1. Overpopulation and Population Control
Miller, G. Tyler (2003) Environmental Science: working with the Earth. Ninth edition. (Chapter 11)

2. What Does Population Density Tell?
‘All too often, overpopulation is thought of simply as crowding: too many people in a given area, too high a population density.’
‘If brute density were the criterion (of overpopulation), one would have to conclude that “Africa is underpopulated”, because it has only 55 people per square mile, while Europe (excluding the USSR) has 261 and Japan 857.”

3. Distribution of Human Population
World
Africa

4. Effective Population Density
If we exclude the desert or impenetrable forest of Africa, the more inhabitable portion is just over ½ of Africa’s area.
Effective density = 117 per sq mile (≃ 1/5 of effective density in UK!)
Even by 2020, Africa’s effective density ⋍ that of France (266 per sq mile), yet few people would consider France is overpopulated.

5. Overpopulation Occurs When…
the long-term carrying capacity of an area is being degraded by its current human occupants.
(**population size of an area relative to the area’s carrying capacity)

6. Identifying Overpopulation
According to World Health Organization (WHO), at present:
1 billion people: living in poverty
10 million people: die each year from malnutrition, starvation, and diseases from drinking contaminated water
Premature deaths: 27,400 people per day
Natural resources: under increasing pressure (depleting)
Main characteristics of overpopulation in animals:
Mass suffering
A high rate of premature death
Deterioration of the environment
Are we overpopulated?

7. Ecological Footprints
Ecological footprint estimates the area of productive land required to
produce the resources used
give room for infrastructure
assimilate the wastes produced (eg carbon dioxide emitted from burning fossil fuels)
at a specified material standard of living.
We have different ecological footprints
 We have different impacts on the Earth
A useful tool to measure and monitor sustainability.

8. Global and Local Ecological Footprints
1997 Ecological Footprint of global population: 2.85; 30% larger than the Earth’s biological productive capacity  rapid depletion of resources
1997 Ecological Footprint of HK: 7.14 (ranked 13th out of 151 countries and regions);
If HK people continued to consume resources and emit carbon dioxide at the same rates
 would need 444 times the existing land area (or 170 times the total area including marine waters) to sustain ourselves!
If the whole world consumed resources and emitted carbon dioxide at rates similar to HK
 would need another two planets to support us!
** Stealing the Earth from our future generations!
(Data: Living Planet Report 2000, WWF)

9. Other Implications of Overpopulation
Wealth Gap  poverty in developing countries
Uneven distribution of food, medical care, education resources, family planning services

10. Environmental Impact of Population
Population size (P)
Affluence (A)
Technology (T)
No. of
People
No. of units
of resources used
per person
Environmental
degradation & pollution per unit of resource used
Environmental impact of population
(environmental impact done by the
technologies used to supply the
resources)
Impact (I)
I = PAT
How can we reduce the environmental impact (I)?

11. Population Control
UN Conference on Population and Development, Cairo 1994 (15,000 leaders and representatives from 179 countries):
By 2054: world population stabilized at 7.8 billion
By 2015: everyone on Earth should have
Access to family planning
Primary education for all children 6-11 yrs of age
Increased involvement of men in child-rearing and family planning

12. Population Projections
1950
1970
2010
2050
1990
2030 5 4 3 6 7 8 9 10 11
United Nations
High TFR (2.5)
Medium TFR (2.0)
Low TFR (1.6)*
POPULATION (billions)
Current worldwide
TFR = 2.8
YEAR
*Aim is TFR of 1.6
High
Medium
Low

13. Methods for Controlling Growth
A government can alter size and growth rate of its population by changing any of the 3 basic demographic variables:
Births
Deaths
Migrations
Most developed countries now have relatively low birth and death rates.
Most developing countries have relatively low death rates but high birth rates.

14. Crude Births and Crude Death Rates
Year
Rate per 1,000 people
Developed countries
Developing countries
Rates of Natural Increase

15. Controlling Migration
Only a few countries allow large annual immigration, e.g. Canada, Australia, USA.
Some migration is involuntary – involves refugees displaced by:
War
Natural disasters (earthquakes, flooding, drought)
Environmental degradation (desertification, deforestation, resources shortage).

16. Empowerment of Women
Women tend to have fewer and healthier children when:
They have access to education and paid jobs outside the home
They live in societies where they have rights

17. Controlling Birth Rates
Focus of efforts to control population growth: decreasing birth rates
Two general approaches:
1. Economic Development may reduce the number of children a couple desires if
They have increased access to education
They have more economic security
They do not need to consider children as old age security
2. Family Planning helps people regulate the number of children they want to have and when

18. 1. Economic Development
Demographers studied western European countries that industrialized in the 19th Century.
Developed hypothesis of population change – demographic transition.
As countries become industrialized, first their death rates then their birth rates decline.
Encourage developing countries make the transition
 Help to reduce population growth

19. The Demographic Transition
Time 40 30 20 10
Birth rate
Death rate
Stage 1
Pre-industrial
Stage 2
Transitional
Stage 3
Industrial
Stage 4
Post-industrial
Rates (per 1000 per year)
Low
Growth Rates
Increasing Growth Rates
Decreasing
ZPG
Negative

20. The Demographic Transition
Four distinct stages:
Pre-industrial stage: harsh living conditions
High birth rates to counteract high infant mortalities
Little population growth
Transitional stage: industrialization begins
Death rates drop
Birth rates remain high
 Rapid population growth
Industrial stage: industrialization widespread
Birth rate drops
 Growth rate slows
Post-industrial stage: relative high living standard
Birth rates falls further, equaling death rate  ZPG;
Then birth rate < death rate  Population decreases

21. Developed and Developing Countries
Population Reference Bureau
Rate (per 1000 of population)
In postindustrial stage
In transitional stage 50 40 30 20 10
1970
1945
1920
1895
Death Rate
Birth Rate
Mexico
1750
1800
1850
1900
1950
Death Rate
Birth Rate
Sweden 40 30 20 10
Most developing countries: transitional phase.
Most developed countries: industrial stage, a few in post-industrial stage.

22. Various forms of contraception
2. Family Planning
Such programs provide educational and clinical services to help couples (how many children to have and when to have them), including:
Birth control – contraception or sterilization
Birth spacing
Health care for pregnant
women and infants
Various forms of contraception
China has been more successful at slowing population growth than India.

23. Yet, compulsory birth control policy: Controversial!
Case Study: China
1960s: Chinese government realized that without strict population control  mass starvation
1970s: efforts made to slow population growth
1979: one-child per family policy introduced
Couples: urged to get married late and have only 1 child
Married couples: free access to free sterilization, contraceptives, and abortion
Married couples who pledge to have 1 child: extra food, larger pensions, better housing, free medical care, salary bonuses, free school tuition for the child, etc (couples will be deprived of all benefits if they break the pledge)
1972 to 2001: TFR 5.7 to 1.8 children per woman
Yet, compulsory birth control policy: Controversial!

24. China’s Future Population
China has ~1/5 of world’s population
11 million people added each year, but only has
7% of world’s fresh water
3% of world’s forests
2% of world’s soils
Greying population – who will take care of the elderly?
Gender imbalance
117 boys: 100 girls in 2000
 Men will outnumber women in China by 60 million!