1. 1 Chapter 21 Population and The Environment

2. 2 Demography: the study of population Demography ( 人口學 ): the scientific study of population. Sociologists are interested in various elements of population: such as fertility, mortality, and migration. A census ( 普查 ) is an enumeration or counting of a population. The constitution of the US requires that a census be held every 10 years to determine congressional representation.

3. 3 This periodic investigation is supplemented by vital statistics ; these records of births, deaths, marriages and divorces are gathered through a registration system maintained by governmental units. Birth-rate is the number of live births per 1,000 population in a given year. (total fertility rate) Death rate is the number of deaths per 1,000 population in a given year. (infant mortality rate)

4. 4 Life expectancy : the median number of years a person can be expected to live under current mortality conditions. Growth rate : the difference between births and deaths, plus the difference between immigrants (those who enter a country to establish permanent residence) and emigrants (those who leave a country permanently) per 1,000 population.

5. 5

6. 6

7. 7 World Population Patterns Demographic transition: is the change from high birth rates and death rates to relatively low birth rates and death rates. A three-stage process: 1. Pre-transition stage 2. Transition stage 3. Post-transition state A population pyramid ( 人口金字塔 ) : a special type of bar chart that distributes the population by gender and age. It is generally used to illustrate the population structure of a society. Zero Population Growth (ZPG): is the state of a population in which the number of births plus immigrants equals the number of deaths plus emigrants.

8. 8

9. 9 The Environment Air Pollution Water Pollution Contamination of Land Kyoto Protocol ( 1997 ) : more than 160 nations gathered for resolving the issue of climate change (greenhouse effect). Environmental justice : a legal strategy based on claims that racial minorities are subjected disproportionately to environmental hazards.

10. 10