Cutting the carbon from your diet

I’ve been digging more deeply into the question of what you should eat if you’re looking to lower your carbon footprint. I’ll have a few posts on this topic coming up, because it’s one of those vexed issues with lots of tradeoffs and corner cases and tricky considerations. But let’s start off by keeping it simple: eat less red meat and dairy.

A lot of people, myself included, happen to enjoy eating meat and dairy. Take solace in fact that “less meat” isn’t necessarily the same as “no meat.” Take further solace in the fact that chicken, fish, and eggs aren’t nearly as problematic as beef. In some future posts, I’ll try to ease the pain with practical tips. For now, though, let’s look at the data.

A recent study dug into the “food miles” debate with a more a comprehensive analysis of the climate impact of food production and transportation, based on the consumption of a typical U.S. household. The results were surprising: although food travels on average over 1,000 miles from farm to plate, this transportation accounts for only 4% of the carbon impact of the average American meal. In other words, even in the ideal scenario that you lived on a farm, you’d only be shaving 4% off your food footprint by eating locally — the rough equivalent of driving 1,000 miles less per year.

On the other hand, shifting just one day per week of red meat consumption to chicken, fish, or eggs achieves a reduction equivalent to 760 miles of driving. Shifting one day of red meat per week to fruits and veggies is the equivalent of 1,160 miles of driving. Swapping red meat entirely for other meats reduces the equivalent of 5,340 miles of driving. And going fully vegetarian is practically like giving up a car: 8,100 miles of driving. And when you think about it, this is good news for most of us. Cutting down food miles can actually be rather difficult. Cutting back on meat is fairly simple.

It’s worth unpacking the study a bit further. First, some perspective: local food devotees have motivations beyond just greenhouse gas emissions. There are plenty of good environmental, economic, social, and culinary reasons for favoring food grown nearby. Likewise, many considerations beyond climate change affect people’s personal decisions around meat consumption. Food can’t be reduced to a single issue.

And now some subtler considerations:

* The study considered the case of the average American household. If you’re reading this blog, there’s a good chance you’re not the average American household. You may already take steps to green your consumption choices, in which case the savings available to you from cutting meat consumption are smaller. Still, reducing your intake of beef and dairy is one of the simplest ways to shed CO2 from your diet.
* The study looks at aggregate food groups, which is entirely unhelpful if you’re trying to figure out how the organic raspberries from Chile compare to the conventionally grown peaches from California; or how the grass-fed, pasture-raised beef compares to that farmed salmon. Needless to say, there is considerable variation in production techniques within food groups. On the other hand, most of us aren’t cooking most of our meals, so the broad rules of thumb are still generally quite useful.
* Beef is even worse than the study makes it appear. The life cycle analysis doesn’t account for land use changes from beef production. A lot of rain forest gets chopped down to make way for cows.
* Consider skipping the soda. The beverage category isn’t a huge source of emissions, but I suspect it’s one of the easiest to cut. (And of course you’ve already given up the bottled water, right?)
* The study contains some unintentional weight-loss advice. Dairy (milk, butter, and cheese) is CO2-intensive and also quite energy dense. Shifting dollars into fruits and vegetables will cut not just carbon but calories from your diet.
* If you’re already a vegetarian, considerations such as food miles and organic farming techniques become proportionately more important. The absolute amount of carbon reductions available don’t change, but the relative importance of these factors increases.
* Globalization of the food supply doesn’t appear to be the big deal you might think, because trucking is so much worse, from an emissions perspective, than ocean shipping. (Planes, of course, are dreadful.)

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  1. tim smith - May 27, 2008

    Please remember to retain units before you say something patently absurd like “replacing one day of beef with chicken is 760 miles of driving.” A look at the paper makes it clear that you really meant to say was that eating chicken instead of beef one day a week can save you 760 miles a year. In case you were wondering, that’s 14.6 miles per meal.

  2. Adam Stein - May 28, 2008

    Right you are. Fixed.

  3. Chad - May 28, 2008

    It is not clear to me at all that eating local foods is ANY better for the environment or saves ANY miles at all. While I usually take my bike to the farmer’s market, most people don’t. I would guess that most people there had to travel for a few miles out of the way to get there and back. Worse yet, the farmers themselves probably live 15 miles away on average. All of a sudden, you are dividing a non-trivial amount of gasoline among a small amount of food. This may very well be MORE fuel/food than the zillion tons of food divided by the gasoline use of a tanker and a train.
    Simply put, our globl supply chain is VERY efficient compared to your local farmer. The supply chain may very well may be able to do a difficult job using less energy than a local farmer is able to do an easy one.
    Indeed, this is probably true of any product. Seventh Generation vs Tide? You aren’t helping the environment at all if you drive an inch to buy the former, or have it delivered. You might be sending a positive message with your choice, but odds are, all it is a message. In reality, these small companies can’t match the efficiency of the supply chain and therefore lose their environmental advantage. This will remain true as long as they are small.

  4. Karen - May 28, 2008

    While I support the basic idea of supporting local farmers (for land & economic reasons) and eating healthier (for health reasons), one fallacy in your premise is that each of the listed food groups is transported separately so there is massive duplication of delivery effort. The fact is most things are transported together in refrigerated rail cars and trucks. Milk may have the highest fuel inefficiency in that it has to be transported in bulk to be processed. Diet studies have also shown, that cutting dairy from ones diet does NOT promote significant weight loss. The key to healthy living is to eat a balanced diet and exercise. In my opinion, it’s more efficient to support local farms and buy regional goods whenever possible. Cut down on the out of season items that are transported from other countries and simply be aware of your choices.

  5. Andrea - May 28, 2008

    Remember that eating locally-grown food has benefits other than environmental. By purchasing from local growers you are putting money directly in the pockets of your neighbors. You’re subsidizing smaller food-producing operations that often use more environmentally-friendly practices than the big growers just as a matter of course. Buying locally-grown food also helps educate yourself and others about your particular region, eating seasonally, and enjoying a variety of food that actually tastes like food (instead of apples that taste like styrofoam). All of these can help change personal purchasing and eating habits, which result in long-term benefits. Environmental consciousness is definitely A benefit of eating locally, but it’s not the ONLY benefit – economic and social benefits are in this case just as important as the environmental.

  6. Sally - May 28, 2008

    It’s great to see more encouragement to drop some meat from our collective diet- but I think its problematic to be touting this study as a reason NOT to eat local.
    Like you mention in your article- there are tons of reasons to eat local besides the reduction of your carbon footprint- including many environmental ones.

  7. Alex - May 28, 2008

    Simply put, our globl supply chain is VERY efficient compared to your local farmer.
    The above premise by a previous author and most of the other comments, seems to me, to be way off. Many of our foods are grown and processed in different parts of our country if not countries. The miles are more than just delivery miles. The foods are shipped back and forth from plant to plant before they even become food and before they even are delivered. As to the efficiency, I’ve heard stories of how Walmart will take items from lets say Colorado, ship them to a main plant only to deliver them back again to Colorado so that everything goes through central distribution. I don’t think the farmer driving back and forth to deliver local goods, or individuals driving to a farmers market can come anywhere close to the number of miles we are talking about.

  8. Chad - May 28, 2008

    Alex, it is not just about the miles driven or shipped…it is about fuel per bushel. If a farmer uses two gallons of gas to sell ten bushels of food some Saturday morning, that is 5 bushels per gallon. A freight train, on the other hand, could ship those same bushels (in a bulk load, of course) clear across the country for the same amount of gas. While I am sure there are plenty of instances of there-and-back-again shipments, the average is going to be a lot shorter. In the end, the difference just isn’t that big.

  9. Jo - May 28, 2008

    A year and a half ago, a friend challenge me to go vegan for the month of February; I shifted to a primarily vegan diet for that month and haven’t looked back. I just wanted to testify that going veggie and even vegan is completely do-able even for young active people who love to eat! Consider substituting out the meat and dairy items you eat regularly with vegan alternatives, step-by-step, and before you know it, you’ll be a healthier person with a much smaller carbon footprint. Good intro and support here:

  10. Jane - May 28, 2008

    Beef grown locally from an already existing grass (green, growing, using CO2!) is way different from mass produced rainforest destroying, long distance, imported, feedlotted beef. I think it is time we started looking at the details of any given bit of food instead of spouting generalizations. It is also time the beef industry reviews its habit of raising calves in one place and shipping them long distances for fattening and slaughter. This industry needs to become both less environmentally harmful and more humane, but eating beef is not in itself inherently harmful. You need to watch the details.

  11. Drew - May 28, 2008

    Chad makes a lot of sense. I’ll add that all but three of many farmers at my local farmers market(Outside Wash DC) use pesticides on some or all of their offerings- I ask before I buy. Most can’t even tell you what was sprayed (insecticide, fungicide, etc.) There are a few who even seem to take mild offense to the question. To Chad’s point, most of them are driving half empty, gasoline, box trucks that from regional locations (not even local)the closest of which is roughly 50-60 miles away and some are well over 100. the ultra-premium prices they charge are I guess how they make money. At any rate, I see anti-efficiency and make my selections carefully.
    Now back to the pesticide they use- which is probably made in China or India (at least the components). There is a racetrack of carbon footprints getting that stuff across the ocean to the synthesis plants- making the deadly chemicals- then out to farms and to commercial sprayers (which include helicopters and airplanes!). Really folks… it is disturbing that few will actually count these things when talking about locally grown- even locally grown organic.
    Whatsmore is that a lot (not all though) of the organic vegetables and fruits in the local grocery store are from farms in the same areas the market farmers are from. And again to Chad’s point were transported en-mass in packed-full,low-sulphur, diesel semis. The quality is usually better and the prices are a lot lower.
    RE the deforestation for beef bullet point- As I have previously posted, one of the number one causes of deforestation in Brazil is to grow SOYBEANS for export (very profitable and much cheaper than ranching cattle). don’t have the source or recall the exact agency’s name but it appeared in an original piece in The Washington Post with this information.
    If we are going to get anywhere this needs to be about objective analysis of everything- especially the parts we don’t want to hear because they don’t fit into our own arguments. It needs to stop being about using climate to promote side-agendas (pro-vegetarian, anti-globalism or otherwise). People are not going to stop being omnivores (look at your canine teeth in the mirror), People in less developed countries deserve the same chance we do to share their talents and wares with the world, etc.
    Dirty energy and polluting industry are winning right now because we are attacking food choice like it is one of the top 3 contributors to global warming.

  12. Adam Stein - May 28, 2008

    I dunno. I’m going to stick up for the generalizations. There are a lot of corner cases when you start digging into food production issues, but most of us really aren’t cooking at home or eating grass-fed beef. Which means the generalizations hold pretty well for most Americans.

  13. Adam Stein - May 28, 2008

    Drew, the soybean argument doesn’t hold up. Much of the demand for soybeans is for animal feed. Purely from the standpoint of basic thermodynamics, there is no way to get around the raw fact that about 90% of stored energy is lost at every step in the food chain. If you want to reduce pressure on Brazilian rainforests, eat the soybeans yourself, rather than passing them through cows. Drawing a box around a plot of land in the Amazon and pretending that tofu is the problem is not objective analysis — it’s a dodge.

  14. Natalie - May 28, 2008

    Thanks for the interesting post. I live in New Zealand, where we are lucky to have a climate and landscape very well suited to dairying, as well as efficient producers.
    A study by Lincoln University – see – looked at the carbon footprint of NZ food products compared to UK food products and found that even with the long distance from NZ to the UK market, the NZ products still had a lower total carbon footprint! This really highlights the importance of considering how something is produced, not just how far it has travelled.
    I hear that cows in the US are largely grain-fed. Cows in NZ eat grass – what they were designed to eat. I’m no agricultural scientist but I suspect this is a big factor in the carbon footprint of dairy and beef products.

  15. Jo - May 28, 2008

    But — Adam’s question still stands — why process your calories through a cow when you don’t have to? That most of the time it’s going to be a resource-wasteful way to eat is eminently reasonable.
    Adam’s proposal for people who care about environment to minimize meat and dairy intake is still a good one. People would do well to sit with this proposal for a minute and take in what it would mean for you.

  16. Natalie - May 28, 2008

    Yes I agree with you, there is still a strong case to reduce meat intake, and I have put this into practice myself as I have not eaten meat for 5 years. I do eat dairy though and this is an important part of my diet. My general point about the complexity of measuring the carbon footprints of foods applies to vegetarian foods as well. The Lincoln University study also looked at onions and found that those too were produced more efficiently in NZ than in the UK, when storage of the UK onions was taken into account.

  17. Chad - May 28, 2008

    Just as a point about being vegetarian: Everyone needs protein, and like the issue of local vs mass produced I addressed above, it is not always clear which protein sources have the least environmental impact. Obviously, beef as bad and pork is nearly as bad, but poultry is actually quite competitive with soy and nuts in terms of yield/acre. So is farm-raised catfish and shrimp. Wild-caught fish can have even a lower environmental impact IF they are harvested sustainably, though this is a tremendous IF nowadays. If you eat fish and are concerned about the rapacious nature of the fishing industry, I recommend the book “The End of the Line” by Charles Clover. It is both a telling expose and helps you learn which fish – and importantly from what are) – are caught in a sustainable manner. (It’s also nice to read a book where the USA doesn’t look so bad compared to everyone else…the Europeans are utterly AWFUL when it comes to ocean exploitation).
    Personally, I consider myself a “75% vegetarian”…in other words, I eat about 1/4th the meat most people like me would, but I don’t go out of my way to avoid it. Total elimination is possible, but I find it far too limiting in terms of both novel experiences and simple pleasure.

  18. Michael - May 28, 2008

    C’mon Chad – go 100% vegan – the planet and your health will benefit! Vegans get plenty of protein through a well balanced diet comprised of soy products, beans, rice, etc. And if you consider the broad range of sustainability impacts of the meat industry (e.g. GHG impact, water pollution, animal cruelty, land use change, worker safety, human health, etc), going vegan makes even more sense.

  19. Jenni - May 28, 2008

    For those of us who can go veggie, we should. For those of us who just can’t, cutting back is a wonderful thing. And cutting back to grass-fed is even better.
    But cutting back is key — there’s just not enough grassland to support 6 billion people with the meat-eating habits of Americans.

  20. Tom H - May 29, 2008

    Several comments have remarked about the benefit, or lack thereof of eating local. Some have described the efficiency of our global food supply chain, others the inefficiencies of it. Some have argued for or against the health benefits of eating meat. Most seem accurate.
    Measuring the impact of our actions is very, very complicated.
    The main issue here, and with almost all similar analysis is that they are based on simplifying assumptions. They have to be: we don’t have sufficiently precise data to measure, or create models that produce tenable results.
    This is not to say that results such as Adam’s are wrong. On the contrary, they are very valuable as long as we take the time to understand the scope of what is being measured, and what assumptions or simplifications are embedded in the results.
    The simple result I took away: red meat, and dairy account for much more climate impact than other foods.
    Some secondary conclusions might be notable, in particular the relative contribution of transportation and delivery seems small.
    But let’s not dissect the data further. Let’s just recognize that red meat and dairy are costly to our climate. So … eat less of it.
    Now, moving on, let’s also consider other ways we can also save. Buy less. Drive less. Use less.
    Start with a little less and you’ll never notice the change. Keep chipping away. Look back in a couple of years of gradual change and the overall benefit can be dramatic. It has been for me.

  21. kiesm - May 29, 2008

    Soy has such a profoundly negative impact on the overall ecology that I wonder if it is really being taken into account here. Not just the mass production and irresponsible agriculture due to its use in so many products, both edible and non-edible, but because we don’t use it as it is intended (yes, even in “healthy” consumption… by U.S. standards, anyway). Did this study take into account the production of soy for feed and non-edible products and the gross misuse of this crop by the U.S.?

  22. Adam Stein - May 29, 2008

    Er…I think so? But the study was just an analysis of carbon emissions. There are other environmental impacts of agriculture which wouldn’t have been considered. Most of this stuff is going to net out the same way, though: beef production is resource-intensive.

  23. Ann - May 30, 2008

    seriously, this was great. gave me some ideas,Measuring the impact of our actions is very, very complicated.

  24. Linda Ralston - May 30, 2008

    I am just curious who you are and what your credentials are.

  25. Cynthia - June 4, 2008

    Wow! Great chart. I think local CSA is the best. However, if I want to survive I’d have to move if I only ate local. The desert southwest is not all that food production friendly. Can think about many places were this is the case…

  26. Doug - June 6, 2008

    Adam, very nice post, with some valuable information. I went back and read through Professors Weber and Matthews paper, and they make some very interesting points that some of the earlier commentors need to see. On average over 80% of the CO2 equivalents produced in the food cycle come from the actual production of the food. Transportation only 11% with the final delivery only 4%. The authors have also estimated the CO2 equivalents of a locavore diet – regardless of whether the food was produced within 100 miles of consumption – most of the GHG emissions result from the production of the food. Red meat and dairy have the greatest impacts. The study is so very fascinating and I’d urge everyone to read the original paper. Definite food for thought and thanks for bringing to our attention.

  27. Annie - June 10, 2008

    To all the vegans who are citing this study as a reason to go vegan: myself, I would instead cite it as a reason to make an effort to go pastured (which avoids having the animals eat what could be “people foods”) and go unprocessed (which will lessen the travel miles of the food). Did the study take into account pastured livestock operations, or was it only considering feedlot and industrial production scale? There’s probably still a higher carbon footprint with pastured, perhaps, but animals do process certain types of food better than humans, so as long as the animals are being fed on foods that humans don’t eat, the system is working in a more efficient way than industrial meat production. If an operation is run carefully and thoughtfully, pastured systems can result in land and local environments that are actually more healthy than they were before the operation began (google Polyface Farm for an example). I prefer to participate in this careful and aware diet of whole foods including limited amounts of meat/dairy than to eat a vegan diet that must be supplemented with processed foods that have been enriched and fortified to make sure that the consumer gets all the necessary nutrients.
    This does raise a question for me, however . . . the best way to make certain that one understands the true meaning of “pastured” is to know your source, to the point of visiting the farm and seeing how everything is being raised. Living in a small city with rural areas less than 10 miles away, I’m able to go visit the chickens, pigs, turkeys, and cows who end up as my dinner (and the closeness incidentally also lowers the travel miles, as my chickens, for instance, go straight from the farm to my freezer). But what about folks in more heavily urban and suburban areas for whom it takes much more effort, time, and fuel to get out and check on the sources? Does it make more sustainable sense to advocate a close-to-vegetarian/vegan diet for folks who live in such areas and who would have a more difficult or impossible time checking their meat sources? Given the wide variety of meanings for “organic” when it comes to vegetable matter, does it matter anyway? And when so many people can’t afford these diets, either because of lower income (prevents one from buying processed organic foods) or because of time constraints (prevents one from having the time to cook from whole foods), are we just being middle-class twits? Sorry, I’m not phrasing this well (I think I’ve skipped a few logical steps in my thought process), so I apologize for any accidental obnoxiousness/offensiveness.

  28. Lorraine - June 16, 2008

    I found the article very interesting but would like to comment from New Zealnd where our transportation issues are far greater because of our isolation. We are becoming very aware of purchasing, not only food, locally. The conundrum occours of course that to sustain our agricultural economy we still want to ship our goods to market.
    I am absolutey blown away thay you guys do not eat at home! Surley that would be the most healthy and efficient use of food. In NZ the average family would dinner eat out (including takeaways) about once a month.

  29. Bernard Brown - July 18, 2008

    I’d just like to add my applause, however late, to the comments on this post. We’re big fans of urging people to cut back on animal products to fight global warming, save water, save habitat, and so on – and in educating people in a way that skips the ideology and points out that this is a powerful tool for helping the environment, similar to putting in a CFL or a low-flow showerhead.

  30. kane - November 2, 2008

    how many food miles would there be a day roughly

  31. Alexander - June 17, 2009

    Yes! This is great. I did it on a challenge between myself and others and haven’t looked back. I kept getting reinforcers and use to be contrarian about it. I am embarrassed about that. It’s been 11.5 years! I love it. I do not miss anything (since I discovered vegan feta about 3 years ago)!