Neither the mega-cities nor the survivalist’s bunker will be viable in a post-oil future. The places with the best chance of surviving an oil peak will be cities of less than a million people, ranging down to well-placed smaller cities and towns. Cities of a million or so existed before fossil fuels—ancient Rome proper held roughly a million people—thus they are clearly possible in a limited-oil era.
Scale works to the advantage of sensibly sized cities. For example, Portland’s 500,000 people are served by two sewage treatment plants that use about 2000 miles of pipe to reach every home. Building this cost in the low hundreds of millions of dollars (exact figures don’t exist). Compare this to the sewage system for 500,000 rural people. That’s roughly 125,000 septic tanks, each with 300 or more feet of drain-field pipe, plus trenching and drain rock for all. A septic system costs about $10,000 to build, so the cost of 125,000 of them is $1.25 billion, several times that of the urban system, and the ruralites need 7000 miles of pipe compared to Portland’s 2000 miles. Of course, composting toilets and graywater systems would obviate the need for both of those unsustainable, resource-intensive methods of waste treatment, but I’m talking about what exists right now. Virtually any service system—electricity, fuel, food—follows the same brutal mathematics of scale. A dispersed population requires more resources to serve it—and to connect it together—than a concentrated one. That fact cannot be gotten around.
Some readers confused my concerns over the sustainability of rural life with my disappointment with the quality of my own rural community. Wonderful rural communities exist (as do wonderful urban ones). We happened not to choose one when we moved to the country, but rather, an area depressed by the collapse of the timber industry, where alcohol, spouse beating, methedrine, and child abuse were rampant responses to a shattered economy. But sadly, that describes most of the rural Pacific Northwest, and much of the rest of rural America. Our county was not unique. Country people in Appalachia, the Rust Belt, and the stricken farm states are not exactly flush with cash and optimistic about the future. There are pockets of prosperity in the rural US, but overall the social and economic picture is miserable, and most people there lack the education and resources to cope with even today’s economy, much less one ravaged by an oil shortage.
Even if a country community is vibrant, having friendly neighbors does not reduce rural America’s immense ecological footprint. In rural areas, a car is even more essential than in suburbia. As the sewage-plant example shows, the laws of physics force a spread-out populace to consume more resources than one that is compact. The key question is, how large can that compact populace be and still be sustainable? What size of community is best for a post-oil world? No one knows the answer, but the mega-cities are surely too large, and the survivalist in his bunker is too small.
My guess at a post-oil scenario is for the disappearance of suburbs and a return to the city/country pattern as it existed for thousands of years before the oil age. In the film, “The End of Suburbia,” James Howard Kunstler calls the suburbs “the greatest misallocation of resources in the history of the world.” I believe as suburbs empty or condense over several decades they will be gutted for their re-usable resources and be replaced by what preceded it until forty years ago: small farms ringing every city, producing food in easy reach of urban markets.
I often hear the assumption that without land, urbanites will starve. Nonsense. Farmers were feeding urban populations long before the oil age, and they will do so after it. New Jersey’s seemingly absurd license plate motto, “The Garden State,” refers to its thousands of vanished market gardens that fed New York City until the 1960s. Even urbanites in triplexes will be able to buy locally grown food.