6 1 urbanization

6-1 Urbanization

6-1 Learning GoalHow long we can continue increasing the earth’s carrying capacity for humans without seriously damaging the life-support system that keeps us and many other species alive.

Human Population Growth Exponential growth (J-curve) in past 200 years

Human Population ExplosionHuman Population Increase Reasons

1. Ability to expand into diverse habitats

Human Population ExplosionHuman Population Increase Reasons

2. Emergence of agriculture

Human Population ExplosionHuman Population Increase Reasons

3. Sanitation systems and control of infectious diseases decreased death rates

How Long Can the Human Population GrowRate slowing, 1.22% but still exponentialUneven global growth (9x’s faster in

developing countries)Most growth in developing countries, least

likely to copeNo population can grow indefinitely2050: 9.5 billion people at current growth

rates

Population Growth Cultural carrying capacity – the max number

of people the earth could support at a reasonable level of comfort and freedom indefinitely

Population Change Population change =

(births + immigration) - (deaths + emigration)

Immigration – people enter country

Emigration – people leave country

World Populations2009: Top 3 countries1.China, 1.3 billion people (1 in 5 people

on earth)2. India, 1.1 billion people (1 in 6 people

on earth)3. USA, 306 million people (1 in 22

people)

Population ChangeFertility rate – average number of

children a woman has.Fertility Rates in 2009: 1.6 in developed countries6.5 in developing countries

Population Change Why has the fertility rate in the US decreased,

but population has increased? Give me specific reasons.

77 yearsLife expectancy 47 years

1900

2000

Married women working outside the home

8%81%

High school graduates

15%83%

Homes with flush toilets

10%98%

Homes with electricity

2%99%

Living in suburbs

10%

52%

Hourly manufacturing job wage (adjusted for inflation)

$3$15

Homicides per 100,000 people

1.25.8

Stepped Art

Fig. 6-5, p. 99