ENVIRONMENTAL SCIENCE 13e CHAPTER 6: The Human Population and Urbanization.

ENVIRONMENTAL SCIENCE 13e

CHAPTER 6:The Human Population and Urbanization

Global Population

• http://www.youtube.com/watch?v=sc4HxPxNrZ0

Core Case Study: Are There Too Many of Us? (1)

• 6.8 billion people• 83 million more each year• 2050: 9.5 billion people at current

growth rates• Most growth in low-income and middle-

income countries• Enough resources for growing

population?

A important question

• Can we provide an adequate standard of living for a projected 2.7 billion more people by 2050 without causing widespread environmental damage?

• Overpopulation vs overconsumption

Core Case Study: Are There Too Many of Us? (2)

• Negative viewpoint– 20% currently lack basic necessities– Declining conditions increase death rate– Increased resource use – Increased environmental degradation

• Positive viewpoint– Technological solutions will increase carrying

capacity– Growing population a valuable resource

Fig. 6-1, p. 94

Crowded street in China: largest population of all countries with 1.3 Billion peopleTogether China and India are home to 1 of every 3 people on Earth

6-1 How Many People Can the Earth Support?

• Concept 6-1 We do not know how long we can continue increasing the earth’s carrying capacity for humans without seriously degrading the life-support system that keeps us and many other species alive.

Human Population Explosion

• Exponential growth (J-curve) in past 200 years

• Three major reasons – Ability to expand into diverse habitats– Emergence of agriculture– Sanitation systems and control of infectious

diseases decreased death rates

How Long Can the Human Population Grow?

• Rate slowing, but still exponential

• Uneven global growth

• No population can grow indefinitely

• 2050: 9.5 billion people at current growth rates

• Most growth in developing countries, least likely to cope

Fig. 1-1, p. 1

Hunting and gathering

Agricultural revolution

Industrial revolution

Black Death—the Plague

Industrial revolution

Fig. 1-10, p. 16

?

2-5 millionyears

13

12

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10

9

8

7

6

5

4

3

2

1

0

8000 6000 4000 2000 2000 2100B.C. A.D.

Exponential Growth: the J-shaped curve of past world population growth

Fig. 6-2, p. 96

Low7.8

12

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3

2

Po

pu

lati

on

(b

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on

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Year

1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050

High10.8

Medium9.5

UN world population projections

Fig. 6-3, p. 97

Elimination of many natural predators

Altering Nature to Meet Our Needs

Natural Capital Degradation

Reduction of biodiversity

Increasing use of the earth's net primary productivity

Increasing genetic resistance of pest species and disease-causing bacteria

Relying mostly on polluting and climate-changing fossil fuels

Interfering with the earth's chemical cycling and energy flow processes

Using some renewable resources faster than they can be replenished

Introduction of potentially harmful species into communities

6-2 What Factors Influence the Size of the Human Population?

• Concept 6-2A Population size increases through births and immigration and decreases through deaths and emigration.

• Concept 6-2B The average number of children born to women in a population (total fertility rate) is the key factor that determines the population size.

Population Change

Population change =

(births + immigration) - (deaths + emigration)

Demographers look at birth rates and death rates

• 2009:China, 1.3 billion people

India, 1.1 billion people

USA, 306 million people

Number of Children

• Fertility rates affect population size and growth rate

• Total fertility rate (TFR)

• 1950-2009: Global TFR fell to:1.6 from 2.5 in developed countries

2.8 from 6.5 in developing countries

Case Study: The U.S. Population Is Growing Rapidly

• Quadrupled in 100 years, despite oscillations in TFR

• Baby boom: High TFR• Current births outnumbering deaths

and legal immigration• Growing faster than other developed

countries• 2050 estimate: 439 million

Baby boom(1946–64)

Replacementlevel

Fig. 6-4, p. 98

Year

Bir

ths

per

wo

man

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

4.0

3.5

3.0

2.52.12.0

1.5

1.0

0.5

0

TFR for US

Factors Affecting Birth Rates (1)

• Importance of children as part of labor force

• Cost of raising and educating children

• Availability of retirement systems

• Urbanization• Educational and employment opportunities for

women

Factors Affecting Birth Rates (2)

• Average marriage age

• Availability of legal abortion and reliable birth control methods

• Religious beliefs, traditions, cultural norms

Factors Affecting Death Rates

• Population growth is also response to decline in crude death rate

• Life expectancy and infant mortality rate important indicators of overall health

• Average life expectancy increased• Infant mortality – barometer of a

society’s quality of life

Supplement 3, Fig. 8, p. S10

*6-3 How Does a Population’s Age Structure Affect Its Growth or Decline?

• Concept 6-3 The numbers of males and females in young, middle, and older age groups determine how fast populations grow or decline.

*Age Structure

• Distribution of population– Prereproductive – Reproductive– Postreproductive

• Country with many young people grows rapidly

• Country with many older people will decline• Developing countries: >30% under 15 years old

Fig. 6-6, p. 102

Fig. 6-6, p. 102

Age Structure Predicts the Future

• 36% of U.S. population baby boomers

• Graying of America

• Over time: increasing percentage of older baby boomers

• Changes the economy

Stepped Art

2035201519851955

Fig. 6-8, p. 103

Tracking the baby-boom generation in the United States. US population by age and sex for years indicated.

Declines Occur in Aging Populations

• “Baby bust” or “birth dearth” – TFR below 1.5 children per couple

• Labor shortages

• Strain on governments for public services

• Fewer taxpayers

*6-4 How Can We Slow Human Population Growth?

• Concept 6-4

We can slow population growth by

-reducing poverty

-encouraging family planning

-and elevating the status of women.

*Stages of Demographic Transition

• Preindustrial

• Transitional – demographic trap

• Industrial

• Postindustrial • Some analysts believe that most of the world’s developing countries

will make a demographic transition over the next few decades, mostly because modern technology can raise per capita incomes by bringing economic development and family planning to such countries. Other analysts fear rapid pop growth, extreme poverty, and increasing environmental degradation in some low-income countries could leave them stuck in stage 2.

Death rate

Total population

Birth rate

Population grows rapidly because birth rates are high and death rates drop because of improved food production and health

Decreasing

Stage 2Transitional

Increasing Very high

Stepped Art

Population growth levels off and then declines as birth rates equal and then fall below death rates

Stage 4Postindustrial

NegativeZero

Populationgrows veryslowly becauseof a highbirth rate(to compensatefor high infantmortality) and ahigh death rate

Stage 1Preindustrial

Growth rate over time

80

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20

10

0

Bir

th r

ate

an

d d

eath

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um

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00 p

er

yea

r)

Low

Population growth slows as both birthand death rates drop because of improved food production, health, and education

Stage 3Industrial

Low

Fig. 6-10, p. 105

Think about it

• Stage 1: birth rate, death rate, population

• Stage 2: birth rate, death rate, population

• Stage 3: birth rate, death rate, population

• Stage 4: birth rate, death rate, population

Family Planning (1)

• Birth spacing, birth control, health care• Increased availability of contraception• 55% drop in TFR of developing

countries• Developing countries

– Almost half pregnancies unplanned– Often lack access to family planning

Family Planning (2)

• Invest in family planning

• Reduce poverty

• Elevate the social and economic status of women

Empowering Women Can Slow Population Growth (1)

• Women tend to have fewer children if they:– are educated

– control their own fertility

– have a paying job outside the home

– do not have their rights suppressed

*Empowering Women Can Slow Population Growth (2)

• Women do almost all domestic housework and childcare

• Women do 60-80% of agriculture, wood gathering, water hauling

• Globally, women do 2/3 of all work for 10% of income

Empowering Women Can Slow Population Growth (3)

• Illiterate woman 64% of world’s population, 70% of the poor

• When daughters considered less valuable, not sent to school

• Poor conditions for women leads to environmental degradation

Case Study: Slowing Population Growth in China (1)

• One-child families• Halved birth rate and drastically

reduce TFR• Improved quality of life• Strict family planning• Sons still preferred – gender

imbalance

Case Study: Slowing Population Growth in China (2)

• Population rapidly aging

• Rapidly growing economy

• Larger middle class increases resource consumption and waste

• Sustainable economic plan needed to avoid environmental degradation

Case Study: Slowing Population Growth in India

• Tried to slow population growth for five decades

• Most populous country in 2015• Problems increase with growing population

– Poverty– Malnutrition– Environmental degradation– Growing middle class – resource consumption

Assignment

• Read Handout: “What do you think? Cultural Choices and the Rate of Population Growth” that discusses the approach to population control taken by two Indian states, Kerala and Andra Pradesh

• Answer the question Which method of population control (that used by Kerala or Andra Pradesh) offers better insights and models for other countries? What are the benefits and limitations of each approach?

• What do you think of the approach taken in Thailand? Why might this approach not work everywhere?

6-5 What Are the Major Urban Resource Environmental Problems?

• Concept 6-5 Most cities are unsustainable because of high levels of resource use, waste, pollution, and poverty.

Urban Living

• Half the world lives in urban areas

• 79% of Americans live in cities

• 50% of world population lives in cities

• Urban areas continue to grow– Natural increase

– Immigration

Major Trends in Urban Growth

• Proportion of urban global population growing

• Number and sizes of urban areas mushrooming

• Rapid increase in urban populations in developing countries

• Urban growth slower in developed nations

• Poverty increasing

Fig. 6-11, p. 108

2004 (estimated)2015 (projected)

Los Angeles13.3 million19.0 million

New York16.8 million17.9 million

Sao Paulo18.3 million21.2 million

Buenos Aires12.1 million13.2 million

Cairo10.5 million11.5 million

Karachi10.4 million16.2 million

Dhaka13.2 million22.8 million

Beijing10.8 million11.7 million

Tokyo26.5 million27.2 million

Shanghai12.8 million13.6 million

Jakarta11.4 million17.3 million

Manila10.1 million11.5 million

Calcutta13.3 million16.7 million

Mumbai(Bombay)16.5 million22.6 million

Delhi13.0 million20.9 million

Mexico City18.3 million20.4 million

Osaka11.0 million11.0 million

Lagos12.2 million24.4 million

Key

Shows populations of 18 megacities (each with 10 million ormore people) in 2009 and their projected populations in 2015. All but 3 are located in developing countries.

Case Study: Urbanization in the United States (1)

• 1800–2009: urban population increased from 5% to 79%

• Migration patterns– Rural areas to large cities

– Large cities to suburbs and smaller cities

– Cities and suburbs to rural areas

– North and East to South and West

Fig. 6-12, p. 109

Almost 8 of every 10 Americans live in urban areas. Areas with names in whiteAre fastest growing metropolitan areas.48% of all Americans live in cities of 1million or more

Urban Sprawl is a product of

• Prosperity• Ample and affordable land• Automobiles• Cheap gasoline• Poor urban planning

• Urban sprawl=growth of low density development on the edges of cities and towns

Urban Sprawl Problems

• Increased automobile use

• Decreased energy efficiency

• Destruction of cropland, forests, wetlands

• Economic deaths of some cities

Fig. 6-14, p. 110

Economic Effects

Urban Sprawl

Natural Capital Degradation

Loss of cropland

Loss of forests andgrasslands

Loss of wetlands

Loss andfragmentation ofwildlife habitats

Land andBiodiversity

Increased use of surfacewater and groundwater

Increased runoff andflooding

Increased surface waterand groundwaterpollution

Decreased naturalsewage treatment

Water

Increased energy useand waste

Increased air pollution

Increased greenhousegas emissions

Can enhance climatechange

Energy, Air,and Climate

Decline ofdowntown businessdistricts

Increasedunemployment incentral city

Loss of tax base incentral city

Advantages of Urbanization (1)

• Economic development

• Innovation

• Education and jobs

• Technological advances

• Longer life spans

Advantages of Urbanization (2)

• Better social and medical services

• Recycling more feasible

• Biodiversity increased

• Increased energy efficiency

Disadvantages of Urbanization (1)

• Unsustainable systems

• Lack of vegetation

• Water problems

• Pollution and health problems

Disadvantages of Urbanization (2)

• Noise pollution

• Climate and artificial light

• Urban heat islands

• Light pollution

Information

Inputs

Energy

Food

Water

Rawmaterials

Manufacturedgoods

Money

Outputs

Solid wastes

Waste heat

Air pollutantsWater pollutantsGreenhouse gasesManufactured goods

Noise

Wealth

Ideas

Fig. 6-15, p. 111

Natural capital degradation: urban areas rarely are sustainable systems. Typical cityDepends on large non-urban areas for huge inputs of matter and energy resources and for large outputs of waste matter and heat.

Urban Poor in Developing Countries

• Slums

• Shantytowns and squatter settlements

• Lack of basic services

Slums Mexico City

Case Study: Mexico City (1)

• Large population

• Severe noise, water, and air pollution

• 50% unemployment

• 100,000 premature deaths per year

Case Study: Mexico City (2)

• 3 million without sewer

• Fecal snow

• Geography contributes to air pollution

• Progress – tree planting and lower air pollution

6-6 How Does Transportation Affect Urban Environmental Impacts?

• Concept 6-6 In some countries, most people live in dispersed urban areas and depend mostly on motor vehicles for their transportation.

Cities Can Grow Outward or Upward

• Compact cities– Transportation by walking, biking, or

mass transit

– Hong Kong, Tokyo

• Dispersed cities– Transportation by automobile

– Most American cities

Automobiles

• Gas guzzlers

• 40,000 people per year die from auto accidents in the United States

• World’s largest source of air pollution

• Lead to urban sprawl and congestion

Reduce Automobile Use

• User-pays system

• Full-cost pricing

• Tax revenues to finance mass transit, bike paths, sidewalks

• High gasoline tax unlikely

• Need to discourage automobile use

Alternatives to Cars

• Bicycles

• Mass transit systems in urban areas

• Bus systems

• Rapid rail

Fig. 6-18, p. 115

Trade-Offs

Are quiet andnon-polluting

Take fewresources tomake

Burn no fossilfuels

Require littleparking space

Secure bike parkingnot yet widespread

Are impractical forlong trips

Provide no protectionfrom bad weather

Provide littleprotection in anaccident

Bicycles

Advantages Disadvantages

Fig. 6-19, p. 116

Advantages

Is expensive to buildand maintain

Is cost-effective onlyin densely populatedareas

Commits riders totransportationschedules

Can cause noise andvibration for nearbyresidents

Reduces carcongestion incities

Causes fewerinjuries anddeaths thancars do

Reduced need formore roads andparking areas

Uses less energyand produces lessair pollution thancars do

Trade-Offs

Mass Transit Rail

Disadvantages

Fig. 6-20, p. 116

Trade-Offs

Can lose money becausethey require affordable fares

Can get caught in trafficand add to noise andpollution

Commit riders totransportation schedules

Can greatly reduce caruse and air pollution

Can be rerouted asneeded

Cost less to developand maintain thanheavy-rail system

Advantages Disadvantages

Buses

Fig. 6-21, p. 116

Trade-Offs

Is costly to run andmaintain

Causes noise andvibration for nearbyresidents

Has some risk ofcollision at carcrossings

Is much more energyefficient per rider than carsand planes are

Produces less pollutionthan do cars and planes

Can reduce need for moreair travel, cars, roads, andparking areas

Advantages Disadvantages

Rapid Rail

*6-7 How Can Cities Become More Sustainable and Livable?

• Concept 6-7 An ecocity allows people to choose walking, biking, or mass transit for most transportation needs; recycle or reuse most of their wastes; grow much of their food; and protect biodiversity by preserving surrounding land.

• What is an Ecocity? What is an example of an ecocity?

Environmentally Sustainable Cities

• Smart growth• Ecocities

– Use renewable energy as much as possible– Build and design people-oriented cities– Use energy and matter efficiently– Prevent pollution and reduce waste– Recycle, reuse, and compost – Protect and encourage biodiversity– Promote urban gardens and farmers markets– Zone for environmentally stable population levels

Homework Assignment

• Go on an ecocity scavenger hunt! Find at least 3 things in Athens or on campus that could be found in an ecocity.

• Take pictures and email them with a description of why you think you would find it in an ecocity

• You may work in pairs or groups of 3 if you wish

Fig. 6-22, p. 117

Smart Growth ToolsLimits and Regulations

Limit building permitsUrban growthboundariesGreenbelts around cities

Public review of newdevelopment

Zoning

Encourage mixed use ofhousing and smallbusinesses

Concentratedevelopment along masstransportation routes

Promote high-densitycluster housingdevelopments

Planning

Ecological land-useplanning

Environmental impactanalysisIntegrated regionalplanningState and nationalplanning

Protection

Preserve existing open space

Buy new open space

Buy development rights thatprohibit certain types ofdevelopment on land parcels

Taxes

Tax land, not buildings

Tax land on value of actual use(such as forest and agriculture)instead of on highest value asdeveloped land

Tax Breaks

For owners agreeing not to allow certain types of development (conservation easements)For cleaning up and developing abandoned urban sites (brownfields)

Revitalization and New GrowthRevitalize existing towns and citiesBuild well-planned new towns and villages within cities

Solutions

*Case Study: Curitiba, Ecocity in Brazil (1)

• Curitiba – “ecological capital” of Brazil

• Inexpensive, efficient mass transit

• High-rise apartments near bus routes, mixed-use structures

• Bike and pedestrian paths

Case Study: Curitiba, Ecocity in Brazil (2)

• 1.5 million trees planted

• Recycling

• Many services for the poor

• Emphasis on ecological awareness, health, literacy

Curitiba Video

• http://www.youtube.com/watch?v=hRD3l3rlMpo&feature=fvw

Fig. 6-23, p. 118

Bus rapid transit system in Curitiba, Brazil. Boarding is speeded up by the use of Extra-wide doors and boarding platforms sheltered by large glass tubes where passengers can pay before getting on the bus.

Fig. 6-23, p. 118

Interdistrict

Citycenter

RouteWorkersFeederDirectExpress

Each of the 5 major spokes has 2 express lanes used only by buses.

Three Big Ideas from This Chapter - #1

The human population is increasing rapidly and may soon bump up against environmental limits.

Three Big Ideas from This Chapter - #2

We can slow human population growth by reducing poverty, encouraging family planning, and elevating the status of women.

Three Big Ideas from This Chapter - #3

Most urban areas, home to half of the world’s people, are unsustainable, but they can be made more sustainable and livable within your lifetime.

Review Growth CurvesReview Growth Curves Exponential Growth

Logistic Growth

Carrying capacity= capacity of a given habitat to support a given species, stated in terms of the maximum population of the species that the habitat can support over a given period

*What will happen to the population size in the future in each of the age structure diagrams?

Fig. 6-6, p. 102

*What will happen here?