This urban life

Even the greenest suburbs can't touch low urban emission rates

Posted by Ryan Avent (Guest Contributor) at 9:25 AM on 21 Oct 2007

Read more about: placemaking | urban planning | sprawl | climate | greenhouse-gas emissions

Last Sunday, the Washington Post published a piece by Joel Kotkin and Ali Modarres which sought to debunk the ideas that dense urban areas are greener than their suburban counterparts and that encouraging dense growth might play a significant role in reducing America's carbon output. The piece was wrong or misleading on practically every point, to the extent that any complete response would take up far more time and space than I have available. Some of the authors' most egregious errors simply must be addressed, however.

Kotkin and Modarres spend the first half of their op-ed arguing that cities contribute to negative environmental outcomes through heat-island effects. The authors acknowledge that such effects can't be linked to global warming but warn that they necessitate increased air conditioner use, leading to greater energy consumption. They neglect to mention that the same effects should also moderate heating needs in winter.

The bigger issue, of course, is what the numbers actually say about energy use in urban areas relative to suburban areas. In fact, urban residents tend to use less energy per person than suburbanites, and the gap is largest for urban families living in dense, multifamily housing. The intuition behind this isn't terribly difficult to grasp; urban homes tend to be smaller than suburban homes, with less surface area exposed to the air, improving the efficiency of heating and cooling. Large, shared boilers and condensers are also likely to prove more efficient than small ones scattered across many detached homes. Kotkin and Modarres argue that suburban homes can be greened more cheaply than large urban buildings, but that's far from clear. Another story in the Post this week suggests that efficiencies can be achieved in urban buildings at zero long-term cost, and businesses are beginning to recognize that potentially profitable opportunities may exist to help green those larger structures.

The largest gap between urban and suburban emissions is generated by disparities in transportation patterns. In dense urban areas, residents can easily substitute driving with walking, biking, or using mass transit. When urbanites do drive within the city, the distances tend to be short. In suburban and exurban areas, substitutes for cars are rare. Automobiles are used for every little errand, and even short trips are long by urban standards.

Recent carbon audits give credence to the role of settlement and transportation patterns in reducing emissions. A study conducted for Greater Washington revealed that per capita transportation emissions in the metropolitan area were less than the national average. Within the Washington area, transportation emissions for the District -- the densest and most transit dependent portion of the area -- were far lower on a per capita basis than in the neighboring Virginia and Maryland suburbs. This despite the fact that the District is home to the area's largest employment concentration, into which hundreds of thousands of suburban residents commute daily. Even the District's numbers pale in comparison with the success achieved in New York City.

Kotkin and Modarres see these statistics and declare them irrelevant, because, as they say, Americans simply prefer suburban life. Absent a calamity of some sort, they suggest, Americans are unlikely to reduce their consumption of low-density life and automobile use. This is simply incorrect. Rail and transit ridership have increased substantially in recent years as congestion and fuel costs have increased. Americans appear happy to use alternative transportation options when they're available, but are prevented from doing so more often by federal transportation policies. While some $40 billion per year in federal tax money is allocated to states, no strings attached, for highway construction and maintenance, transit projects are granted a little over $1 billion per year, and that money comes with substantial oversight and regulation as to its use. Amtrak will probably receive about $1.4 billion next year thanks to the support of dedicated Congressional backers. The Bush administration, by contrast, has consistently sought to remove Amtrak's operating subsidy from the federal budget.

Whatever American preferences for suburban relative to urban living, there can be no question that the size of the nation's suburban population has been artificially enlarged through poor policy choices. Disparities in transportation funding are one source of overextensive suburban growth, but there are many others. Commuters are not faced with the cost of the negative congestion and pollution externalities they impose on others. If commuters were required to pay congestion charges and pollution or emission taxes, cities would almost certainly be much denser and suburban development far less extensive. Kotkin and Modarres argue that driving and suburban development are increasing in Europe, where transit is better funded and gas taxes are much higher. Perhaps so, but they fail to mention that European cities remain much denser than their American counterparts, and Europeans emit far less carbon per capita than Americans. It's simply dishonest to discuss the preferences of American commuters without mentioning the massive social subsidies suburbanites receive.

Improvements in urban efficiency and in suburban efficiency are fine goals. If we're interested in significant reductions in carbon emissions, we ought to concentrate more on making the suburbs like the cities: denser, more walkable, and transit-oriented. In the end, any effective measure that we adopt to reduce carbon emissions -- be it a cap-and-trade regime or a carbon tax -- is going to increase the cost of driving and suburban life. This will increase the incentive for Americans to live densely and use transit or other alternative transportation modes. There's no good reason why we shouldn't begin helping this transition along now, by increasing transit funding and subsidizing denser development.

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8 Comments | Post a Comment

Apartment buildings are more efficient...

...because the roof, through which so much heat escapes, is shared by up to 1000 people (about the building I'm in now) vs. a roof for every four people in a typical suburban home. Plus, many other services, such as recycling or retrofitting, can benefit from the economies of scale of apartment buildings.

Great post -- and great point at the end, that cap-and-trade/carbon taxes would lead to a greater demand/need for public transit.

by Jon Rynn at 3:32 PM on 21 Oct 2007

Wait Until The Volt Gets Here

A study conducted for Greater Washington revealed that per capita transportation emissions in the metropolitan area were less than the national average

That's because people in the suburbs drive huge vans and SUVs and urbanites drive KIAs.

But that doesn't mean that people in the suburbs "have to" drive big cars.

A more meaningful figure would be per capita emissions segregated by the car size the person owns.

And in 2010 the Chevy Volt will give us a 200 mpg car, so all this arguing is a waste of CO2 gas.

by jabailo at 4:36 PM on 21 Oct 2007

suburban v. urban

I think that while there are clear efficiency benefits to living in a city, there are moderating influences. For example, the heating costs will also be higher due to the wind tunnel effect present in cities. As you know, heat escapes much quicker with increase in flow rate of fluids. In suburbs, or low-height residences, there are typically a wealth of trees acting as wind breaks, lowering the gas movement across the residences. Also, typically in cities, heat is paid for by the landlord, and thermostats are either non-existent or broken (I speak from having been in MANY apartments), which generally leads to open windows and heat escape (once again, this is exactly what happens in MANY apartments).

Also, in cities, the people that drive and 'can easily substitute driving with walking, biking, or using mass transit', generally do not substitute it and drive. Hence, the recent proposal by Michael Bloomberg (mayor of NYC) to impose a tariff on entering Manhattan below mid-town: traffic congestion. And, in case you didn't know, if a car is moving 0 mph, its mpg is 0. So, while per capita vehicle fuel consumption is lower, when considering all the people that don't own a car (typically they cannot afford it), per vehicle fuel consumption is greater in the city. Plus, from a health perspective, concentrating the nitric oxides and resulting ground level ozone on street level is, simply, BAD.

Another aspect of cities that does not appear here is food production and delivery, which typically takes place from far beyond the city (read CO2 emissions, nitrogen emissions, higher food prices) and concentration of nitrogen in sewage that causes sever coastal eutrophication, oxygen depletion or hypoxia, and degradation of aquatic systems. Furthermore, steel and cement production for construction purposes is responsible for high CO2 emissions and elevated calcium and magnesium deposition, which further causes rather strange effects on the ecosystem.
In contrast, most suburban houses are built out of wood, which is a carbon sink.

So, the case that the author of this post, Ryan Avent, is not as clearcut as it seems superficially.

Also, this is a PS, I do believe that people are choosing the things that they want: suburbs, quiet life, owning a car, etc. or urban, high density, etc.

by atreyger at 10:01 PM on 21 Oct 2007

food miles

atreyger: "Another aspect of cities that does not appear here is food production and delivery, which typically takes place from far beyond the city (read CO2 emissions, nitrogen emissions, higher food prices)"

I think food travels pretty much the same distance for suburbanites and as urbanites. There aren't many farms left in the suburbs any more.

by amc89 at 9:05 AM on 22 Oct 2007

Living in cities is definitely more efficient...

and don't forget about all the roads that criss-cross the countryside so that people can live out in the "wilderness"- these dissect ecosystems and make it harder for many species to have the area they need.

As to food miles, cities benefit from economies of scale- yes, you need to truck food to cities but once there it's a very efficient way to distribute it.

Economic Illiteracy Harms The Planet! www.voicesofreason.info.

by Jason D Scorse at 10:22 AM on 22 Oct 2007

I could afford a car in NYC...

...and I didn't get one, partly because it's very expensive to park, etc in NYC and partly because the subways and buses are right there. A car-free city would obviously be much more efficient than suburbs, and would be possible in much of manhattan, and with a little work, much of the boroughs, and many districts in other cities and towns across the country.

As for the advantages of trees, that's a good argument for putting more trees in cities, maybe even eliminating a traffic lane or two. And as I said, it is easier per person to heat up or cool down a large building than a smaller one.

According to Leinberger, about 30-40% of the population would like to be in "walkable urbanity", as he puts it, while only about 5% currently is walkable, so people are not really living where they would like to live right now -- and I would wager that if 40% of the country lived in walkable areas, another chunk would look at that lifestyle and prefer it.

by Jon Rynn at 11:27 AM on 22 Oct 2007

JR, JDS

JR,
Clearly, one person represents the entire population of 8 million. I am being snotty, but what about the rest of the people that choose to buy a car? And how about the negative aspect of concentrating so many cars and so many people with the detrimental aspects of nitrogen oxides and ozone? And how about the lower emission controls on public transportation and utilities?

JDS,
I challenge you to name those species. I know the answer, but do you? Plus, how are you exactly supposed to move the food and fiber to the cities? Teleportation does not yet exist.

Also, I am by no means saying that everyone should live in the burbs, I was talking about downsides of big cities. In my opinion, local urbanized centers of between 25-100K people are a good way to go.
And finally, in my opinion cities create a clear and obvious disconnect from the natural surroundings breeding precisely the kind of a society that we have: consumerist, selfish, striving for stardom, and the rest of it.

Pick the evil.

by atreyger at 4:58 PM on 23 Oct 2007

Concerning the lesser of two evils...

First, I've never understood the idea of driving a car within and without the suburbs to be near nature, the suburbs and highways destroyed "nature" (besides, as I liked to tell my out-of-town friends: "Who needs nature in NYC, we have Central Park!").

Second, NYC and many other cities and towns would be much better off car-free (there's a whole website that goes with the book, car-free cities). So the greater pollution in the cities occurs because of cars, which shouldn't be there.

Third, public transit should all be electrified, and as I've tried to argue in the past, subways are very efficient, and could be completely powered from renewable sources.

Fourth, 25-100K people for a town is actually a very nice figure, I now live in a town near the limit of that size, and we are surviving without a car (although it would be easier with one). I think James Howard Kunstler and Richard Heinberg and others would agree on that size, and cities for much of history where actually near that. But I also think that there is a role for cities that are also as big as NYC-- it's simply more efficient space-wise, with a good transit system it is much easier to move things and people around.

I think the distinction between the town size and the big city size needs to be explored, and it is a shame that people lump the two together and claim cities in general won't work, or deny the benefits of big cities. But it's an important topic, me thinks.

by Jon Rynn at 6:33 PM on 23 Oct 2007

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