Page 370 - Environment: The Science Behind the Stories

consumption. Thus, although urban and suburban citizens from city lights may impair sleep and obscures the night sky,
tend to consume more than rural ones, the reason could simply impeding the visibility of stars.
be that they tend to be wealthier. City residents suffer thermal pollution as well, because
cities often have ambient temperatures that are several degrees
Urbanization preserves land higher than those of surrounding areas. This urban heat
island effect results from the concentration of heat-generating
Because people pack densely together in cities, more land buildings, vehicles, factories, and people. It also results from
outside cities is left undeveloped. Indeed, this is the very idea the way that buildings and dark paved surfaces absorb heat
behind urban growth boundaries. If cities did not exist, and if during the daytime and then release it slowly at night, warm-
instead all 7 billion of us were evenly spread across the planet’s ing the air and interfering with patterns of convective circula-
land area, no large blocks of land would be left uninhabited, tion that would otherwise cool the city (FIGURE 13.19).
and we would have much less room for agriculture, wilder- These various forms of pollution and the health risks they
ness, biodiversity, or privacy. The fact that half the human pop- pose are not evenly shared among urban residents. Those who
ulation is concentrated in discrete locations helps allow room receive the brunt of the pollution are often those who are too
for natural ecosystems to continue functioning and provide the poor to live in cleaner areas. Environmental justice concerns
ecosystem services on which all of us, urban and rural, depend. (pp. 158–159) center on the fact that a disproportionate number
of people living near, downstream from, or downwind from
Urban centers suffer and export pollution factories, power plants, and other polluting facilities are people
who are poor and, often, people of racial or ethnic minorities.
Just as cities import resources, they export wastes, either
passively through pollution or actively through trade. In so
doing, urban centers transfer the costs of their activities to
other regions—and mask the costs from their own residents. FAQ Aren’t cities bad for the environment?
Citizens of Indianapolis, Columbus, or Buffalo may not recog-
nize that pollution from nearby coal-fired power plants wors- Stand in the middle of a big city and look around. You see con-
ens acid precipitation hundreds of miles to the east. Citizens crete, cars, and pollution. Environmentally bad, right? Not nec-
of New York City may not realize how much garbage their city essarily. Cities have a mix of consequences, but the widespread
produces if it is shipped elsewhere for disposal. impression that urban living is less environmentally friendly than
However, not all waste and pollution leaves the city. Urban rural living is largely a misconception. Consider that in a city
residents are exposed to heavy metals, industrial compounds, you can walk to the grocery store instead of driving. You can
and chemicals from manufactured products that accumulate take the bus or the train. Police, fire, and medical services are
in soil and water. Airborne pollutants cause photochemical close at hand. Water and electricity are easily supplied to your
smog, industrial smog, and acid precipitation (Chapter 17). entire neighborhood, and waste is easily collected. In contrast,
Fossil fuel combustion releases greenhouse gases and pollut- if you live in the country, resources must be used to transport
ants that pose health risks. all these services for long distances, or you need to burn gas-
Urban residents also suffer noise pollution and light pol- oline and time traveling to reach them. By clustering people
lution. Noise pollution consists of undesired ambient sound. together, cities allow us to distribute resources efficiently, while
Excess noise degrades one’s surroundings aesthetically, can also preserving natural lands outside the city. In many ways,
cause stress, and at intense levels (such as with prolonged each person receives more, with less environmental impact, in
exposure to the sounds of leaf blowers, lawn mowers, and a city than in the country.
jackhammers) can harm hearing. The glow of light pollution

95°F (35°C) CHAPTER 13 • THE URB AN ENVIR ONMENT : CREATING SUSTAIN ABLE CITIES
Heat emanates
from urban areas

88°F (31°C) 88°F (31°C)

Farmland Suburbs City center Suburbs Forest

FIGURE 13.19 Cities produce
urban heat islands, creating
temperatures warmer than sur-
rounding areas. People, buildings,
vehicles, and factories generate
Vegetation keeps forests, Pavement and other surfaces in heat, and buildings and dark paved
farms, and parkland cities absorb sunlight and Cars, buildings, industry, and surfaces absorb daytime heat and
relatively cool re-radiate heat at night people radiate heat in urban areas
then release it slowly at night. 369

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