According to Timothy Beatley, an urban-planning professor at the University of Virginia and the author of Green Urbanism, the per-capita carbon dioxide emissions of American cities are almost twice as high as those of their European counterparts. Hardly surprising, since European cities are denser and more compact, homes are smaller, and people rely to a far greater extent on mass transit. So if Americans are to significantly reduce their carbon footprint, we will have to do a lot more than switch to reusable shopping bags and recycle our soda cans. But as a recent conference on "urban design after the age of oil" at the University of Pennsylvania (where I teach) demonstrated, there is something of a disconnect between the global-warming problem and the available solutions.
The problem is easily stated. In 1950, the global emission of carbon dioxide was 6 billion tons a year. Thanks to population growth, urbanization, the expansion of wealth, and massive industrialization around the world, by 2008 this has increased fivefold to 30 billion tons a year. Assuming that nothing is done to reduce emissions, by 2058, they will be 60 billion tons a year. Thus, to reduce global warming, whose effects are already beginning to be felt, it will be necessary to take drastic measures just to stay at the present level, never mind actually making real progress. For example, to reduce the number of coal-fired generating plants, nuclear capacity in the United States will have to be doubled. To reduce car emissions, either Americans will have to drive half as many miles per year or cars will have to be twice as efficient. Buildings will have to use 25 percent less electricity.
The Penn conference featured many speakers proposing changes, large and small, as to how buildings and cities should be designed. The scientists were hard-nosed and slightly scary. Planning consultants were authoritative and self-assured—as planning consultants tend to be. They described new carbon-neutral cities, with wind farms and solar arrays, green roofs and urban farms, far-ranging mass transit, and large-scale water recycling. The Power Point images were mesmerizing. Most of the projects appear to be in the Gulf states. In the present economy, most are, I suspect, on hold.
A word that came up frequently was holistic, the implication being that we shouldn't change one thing until we know how it affects everything else. But that is not the way cities develop. The technologies that improved urban life in the past—gas lighting, pressurized water, electricity, streetcars, elevators—were developed separately, each according to its own technological schedule. This autonomy accounted, in large part, for the success of the industrial age. The other implication of holistic is that, by taking everything into account, we can control the future. But technologies have always had unintended consequences. Streetcars, for example, which replaced horse-drawn omnibuses and were not only faster but considerably cleaner, also encouraged suburban growth, enabled commercial strips to develop along rights of way, and created amusement parks (Coney Island in New York, Natatorium Park in Spokane, Wash.) as end-of-line destinations. One would expect green technologies to similarly produce unforeseen side effects.
Another thing strikes me about green urbanism. Even assuming that anything at all gets built in the coming economic depression—during the Great Depression of the 1930s, building construction virtually halted—creating new cities and reconfiguring old ones will take many decades. We don't have that much time. On the other hand, Americans' rapid change in driving habits during the gas-price run-up of summer 2008 suggests that people can quickly alter the ways they behave: driving less, walking more, turning down the thermostat, turning off the lights. Yes, we should eventually change the way we build and plan cities, but it might be more effective in the short run to change the way we live in them.
Most of the planners at the Penn conference emphasized technological fixes, but if the point of no return has already been passed in global warming, as some of the scientists at the conference suggested, protective measures are at least as important, not least against the anticipated rise in sea levels. In that regard, I note an interesting news item from the Netherlands. The Dutch Parliament has asked a commission on coastal development to examine the idea of building a massive man-made island in the North Sea. The 31-mile-long island will provide 274,000 acres for housing and farming. Not coincidentally, the so-called Tulip Island (named because of its shape) will also act as a storm-surge barrier. The Dutch, who have managed water in their low-lying country for centuries, are the canaries in the coal mine as far as rising sea levels are concerned. Other coastal cities—and most large cities are on the water—should take note.