Population Dynamics and Global Trends in the 21st Century
Reliability of Demographic Data
Data reliability varies across countries and requires correction and updates. Factors influencing reliability include census completeness (e.g., conflicts in Cambodia and Afghanistan), statistical service quality (e.g., Bhutan), and data update methods (e.g., Iceland). A 1% error margin is generally acceptable. Developed countries with high literacy rates and democratic systems tend to have more reliable data.
Demographic Transition Model
This model describes population changes over time based on birth and death rates:
- High Stationary Phase: High birth and death rates with fluctuations due to famine, disease, and war.
- Early Expanding Phase: High birth rates and declining death rates due to improved diet, leading to population growth.
- Late Expanding Phase: Declining birth rates and stabilizing death rates, slowing population growth.
- Low Stationary Phase: Low birth and death rates with minimal population growth.
Population Dynamics
Population dynamics refers to growth or decline based on:
- Birth Rate: Live births per year.
- Mortality Rate: Deaths per year (calculated per thousand).
- Vegetative Growth: Birth rate minus mortality rate.
- Migration Growth: Immigration minus emigration.
- Total Growth: Vegetative growth plus migration growth.
Aging Population
Globally, the population over 65 is increasing. Key metrics include:
- Aging Rate: Percentage of people 65+.
- Population Aging Rate: Ratio of older people (65+) to young people (0-14).
Causes of Aging
- Reduced fertility (fewer young people).
- Decreased mortality (increased life expectancy).
- Migration (young adults moving for work).
Consequences of Aging
- Changing generational relationships.
- Increased public spending on social protection.
- Impact on productivity, investment, and consumption.
- Job creation in elder care.
- Changes in voter behavior.
- Increased loneliness and poverty among some elderly.
Fertility and Culture
Fertility is a clearer measure of demographic growth than population size. Key concepts include:
- Gross Reproduction Rate: Ratio of children born to women in one generation to the number of women in that generation.
- Net Reproduction Rate: Gross reproduction rate adjusted for female mortality.
- Synthetic Index of Fertility (ISF): Average number of children per woman, assuming constant fertility.
Factors Influencing Fertility
- Economy: Agrarian societies tend to have higher fertility rates.
- Culture: Family size preferences, religion, women’s decision-making power.
- Biological factors: Age, duration of marriage.
- Social factors: Forms of union, religion, child mortality, economic conditions.
Demographic Policies
These are policies implemented by states to influence population variables:
- Promoting or discouraging fertility.
- Controlling birth rates, mortality, migration, and family structures.
- Social development measures, such as access to contraceptives and education.
- Incorporating women into the workforce.
Population Pressure on the Environment
Population growth impacts the environment through:
- Increased demand for non-agricultural land.
- Depletion of finite resources (e.g., oil, water).
- Deforestation and ecosystem destruction.
- Increased greenhouse gas emissions.
Two Perspectives on Population Limits
- Malthusianism: Population growth will outstrip food production, leading to poverty.
- Neo-Malthusianism: Population growth hinders development in less developed countries.
- Populationism/Marxism: Larger populations stimulate economic development by creating demand and labor.
Population Projections for the 21st Century
Projections consider factors like birth rate, mortality, fertility, aging, life expectancy, and migration. Fertility is declining in less developed countries and increasing in developed countries.