Thursday, January 25, 2007

Green Manhattan

Great read on how dense cities are actually the greenest way to live.

Because densely populated urban centers concentrate human activity, we think of them as pollution crisis zones. Calculated by the square foot, New York City generates more greenhouse gases, uses more energy, and produces more solid waste than most other American regions of comparable size. On a map depicting negative environmental impacts in relation to surface area, therefore, Manhattan would look like an intense hot spot, surrounded, at varying distances, by belts of deepening green.

If you plotted the same negative impacts by resident or by household, however, the color scheme would be reversed. My little town has about four thousand residents, spread over 38.7 thickly wooded square miles, and there are many places within our town limits from which no sign of settlement is visible in any direction. But if you moved eight million people like us, along with our dwellings and possessions and current rates of energy use, into a space the size of New York City, our profligacy would be impossible to miss, because you’d have to stack our houses and cars and garages and lawn tractors and swimming pools and septic tanks higher than skyscrapers. Spreading people out increases the damage they do to the environment, while making the problems harder to see and to address.

Because of their density, cities have higher usage per square mile, but lower usage per capita. And per capita usage is more important.

Some other interesting points:
  • Apartment buildings are some of the most inherently energy efficient residential structures in the world.
  • A study by Michael Phillips and Robert Gnaizda, published in CoEvolution Quarterly in 1980, found that an ordinary apartment in a typical building near downtown San Francisco used just a fifth as much heating fuel as a new tract house in Davis, a little more than seventy miles away.
  • Elevators, which, because they are counterweighted and thus require less motor horsepower, are among the most energy efficient passenger vehicles in the world.
  • The average Manhattanite consumes gasoline at a rate that the country as a whole hasn’t matched since the mid-nineteen-twenties.
  • Eighty-two per cent of Manhattan residents travel to work by public transit, by bicycle, or on foot. That’s ten times the rate for Americans in general, and eight times the rate for residents of Los Angeles County.
  • People who live in cities use only about half as much electricity as people who don’t, and people who live in New York City generally use less than the urban average.
  • New York City is more populous than all but eleven states; if it were granted statehood, it would rank fifty first in per-capita energy use.
  • Public transportation only works when you have over 7 dwellings per acre.
Phoenix is the sixth-largest city in the United States and one of the fastest growing among the top ten, yet its public transit system accounts for just one per cent of the passenger miles that New York City’s does. The reason is that Phoenix’s burgeoning population has spread so far across the desert—greater Phoenix, whose population is a little more than twice that of Manhattan, covers more than two hundred times as much land—that no transit system could conceivably serve it. And no amount of browbeating, public-service advertising, or federal spending can change that.

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