beef; and we can work out that intensive farming techniques that produce lakes of sewage are going to be worse for the environment than techniques that don't. But kilo-for-kilo, what forms of meat are better or worse for the environment -- particularly, but not necessarily just in terms of methane production?

(No answers beginning "I'd guess..." or "It seems logical that..." please. I'm already 95% sure the league-table will go red meat > poultry > fish. I need facts and numbers to back that up.)
posted by Hogshead to Pets & Animals (20 answers total) 2 users marked this as a favorite
Since there's no consensus as to what "worse for the environment" means, there's no way to answer your question.
posted by Steven C. Den Beste at 4:43 PM on February 1, 2007 [1 favorite]

i can't back this up, but i get the impression that pig farming is really bad for some reason (feel like i've heard about this a lot).
posted by lgyre at 5:35 PM on February 1, 2007

This is a big topic, and I don't have much to add, other than to note, a lot of what is bad about pig farming is that it basically a bunch of pigs in a small space for their whole lives. Cattle ranching has been going more and more that direction (more time on feedlots, less time on pasture).
posted by Good Brain at 5:58 PM on February 1, 2007

I googled “livestock feed conversion efficiency” and found this.
posted by Huplescat at 6:16 PM on February 1, 2007

I'd avoid pork too.
posted by ensign_ricky at 6:59 PM on February 1, 2007

Find an organic, antibiotic-free meat producer local to you, in order to minimize the miles traveled to market. Buy truly free-range poultry that subsist on bugs, seeds, and whatnot (no feed!), and why eat the chicken when you can eat their eggs? Try grass-fed meat and make sure it's not grain-finished. Grass-fed beef don't eat each others' brains, either, so the risk of BSE is lower. Better yet, explore entomophagy and microlivestock!

More to the point, there's this, and you could check out this Eating Green Calculator. Just enter 1 for one food type and zero for the rest to figure out the estimated environmental impact, by weight, for each food type.
posted by chudder at 7:44 PM on February 1, 2007

The environmental impact is more tied to the farming method than the kind of animal. Grass-fed meat from a small local farm has less of an impact than its factory-farm-raised counterpart.
posted by altcountryman at 7:44 PM on February 1, 2007

In terms of methane, there's lots of information starting on page 95 of The UN Food and Agriculture report Livestock's Long Shadow (discussed here and here). Page 96 of the report says that in 2002 19% of total US methane emissions came from enteric fermentation inside cattle (beef and dairy together). That is 71% of all US agricultural methane emissions for the year.

The chart on page 99 shows cow and pig manure emissions (manure fermenting outside of the animals) to be about equal in their contributors of methane, while each is about 10 times the emissions of poultry manures.

Discussion of nitrous oxide emissions (another bad greenhouse gas) begins on page 101. On a quick skim it looks like it is more difficult to measure but cattle manures are far and away the worst offenders, about three times greater than the other types of livestock combined.

The report does not include any pound for pound or calorie for calorie comparisons for these emissions.

To answer your more general question is difficult because of what SCDB says. Spend some time with that report to get an idea of how many different ways environmental impact can be measured.

On preview: Despite romantic notions, I have yet to see any reason to believe that organic this-or-that is always better for the environment.
posted by peeedro at 7:56 PM on February 1, 2007 [1 favorite]

in terms of energy depleted from the environment

farmed fish > wild caught fish
big fishes > leetle feeshes (or forms of sea life generally)
farmed > anything I hunt or raise myself

source: Second law of thermodynamics.
posted by Ambrosia Voyeur at 8:02 PM on February 1, 2007

Like most people are saying; buy grass fed, buy local.
Also, since the amount of grain needed/ methane produced is in obvious proportion to the longevity of the animal, why not eat more veal? The old horror stories about crates and the dark still put a lot of people off, but if you stick to local meat from farmers that you trust, you ought to be able to guarantee that the meat has been raised well.
posted by sann1657 at 10:52 PM on February 1, 2007

People using the second law of thermodynamics to try to justify all sorts of things which it really doesn't is a peeve of mine. Ambrosia Voyeur's rankings may or may not be correct, but if they are it's not because the second law of thermodynamics says it has to be that way.
posted by DevilsAdvocate at 5:09 AM on February 2, 2007

[begin rant]

Greetings to all from 2007. I think "buy local organic" is a lovely sentiment, but unreasonable. We do not all live in the San Francisco bay area. Have you considered how difficult it is to purchase local, organic meat, fish, or produce in most of the Midwest? What about around the Rocky Mountains? The Southwest?

Yes, there are places where this is possible but once you move outside the major metro areas, c'est impossible. And if you really think that living in Phoenix is better for the environment than living in suburban or rural Arizona, you need to broaden your statistics.

If someone has an environmental solution that doesn't work for folks in Kansas or Iowa or Nebraska (where local = soybeans, corn, and wheat), then it is a lousy solution.

[end rant]
posted by terceiro at 6:02 AM on February 2, 2007

On reconsideration: I don't mean to a) derail this thread or b) sound like such an ass. I simply want to point out that "buy local and organic" is difficult/impossible for a large swath of the United States and hence smacks of elitism. And answers for global problems that are only available for the elite cannot make much difference.

Sorry about the textual assheadedness above.
posted by terceiro at 6:05 AM on February 2, 2007

The answer is that it's very hard to total up all of the damage / impact of raising animals (or for that matter, doing or not doing anything). The world is a complicated system, and so building an accurate model of it, with a set of which things matter, and then a discount factor for each (so that one can say, for instance that nitrous oxides is .9 x as bad as methane which is 1.4 x as bad as dioxins or whatnot).

So you're not going to find a definitive answer. There isn't one.

Here are some things to pay attention to:

1. How much does our animal in question eat? How does this food get to the animal (Is it brought in by truck or grown at the spot where the animal is? )? How is *this* foodstuff grown?

2. How much does this animal shit? What happens to this shit? (Pig shit goes into huge shit-ponds, for example, and cow shit, while the animals are raised in pasture (6-10 weeks or something), is left as fertilizer. This migh be counteracted by the fact that once the animals move to the lot, they just live in their shit which is I guess washed into rivers and stuff.) What is in their shit that is bad? (Lots of scientists believe that many of the hormones that we inject into animals gets out into the environment in their shit. Which means that lots of estrogen-mimicking organic molecues are in our fresh water sources. Fun. Think this has anything to do with a weird phenomena of girls getting their periods at age 8 or 9? I do.)

3. How much does this animal cost to butcher, store, transport, package, prepare and consume? Do you eat meat grown in Japan (saying you live in the U.S.)? Do you eat meat grown in Brazil, Argentina? (hint: you probably do if you eat fast food) Lots of meat products are frozen at least for some of their journey to your plate. This refrigeration (and packaging) costs money and resources.

So, in sum, it's a hard fucking calculation. The idea that you could just reduce this problem down to methane tables per kilo is simplistic and might lead you astray. There is no "Moral Calculus" that works for these kinds of situations. In Jeremy Bentham's day, it was possible, or at least more possible, to perform these kinds of calculations on various decisions that we make. This is Bentham's genius: turning a hard moral choice into a math problem. But the sheer size of the systems we deal with today (the meat production system, the transportation system, the advertising system that suggests to you that eating meat for 20 meals per week, etc.), their complexity, interconnectedness, and their non-linearity (changes in one system have unintended consequences for other systems -- think of all the large systems I've brought up and then add the labor consequences of all of this (i.e., outsourcing and de-skilling of food production) -- and you can see that answering this question might take your entire life.
posted by zpousman at 6:08 AM on February 2, 2007

DevilsAdvocate, IANAScientist,but I do base my diet on this type of thinking. If you could refute my usage of this law (which I learned in a discussion of what to do when stranded on a desert island with a hen and a bag of grain in high school biology) I would appreciate it. Take as a case the better sustainablitly of bay scallops to jumbo scallops.
posted by Ambrosia Voyeur at 11:11 AM on February 2, 2007

AV, I'm not saying your conclusions are wrong. I'm only saying that your conclusions do not follow from the second law of thermodynamics. Your conclusions may be entirely correct, but for other reasons.

I'm not sure how you think that the second law of thermodynamics supports your conclusions at all--if you could explain that, I could attempt to refute your reasoning. I can't refute your reasoning when I don't even know what that reasoning is!
posted by DevilsAdvocate at 12:14 PM on February 2, 2007

Ambrosia Voyeur: The treatment of thermodynamics gets in high school biology classes is hardly rigorous or complete. The second law is frequently misused or misunderstood, so take care when evoking it unless you understand it very well.

Here is a direct contradiction of the first line of your earlier generalization:

"Naylor et al. (1998) also proposed that certain types of fish, particularly salmon and shrimp, are actually net consumers of fish, requiring as much as 3 kg of fish in their feed to produce 1 kg of farmed fish. Overall, these species represent a relatively small proportion of total aquaculture production (Figure 3). Furthermore, Forster (1999) points out that, based on classic values of energy flows, 10 kg of forage fish are required to produce 1 kg of a carnivore—such as salmon—in the wild. If by-catch values are taken into account, at least another 5 kg of fish can be added to the equation. Based on these considerations, even if farmed salmon or shrimp do utilise 3 kg of fish to produce 1 kg of weight gain, this would actually represent a significant ecological advantage compared to 10–15 kg of fish used or wasted in the growth and capture of 1 kg of wild salmon or shrimp. Also, when considered in toto, aquaculture is a huge net producer, generating 3.5–4.0 kg of food fish for each kg of pelagic fish used in fishmeal production." [em. mine]

This is not to say that your generalization is always wrong but that this is a very difficult question and broad generalizations don't always hold up. You admit to not being a scientist, so why do you imply that you understand thermodynamics and the energy economies of environmental systems well enough to make these broad generalizations? Explain or cite some data please.

On preview, what DevilsAdvocate said more politely.
posted by peeedro at 12:22 PM on February 2, 2007

No need to get wound up, I said I was looking for a better understanding and your point, peedro, seems totally correct, though unnecessarily condescending. Meet a layperson, see how she thinks. I probably should never have come into it without the data the OP requested, but one does tend to think one's rationale for daily choices is true.

My understanding of the law as I used it postulates that energy put into food doesn't all come out as energy for us when we eat it. In the island story, you are to eat the chicken promptly so it doesn't lose energy as heat and waste away, followed by eating the grain. This concept is untrue of farmed fish, as you point out, peeedro, because they don't swim around burning calories they have to obtain themselves; they get fed.

I guess my utilization of the law in my personal food choices is in a manner that applies to the expenditure and loss of commodities we humans control in the production of farmed meats, rather than resources that, in sustainable fishing, are in natural abundance. Eating from the bottom of the food chain (leetle feeshes) does conserve in accordance with the law, doesn't it? Like eating eggs in lieu of chickens as some mentioned above?
posted by Ambrosia Voyeur at 2:58 PM on February 2, 2007

My understanding of the law as I used it postulates that energy put into food doesn't all come out as energy for us when we eat it.

That's a fair enough statement, but the thing to keep in mind is that the second law says nothing about how much energy is lost in the process. It just says that some will be lost. Maybe 0.1%, maybe 99.9%, maybe something in between. And there's no requirement that different types of food are all equally efficient at using the energy they're raised on, or that they're all equally efficient at transferring their energy to humans.

In the island story, you are to eat the chicken promptly so it doesn't lose energy as heat and waste away, followed by eating the grain.

And what makes you think the chicken loses energy faster than the grain? OK, I'm being facetious, I'm sure it does, but my point is there's nothing in the second law that says the chicken has to lose energy as heat faster than the grain does.

Eating from the bottom of the food chain (leetle feeshes) does conserve in accordance with the law, doesn't it?

That's true if the choice is between eating little fishes and eating somthing else which itself would be fed on those very same little fishes (if you're comparing bay scallops to sea scallops, per above, that doesn't apply since sea scallops don't eat bay scallops!); and if the energy lost in the one-step transfer of little fish -> humans is less than the energy lost in the two-step transfer of little fish -> predator -> human (which is probably true, but there's nothing about the second law of thermodynamics which says it has to be true).

Like eating eggs in lieu of chickens as some mentioned above?

I think the rationale behind that was simply that over the entire lifetime of the chicken, you can get more nutritional value from eating its eggs than you can by just killing the chicken straight off and eating it. When you take into account the fact that you'll need to provide more feed to keep the chicken alive throughout its natural lifetime than you would to simply bring it to maturity and eat it, I'm not sure which is more efficient. And the second law of thermodynamics doesn't answer that question - it says that some of the energy from the feed is lost in the process, but not how much is lost in one method vs. the other.
posted by DevilsAdvocate at 5:15 PM on February 2, 2007

Okay, DevilsAdvocate, you've definitely poked holes in my original schema, thanks. To keep my comments relevant, here's a link to the sustainable seafood page at the Monterey Bay Aquarium.

The scallops thing is an example of not eating something that has to survive a long time first (king crabs and jumbo scallops both have to grow a long time to reach their premium size, a longer time than dungeness crabs and bay scallops.)
posted by Ambrosia Voyeur at 7:42 PM on February 2, 2007

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