URBANIZATIONURBANIZATION

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

Population in MillionsUnited Nations Population Division 2001

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

Water625,000 tonnes

Fuel9,500

tonnes

Food2,000

tonnes

Daily Inputs

U.S. city of 1

million people

Daily Outputs

Air pollutants950 tonnes

Rubbish9,500

tonnes

Sewage500,000tonnes

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.

0 15085

Normal breathing

Quiet ruralarea

Vacuumcleaner

Permanentdamage begins

after 8-hrs

Rockconcert

Noise levels in decibels (dbA)

Militaryrifle

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.