Monthly Archives: May 2012

Throwing Fuel on the Fire

This week I will continue to point out the folly of increasing density toward realizing sustainability. Before I get started, I’d like to thank all of the folks who’ve taken a moment to send me a message about the blog. I really appreciate the comments and great feedback I’ve received, particularly from non-planners. I urge you to continue thinking critically about the content I introduce here, and don’t be afraid to get a conversation going in the comments section!

Additionally, I’d like to mention that I attended the Age of Limits Conference in Artemas, Pennsylvania over the weekend. The conference was held at an “interfaith sanctuary” which amounted to a campground, farm, ranch, and nature preserve – a nice, bucolic setting. It was hot and humid all weekend, and all of the presentations occurred outdoors within open air pavilions. The speakers included John Michael Greer and Dmitri Orlov, among others. There were about 60 attendees there, mostly from the eastern half of the country, but all regions were represented. The conference was pretty informal which gave attendees frequent opportunities to mix and meet with the presenters. I had a delightful chat with Greer for quite a bit about his books and influences. I enjoyed the conference very much and plan on going next year if they decide to host it again.

As you know, I’ve spent the last few weeks seeking to upend a persistent and entrenched myth within insular planning that the pursuit of sustainability can best be boiled down to “density good, sprawl bad”, as if these were two endpoints on a continuum. This myth presupposes that New York City, for example, represents the ideal sustainable arrangement of living.

Last week, I suggested that I would be discussing what I believe is the true nature of the relationship between density and sprawl in this week’s post. However, after having read over that post again, I feel that my criticism of density was incomplete and required more evidence and clarification. After all, I want to make it overwhelmingly clear that by criticizing density I am not advocating a position even remotely resembling that of Joel Kotkin or other suburbanization apologists.

Now, everybody who moves to a bigger city likes to feel that by doing so they lessen their impact on the environment. And insular planning gives them absolutely no reason to think that they’re not. But last week I showed how studies of urban metabolism reveal higher density to be a counterproductive strategy to realizing sustainability.

The research of Geoffrey West and his colleagues demonstrate that increases in urban density relate to infrastructure sublinearly; that is to say that as cities increase in size, the infrastructure costs per capita fall. However, they also found that increases in urban density relate to consumption superlinearly; that is, as cities increase in size, consumption per capita rises. In short, more-densely populated cities allow urbanites to leverage greater infrastructural efficiencies into a higher material standard of living which more than offsets the environmental benefits of moving to the city in the first place.

I described this process as a positive feedback loop of urbanization:

denser population –> greater economies of scale –> increased production –> greater affluence –> higher rates of consumption –> greater ecological impact, higher urban metabolism and inducement to densify further

In essence, as cities get bigger their metabolisms proportionally increase, not decrease. Correspondingly, that means more consumption and more energy and material throughput – hence, less sustainability. By ignoring all of the ramifications of increasing density, insular planning is working against the interests of posterity. Ecologically, this is a dead end strategy that will end in tears, and worse.

I’m going to take a moment to elaborate on the mechanics of the positive feedback loop described above to show the faultiness of insular planning’s policy goal of increasing density. What you’ll see is that increasing levels of density are correlated with higher rates of ecological impact, not lower.

It’s instructive and worth noting at the outset that the positive feedback loop shown above loosely correlates with Paul Ehrlich’s I=PAT formula, where I (impact) = P (population) x A (affluence) x T (technology). In other words, the more populated (and densely populated), affluent and technologically endowed a given city, state, nation, or world, the more ecological impact it delivers onto the environment.

The first variable, population (P) is important because it serves as a multiplier of the other two variables affluence (A) and technology (T). And as Geoffrey West’s research shows us, this variable is not static, but intensifies as density increases.

Cities with higher populations and densities – metastatic cities – offer greater economies of scale than areas with low populations and densities – rural areas. Over history people have continuously leveraged the economies of scale that increasingly large cities afforded them by reinvesting those efficiency gains back into the flow structures of society. These flow structures include the social, technological, economic, and physical organization of society in terms of its population, occupations, diversity, institutions, and functions.

Cities with higher populations and the greater economies of scale they afford contribute to higher rates of production and higher rates of affluence. One of the main economies of scale cities offer is that of specialization. With such a large amount of people collected in one spot, people tend to recognize the benefits of dividing labor and specialization of different tasks. This is reflected in the economic phenomenon of comparative advantage, which emphasizes “doing what you do best and trading for the rest.”

In other words, by specializing and then trading for the services of those who specialize in something else, more can be produced overall than would otherwise be possible. And, roughly speaking, this production of additional goods and services per capita translates into greater wealth per capita than would otherwise be possible.

The opposite is true too. You might notice for example that there are no valets at roadside diners. The reason of course is because rural areas don’t have the population densities necessary to support specialization to the degree that larger cities do, and correspondingly don’t produce as much per capita and hence remain poorer by comparison.

That leads to the second variable, affluence (A). Due to their higher affluence, metastatic cities are consumption hotspots relative to their rural surroundings: more goods and services are supplied and consumed there per capita than in rural locations. This relative affluence offsets any environmental benefits that may be gained by lower per capita costs of infrastructure in metastatic cities.

For instance, though affluent metastatic city residents may be driving less than their rural counterparts, they have increased consumption in nearly every other category of goods and services. Whatever savings are being achieved by not owning a car are more than counterbalanced by the purchase of increased airplane flights, take-out meals, clothing, and other discretionary spending. In short, all the money gets spent one way or another on stuff that requires energy for its manufacture, shipping, use, maintenance and disposal.

Additionally, this relative affluence leads to a greater likelihood of population autonomy. Smaller households have larger per-capita rates of consumption than small ones. For example, three people living in three apartments have to own three vacuum cleaners, while a family of three people owns only one. Or, this relative affluence can indirectly result in higher rates of resource waste, as the affluent can afford to be more wasteful than the poor.

In short, the societal consumption driven by higher rates of affluence — our collective desire for technological gadgetry, fancy coffee drinks and the latest fashions — more than outweighs the ecological benefits of local mass transit.

Cities with higher rates of consumption negatively affect the environment at greater rates than cities with lower rates of consumption. Affluence insulates the relatively wealthy from direct ecological impacts. When we look around us in metastatic cities, we often do not see the direct ecological impacts being borne by others including the poor, future generations and other species. For example, much manufacturing has moved offshore and taken with it the direct evidence of ecological degradation that metastatic cities require for their operation. Yet, this manufacturing is still being performed (though with less environmental regulation), and the impacts are still being generated. It’s just that they are now embedded in the available energy and resources we enjoy which buoy our standard of living.

In this same vein, when we think about ecological impacts, we generally only think about the energy and resources that we can see being used by our own eyes in real time, directly. For example, you might think that most of our transportation costs and impacts are for moving ourselves around. However, most of our ecological impact is not from the available energy and resources that we pay for directly and the emissions that result; most of it is from the available energy, resources, and emissions associated with the creation and transportation of consumables – the indirect ecological impacts of consumption.  A recent study* found that an estimated 44% of CO2 emissions are tied up in the manufacture, packaging, transportation, and disposal of the goods we consume – much more than the carbon impact of moving ourselves around (which is still high). That same study found that only approximately 10% of an average household’s ecological impact is from direct impacts.

Perhaps you’re not surprised to hear that overconsumption is a huge contributing factor to ecological impacts. However, the insidious thing about it is that those effects are seamlessly embedded in everyday life and experience within the metastatic city and therefore are easy to forget about.

And now we arrive at the final variable, technology (T). Cities with higher rates of technological application negatively affect the environment at greater rates than cities with fewer technological applications. That’s largely because technological applications either directly or indirectly utilize fossil fuels which themselves have harmful effects on the environment.

Additionally, greater relative affluence in metastatic cities allows for the purchase of more technological applications than would otherwise be possible in rural, less affluent areas. And when you consider the preponderance of these applications – all the automobiles, computers, dishwashers, leafblowers, and so forth – you begin to understand the scale of the issue.

All of these fossil fuel-reliant technologies result in increased CO2 emissions. Therefore, it is unsurprising that metastatic cities have disproportionately higher CO2 emissions than rural areas: the 50% of humans who live in metastatic or metastasizing cities are responsible for 75% of all CO2 emissions. It’s no coincidence that CO2 gas domes in China and the US hover over metastatic cities – that’s where the people are, after all. And the CO2 gas domes that exist in rural areas are from power plants that supply metastatic cities with their electricity.

The I=PAT equation implies that the availability of cheap fossil fuels have blown the positive feedback loop of urbanization into a hypertrophic mode that’s causing ecological degradation on a scale never before possible in human history.

A natural question at this point might be if cities are capable of existing sustainably at all. Of course they can, because they did so in the past. We planners need to begin crafting policies which advocate for moderate density and figure out ways to de-scale outsized metastatic cities. This doesn’t have to mean getting “back to the land” necessarily, though there might be some of that. Certainly it won’t entail further suburbanization, however.

Additionally, the I=PAT equation shows that policies which support increasing population density, rising affluence, and expansion of technological application will only serve to further exacerbate ecological impact. Doing so is akin to throwing fuel on the fire.

I recognize these findings are quite challenging to the preconceptions of insular planning. But in order to establish sustainable living arrangements, we need to acknowledge that simply packing people high and tight and expecting public transportation to offset the subsequent effect of increased density is not going to have the desired effect of reducing ecological impacts.

I do acknowledge that density is important up to a certain point. However, I’m also suggesting that a little nuance is called for, depending upon the environmental limits imposed on a given city by its supporting region. Just recommending greater density ad infinitum is a foolish, intellectually dishonest policy stance totally out of line with the limitations of ecological reality.

Lucky for us, there are examples throughout history of authentic cities – that is, moderately-dense urbanized areas that command a stable range ecological impacts commiserate with resources available regionally in real time. In the not-too-distant past these living arrangements served as communities which deepened our psychological world, provided a cosmopolitan atmosphere for artistic and cultural development, fostered education, and enabled the development of appropriate technologies which improve the lives of people – all in a vibrant, walkable, fixed spatial dimension with a sense of place. Not only are authentic cities sustainable, they present a more liveable arrangement of living than metastatic cities.

Perhaps we could learn a bit from these historic examples in imagining a way forward. If applied correctly, that knowledge could go a long way in making the transition process less painful. In future posts I will discuss appropriately-scaled authentic cities of the past and consider lessons we can learn from them.

It sure took a long time to get here, but now I’m set to discuss why you shouldn’t fall for the old “density vs. sprawl” false dichotomy. In doing so, I’m going to cover a little more ground relating to density including the relevance of embeddedness, the side effects of urban metastasis, and the confusion within insular planning between the concepts of liveability and sustainability.

*Consuming Australia, Australian Conservation Foundation study, 2007

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A Stampede of Accelerating Elephants

Over the Age of Exuberance, Westerners created and expanded a way of life based on the exploitation of cheap and readily-available fossil fuels by inventing and distributing increasingly efficient fossil fuel-burning technologies far and wide. In short, we used our ingenuity to enrich ourselves at the cost of the environment.

An economist would call this growth extensive; that is to say, based on the expansion of the quantity of inputs in order to increase the quantity of outputs. Now that the limits to growth are coming into sight, this type of growth is being subjected to diminishing returns. Worse still, it has no positive effect on per-capita magnitudes in the long-run because it reinvests efficiency gains back into the system.

This is the essence of the rebound effect – an empirically demonstrable phenomenon that describes changes in levels of consumption of a resource when the efficient use of that resource improves. What it shows is that efficiency gains in the short run spur increases in energy consumption in the long run, thus offsetting any environmental benefits.

It’s worth considering that at any point during the Age of Exuberance – at least in theory – those efficiency gains could have been retired for the benefit of the environment. We could have applied our considerable ingenuity toward making existing inputs go further, thereby reducing environmental impacts. This is what economists call intensive growth – the increasingly efficient use of a declining quantity of inputs in the production of a fixed number of outputs.

Under this model, as efficiency rises, those gains are retired out of the system. Retiring efficiency gains has a two-fold happy consequence: first, it helps the environment. Second, it results in greater amounts of leisure time within society (to the degree that the benefits are distributed equitably).

Those are the two choices: enrich ourselves or help the environment. Yet insular planning exhibits a distinct futility in gripping this fact; it mistakenly proposes policies that suggest that we can have our efficiency “cake” and eat it too.

I want to be clear that I do believe energy efficiency strategies have a part in any self-respecting sustainability strategy. However, I also want to show that history has demonstrated efficiency cannot all by itself lead to the hoped-for result of less energy consumption in the long, or even medium run. And like it or not, that’s the only way to relieve impacts on our finite planet.

To be sure, the pursuit of efficiency is a categorical imperative within insular planning. But not even it can hold a flame to perhaps the single overarching sacred cow of insular planning: the promotion of higher density.

Now, there’s nothing intrinsically wrong with density. It’s good – just not infinitely so. It’s an important factor in ensuring sustainability. But like efficiency, there are some nuances to employing density that insular planning fails to take into consideration. Nuances which, if ignored, can have deleterious consequences in realizing sustainability.

Density is such a loaded concept that I’m going to have to take a moment to make myself perfectly clear. The basis of my concern regarding density has NOTHING in common with the premises of Joel Kotkin or other boosters of suburbanization. In other words, by criticizing density’s role I am not advocating sprawl by default – quite the contrary. I don’t believe density and sprawl are two endpoints along some sort of mythical continuum. I’ll talk in some detail about this next week.

Before we get into a discussion of density, it might be useful to review some of the foundational concepts I’ve discussed in prior posts. Early on, I asked readers to step back and momentarily consider cities in physical terms rather than in purely social, economic, and political terms. While it’s true that cities are complex manifestations of human actions and interactions, those actions and interactions are grounded in physical reality. From this, we can conclude that cities are subject to physical and natural laws.

I introduced these concepts in the Laws of the Jungle series of posts a few weeks back. In short, I discussed in detail how cities operate as dynamic dissipative systems, are subject to the laws of thermodynamics, possess a metabolism, and interact with other systems ecologically.

We’re going to take these ideas a little further this week to show insular planning’s error in pursuing density at all costs. In doing so, I’ll be drawing on the work of a few scientists and physicists such as Geoffrey West, Luis Bettencourt, and James H. Brown. They’ve done a good bit of work on measuring the urban metabolism of cities and I think you’ll be interested in what they found.

The uninitiated should know that studies of urban metabolism facilitate the description and analysis of the flows of the materials and energy into, within, and out of cities. They also provide a holistic perspective to encompass all of the activities of a city in a single model.

The use of the word “metabolism” connotes a biological basis. The concept of imagining the city as a live being is nothing new – people have noted the metabolic character of cities for a long time running now. Plato talked about the city as a “corporeal body” thousands of years ago, for instance.

However, it wasn’t until 1965 that a sanitary engineer in Baltimore named Abel Wolman first formalized the concept in “The Metabolism of Cities”. He keenly noted that cities possess energy and material appetites in the form of a metabolism which governs its internal processes. For instance, cities consume resources like food, water, timber, and air, and produce finished goods, pollution and waste as outputs.  

In 1996, West et al. attempted to go even further in demonstrating how the urban metabolism concept was more than just an interesting biological metaphor by applying Kleiber’s Law to cities to see if they scaled in the same way as animals do.

Kleiber’s Law, named after Max Kleiber’s biological work in the early 1930’s, is the observation that an animal’s metabolic rate scales to the 3/4 power of the animal’s mass. In other words, doubling the mass of an animal requires only an 85% increase in energy requirements. This reflects efficiency in gaining size – an economy of scale.

The implication of this sub-linear relationship is that larger species need less energy per pound of flesh than smaller ones. For instance, while an elephant is 10,000 times the size of a guinea pig, it needs only 1,000 times as much energy.

West et al. found that the same economies of scale apply to the infrastructure of cities also. In city after city, the infrastructural indicators of urban metabolism, like the number of gas stations, total surface area of roads, or total length of phone, water, and sewer lines showed that when a city doubles in size, it’s infrastructural energy and resource demands rise by only 85%. This revelation suggests that the real purpose of cities over time has been to maximize economies of scale, just as big animals do.

West’s discovery of the applicability of Kleiber’s Law to cities would seem to confirm the steadfast belief within the insular planning community that our densest cities are the truest centers of sustainability because they promote efficient use of infrastructure.

The belief that density is inherently environmentally beneficial permeates planning literature. For instance, Peter Huber and Mark Mills’ influential 2000 essay “How Cities Green the Planet” triumphantly proclaims that the skyscraper is “America’s great green gift to the planet.”

Indeed, the standard policy within insular planning reads something like:
“By increasing density (along with efficiency and renewable energy) we can provide for a workable transition to a new arrangement of living comprising a world full of increasingly dense, technologically-intensive, affluent, and even ‘greener’ metropolises.”

If infrastructural efficiency was the only effect of increasing density, I’d be right up there with everybody else throwing roses and blowing kisses. However, Kleiber’s Law doesn’t tell the whole story when it comes to the metabolism of cities.

When West et al. expanded their research beyond just the infrastructural implications of increasing density, the picture changed.

They were surprised to find that Kleiber’s Law was inverted in cities regarding the average person’s rates of consumption. The research shows that if a person moved from one city into another one twice as big, all of a sudden they did 15% more of everything. In other words, the scaling laws observed for consumption run in the opposite direction to rates of change observed for infrastructure, thereby more than offsetting any environmental benefits.

In city after city, the consumption indicators of urban metabolism, like economic activity, income, water consumption rates, pollution, and garbage showed that when a city doubles in size, it requires an increase in resources and waste sinks of 115%.

The implication of this super-linear relationship is that larger cities need more energy and resources per capita than smaller ones because their average citizen owns, produces, consumes, and wastes 15% more than their less urbane counterparts. In effect, when cities densify, they become more consumptive, which offsets any infrastructural efficiencies provided by Kleiber’s Law.

The end result is a positive feedback loop: a bigger population means more economic activity for each person, which encourages more people to move to the city, which results in more economic activity, and so on. This explains why one half of all people on Earth now live in cities and why one million more are moving to cities weekly: they’re seeking out a way of life that allows them to leverage greater infrastructural efficiency into a higher material standard of living.

Every other creature in nature gets slower as it gets bigger. That’s why elephants plod along. But in cities, the opposite happens. As cities get bigger, everything starts accelerating. Metabolically speaking, big cities function like elephants that are proportionally faster and more consumptive than mice. Think about that for a minute. And then consider that insular planning is essentially encouraging the creation of a stampede of accelerating elephants in the form of multiple, growing metastatic cities.

Ecological principles tell us that absent of energy and resource constraints, dynamic dissipative systems are free to continue to expand until they hit hard, physical limits provided by the larger environment around them. These limits inevitably come, and when they do, the growth of the system tapers off in line with what the larger environment will allow.

Anyone who believes that cities are exempt from this constraint is fooling himself. The reason that cities have been able to invert Kleiber’s Law up to now is because, until recently, there have been few constraints on the energy and resources available to the many metastatic cities that now dot the planet. That’s a purely temporary strategy, as we’re currently bumping up against the edges of what we know is a closed system.

I’m certain that if West et al. were to study the metabolic rate of an algae bloom he would find it would resemble the exponential growth of metastatic cities over the Age of Exuberance. The only question is what happens when those hard limits are reached: will it resemble an S-curve – a slow, steady equalization with our larger environment? Or will it result in a crash? We cannot know the answers to these questions definitively, but we do know that our ancestors lived within limits and that we will increasingly do the same over the remainder of this century.

We need a new way of planning which presents a more-nuanced view of density. It would be madness to continue advocating a policy which so clearly conflicts with the hard limits of physical reality.

Though the ideas I’ve ushered forth this week should be considered only the crudest of starting points, I believe they have major implications for how we need to reimagine sustainability planning best practice. For starters, it suggests that the density ideal should be scrutinized closer for its alleged environmental benefit.

If you’ve gotten this far, you are probably well convinced that my critique of density does not imply advocacy of sprawl. I believe the density vs. sprawl dichotomy is a false one; I’ll spend a good bit of time next week unpacking this red herring.

For more about Geoffrey West and his theory, check out:
The Economist talk

NYT Magazine article
Radiolab episode

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