ch 9.2 changing population trends. the demographic transition describes how populations can change...

CH 9.2

Changing Population Trends

The Demographic Transition

Describes how populations can change as countries develop.

Industrial development causes economic and social progress that

affects population growth.

Phase 1 (pre-industrial):* BR & DR both at high levels.* Population size stable.* Most of world was in this stage prior to ag & ind revolutions…

Phase 2 (transitional):* Population “explosion” occurs.* DR declines as hygiene, nutrition education improve.* BR remains high.* Doubling time short.

Phase 3 (transitional):* Population growth slows as BR decreases.* Population size stabilizes as BR & DR get closer.* Population much larger than before the transition.

Phase 4 (post-industrial):* BR drops below replacement level.* Population size begins to decrease.* Takes from 1 to 3 generations for phase 4 to be reached.

Women & Fertility• Increasing education & economic independence are

important factors in decline of birth rates.• In demographic transition phase 2, lower death

rates are due to better-educated mothers.– Better survival rates(no need to have 4 babies so 2

survive past childhood).– Women learn “family planning” techniques.– Women are able to contribute more to family’s

prosperity because less time & energy are spent on bearing/caring for children.

– Countries wanting to reduce BR have placed a priority on the education of women!

…women controlthe breeding inmost species…

Women & Fertility

• Large families may be good if kids work or take care of older relatives…or if it’s 1824…

• …but as countries modernize, both parents work - $ spent on child care make kids a financial burden rather than an asset.– Current TFR in developed countries: 1.6 children

per woman…– Current TFR in developing countries: 3.1 children

per woman!

Changing Population Trends• Countries that have “phased “ through the

demographic transition have large, stable populations and long life expectancies…

• ..but on their way, their rapid population growth (phase 2) has created environmental problems as their infrastructure becomes overwhelmed.– suburban sprawl…overcrowded schools…polluted

rivers…barren land…inadequate housing

Ciudad Juarez

Anywhere, CA

Problems of Rapid Growth• A rapidly growing population can use up

resources faster than the local environment can renew them.

• Vegetation…water…land…

Fuelwood Shortage• …in poor countries, wood is primary fuel

source (cooking/heat)…• Deadwood cannot supply need for rapidly

growing population…living trees go down! Deforestation results.

• Water supplies sometimes must boiled for sterilization against waterborne pathogens…without enough fuelwood, bad water can result in disease & malnutrition.

Unsafe Water• Poorer countries may use the same water source for

drinking, bathing washing clothes, and sewage disposal…

• Without the proper infrastructure (separation of sewer lines & fresh water lines) local water supplies can become breeding grounds for organisms that cause disease:– Dysentery– Cholera– Typhoid

Land

• Competition for available land: agriculture…housing…natural habitats

• Arable land can be reduces by suburban sprawl…urbanization leads to traffic jams, inadequate infrastructure, pollution…housing for extra humans leads to high cost and reduces the area originally inhabited by the wild species.

Demographic Diversity• Not all countries are progressing through the

phases of the demographic transition according to the model.– some have modern industries, but income

remains low…– some have stable, educated populations with little

industrialization…– some are “stuck” in the second phase, but cannot

make enough economic/educational advancement to reduce the BR.

Least Developed Countries

• Little/no development.• Both DR & BR increasing.• United Nations identifies these countries for

priority treatment (foreign aid & other perks) to help their population growth & environmental issues.

Managing Development & Economic Growth

• LD countries recognize that population growth prevents them from economic development.

• Countries have tried to reduce BR by:– Public advertising/education– Family planning programs– Economic incentives– Legal punishments

ICPD(International Conference on Population & Development)

• Provide access to family planning methods & reproductive health services.

• Reduce infant and child mortality rates.• Lower maternal mortality rate.• Provide access to primary education; focus on

secondary education access for girls & women.

The Future

• Human population is more than 7 billion and still increasing.

• The world’s population growth rate peaked @ 1990…

• Fertility rates in both developed/less developed countries are also declining…

• If this trend continues, world population growth would eventually stop.

Population Growth in the three most populous countries, 1950-2050

Japan

Madagascar

Japan• Pop. 127.77 million• Population growth

rate = -0.088%• Total fertility rate =

1.23• Arable land = 11.64%

Madagascar• Pop. 19 million

• Population growth rate = 3.008%

• Total fertility rate = 5.24

• Arable land = 5.03%

Japan• GN income per capita is

$28,450• 2nd wealthiest country in

the world• 99% of the country is

literate• Life expectancy = 82.02

years• People living with

HIV/AIDS: 0.009%

Madagascar•GN income per capita is $800

•Population below poverty line = 50%

•68.9% of the country is literate

•Life expectancy = 62.14 years

•People living with HIV/AIDS: 0.74%

…thanks for your kind attention!