1. Human Population Envi 201 Spring 2004

2. Key Concepts n Exponential Growth – Rule of 70 n Demographic transition n Age structure and population momentum n Causes of fertility decline n Links between fertility decisions and environment (Dasgupta article)

3. Exponential Growth n Quantity grows by the same relative amount (g) each year n P (next year) = P (this year) * (1+g) n At time t, P = P 0 x (1+g) t

4. Exponential Growth n Quantity grows by the same relative amount each year n Doubling time d is constant

5. Rule of 70: n Doubling time x growth rate = 70 n Examples: r, growth rate, % per year d, doubling time, years 107 170 235

6. World Population Growth

7. World Population Grew Slowly Through 1945…Then accelerated…Then slowed

11. Trends in Population Growth Worldwide Population Increase and Growth Rate, Five-Year Periods Millions Percent increase per year Source: United Nations, World Population Prospects: The 2002 Revision (medium scenario), 2003.

12. Growth Rates have Peaked…

13. Alaska Population: Average Annual Rates of Growth (due to births, deaths, and net migration)

14. The Demographic Transition n Stage I: high birthrates and death rates n Stage II: continued high birthrates, declining death rates n Stage III: falling birthrates and death rates, eventually stabilizing

17. Replacement Rate would be 2 children per woman

18. Population Momentum n Lots of young people n Although each woman may have total fertility = 2 children, n There are many more future mothers than current mothers

21. Native Age Structure Does Alaska have Population Momentum?

22. Replacement Rate would be 2 children per woman

24. Testing the Relationship: n Bangladesh fertility dropped from 7.0 to 3.8 between 1970 and 1998 n Bangladesh income per capita in 1998 is supposed to be $2200 in 1980$…. n Latest HDR says $1602 year 2000$ n Fertility has dropped faster than curve predicts