Urbanization
Curitiba, Brazil: an ecocity
• In 1969, the city focused on mass transit and now
has the world’s best bus system
– 70% of people use mass transit
• All high-rise buildings devote the bottom 2 floors to
stores (reduces need to travel)
• Recycles 70% of paper and 60% of metal, glass, and
plastic
• The city uses old buses as roving classrooms to
teach skills, and as health clinks and day-care
centers
• The poor get free medical care and can exchange
recyclables for food and bus tokens
• The city also provides free taps of safe water
throughout poor areas
Why do people move to urban
centers?
• As the industrial revolution created more
jobs in urban centers, fewer people were
needed on farms
• Urbanization is the shift of population from
the countryside to towns and cities
– in developed countries, urbanization has slowed,
because 3 out 4 people already live in cities,
towns, and suburbs (smaller communities that
ring cities)
– In developing nations, urbanization is drastically
increasing
Urban Cities Today
• Today, 46 cities hold more then 5 million
people, and 20 cities hold more than 10
million people
• Less than 5% of North American urban
dwellers like in large cities; most live in smaller
cities such as Portland or Austin
Major Urban Regions in the US
Fig. 25-6
p. 665
Why is urban growth so rapid?
• More people are moving from farms to cities
than are moving from cities to farms
• The human population overall is growing
• Most fast growing cities today are in the
developing world
– Many are facing overcrowding, pollution, and
poverty
Practice Question
The two continents with the greatest increase in
urbanization are
1) North America and Africa
2) South America and Australia
3) Africa and Asia
4) Asia and North America
5) Europe and South America
The suburbs
• As cities become more
crowded, unemployment
rises and poverty and crime
increase
• Many affluent city dwellers
chose to move outward to
the cleaner, less crowded,
and more park-like
suburban communities
surrounding cities
• Suburbs provide more
space per person, but need
more roads, have traffic,
and large-scale habitat
destruction
Urban Sprawl
• Sprawl is the spread of low-density urban or
suburban development outward from an
urban center
Urban Sprawl
• There are two
main components
of sprawl
– Human
population
growth
– Per capita land
consumption is
increasing
Practice Question
The growth of suburbs and urban sprawl were
primarily facilitated by
1) The development of indoor plumbing
2) The proliferation of automobiles
3) A lack of vested ecosystems
4) Rebates and other legislative incentives
5) A decrease in the cost and time required for
house construction
Negatives to sprawl
• Transportation: people mostly drive cars due
to a lack of transportation options
• Pollution: CO2 emissions increase, as do NO2
and SO2 emissions
– Water pollution is estimated to be 16 times
greater on paved areas than from vegetated areas
Negatives to sprawl
• Health: some studies indicate that sprawl
promotes physical inactivity
– This leads to other health issues
• Land use: more land is developed and less is
left as forests, fields, or farmland
• Economics: tax dollars are spent on new
infrastructure on the outskirts of cities (ex:
roads, telephone lines, sewers)
Advantages to urbanization
• Economics: cities are centers of economic
development and jobs
• Health: lower infant mortality rates, long lives,
and better access to health care
• Environmental: recycling is more
economically feasible, preserves biodiversity
Disadvantages to urbanization
• Unsustainable systems: occupy 2% of land
area and use ¾ of earth’s resources
• Lack of plants: most trees, shrubs, and other
plants are destroyed
• Water problems: cities have a high demand for
water
– Also, flooding problems occur
Urban Areas: Inputs and Outputs
Fig. 25-11 p. 669
Practice Question
All of the following are environmental advantages of
urbanization as compared to rural living EXCEPT
1) Increased feasibility of recycling
2) Increased per capita expenditures on
environmental expenditures
3) Reduced use of land
4) Reduced stress on wildlife habitats
5) Reduced climactic impact
Disadvantages to urbanization
• Pollution and health problems: high density and
resource consumption leads to high levels of air and
water pollution, as well as waste disposal issues
– Also increases the spread of infectious diseases
• Climate and artificial light: cities are warmer, rainier,
foggier, and cloudier than suburbs
– Creates large amounts of artificial light
• Poverty and social problems
Urban Heat Island
 The large amounts of heat generated by
cars, factories, furnaces, lights, etc
create an “urban heat island”
 This phenomenon describes urban and
suburban temperatures that are 2 to 10°F
(1 to 6°C) hotter than nearby rural areas
Case study: Mexico City
• 19 million people live there, with 400,000
arriving each year
• Severe air pollution, 50% unemployment,
deafening noise, overcrowding, traffic
congestion, inadequate public
transportation, and a high crime rate
– 1/3 of the residents live in slums with no running
water and electricity
– 3 million people have no sewers facilities—large
amounts of human waste are all around the city
– Has one of the world’s worst smog problems
Case study: Mexico City
• Air and water pollution cause
100,000 premature deaths
per year
• Water demands have
drained the aquifers so much
that parts of the city have
subsided 30 feet
• The city has made some
progress with pollution in
recent years and has started
to plant trees
City Planning
• City planning is the
professional pursuit
that attempts to design
cities so as to maximize
their efficiency,
functionality, and
beauty
• Chicago was the first
American city that was
thoroughly planned
City Zoning
• In zoning, various parcels of land are
designated for certain uses
– Zoning can be used to control the growth of a city
• Zoning is not very effective in protecting the
environment, because it is not a concern for
politicians when making decisions
Preserving open space
• Urban growth boundary model encourages
certain types of development that prevents
destruction of important environmental areas
• The traditional method is to preserve large
blocks of open space as parks
Practice Question
A city is immersed in a brownish tinted smog. What
can be inferred from this observation?
1) UV rays had nothing to do with the formation of
this brownish haze
2) The automobiles in the city alone are responsible
for this brownish haze
3) A nearby coal-fired factory is responsible for this
brownish haze
4) Nitrogen dioxide is responsible for this brownish
haze
Smart Growth
•
Smart growth is a city planning concept in
which a community’s growth is managed in
ways that limit sprawl and improve
residents’ quality of life
1. Mix land uses
2. Take advantage of compact building design
3. Create a range of housing opportunities
Smart Growth
4. Create walkable neighborhoods
5. Foster distinctive, attractive communities
6. Preserve open space, farmland, natural beauty, and
critical environmental areas
7. Strengthen and direct development towards
existing communities
8. Provide a variety of transportation choices
9. Make development decisions predictable, fair, and
cost-effective
10. Encourage community collaboration in decisions
Transit Options in Cities
• As long as an urban center is large enough to
support the infrastructure, mass transit
options are cheaper, more energy-efficient,
and cleaner than roadways
Pros
Rail
Buses
Bikes
Cons
The Benefits of Rail Transit
• Building and maintaining mass transit can be
very expensive
• Cities that have rail service as a major
component of their transportation systems
had 36% fewer per capita traffic deaths each
year, and residents drove 21% fewer miles
– They are also cheaper than bus-only systems
– Systems with only moderate rail systems did not
find the same benefits
Urban Sustainability
• This idea seeks ways to increase the good that
comes from urban centers and minimize the
bad
• A city that imports all its resources and
exports all its wastes is not sustainable
• Many cities around the country are trying to
become more sustainable
Case Studies: Cities
• New York: green initiatives
• Mexico City: huge population growth has led
to overcrowding and environmental problems
• Curitiba, Brazil: great mass transit and
environmental planning
• Los Angeles or Las Vegas: urban sprawl
• Rizhao, China: mostly solar powered city