2. 6-1 Learning Goal
How 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.
6. Human Population Explosion
Human Population Increase Reasons
3. Sanitation systems and control of
infectious diseases decreased death rates
7. How Long Can the Human Population
Grow
Rate slowing, 1.22% but still exponential
Uneven global growth (9x’s faster in
developing countries)
Most growth in developing countries, least
likely to cope
No population can grow indefinitely
2050: 9.5 billion people at current growth
rates
8. Population Growth
Cultural carrying capacity – the max number of
people the earth could support at a reasonable
level of comfort and freedom indefinitely
9.
10.
11. Population Change
Population change =
(births + immigration) - (deaths + emigration)
Immigration – people enter country
Emigration – people leave country
12. World Populations
2009: Top 3 countries
1.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)
13. Population Change
Fertility rate – average number of
children a woman has.
Fertility Rates in 2009:
1.6 in developed countries
6.5 in developing countries
14. Population Change
Why has the fertility rate in the US decreased, but
population has increased? Give me specific
reasons.
15. 77 years
Life 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
1.2
5.8
Stepped Art
Fig. 6-5, p. 99
