5. Human population growth. This lecture will help you understand:. Human population growth Demography Affluence, technology, the status of women, and the environment Population control programs Demographic transition theory Consumption and the ecological footprint
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Human population growth
greater-than-exponential growth rate
human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS)
total fertility rate (TFR)
The world’s population now exceeds 6 billion people.
The UN marked this symbolically by declaring a child born in 1999 in war-torn Sarajevo as the six-billionth baby.
Some say NO:
People can find or manufacture additional resources to keep pace with population growth.
Nations become stronger as their populations grow.
Some say YES:
Not all resources can be replaced.
Even if they could, quality of life suffers.
Nations do not become stronger as their populations grow.Is population growth really a problem?
Demography is the study of human populations.
Human populations exhibit the same fundamental characteristics as do populations of all other organisms.
Nations vary from China’s 1.3 billion down to Pacific island nations of 100,000.
Shown are the 15 most populous countries, and selected others; 2002 data.
Demographers project population growth trends to estimate future population sizes.
Different fertility rate scenarios predict global population sizes in 2050 of 7.4 billion, 8.9 billion, or 10.6 billion.
All these projections assume fertility rates below today’s; at today’s rate, the population would reach 12.8 billion.
Humans are unevenly distributed, living at different densities from region to region.
Age structure can influence population growth rates.
Canada (left) has a much slower growing population than does Madagascar (right).
Demographers project that China’s population will become older over the next two decades.
China’s aging population will mean fewer working-age citizens to finance social services for retirees.
The United States’ “baby boom” is evident in age bracket 40–50. U.S. age structure will change as baby boomers grow older.
A population’s sex ratio can affect its growth rate.
Population growth depends on rates of birth, death, immigration, and emigration.
(birth rate + immigration rate)
– (death rate + emigration rate)
= population growth rate
Immigration and emigration play large roles today.
Refugees from the 1994 Rwandan genocide endured great hardship, and deforested large areas near refugee camps.
Change due to birth and death rates alone, excluding migration
Is often expressed in % per year
China’s rate has fallen with fertility rates. It now takes the population 4 times as long to double as it did 25 years ago.
The annual growth rate of the world population has declined since the 1960s.
(But the population size is still rising!)
Total fertility rate (TFR) = average number of children born per woman during her lifetime
Replacement fertility = the TFR that keeps population size stable
For humans, replacement fertility is about 2.1.
African nations have the highest TFRs.
European nations have the lowest TFRs.
Demographic transition = model of economic and cultural change to explain declining death rates, declining birth rates, and rising life expectancies in Western nations as they became industrialized
Proposed by F. Notestein in the 1940s-1950s
The demographic transition consists of several stages:
Pre-industrial stage: high death rates and high birth rates
Transitional stage: death rates fall due to rising food production and better medical care. Birth rates remain high, so population surges.
Industrial stage: birth rates fall, as women are employed and as children become less economically useful in an urban setting. Population growth rate declines.
Post-industrial stage: birth and death rates remain low and stable; society enjoys fruits of industrialization without threat of runaway population growth.
Female literacy and school enrollment are correlated with total fertility rate:
More-educated women have fewer children.
Family planning, health care, and reproductive education can lower TFRs.
A counselor advises African women on health care and reproductive rights.
Nations that invested in family planning (green) reduced TFRs more than similar nations that did not (red).
Bangladesh reduced TFR from 7.1 to 4.6 in 25 yr, and is at 3.3 today.
Family planning, education, and outreach were responsible.
From The Science behind the Stories
AIDS cases are increasing rapidly worldwide.
Infects 1 in 5 people in southern African nations
Infects 5 million new people each year
Kills babies born to infected mothers
Has orphaned 14 million children
98% of the next billion people born will live in developing nations.
Population growth can lead to environmental degradation.
Overpopulation in Africa’s Sahel region has led to overgrazing of semi-arid lands.
Poverty can lead to environmental degradation…
wealth and resource consumption can produce even more severe and far-reaching environmental impacts.
The cumulative amount of Earth’s surface area required to provide the raw materials a person or a population consumes and to dispose of or recycle the waste that is produced
Residents of some countries consume more resources—and thus use more land—than residents of others.
Shown are ecological footprints of an average citizen from various nations.
Residents of developed nations have larger houses, more possessions, and more money than residents of developing nations.
The richest 20% of the world’s people consumes 86% of its resources, and has >80 times the income of the poorest 20%.
Many governments of developing countries are experiencing “demographic fatigue,” unable to meet the social, economic, and environmental challenges imposed by rapid population growth.
This raises the question:
Will today’s developing countries successfully pass through the demographic transition?
Shows how Population, Affluence, and Technology interact to create Impact on our environment.
Further factors can be added to the original equation of Holdren and Ehrlich to make it more comprehensive.
“Access to reproductive health care, including family planning, is a basic human right.”
“Governments do not have an interest in further reducing fertility. Nor should they have the authority to do so.”
Using the I = P A T equation, what would happen if the population doubled?
a. Affluence and technology would decline.
b. The environment would become more sensitive.
c. The environmental impact would double.
d. Nothing, because Earth can compensate.
What has allowed us to increase Earth’s carrying capacity for our species?
d. All of the above
Which statement is FALSE?
a. The global population growth rate is decreasing.
b. The global population is increasing.
c. At a TFR of 2.4, a human population grows.
d. Populations with age distributions skewed toward young people grow more slowly.
Women who are more educated tend to… ?
a. Have higher TFRs.
b. Live in developing nations.
c. Have fewer children.
d. Contract HIV/AIDS.
Should the United States fund family planning efforts in other nations?
a. Yes, without reservation
b. Yes, in nations whose programs it approves
c. Only if it can influence the nations’ policies
d. Never under any circumstances
What happens during the “transitional stage” of the demographic transition?a. Birth rates rise; death rates drop; population increases
b. Birth rates drop; death rates drop; population decreases
c. Death rates drop; birth rates are stable; population increases
Do you believe that national governments should implement policies, subsidies, or other programs to reduce birth rates?
a. No, not at all
b. Yes, but only positive incentives for fewer children
c. Yes—penalties for too many children
d. Yes, both incentives and penalties