Cities: still greener than small villages

The review of Green Metropolis kicked off a discussion that illustrates some of the confusion that crops up in discussions of density. Hoisting a representative snippet up from comments:

> I think people can be extremely green in either rural or urban settings, it’s a matter of intent. Hard to measure the difference in impact – an urban setting allows for a much more communal way of using and reusing resources, but on the other hand, if the concentration of people is greater than the city can naturally sustain, the expense and difficulty of importing food and fuel and exporting waste may mitigate what is saved by sharing.

This was followed by some further speculation that maybe the ideal density is some village type thing where people are reasonably close together, but still able to sustain themselves from the surrounding land.

Partly this line of thinking reflects the ongoing myth that sustainability is best measured by proximity to a farm. I recently read that a freight train can move a ton of goods 460 miles on a single gallon of diesel. Your car can move a bag of groceries about 20 miles on a single gallon of gasoline. Sustainability is best measured by proximity to a *supermarket*, not a farm.

The bigger conceptual problem, though, is the conflation of population size and population density as determinants of environmental impact. Any population of a given size requires a certain amount of agriculture to support it. If the attendant farming places excessive pressure on natural ecosystems or otherwise threatens to exhaust the land itself, then it might be said that the population is “unsustainable.” But that issue has little to do with *where* those people live in relation to the farmed land. Generally speaking, greater density is always going to come out ahead from an environmental perspective.

Take a state with a lot of agriculture like, say, Nebraska. Imagine two extremes: in the first scenario, the population of 1.7 million Nebraskans are distributed evenly throughout the state, so that all the lawyers, accountants, school teachers, and dentists (because even in Nebraska relatively few people work as farmers) are scattered amongst the corn fields; in the second scenario, the entire non-farming population of the state is placed in downtown Omaha.

Which is likely to be more sustainable? Scenario 2, by a mile. Even in scenario 2, Omaha wouldn’t be amazingly dense — it would be considerably more spread out than, say, Brooklyn — but people would likely be driving less, living in smaller houses, and making better use of mass transit. The very small (or, more likely, non-existent) environmental impact of food transportation will be more than offset by the inherent efficiencies of city living.

Green Metropolis illustrated this point nicely with a discussion of water use. A common complaint lodged against cities is that they “steal” water from neighboring watersheds. Indeed they do: New York siphons a vast amount of water from upstate New York. But from an environmental perspective, it is far preferable to concentrate people in cities and have them draw water from the surrounding area than to sprinkle them across those watersheds. Suburbia tends to bring with it lawns and all sorts of other things that would only despoil sparsely settled areas and place even heavier pressure on water resources.

A final point, and then I’m done (for now) belaboring this issue: the comment up top suggests that either rural or urban residents can lead sustainable lives, as long as the intent is there. But that’s just it: intent doesn’t really enter into the picture for the majority of folks. Cities have a lower per-capita footprint not because their residents are more virtuous, but because efficiency is built into their basic fabric.

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  1. Tony S, UK - November 4, 2009

    Your comments that food delivery to cities is small in comparison to the travel of its consumers is true, but your argument is one dimensional – you haven’t included how ‘sustainable’ the actual growing and processing of food is in the first place.
    I know you’re trying to compare an urban and rural scenario on simple grounds, but when you look at the environmental impacts of food, you find that the MASSIVE majority is in its growing and production – meaning concentrating on travel (be it consumer or delivery) just isn’t that important.
    See my example of the life cycle carbon impacts of a UK loaf of bread below:

  2. kirk s. nevin - November 4, 2009

    The question is: Can humans in 2009 live sustainably?
    Consider that there are 6.83 billion of us.
    I’ve visited some of the places where humans are poorest… rural Laos is a good example. Consumption levels are extremely low, both in terms of manufactured goods and food. Yet, if you look carefully, the ecodestruction is horrendous… even the local boys don’t swim in the polluted rivers, the forests are long gone, climate change has eliminated the regular rains of the monsoon. And considering that those local rivers depend on Himalayan glacier-melt (which is rapidly being depleted, again by climate change), there is no way those communities can be considered sustainable over the long term.
    My conclusion is that we’ve had a good ride, but that we have exceeded the carrying capacity of the Earth. And that the ride from here on is all downhill. You can choose to enjoy that ride, or not, but we will all be on the same train. Duck as we enter the tunnel!

  3. Jane - November 4, 2009

    To me, the big question is what we can do to make rural life sustainable so we don’t all have to live in cities if we don’t want to.

  4. Jeff C. - November 4, 2009

    Re: “stealing” water: Cook Co. (IL) is encouraging residents, urban and suburban, to install rainbarrel systems to ease demands on the water supply/reclamation/distribution system. The models for rainbarrels come not from city systems, but from rural systems—the most incredible from rural Australia.

  5. Anonymous - November 4, 2009

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  6. Chuck - November 4, 2009

    Living in a small town, ~5,000 people, we drive one mile to the supermarket for our food. Traffic on the highway is sparse enough for me to drive my 60mpg motorcycle 21mi/day safely to work on dry days. We never water our lawns. Yes, when we lived “in the city,” we drove less. But I couldn’t stand breathing all the pollution. Sorry to hear I’m so unsustainable.
    BTW, the true food distribution costs need to account for:
    A) Train: Getting food to the supermarket distribution center. (Relatively speaking: negligible.)
    B) Truck: Getting food from distribution center to supermarket.
    C) Car/bus/walk: Getting food from supermarket to home. (Studies done in UK indicate that walking generates as much CO2 as car for transporting groceries.)
    I’m pretty certain that (B) is a long distance for both the center of large cities as well as rural towns.
    Maybe the solution is not force 99% of rural people into cities, but to improve the distribution network in suburban and rural areas. First solution degrades the quality of life for a lot of people while the second solution improves it. (I’m assuming that most rural and suburban people live in these areas by choice as demonstrated by surveys that I’m aware of.)

  7. Adam Stein - November 4, 2009

    Tony, I don’t see any disagreement here. Food miles do not make up a significant proportion of the environmental impact of food, so proximity to farms is not a meaningful gauge of one’s footprint. Agriculture itself, though, obviously has a very big impact.

  8. Adam Stein - November 4, 2009

    I hope this is kind of obvious, but I’ll say it anyway: this post isn’t a criticism of how any individual chooses to live. Americans, myself included, are complete energy hogs. Energy consumption is largely determined by structural issues, and that’s what drives my interest in this topic: how do we create structures that lessen our environmental impact?
    So, sure, improving transportation efficiency will disproportionately reduce the environmental impact of suburbs. I’ve made the point before about how electric cars could very well end up creating a somewhat greener form of sprawl.
    That said, cities will always have an environmental edge, and my impression is actually that a majority of people prefer to live in denser areas. Worldwide, rural areas continue to thin out, and cities continue to grow. The important thing, I think, is to address the quality of life issues in cities, such as pollution, so they’re as appealing as possible to the greatest number of people.

  9. Anon - November 4, 2009

    You have neglected to take into acocunt how self contained most rural families are. Many grow an abundance of their own food as well as livestock for personal consumption. So didtance travelled to the supermarket…walking out the back door. Many of us in rural areas leave the farm on an infrequent basis to stock up on dry goods. I think you have failed to take into account how often someone covers the distance, not just how great that distance is. I’m assuming you are a born and bred city boy… By the way, we run on solar and a catchement system.

  10. kib - November 4, 2009

    The original post was mine – how flattering! When I wrote it, I was responding to another poster who spoke of the low footprint of “farmers”, for which he took some flak; I felt he was actually referring to people who were conscientiously going back to the land with the idea of sustainability in mind. The point I was trying to make was that people intentionally living lightly can probably do so more wholly in a rural setting, like Anon above, but agreeing with you that concentrating the less ecologically conscious in cities is most likely the more eco-friendly solution.

  11. Chad - November 4, 2009

    Really? My family comes from a rural area full of dairy farms in the upper midwest. The ~10% of folks that are farmers all own monster trucks and are about as far from green as one could imagine. Everyone else drives their almost-as-big trucks to Wal-Mart every weekend, except when they drive them downstate to get even cheaper stuff and maybe catch a movie or eat some cheap Chinese food.
    I really can’t think of anyone back there who I would consider an environmentalist. Most still have the mentality that there is far more than they could ever take, so take they do. They also whine like stuck pigs the moment the gub’ment tries to stop them from doing so.

  12. Garrison Collette - November 5, 2009

    Interesting topic…but you ignore the basic systemic assumptions of human existence. As O’brien’s Ishmael points out, humans live apart from the natural system but it has not always been this way; indeed the very definition of natural precludes the modern human way of life.
    But consider animals; bears are solitary and they move around a lot (lots of transportation energy costs); they also take up huge areas that they call their own. So by your analyses, bears are less sustainable than a colony of ants. But because they are part of the natural system, neither bears nor ants are unsustainable, nor could they ever be. The problem is every little thing that we do that deviates from the natural system; population carrying capacity is universal, whether food is from farms or from an antelope kill, so the argument that humans can become unsustainable via exceeding carrying capacity doesn’t hold water. The only thing that is unsustainable is choosing to violate the natural system. Examples of this are:
    -agriculture: pollution via fertilizer or intensive cultivation. No agriculture should ever take place, not on one square inch of land anywhere, that degrades the soil over the long term;
    -transport: You can choose to burn fossil fuels, but its unnatural if you create harmful byproducts that are not beneficial to the natural system. CO2 is beneficial to plants, but particulates are not beneficial to anyone. So a gasoline-powered fuel cell where the CO is reformed into CO2 is perfectly sustainable. Because petro will run out, I put this under the carrying capacity rule-you just run out, nobody gets hurt but nobody drives.
    -Manufacture:Anything you create that can’t be used as food is unsustainable. Biodegradable substitutes exist for every single one of the things we use.
    -Energy: This is the hardest one, because doing all the others are tied to energy. Again, no harmful byproducts are possible. Now, sustainability doesn’t include things like bird deaths from your energy source, say wind. But then again the carrying capacity argument holds; too much population will degrade any system, same for wind mills.
    I guess what I’m trying to say is that its okay if we die off every now and then, as long as along the way we never make a choice that violates the natural rule. It should be ingrained in us, like it is in animals, that the option of killing everything else so that we can live via our systematic approach to life is not an option at all. We should all feel that we should die before we’d create any situation where our living endangers any other living thing that we don’t benefit directly by killing (food, clothing, defense, etc). Its just a series of choices, or in the case of the uninformed, non-choices. Just a thought-its all about context isn’t it? I love the idea of living at a western std of living while doing no harm, but since we as humans depend upon other humans, we’d all have to make that choice. So in the long term, so compromises are possible when it comes to doing harm.
    But then again sometimes bears will kill humans outside the realm of defense or food, so there’s where intent comes in…

  13. Pete Murphy - November 5, 2009

    Per capita carbon emissions are meaningless. The planet doesn’t give a damn about per capita emissions. The only thing that matters is total emissions. Total emissions are a function of population X per capita emissions. Do the math and you can no longer claim that cities are greener than rural communities. Which would have a greater impact on reducing emissions? Eliminating all cities, leaving nothing but rural communities, or filling all remaining rural space with more city? The answer is obvious.
    What is not so obvious is that advocating reductions in per capita consumption in order to achieve reductions in emissions is a recipe for soaring unemployment and poverty. Per capita consumption and per capita employment are inextricably linked. The only way to achieve the needed reductions in emissions while allowing all people of the world to enjoy a high standard of living is through (over time) reducing our population.
    Pete Murphy
    Author, “Five Short Blasts”

  14. r4 card - November 6, 2009

    We all yearn for our own personal space, a little fresh air and elbow room. Owen doesn

  15. ConsciouslyFrugal - November 6, 2009

    Hmmm…I tried to ask this question yesterday, but there must have been something offensive in my post (apologies!). So, let me try again!
    You said, “my impression is actually that a majority of people prefer to live in denser areas.”
    Could you let us know where/how you got this impression? Because the data I’ve read doesn’t support it (the GCIM, Joel Spring, heck even the Daily Yonder!)
    The offering of density-related, lower-impact resources in urban areas is a bit of a no-brainer. What concerns me is the fact that there has been such a massive drain of resources–talent, opportunity, and industry to just name a few–from rural areas, making migration necessary for many. Necessity doesn’t equate desire.
    I have to chime in with Jane. We need a more equitable distribution of resources so that migration isn’t necessary if it is undesired. Efficiency can also be built into rural areas, but it requires political might and the kind of advocacy that brain and resource drain due to migration do not inspire. So, how can we ensure that we all live in areas with built-in efficiencies?

  16. Adam Stein - November 7, 2009

    No comments were moderated — it must have just gotten caught in our spam filter. Regarding preferences, I was referring to the general migration pattern over the past century. In 1900, about 13% of people lived in cities. Recently, the figure passed the 50% mark, and all future population growth is expected to occur in cities:
    This is a global phenomenon, and obviously there are more complicated things going on at regional levels.
    This is, as you note, an economic phenomenon. But I don’t really see how you can separate “necessity” and “desire” in the way that you’re implying. People want certain material advantages, so they move to cities. There are tradeoffs involved, as with everything in life.
    I’d also note that we already as a society pour tons of resources into rural areas. It’s true that resources are not equitably distributed now — they’re disproportionately taken from urban areas and given to rural ones. One can argue about whether this is good or bad (certainly it’s not good for the environment), but it’s definitely happening.
    As an aside, this discussion has taken on a bit of an urban vs. rural cast, but really I think the big issues in terms of greenhouse gas emissions are 1) finding ways to make cities as green and also as appealing as possible, because that’s where the majority of the world’s population will be in 2050; and 2) figuring out ways to transfer some density benefits to suburbs and exurbs.

  17. ConsciouslyFrugal - November 7, 2009

    Thanks for the reply, Adam.
    I’m well aware of global migration patterns, and I happen to be part of that pattern. I suppose I’m noting an emotional divide between desire and necessity.
    The urban vs. rural you’ve noted in the comments section highlights this emotional divide. Necessity forced, as a result of a lack of adequate resources (where in the world are you getting your information regarding “tons” of resources being funneled into rural areas disproportionately? Because I’ve spent the past 15 years reading research on the subject and I’ve found quite the opposite to be happening. The “brain drain” and flight of industry being the two most commonly cited phenomena), us to move to areas in which we have no desire to live, but must for economic reasons. “Forced” is a word I commonly hear used. A bit different sentiment than “desired.”
    Unfortunately, that’s an entirely different conversation, as you note. But just so ya know–I suspect that’s why a few of your readers bristled.

  18. Adam Stein - November 7, 2009

    When I refer to tons of resources, I mean public money. If you look at where the federal government raises its budget and where it spends it, you see a big flow of money from metropolitan areas to rural. This reflects the basic political reality in the US: rural regions wield far greater political power than urban ones per capita because of the structure of our institutions — particularly the senate.
    Fair enough points about brain drain and industrial migration. But is this really an issue that we can or should address politically? Agriculture used to be the biggest source of employment in our economy. It never will be again. Cities are much better for the environment than exurbs, and we’re facing a global resource crisis. What kind of society should we be trying to create?

  19. Adam Stein - November 7, 2009

    By the way, thanks for being a good sport about this. I hope it didn’t seem like I was picking on you — I find this to be an interesting topic, so I wanted to write about it some more. I agree that some individuals who choose to go “back to the land” can live very sustainably, but you still run into the population size issue. If a large number of people tried to do this, it wouldn’t be sustainable at all.

  20. ConsciouslyFrugal - November 8, 2009

    We absolutely should address these issues politically. Problems resulting from rural poverty are significant, and I’m not about to ignore 20% of the population simply because they live in what is considered to be an inconvenient location prone to greater impact than high density areas.
    I would need a novel to properly blabber about this. ( has several great articles on this subject, however.)
    ANYHOO, I’d be curious to see how public funds are dispersed. How much is going to *explicative* Monsanto vs. small town America? We need to explore more of the micro within the macro of these trends–quality of life issues, cultural impact, blah blah blah. It’s just far more complicated than resource depletion, therefore high density=good, low density=bad. What good is transportation efficiency if we continue to orient our lives around excessive consumption and pharmaceuticals due to quality of life issues? Or the destruction of family and culture because our big ag. policies are undermining economies across the globe?
    20 years ago, I read about how destructive cities were. Now, it’s the rural world that’s causing harm. I find it hard to believe that the ridiculous romanticism around the “back to the land” movement and the hostility of the urban left (of which I am an unfortunate member) toward rural America doesn’t play into how we frame these issues.
    I live in the big sprawl known as Los Angeles and it isn’t even remotely as “green” or efficient as my little rural hometown. Surely, we can fix LA and expand my hometown’s progressive policies in other rural areas? Surely we can fix the Farm Bill so that we don’t undermine rural communities globally?
    Short version–it’s not either/or. It can’t be. We can’t ignore large percentages of the population globally. In the words of Van Jones, “there are no throw away people.” (Sorry, it looks like I wrote that novel after all!)

  21. Camera Accessories - November 8, 2009

    I agree that the people in cities are more efficient than those in the villages, but the fact remains that most of the cities are congested than the villages resulting into the deficiency of fresh air. So the city may be greener, but with respect to the population it is not enough.

  22. Rich Legault - November 17, 2009

    Hi Adam,
    I don’t know where you read this ‘fact':
    “a freight train can move a ton of goods 460 miles on a single gallon of diesel.”
    but it is completely untrue. A freight train engine, with nothing attached, cannot move itself 460 miles on a gallon of diesel fuel. It is unlikely to even move itself 20 miles. The 460 MPG figure is nothing but ridiculous AAR propoaganda.
    Thanks for an otherwise thoughtful article!

  23. Adam Stein - November 17, 2009

    I recall reading it in one of the articles about Warren Buffett’s recent investment in rail. You’re right that the claim seems absurd on its face, though. I assume it refers to a marginal gallon — meaning that one extra gallon is used per every ton of cargo added to a train.
    But this isn’t really a fair way of measuring freight emissions. I’m going to see if I can find some better info.

  24. Adam Stein - November 17, 2009

    OK, I looked up the figure from the World Resource Institute, generally the gold standard in this sort of thing. And actually the figure I used up top is basically right. Assuming I did the conversions correctly, the WRI says that a gallon of diesel is required to move a ton of goods 238 miles. This is lower than the figure I cited, but there’s a good amount of variation in these sort of calculations based on the type of train, etc. So the original figure is not really so far off.
    I now see where we both went astray. A locomotive can’t move itself 460 miles on a single gallon of fuel, but of course that figure was the per-ton fuel amount. An engine weighs a lot more than one ton, so you have to multiply through. Also, I bet trains get more efficient the more heavily they’re loaded.

  25. Rich Legault - November 20, 2009

    Hi Adam,
    Thanks for investigating further!
    I have to say that I don’t think discounting the weight of the train itself results in an accurate representation of tranport efficiency.
    Using this method, my car (a 2000 Honda Insight, which actually has gotten 63.2 MPG over 119,000 miles) gets 632 miles per gallon, as I only account for 10% of the total weight. I realize that the goods being transported likely weigh more than the train does, but I would like to see a total figure. How many gallons of diesel fuel does it take to move X tons of cargo Y miles from start to destination, including any efficiency-killing stops along the way.

  26. Adam Stein - November 21, 2009

    Hi Rich,
    The figures I quoted above don’t ignore the weight of the train. The energy cost of moving the locomotive gets allocated to the cargo, which is what you want to do when comparing the efficiency of different shipping methods. The WRI has provided the number you’re looking for: It takes one gallon of diesel fuel to move one ton of goods 238 miles. The WRI’s methodology undoubtedly takes account of real-world transportation conditions, such as starts and stops.
    This figure maybe shouldn’t be so surprising. Your Insight weighs about a ton, so it’s getting about about 63 miles to the ton-mile. Now think of the efficiency advantages of trains compared to cars: steel wheels on steel rails, less wind drag because of a tiny cross-section, extremely low acceleration, and infrequent braking. It’s no wonder they’re four times as efficienct as your car.