Urbanization
Roughly a century ago, many people in the United States began to move from rural areas to large cities. The last 50 years have seen an increased movement from those cities to the surrounding areas. Suburbs are areas that surround metropolitan centers and have low population densities compared with urban areas. Since 1950, more than 90% of population growth in metropolitan areas has occurred in suburbs, and two our of three people now live in suburban communities.
More than 75% of people in developed countries live in urban areas and that number is expected to increase slightly over the next 15 years. In developing countries, 48% of people live in urban areas. This number will probably increase to 56% by 2030. Of the 20 largest cities in the world, 16 are in developing countries. Worldwide, almost 5 billion people are expected to live in urban areas by 2030.
Urban living in both developed and developing countries present environmental challenges. Most developed countries employ city planning. As urban areas expand, experts design and install public transportation facilities, water and sewer lines, and other municipal services. In addition, while urban areas produce greater amounts of solid waste, pollution and carbon dioxide emissions than suburban or rural areas, they tend to have smaller per capita ecological footprints.
Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle. Urbanization, through the burning of fossil fuels and landfills, affects the carbon cycle by increasing the amount of carbon dioxide in the atmosphere.
With urbanization comes more stormwater runoff due to impervious services. Impervious surfaces are human-made structures--such as roads, buildings, sidewalks, and parking lots--that do not allow water to reach the soil, leading to flooding. Methods to increase water infiltration include replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation, and building up, not out.
Urban Sprawl
If you have ever been to a strip mall, you are familiar with the phenomenon known as urban sprawl.--urbanized areas that spread into rural areas and remove clear boundaries between the two. The landscape in these areas is characterized by clusters of housing, retail shops, and office parks, which are separated by miles of road. Large feeder roads and parking lots that separate "big box" and other retail stores from the road discourage pedestrian traffic.
Urban sprawl is the change in population distribution from high density areas to low density suburbs that spread into rural lands, leading to potential environmental problems.
Urban sprawl has had a dramatic environmental impact. Dependence on the automobile causes suburban residents to drive more than twice as much as people who live in cities. Between 1950 and 2000, the number of vehicle miles traveled per person in U.S. suburban areas tripled. Because suburban house lots tend to be significantly large than their urban counterparts, suburban communities also use more than twice as much land per person as urban communities. Urban sprawl tends to occur at the edge of a city, often replacing farmland and increasing the distance between farms and consumers.
The advent of the automobile and the subsequent development of the interstate highway system in the 1950s and 1960s changed everything. Today we think nothing of working in the city during the day and commuting home to the suburbs at night. With rapid, comfortable transportation by automobile between urban and suburban areas, it became possible to work or play in the city and then return home to a large home in a quiet neighborhood. For the first time in history, people could enjoy the best of both worlds.
Roughly a century ago, many people in the United States began to move from rural areas to large cities. The last 50 years have seen an increased movement from those cities to the surrounding areas. Suburbs are areas that surround metropolitan centers and have low population densities compared with urban areas. Since 1950, more than 90% of population growth in metropolitan areas has occurred in suburbs, and two our of three people now live in suburban communities.
More than 75% of people in developed countries live in urban areas and that number is expected to increase slightly over the next 15 years. In developing countries, 48% of people live in urban areas. This number will probably increase to 56% by 2030. Of the 20 largest cities in the world, 16 are in developing countries. Worldwide, almost 5 billion people are expected to live in urban areas by 2030.
Urban living in both developed and developing countries present environmental challenges. Most developed countries employ city planning. As urban areas expand, experts design and install public transportation facilities, water and sewer lines, and other municipal services. In addition, while urban areas produce greater amounts of solid waste, pollution and carbon dioxide emissions than suburban or rural areas, they tend to have smaller per capita ecological footprints.
Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle. Urbanization, through the burning of fossil fuels and landfills, affects the carbon cycle by increasing the amount of carbon dioxide in the atmosphere.
With urbanization comes more stormwater runoff due to impervious services. Impervious surfaces are human-made structures--such as roads, buildings, sidewalks, and parking lots--that do not allow water to reach the soil, leading to flooding. Methods to increase water infiltration include replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation, and building up, not out.
Urban Sprawl
If you have ever been to a strip mall, you are familiar with the phenomenon known as urban sprawl.--urbanized areas that spread into rural areas and remove clear boundaries between the two. The landscape in these areas is characterized by clusters of housing, retail shops, and office parks, which are separated by miles of road. Large feeder roads and parking lots that separate "big box" and other retail stores from the road discourage pedestrian traffic.
Urban sprawl is the change in population distribution from high density areas to low density suburbs that spread into rural lands, leading to potential environmental problems.
Urban sprawl has had a dramatic environmental impact. Dependence on the automobile causes suburban residents to drive more than twice as much as people who live in cities. Between 1950 and 2000, the number of vehicle miles traveled per person in U.S. suburban areas tripled. Because suburban house lots tend to be significantly large than their urban counterparts, suburban communities also use more than twice as much land per person as urban communities. Urban sprawl tends to occur at the edge of a city, often replacing farmland and increasing the distance between farms and consumers.
The advent of the automobile and the subsequent development of the interstate highway system in the 1950s and 1960s changed everything. Today we think nothing of working in the city during the day and commuting home to the suburbs at night. With rapid, comfortable transportation by automobile between urban and suburban areas, it became possible to work or play in the city and then return home to a large home in a quiet neighborhood. For the first time in history, people could enjoy the best of both worlds.
Smart Growth
People are beginning to recognize and address the problems of urban sprawl. One approach, smart growth, focuses on strategies that encourage the development of sustainable, healthy communities. The EPA lists 10 basic principle of smart growth:
Of course, no individual new development or neighborhood plan is likely to incorporate all of these ideals, but as a guide to thinking about how to build communities, the smart growth concept has been quite successful.
People are beginning to recognize and address the problems of urban sprawl. One approach, smart growth, focuses on strategies that encourage the development of sustainable, healthy communities. The EPA lists 10 basic principle of smart growth:
- Create mixed land uses (residential, retail, educational, recreational, business, land)
- Create a range of housing opportunities and choices (mixed income)
- Create walkable neighborhoods
- Encourage community and stakeholder collaboration in development decisions
- Take advantage of compact building design (multi-story with parking garage)
- Foster a distinctive, attractive communities with a strong sense of place.
- Preserve open space, farmland, natural beauty, and critical environmental areas
- Provide a variety of transportation choices
- Strengthen and direct development toward existing communities
- Make development decisions predictable, fair and cost-effective
Of course, no individual new development or neighborhood plan is likely to incorporate all of these ideals, but as a guide to thinking about how to build communities, the smart growth concept has been quite successful.
Smart growth can have important environmental benefits. For example, compact development reduces the amount of impervious surface, and allows room for more trees to be planted, both of which reduce runoff and flooding downstream. A 2000 study found that smart growth in New Jersey would reduce water pollution by 40% compared with the more common, dispersed growth pattern. By mixing uses and providing transportation options, smart growth also reduces fossil fuel consumption. A 2005 study in Seattle found that residents of neighborhoods incorporating just a few of the techniques to make non-auto travel more convenient travelled 26% fewer vehicle miles than residents of more dispersed, less connected neighborhoods. A 2012 San Francisco State University study found that similar smart growth practices led to a 20% reduction in miles travelled in 18 urban areas across the United States.