Curbing Sprawl to Fight Climate Change
If governments do not act quickly to discourage the building of cities for cars, the international effort to control global warming will become much more difficult, reports a new study by the Worldwatch Institute, a Washington, D.C.-based research organization. Sprawling urban areas are helping to make road transportation the fastest growing source of the carbon emissions warming the earth's atmosphere.
"Wind turbines, energy-efficient cars, and other new technologies have received much attention in recent debates over energy policy, but we've been neglecting the role that urban design can play in stabilizing the climate," said Molly O'Meara Sheehan, author of City Limits: Putting the Brakes on Sprawl. "Local concerns like clogged roads, dirty air, and deteriorating neighborhoods are already fueling a backlash against sprawl. Understanding the role of sprawl in climate change should only speed up the shift towards more parks and less parking lots. We can have healthier, more livable cities and protect the planet from climate change too."
A large body of research shows that sprawl already wreaks havoc on people's health. Each year, traffic accidents take up to a million lives worldwide. In some countries, the number of lives cut short by illness from air pollution exceeds those lost to accidents. And by making driving necessary and walking and cycling less practical, sprawling cities widen waistlines by depriving people of needed exercise.
Cities in the United States have been sprawling for decades, spreading out much faster than population growth. Chicago, for example, saw a 38 percent increase in population from 1950 to 1990, but the city's land area grew more than three times as fast, a 124 percent increase.
But U.S. citizens are increasingly dissatisfied with sprawl. A recent national poll found that sprawl topped the list of local concerns. And in the year 2000 election, U.S. voters approved some 400 local and state ballot initiatives addressing sprawl-related problems. At least 38 U.S. states have passed laws creating incentives for more compact development.
"The United States has the world's most car-reliant cities," said Sheehan. "U.S. drivers consume roughly 43 percent of the world's gasoline to propel less than 5 percent of the world's population. The big question facing the United States today is whether we can turn away from a car-centered model and develop better land-use practices and less destructive transportation systems."
By the end of the decade, the majority of the world's people will live in urban areas. The urban design decisions made today, especially in cities in the developing world where car use is still low, will have an enormous impact on global warming in the decades ahead. Adoption of the U.S. car-centered model in these places would have disastrous consequences.
Thirty years from now, for example, China, excluding Hong Kong, is expected to have 752 million urban dwellers. If each were to copy the transportation habits of the average resident of the San Francisco area in 1990, the carbon emissions from transportation in urban China alone could exceed 1 billion tons, roughly as much carbon as released in 1998 from all road transportation worldwide.
"Some cities in developing countries have already proved that a strategy of de-emphasizing cars and providing public transit instead can work," said Sheehan. One outstanding example is the city of Curitiba, Brazil. Starting in 1972, Curitiba built a system of dedicated busways and zoned for higher-density development along those thoroughfares - and is now enjoying better air quality and more parks for its 2.5 million people.
Today, other Latin American cities are adapting elements of Curitiba's system. Bogot?, Colombia, has recently launched a similar bus system, the TransMilenio, expanded its bike paths, and tried a bold "car-free" day, where in the middle of the work week, the city of 6.8 million functioned as normal - but without cars. Bogot?'s story also illustrates the importance of higher population density to support buses and cycling: if Bogot? sprawled like a typical American city, it would cover more than 20 times as much land area.
Another indication of the reaction against sprawl is the growth of light rail and other forms of public transit. A surge in light rail construction has brought the total number of systems in Western Europe to over 100 in 2000, the highest point since 1970. In the United States, public transportation use has increased for five straight years, following decades of decline. Planners in Portland, Oregon, estimate that a new light rail line there has saved the region from building eight new parking garages and two extra lanes on major highways.
Road transportation is the fastest-growing source of carbon emissions:
Denser cities tend to have lower carbon emissions from transportation:
Sources: Figure 1 based on International Energy Agency, CO2 Emissions from Fuel Combustion, 1971