some topics discussed population growth limits to growth human demography demographic transition...
Post on 20-Dec-2015
218 views
TRANSCRIPT
Some Topics Discussed
• Population growth
• Limits to growth
• Human demography
• Demographic transition
• Family planning and fertility control
• The future of human populations
ESC110 Chapter 4. Human Populations
Population Growth
World population now over ?? billion
Population = Pollution??
• World pop:World pop: – 2003 = 6,271,470,983– 2004 = 6,345,338,406– 2005 = 6,413,322,261 At 9AM Jan 18
• US pop:US pop:– 2003 = 290,131,722– 2004 = 292,484,293– 2005 = 295,279,623 At 9AM Jan 18
1 birth every 8 secs1 death every 13 secs1 intnl migrant (net) every 26 secs1 NET person every 12 secs
http://www.census.gov/main/www/popclock.html
Current Birth and Death Rates
• Every second: 4 or 5 children are born, while 2 other people die
• Net gain: 2.5 humans added to the world population every second
• 78 million added every year
Effect of Birth Rate and Death Rate on Population Size
Human Population Levels Throughout History
Population Growth
Africa
Asia & Oceania
N Amer
Europe
Latin Am & Carib
World Resources 1998-99
Growth to a Stable PopulationGrowth to a Stable Population
Overshoots and Diebacks
Basic Causes of
Environmental Problems
(McKinney & Schoch)
P x A x TP x A x TEnvironmental Environmental Impact =Impact =
P = population densityA = affluenceT = technology
P = number of peopleA = affluence or average resource-use per personT = technology or the beneficial & harmful environmental effects of the
technologies used to provide & consume each unit of resource
Projected Population Growth
Africa
Asia & Oceania
N Amer
Europe
Latin Am & Carib
Table 4.3
Stabilization ratio = crude birth rate/crude death rate
Africa
Dev’g
S&C Amer
Asia
Dev’d
Limits to Growth
Varying Perspectives • Overpopulation causes resource depletion and
environmental degradation• Human ingenuity and technology will allow us
to overcome any problems - more people may be beneficial
• Resources are sufficient to meet everyone's needs - shortages are the result of greed, waste, and oppression
Decisions on how many children to have are influenced by many factors, including culture, religion, politics, need for old-age security, and immediate family finances.
Biosphere 2
Human Demography
• Demography - vital statistics about people, such as births and deaths
Two demographic worlds– Less-developed countries represent 80%
of the world population, but more than 90% of projected growth
– Richer countries tend to have negative growth rates
By 2050, India will probably be the world’s most populous country.
World Population Density
Fertility and Birth Rates• Fecundity - physical ability to reproduce
• Fertility - the actual production of offspring
• Crude birth rate - number of births per year per thousand people
• Total fertility rate - number of children born to an average woman during her reproductive life
• Zero population growth (ZPG) – occurs when
births + immigration = deaths + emigration
Regional Declines in Total Fertility Rates
As incomes rise, so does life expectancy.
Population Growth -Opposing Factors
Pronatalist pressures• Factors that increase people’s desires to have
children (eg, enjoy family, help earnings, high death rate, help when older, males valued, male pride, etc)
Birth reduction pressures• Factors that tend to reduce fertility (eg, educated
women & careers, higher family earnings, etc)
Demographic Transition
• Optimistic view - world population will stabilize during this century
• Pessimistic view - poorer countries of the world are caught in a "demographic trap" - helping poor countries will only further threaten the earth's resources
• Social justice view - overpopulation due to a lack of justice, not resources
Infant Mortality and Women's Rights
Birth Control
Methods
Family Planning
The Future of Human Populations
U.N. Projections
Summary:
• Population Doubling Times• Role of Technology • Two Demographic Worlds• Fertility and Birth Rates• Mortality and Death Rates• Population Growth Factors• Demographic Transition• Future of Population Growth