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What is carbon-friendly?
Can this result be true? The guy claims that food production and refrigeration is so energy-expensive that it is more carbon-friendly to drive your car than to walk. Walking requires that you eat more to make up the lost energy, as you can lose only so much weight (what's the relevant margin here? Ten feet of walking? A lifetime of walking?).
It is also claimed that: "Paper bags cause more global warming than plastic." Here is the book, I've ordered it and will report in due time. In the meantime, here is Ezra's coverage.
From Chicagoboyz, here is a good post on whether tangerines from a distance can be more carbon-friendly than local fruit. Here is an earlier MR post on the same.
Posted by Tyler Cowen on August 5, 2007 at 09:12 PM in Science | Permalink
Comments
I can't believe this result. I anticipate your report on this.
Posted by: Samson at Aug 5, 2007 9:46:01 PM
Apparently, it's true if you eat beef and only beef.
mmmm. beeef.
Posted by: lardlad at Aug 5, 2007 9:50:52 PM
I'm skeptical. The calculation presumes that all the calories consumed by walking are replaced by beef (and only beef), which is a notoriously carbon-intensive food source. It is entirely possible, of course, to replace with other, less carbon-intensive foodstuffs. It is also unclear how the author estimates the carbon-intensity of beef production, e.g., whether he includes the transportation cost of getting the food from the farm to the consumer's fridge.
The author's point (which is obvious from reading the post on food at his own website) is not that we should drive more and walk less, but that we should reduce the carbon-intensity of the foods we consume. Again, I am skeptical, not as a matter of principle but because it seems far less important than many other steps we might take to reduce the overall level of greenhouse gas emissions. After all, in the US at least, agriculture is a relatively minor source of greenhouse gas emissions. The power industry, other industries, and transportation all produce between 2.5 and 5 times the emissions of agriculture (according to figures from the US EPA's Inventory of Greenhouse Gas Emissions and Sinks 1990-2005 (April 2007)). And the author provides no reason to believe that the costs of reducing emissions from agriculture would be cheaper than the costs of reducing emissions from the big emitters, especially electric power plants.
Posted by: Dan Cole at Aug 5, 2007 9:59:34 PM
Yeah, it's pretty well known that a vegetarian or vegan diet is much more energy-efficient than an omnivorous one.
Posted by: Nick Tarleton at Aug 5, 2007 10:04:53 PM
It generally takes 10x more energy each time you go up a level on the food chain. Herbivore meat is 10x more energy-intensive than the plants the meat ate while it was an animal. Plug that back-of-the-envelope number into the figures given in the story, and walking beats driving again, by a factor of 2.5 or so.
Posted by: James Grimmelmann at Aug 5, 2007 10:05:06 PM
And does organically grown food (beef or otherwise) use less energy?
Posted by: Nick Tarleton at Aug 5, 2007 10:10:08 PM
I like to say that a vegan taking the elevator is saving more energy than the meat-eater climbing the stairs. (I'm not sure if the numbers here are exact, but not all diets do the same thing to the environment, as noted here.)
Side note about elevators: They're great to take even if you are going up only three flights. By pushing the button it forces you to wait; and so it's a great opportunity to practice your patience. The longer it takes the more meditative you can be.
Posted by: Macneil at Aug 5, 2007 10:11:44 PM
I can see how plastic bags could be better than paper from a carbon standpoint (though, couldn't you also argue that increased demand for paper results in higher value for trees which leads to more trees being planted?), but I don't think the "drive, don't walk" argument makes much sense.
Most people aren't going to walk more than a mile to get somewhere anyway, so the "drive, don't walk" argument would only work in dense urban areas. But walking less than a mile doesn't burn a whole lot of calories, certainly not enough to require a big slab of beef! I am fortunate enough to live in Adams Morgan in DC, where I can and do walk everywhere (in fact, I don't own a car). To use a car, I would have to first purchase a car (stimulating demand in an industry that is quite energy intensive). Then, let's say I wanted to go get groceries. Is this guy saying that instead of walking the half mile to the Safeway, I should get in the car, drive over there, look for a parking spot, then walk probably one-tenth to one-quarter of mile from the nearest parking spot to the store?! Then walk back to the car? And from the car to my apartment, which could be quite a ways considering I never see a whole lot of open parking spaces on my street. Add in the physical stress (faster heart rate, etc.) of driving and trying to park around my neighborhood and I doubt you'd conserve any calories. And, if everyone started doing this (meaning, people without cars bought them and drove them more within the city), there would be fewer parking spots, which would require longer walks from parking spots to destinations.
Not only is the result likely not correct, it's simply not practical.
Posted by: dave at Aug 5, 2007 11:02:19 PM
I meant to say it's not practical to drive instead of walk even if it's true that driving is less energy intensive than walking (though I doubt it).
ALSO, if everyone became a couch potato, I imagine there'd be a noticeable health effect, which may have negative consequences in terms of energy consumption. (Though that could go the other way, too... For instance, if more people died sooner from things like heart disease, consumption may decline)
Posted by: dave at Aug 5, 2007 11:10:15 PM
Another reason for a global carbon tax. It makes being environmentally smug so much more straightforward. No need to rely on all these complicated estimates of what's really better. Just be cheap.
Posted by: Kevin at Aug 5, 2007 11:15:28 PM
I don't know about energy intensity, but I believe that the consumer cost of the extra food is probably higher than the cost of gasoline.
I calculated that I burn about 1000 calories cycling for 25 miles. The way I normally eat, that costs about the same as a gallon of gasoline. And biking is more energy efficient than walking.
The key, though, is that if people drive instead of walk they don't go "the same distance," they go much, much, much farther.
Posted by: ed at Aug 6, 2007 1:25:47 AM
I don't know about energy intensity, but I believe that the consumer cost of the extra food is probably higher than the cost of gasoline.
I calculated that I burn about 1000 calories cycling for 25 miles. The way I normally eat, that costs about the same as a gallon of gasoline. And biking is more energy efficient than walking.
The key, though, is that if people drive instead of walk they don't go "the same distance," they go much, much, much farther.
Posted by: ed at Aug 6, 2007 1:26:00 AM
Depending on how long you use them, paper bags are four times 'worse' for the environment than plastic bags. The best is to take a textile shopping bag that you use for several years, of course, and it seems to me that this is the nub of the problem. We are arguing like shoolkids in the playground about what is better and what is worse, while the solution is staring us in the face.
Agriculture is a relatively minor source of greenhouse gas emissions. But it is a huge user of water - the biggest you've got. It's not *just* about greenhouse gases, it's about living sustainably, which won't happen until your government gets it. Switching to biofuel won't do it; to supply biofuel for 50% (that's half) of the car miles in the USA would require all (that's 100%) of the arable land to be turned over to biofuel production. That might well go wome way towards solving the obesity problem ...
Meanwhile, carry on having these arguments. They don't get us as far as learning how to use less.
Posted by: Peter Warne at Aug 6, 2007 1:51:19 AM
It should also be noted that quite a few ppl have enough body fat so that the cost of walking more wouldn't cause them to eat more.
For that matter the health problems that come along with being overweight cost quite a bit of energy too.
Posted by: Factory at Aug 6, 2007 4:30:14 AM
The assumption here is that more exercise results in great food intake. My experience is that the food intake remains largely similar, but some just choose to burn the calories, instead of storing them in public places...
How much less food do you eat if you burn less calories? Are couch potatoes and car junkies more prone to skip a meal a day? That would make the real difference in this situation.
Posted by: sam at Aug 6, 2007 5:28:58 AM
Imagine if the report said "Driving to the gym uses less carbon than jogging the same distance"
Posted by: ths at Aug 6, 2007 5:53:54 AM
On top of the 'beef is inefficient as energy deliverer': I googled some calorie values for beef, and apparently 180 calories/100 grams, as used in the calculation, is very, very lean beef. Switching to fatter beef, like a steak with a bit of fat attached, or ground beef already raises the figure to 280/100 grams.
On top of that, why not use cycling as alternative to cars? Seems more realistic for 3 mile distances, and it is far more energy efficient. Cycling uses something like 25 calories per mile, if you don't drive at exercise speed.
So, just switching to cycling and eating only ground beef instead of only lean steak already closes the gap with a car.
Posted by: marius at Aug 6, 2007 6:09:12 AM
On top of the 'beef is inefficient as energy deliverer': I googled some calorie values for beef, and apparently 180 calories/100 grams, as used in the calculation, is very, very lean beef. Switching to fatter beef, like a steak with a bit of fat attached, or ground beef already raises the figure to 280/100 grams.
On top of that, why not use cycling as alternative to cars? Seems more realistic for 3 mile distances, and it is far more energy efficient. Cycling uses something like 25 calories per mile, if you don't drive at exercise speed.
So, just switching to cycling and eating only ground beef instead of only lean steak already closes the gap with a car.
Posted by: marius at Aug 6, 2007 6:09:20 AM
On top of the 'beef is inefficient as energy deliverer': I googled some calorie values for beef, and apparently 180 calories/100 grams, as used in the calculation, is very, very lean beef. Switching to fatter beef, like a steak with a bit of fat attached, or ground beef already raises the figure to 280/100 grams.
On top of that, why not use cycling as alternative to cars? Seems more realistic for 3 mile distances, and it is far more energy efficient. Cycling uses something like 25 calories per mile, if you don't drive at exercise speed.
So, just switching to cycling and eating only ground beef instead of only lean steak already closes the gap with a car.
Posted by: marius at Aug 6, 2007 6:09:27 AM
Is it really necessary to subordinate everything to the holy grail of a low-carbon life? I would think that your health matters too. Then I would walk more, drive less by car, and not worry too much about my carbon footprint. These environmentalists are really getting annoying.
Posted by: ivan at Aug 6, 2007 7:42:02 AM
Nick, I'm not an expert by any means but my intuition is that organically grown beef is less energy efficient, since it's less cost-efficient. But I could be totally wrong.
But all this discussion misses the point - environmentalism, like almost everything else in the world, is about tradeoffs. What's good for global warming may be bad for water quality - say if all those hybrid car batteries are improperly disposed and leak toxins into our groundwater. What's good for air quality may be bad for waste management, etc. I once met a businessman whose company cut down large swaths of rainforest in Malaysia/Indonesia for lumber, who argued that by capturing the carbon in the lumber, he was actually helping with global warming because young, replanted forests capture carbon from the atmosphere at a much faster rate than mature forests. This is true, but doesn't address the deforestation/species diversity arguments against cutting down rainforests, and it assumes that he's telling the truth about replanting trees (I didn't believe him, for what it's worth).
But global warming is only one problem - anyone who has been to China can argue that China has more pressing environmental issues than just reducing greenhouse gases. Smog and water quality are terrible. I'm sure they have an acid rain problem, too, with the amount of electricity they produce from coal. Not to mention the environmental devastation of the flooding from the Three Gorges Dam (which will release greenhouse gases from decaying vegetation for decades).
Posted by: Shane at Aug 6, 2007 8:17:19 AM
Oh and also - when I was in Malaysia it seemed that one of the highest priority environmental issues that the locals cared about was reducing one's detergent footprint, since much of it washes into the sea and ruins the coral reef (which the locals cared about because their tourist-dependent economy included lots of scuba/snorkeling shops). Granted, I was there for scuba, so my sample might be heavily biased, but still.
Posted by: Shane at Aug 6, 2007 8:22:27 AM
I first heard this idea from Michael Bluejay; he claims that walking can be more or less fuel-efficient than driving depending on the walker's diet, but cycling is essentially always more fuel-efficient.
What he doesn't factor in -- and I'm not sure how one would even do this! -- is that in a society where lots of people are walking or cycling, population is probably denser and distances traveled are shorter. (A thirty-mile driving commute is fairly common. A thirty-mile biking commute would be insane.)
Posted by: Isabel at Aug 6, 2007 10:39:58 AM
"Is it really necessary to subordinate everything to the holy grail of a low-carbon"
"But global warming is only one problem"
"These environmentalists are really getting annoying."
And nuclear war is just one among many kinds of security problems...duh!
Posted by: aaron_m at Aug 6, 2007 10:50:24 AM
I reported about a month ago that the carbon footprint of the average day's driving was about the same as that in the production of a couple of cheeseburgers, so I'm not surprised by this sort of result at all.
Posted by: David Tufte at Aug 6, 2007 10:53:26 AM
**Warning** Breathing will negatively impact your carbon footprint. You will be taxed per breath. No running, or strenuous activity is to be allowed.
Posted by: Jacob at Aug 6, 2007 12:29:16 PM
This highlights the problem with 95% of environmentalism. Shallow thinking that ignores the secondary and tertiary effects of the behavior. For instance, genetically modified foods will slash carbon use, yet most environmentalists oppose GM foods.
And then there are those who not only want centralized economic planning, itself an utter failure of biblical proportions, but also want to turn it over to these morons who do not consider all the factors, let alone do not even believe in unintended consequences. History repeats for the second time.
Posted by: 8 at Aug 6, 2007 12:31:33 PM
Organic, grass-fed beef is presumably less energy-efficient than commercial, corn-fed beef, which might be a problem if the earth were in danger of running out of energy, which it is not. The difference is that, in the case of organic grass-fed beef, the energy inputs all come from--and this is a crazy idea--the sun, an energy source which is famously abundant and carbon-neutral. Non-organic corn, by contrast, gets a substantial portion of its energy from consuming oil (in the form of chemical fertilizer), not to mention the fossil fuels involved in transporting the corn from where it is grown to the feedlot. (In the case of grass-fed beef, the transportation costs involve cows walking around a field--although as we've seen, walking is apparently very carbon intensive.)
Note that there is such a thing as corn-finished organic beef, although it's not a particularly good idea to feed cows corn without the constant therapeutic levels of antibiotics required to control the resulting gastrointestinal disease. (Cow stomachs are designed to eat only grass.)
As for overall carbon footprint in raising beef, the more significant component is actually methane released by the cows' digestion. According to the information here, methane production is considerably higher with grass-fed beef, but the carbon sequestration from the required grassland is great enough to make the entire process slightly carbon negative.
Posted by: Dave H at Aug 6, 2007 2:20:33 PM
That is one of the nuttiest analyses I have ever seen. First, it assumes, quite wrongly, that most Americans would need to make up the calorie expenditure. An American man who is 30 pounds overweight, maintaining a stable weight on, say, 2,700 calories a day, doesn't need to eat a calorie more when he starts walking three additional miles a day. He just finds, in a year, that he weighs 20 pounds less. And no, he doesn't need to start eating more then. He will find that the same 2,700 calories maintains his lower weight, albeit at a higher level of exercise, as they did his former greater weight, at a lower level of exercise. Second, as others have pointed out, it assumes any calorie difference is made up from one of the most expensive foods -- beef -- rather than from something fairly cheap, like potatoes or lentils. Neither of which require refrigeration. Third, it tries to fully account for the cost of the production of that beef, but completely ignores the considerable cost of driving, except for the fuel burned.
Posted by: Russell at Aug 6, 2007 6:35:53 PM
"Driving a typical UK car for 3 miles [4.8km] adds about 0.9 kg [2lb] of CO2 to the atmosphere."
But what is the carbon footprint of 180 calories of the typical UK diet? For this to be a fair comparison, we should also assume that the car is a Hummer...
The guy's point may have been more clearly made in the interview--eat more vegan foods to lower your carbon footprint. The reporter, as usual, finds the most sensational angle possible.
Posted by: lucas at Aug 6, 2007 7:39:50 PM
If people generate more carbon dioxide emissions than cars the solution is obvious: Tax reproduction.
We could even use the tax to build roads and cars.
Posted by: Randall Parker at Aug 6, 2007 10:51:57 PM
I sense a curious similarity between all these "carbon footprint" arguments and the medieval theologians arguing about how many angels could dance on the head of a pin and whether the world was created at 9:00 AM or 4:36 PM on April the ninth in 4400 B.C.
Check your premises, as a famous non-vegetarian said. Oh, and grow up.
Posted by: Robert Speirs at Aug 7, 2007 4:49:27 PM
I think the takeaway from this is that even simple comparisions of carbon footprints (drive 10 miles to the farmer's market for local produce vs 1 mile to the grocery store for bulk-shipped produce for example) are highly contingent on a plethora of minor details about the respective choices and the lifestyle of the the chooser (I'm guessing partially hydrogenated vegetable fats and HFCS have pretty good Cals/g CO2 emitted numbers, but how how carbon intensive is treating diabetes or heart attacks of over-consumers?). And even then, that's not the only metric that matters - land usage impacts the albedo. That's why using the price signals from C (and other warming-relevant factors) taxes or equilvalents (cap & trade, etc) at (or very close to) the point of emission are the only really effective way of minimizing the factors that go into warming.
Posted by: MattXIV at Aug 7, 2007 7:03:11 PM
OK, public forum, do I have my calc right now?
This page claims (citing the Farmer's Almanac):
"Americans are 2,300,000,000 (over two billion) pounds overweight. We average about nine and a half pounds overweight. Overweight Americans cost about a million extra gallons of gasoline per year."
we carry 3500 calories per pound and burn 100 calories per mile (googling for common figures), so:
(2,300,000,000 * 3,500) / 100 = 80,500,000,000 miles.
We as a nation can walk 80 billion miles before we work off our overweight.
Working from the other number ("We average about nine and a half pounds overweight."):
(9.5 * 3,500) / 100 = 332.5
We can afford to walk on average 332 miles apiece.
(I agree with many above that choosing beef was a sneaky corner-case. There are very many foods with lower upstream GHG contributions. Note the old Walker Crisps bag with only 75g of CO2 head-to-tail.)
Posted by: odograph at Aug 8, 2007 10:26:15 AM
BTW, I think the message "driving is better than walking" was chosen for shock value and shameless self-promotion. Shock value would be OK if it sent the right message ... but given our overweight, and the wide variety of foods with lower impacts than beef ... this is sending the wrong message.
It should have been "walk and eat potato chips."
That would have made everyone happy, and as it happens, healthier.
Posted by: odograph at Aug 8, 2007 10:30:30 AM
