URBANIZATION
AND SUSTAINABLE CITIES
Miller (2003): Chapter 11
Urbanization
 An urban (or metropolitan) area = a town or a city
plus its adjacent suburbs with a population of >2,500
people
 A rural area = an area with < 2,500 people
 A country’s degree of urbanization = percentage of
its population living in an urban area
 Virtually all the population growth expected during the
next 30 years will be concentrated in urban areas
What Is Urban?
Definition of “urban” varies widely from country to
country. Some countries distinguish between rural
and urban based on:
 Size or density of localities
 Administrative considerations (only major cities are
classed as urban)
 The percentage of persons not dependent on
agriculture
 Some nations define all of their population as living in
urban areas (e.g. Singapore). Some nations define
none of their population as urban (e.g. Polynesia
(South Pacific Islands))
Urban Growth
Urban areas grow in 2 ways:
1. Natural increase of its population (births)
2. Immigration (mostly from rural areas – the biggest cause of
urban growth)

Proportion of the global population living in urban areas: 2%
(pre-industrial period)  46% (2001) (~160,000 people added
to world’s urban areas each day)

UN projections: by 2050, ~63% of world’s people will be living
in urban areas, with 90% of this urban growth in developing
countries

Number of large cities (>1 million people): increasing rapidly
throughout the 20th century

Urban growth is much slower in developed countries than in
developing countries (still, projection: 79% (current)  84%
(2025) in developed countries)
Megacities
 1900: 19 cities had >1 million people (95% of the population
then were rural)
 2001: more than 400 cities have >1 million people
 Increasingly, there are more megacities (cities with populations
>10 million people)
 1985: 8 megacities
 2001: 16 (13 of them in developing countries)
 As they grow and sprawl outward, separate urban areas
may merge to form a megalopolis (= a very large city, or a
region made up of several large cities and their surrounding
areas in sufficient closeness to be considered a single
urban complex)
World’s Largest Cities
Tokyo (1)
26.5
Mexico City (2)
18.3
Sao Paolo (3)
18.3
New York (4)
16.8
Mumbai (5)
16.5
Los Angeles (6)
13.3
Shanghai (10)
12.8
0
5
10
15
20
Population in Millions
United Nations Population Division 2001
25
30
Tokyo – world’s largest megacity
 Japan: one of the most highly urbanized countries in
the world
 Nearly 80% of Japan's 125 million people: live in
cities throughout the country
 The three largest urban centres in Japan: Tokyo,
Osaka and Nagoya metropolitan areas
 Tokyo: by far the largest metropolitan area with >25%
of the total population living in its centre and
surrounding areas
Urban Poverty
Poverty is becoming increasingly urbanized as more poor people
migrate from rural to urban areas.
U.N. estimates ~ 1 billion people live in slums (heavily
populated urban areas characterized by substandard
housing) of inner cities, or in vast illegal squatter
settlements (squatter = person who takes unauthorized
possession of unoccupied premises) and shantytowns (slum
areas of a town or outskirts of a town, consisting of huts or
shanties)
Often the land in squatter settlements is not suitable for human
habitation because of:
 air and water pollution
 hazardous wastes from nearby factories
 the land is prone to natural disasters (earthquakes,
volcanoes, flooding)
 Diseases are common and frequent in squatter
settlements and shanty towns
 Many cities do not provide adequate services
(drinking water, sanitation facilities, electricity, food,
heath care, housing, schools, jobs) to squatter
settlements (lack money, and fear even more rural
poor moving in)
 Many city governments try to destroy squatter
settlements or send police to drive illegal settlers out
(people then move back in or develop another
shantytown somewhere else)
Case Study: Mexico City
 Population: ~18 million people (the
world’s second most populous city,
~1/5 Mexicans live in Mexico City)
 >2000 people move into the city
from poor rural areas every day
Mexico City suffers from severe air pollution:
 Some 4 million motor vehicles and 30,000 factories pour
pollutants into the atmosphere
 The city lies in a natural basin surrounded by mountains,
frequent thermal inversions trap polluted air at ground level
 Living in Mexico City and breathing the air
= smoking 3 packs of cigarettes a day!
 Government has tried to improve this (e.g. having buses
and trucks running on LPG, enforcing stricter industrial
emission standards, planting trees), still, fail to meet
minimum air quality standards on average 300 days a
year
Mexico City, with the
volcano Popocatépetl
in the background
Mexico City – Urban Problems
Mexico City also suffers from:
 Very high unemployment (~50%)
 A soaring crime rate (robbery, assault, murder)
 Severe noise pollution
 Bad traffic congestion
 Inadequate housing (>1/3 of the people living in slums
with no running water or electricity)
 Inadequate sanitation ( widespread infectious
diseases such as hepatitis)
Environmental Problems
Urban areas are not self sustaining!
 Survive only by importing food, water, energy,
minerals, and other resources from somewhere else
 Produce vast quantities of wastes
 Affect the health of their inhabitants
but also the environmental health of rural areas
and the health of the planet
 Often, agriculture and cities develop in similar areas
 expanding urban areas = using up agricultural
land
Daily Inputs
Water
625,000
tonnes
Fuel
9,500
tonnes
Food
2,000
tonnes
Daily Outputs
U.S. city
of 1
million
people
Sewage
500,000
tonnes
Air
pollutants
950 tonnes
Rubbish
9,500
tonnes
Environmental Problems Of Cities
 Most cities: have few trees and other plants
 Most cities: produce little of their own food
 Many cities: have water supply and flooding
problems
 Many coastal areas: popular
for urban development
 Many natural coastal
habitats have been cleared,
drained, and filled in for
urban development
Urban Microclimate
 Materials used in urban construction: conduct more
heat than vegetated areas
 Buildings and vehicles: release significant amounts of
heat energy from burning of fossil fuels
 Urbanization can therefore its own microclimate
 Temperature of a city: several degrees warmer than
surrounding rural areas
 Cities are urban heat islands
Urban Heat Island Profile
This means cities tend to be warmer, rainier,
foggier, and cloudier.
Urban Pollution
 Urban residents suffer higher pollution levels than
surrounding rural areas.
 Sheer numbers of people in cities mean urban areas
are major contributors to air pollution and enhanced
greenhouse effect.
 Most urban residents suffer from excessive noise.
Noise levels in decibels (dbA)
85
0
Normal
breathing
Quiet
rural
area
Vacuum Permanent
damage
cleaner
begins
after 8-hrs
150
Rock
concert
Military
rifle
What are the environmental
benefits of cities?
Environmental Benefits
Recycling is more feasible economically
- large concentration of materials.
 Environmental pressures from population growth are
reduced
- because birth rates are usually much less in urban
areas.
 Spending per person on environmental protection is
higher in urban areas.
 But, concentrating people in urban areas may not help
preserve biodiversity or restrict habitat loss because of all
the land needed to support urban residents.
Transportation and Urbanization
 Motor vehicles provide convenient transport and
mobility
 Much of the world’s economy built on producing
automobiles and supplying roads and services for
them
 Transport causes many deaths and accidents per
year
 Also biggest source of air pollution (15% of CO2
emissions), producing smog
 Worldwide, 1/3 of urban land is devoted to roads, car
parks, gas stations.
Urban Transport
 Dispersed car-centred cities use 10 times more energy
per person for transport than more compact cities with
mass-transit transport systems
 In North American, Australia and some European cities
- have dispersed, car-centred cities with low population
density
 The outskirts of the urban areas, or suburbs, spread out
to cover large amounts of former ‘green spaces’, this is
urban sprawl
Sustainable Cities
 Sustainable city: takes only the resources that are
needed, can be continuously recycled, or returned to
the environment in the least harmful way
 In reality, no city is completely sustainable.
 Curibita: located in S. Brazil, population 1.6 million
 One of the fastest growing cities in Brazil, but has
managed to expand while maintaining a good quality
of urban life
 Has consistent planning and innovative urban
solutions – high praise and environmental awards as
an ecocity (or ‘green city’)
The Greening of Curibita
 From 1974: large tree planting scheme. Now has high
ratio of green area per inhabitant (52 m2), with large
parks and recreational areas.
 Low air pollution: Curibita is not built around the car but
is people-oriented.
 Integrated land-use and transportation system
 Flooding problems solved by diverting water to lakes in
the parks
 Strict water pollution control laws
 In 1989: a “garbage that is not garbage” campaign, in
which city residents recycle one-third of all solid waste.