Bright Lights, Big City

  Part one of a three part series.
  Part 2: Reaping What We Sow
  Part 3: Urbanization’s Aftermath
      Page 2

Watching the familiar, rural landscapes of our youth give way to suburban sameness has become as much a part of modern American life as portable electronics, instant food, and wasted time in front of the television. Nearly all of us have had the disappointing experience of returning to what used to be the woods near our childhood homes and finding a new subdivision. Or we have been shocked to see that some corporate entity has erected aluminum-sided duplexes and an outlet mall in the middle of our favorite vacation spot.

Like it or not, throughout this century, the United States has undergone a steady process of urbanization as a larger and larger percentage of the population has moved towards the cities. While increasing urbanization may have some positive impacts on our environment, such as the lower birth rates that come with a city lifestyle, scientists are becoming more concerned about the negative long-term effects. Unlike rural communities, urban sprawl completely transforms the landscape and the soil and alters the surrounding ecosystem and the climate.


Las Vegas Sprawl
Suburban sprawl outside Las Vegas, Nevada. (Photograph courtesy Philip Greenspun)


Global City Lights


Marc Imhoff, a biologist at NASA’s Goddard Space Flight Center, is one of these concerned scientists. For the past six years, he and a team of researchers have been looking for ways to measure the effects of urbanization on the biological productivity in the U. S. and other countries around the world. They created a method of mapping urbanization on a countrywide scale by using satellite images of the light cities generate at night. With the resulting city lights maps, they are now zeroing in on the impacts urban sprawl has on the food we eat, the air we breathe, and the ecosystem within which we live.

next Seeing the Light

The data used in this study are available in one or more of NASA's Earth Science Data Centers.


Global city lights. The Eastern U.S., Europe, and Japan are brightly lit by their cities, while the interiors of Africa, Asia, Australia, and South America remain (for now) dark and lightly populated. (Data courtesy Marc Imhoff of NASA GSFC and Christopher Elvidge of NOAA NGDC. Image by Craig Mayhew and Robert Simmon, NASA GSFC.)

High-resolution versions of this image are available on the Visible Earth