Sunday, January 02, 2011

The vulnerable future of large cities

"We often think of future wars in apocalyptic terms - nuclear weapons slamming into city centres and such like. But our modern cities are so brittle that far less spectacular attacks could bring them to ruination. In this they are very different from the London that withstood the blitz. Today's cities rely upon highly sophisticated and easily disrupted technology to deliver water, goods, fuel and power to populations of ten million or more, in a just-in-time manner. Imagine a city like New York or London without a functioning electricity grid. People living in high-rise buildings would probably be trapped. With water pumps not working, both the removal of sewage and the supply of clean water would immediately become problems. Communications would be cut, traffic flows and rail services paralysed, and with no refrigeration food would quickly spoil. At night the streets would be plunged into darkness. Local generators might keep hospitals and other vital infrastructure going for a while, but within weeks the city would have to be abandoned. Where would the millions go? If the disruption were sufficiently prolonged it's fair to question whether the city would ever be reoccupied."

- Tim Flannery, Here on Earth: An argument for hope
(Melbourne: Text Publishing, 2010), 230.

Having rejected the apocalyptic image of the nuclear device detonating over a city centre, Flannery nonetheless indulges in an equally apocalyptic image of an immediate and irreversible cessation of an entire megacity's electrity grid lasting weeks or longer. While his point about the vulnerability of large modern cities with complex supply chains is probably quite valid, his example is far-fetched and insufficiently justified. What could cause such an event? As far as I am aware, no megacity is supplied by a single power station. No megacity grid has a single central and irreplaceable piece of infrastructure. No megacity with a major blackout would not have an army of hundreds or thousands of workers to attempt to fix such a problem as soon as it arises. Most high-rise buildings have fire stairs and emergency exits. Even the bleakest (non-nuclear) post-apocalyptic future would see the ruins of the great cities as vast depositories of resources. Medieval huts were built amongst (and from) the ruins of ancient Rome.

Flannery's illustration itself illustrates a lack of imagination in contemplating a more difficult future. Very large cities already face a range of problems in which they struggle under the weight of their own complexity and this is highly likely to increase in the bumpy decades ahead. No city prior to the widespread exploitation of fossil fuels supported a population much above a million. The fate of megacities in a world of increasingly expensive energy is unclear. However, the kind of scenario that Flannery paints is a lazy shorthand for the incredibly complex series of questions faced by political authorities, communities and individuals as our largest infrastructure investments - our cities - become increasingly problematic. The staggering sunk cost that cities represent means that decline or abandonment will likely be piecemeal rather than sudden.

Sunk costs of existing infrastructure also provide a very high incentive to make things work. For instance, in a future where just-in-time agribusiness-to-supermarket supply chains become less reliable and so threaten food security, I doubt it would take long for suburban lawns to be converted to gardens.

Even great catastrophes such as that experienced by New Orleans in 2005 do not suddenly wipe a city clear of inhabitants. It may well be the case that the population never recovers to pre-Katrina levels as the cost of building levees will rise faster than sea levels, making more and more of the city uninhabitable. And the precise conditions faced by each city are unique. Not every coastal city is as threatened as New Orleans by rising seas.

Whether it is wise to live in a very large city is a complex question. Yet such judgements are not aided by visions of the future based on simplistic assumptions or apocalyptic nightmares.


Matthew Moffitt said...

You check out this photographic study on urban decline in Detroit from The Guardian

Anonymous said...

There are many reasons that communities change. Even now Sydney faces societal breakdown in some suburban areas with established ghetto's through failed social engineering.

While I doubt wholesale failure of electrical supplies will happen in a city environment causing its downfall. A cities water supply is a far different scenario.

Most cities only have one major source of water coming into that city. If that was disrupted even for a relatively short period of time major disruption and health problems can occur within that time period.

byron smith said...

Matt - Thanks - I saw that story but haven't had a chance to look at the pictures yet. Detroit is an interesting case study, however, also has a number of factors that make it less than typical. I guess every city is different and so making blanket statements is always going to be risky, but the urban decline in Detroit can still give a heads up of some of the threats and opportunities that more urban areas might face in some of the futures we're heading towards.

Craig - Yes, you're right that water supplies are probably the weakest link for major cities, and once a scare happens, panic buying of water bottles can exacerbate the situation through hoarding. Speaking of which, a disruption of the food (or fuel) supply could spark similarly counterproductive behaviour, where attempts at self-protection in a situation of scarcity lead to a more dangerous situation for everyone.

The UK fuel protests in 2000 were an interesting example. It took only a few days for fuel shortages to stop just-in-time food shipments to supermarkets, which resulted in panic buying and significant shortages in some areas. As a result, security at nodes in the fuel distribution network has been increased (and I think some supermarkets moved to slightly less just-in-time practices, though I'm not sure whether these have lasted). The recent snow storms led to fears of similar scenes, though they did not last long enough (or cover the whole country uniformly) and so panic didn't get a foothold.

But such disruptions are (a) always possible and (b) perhaps becoming more likely for a variety of reasons. Building some more breathing space into the system can help to improve resilience, which may include increasing the amount of food and water stored in households as well as elsewhere within the supply chain.

Anonymous said...

At St Eutychus I spotted this fascinating article about a physicist who reckons he has found the mathematical constants that govern every city:

After two years of analysis, West and Bettencourt discovered that all of these urban variables could be described by a few exquisitely simple equations. For example, if they know the population of a metropolitan area in a given country, they can estimate, with approximately 85 percent accuracy, its average income and the dimensions of its sewer system. These are the laws, they say, that automatically emerge whenever people “agglomerate,” cramming themselves into apartment buildings and subway cars. ...

"What we found are the constants that describe every city,” he says. “I can take these laws and make precise predictions about the number of violent crimes and the surface area of roads in a city in Japan with 200,000 people. I don’t know anything about this city or even where it is or its history, but I can tell you all about it. And the reason I can do that is because every city is really the same.”


byron smith said...

Arthur - You're right, it's a very interesting article. Here was a key part that relates closely to the contents of my post:

"In city after city, the indicators of urban “metabolism,” like the number of gas stations or the total surface area of roads, showed that when a city doubles in size, it requires an increase in resources of only 85 percent.

"This straightforward observation has some surprising implications. It suggests, for instance, that modern cities are the real centers of sustainability. According to the data, people who live in densely populated places require less heat in the winter and need fewer miles of asphalt per capita. (A recent analysis by economists at Harvard and U.C.L.A. demonstrated that the average Manhattanite emits 14,127 fewer pounds of carbon dioxide annually than someone living in the New York suburbs.) Small communities might look green, but they consume a disproportionate amount of everything. As a result, West argues, creating a more sustainable society will require our big cities to get even bigger. We need more megalopolises."

Sounds good, doesn't it? And yet...

"But the superlinear growth of cities comes with no such inherent constraints. Instead, the urban equations predict a world of ever-increasing resource consumption, as the expansion of cities fuels the expansion of economies. In fact, the societal consumption driven by the process of urbanization — our collective desire for iPads, Frappuccinos and the latest fashions — more than outweighs the ecological benefits of local mass transit. [...] we have created a lifestyle where we need more watts than a blue whale."

And the result?

West describes cities as the only solution to the problem of cities. Although urbanization has generated a seemingly impossible amount of economic growth, it has also inspired the innovations that allow the growth to continue.

"There is a serious complication to this triumphant narrative of cliff edges and creativity, however. Because our lifestyle has become so expensive to maintain, every new resource now becomes exhausted at a faster rate. This means that the cycle of innovations has to constantly accelerate, with each breakthrough providing a shorter reprieve. The end result is that cities aren’t just increasing the pace of life; they are also increasing the pace at which life changes."

So, to stay alive, we have to innovate ourselves to death. Collapse is the result of decreasing marginal returns on complexity, just as Tainter has argued. This is more or less the same argument applied to cities.

And then applied (with much shorter life-spans) to companies.

Thanks - great link.

byron smith said...

(The paragraph that begins "West describes cities" ought to begin with a quotation mark.)

byron smith said...

Guardian: Population of New Orleans down by 30%.

byron smith said...

Orion: Back to the future: a roadmap for tomorrow's cities. John Howard Kunstler's take on the future of US cities.