6 1 urbanization
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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