The Human Population

and Its Impact

Chapter 6

Reasons for human population increase:

Movement into new habitats and climate zonesEarly and modern agriculture methodsControl of infectious diseases through

-Sanitation systems-Antibiotics-Vaccines

:

Death Rate

10,000 yrs ago- 5 million1930- 2 billion1975 – 4 billion2011 – 7 billion

2050 – 9.5 billion

UN World Population Projections by 2050

World population is

growing exponentially at a rate of

1.21%

2.0 children

1.5 children

2.5 children

The prospect of

stabilization in the near future is nil.

We are moving from a J-Curve to an S-curve

What does a 1.21% growth rate mean?

• There were about 83 million people added to the earth in 2010

• Which is about 227,000 people every day• Which is 2 more people every time your

heart beats

Population growth in developing countries is increasing 15 times faster than developed

countries

By 2050, 97% of growth will be in developing countries

Should the optimum sustainable population be based on cultural carrying capacity?

Optimum level that allows people to live in reasonable comfort and freedom and still have

sustainability

How Long Can the Human Population Keep Growing?

• Thomas Malthus and population growth: 1798 (Populations increase exponentially , food supply increases linearly. Wrong!! Actually-food-exponentially due to genetic and technological advances)

• Humans have altered 83% of the earth’s land surface

• Can the human population grow indefinitely?

What is really the problem?

• Overpopulation? This is degrading our planet. (82% of population is in less developed nations)

• Overconsumption? Americans ecological footprints are 4.5X larger than the average Chinese and 9.5 times larger than the average Indian

• Technology? These advances have helped eliminate environmental resistances

• How do we alter nature?

Current and projected population sizes by region

The World’s 10 Most Populous Countries in 2008

Resources depletion and degradation

The Human Population Can Grow, Decline, or Remain

Fairly Stable• Population change

– Births: fertility– Deaths: mortality– Migration

• Population change =

(births + immigration) – (deaths + emigration)

• Crude birth rate=# of live births per 1000 people in a population

• Crude death rate=# of deaths per 1000 people in a population

Women Having Fewer Babies but Not Few Enough to Stabilize the

World’s Population

• Fertility rate- # of children born to a woman during her lifetime–Replacement-level fertility

rate- avg. # of kids that a couple must bear to replace themselves.

– 2.1 developed-2.5 in developing Total fertility rate (TFR)- avg. # of kids born to a woman during reproductive years.

TFR in 2010:

1.7 per woman in developed

countries

2.7 per woman in developing

countries

• In 2010, TFR in developing countries dropped from 6.2 to 2.7 and in developed countries, from 2.8 to 1.7

• In China, the TFR dropped from 5.7 to 1.5 (from 1972-2010)

Birth Rates in the U.S. from 1910 to 2008baby boom TFR= 3.7

2010 TFR= 2.1

Some Major Changes That Took Place in the U.S. between 1900 and 2000

• Children as part of the labor force

• Cost of raising and educating children

Fact: : It costs to raise a child in the US from birth to 18.

• Availability of private and public pension

• Urbanization

• Educational and employment opportunities for women-TFR is low as education

Several Factors Affect Birth Rates and Fertility Rates

$220,000

Several Factors Affect Birth Rates and Fertility Rates

• Average age at marriage (the older they are when they marry, the fewer children they usually have)

• Religious beliefs, traditions and cultural norms

Reducing Births PROS• better than raising death rate

• we already fail to provide basic necessities for one-fifth of the world

• over pop. Is the main reason for environmental degradation and resource over consumption

• technology is the key to economic power, not more people

• freedom to reproduce should only apply if it does not reduce the quality of other peoples lives

CONS*people live longer*some people believe that the world can support

millions more*people are our most valuable resource

• Infant mortality rate

• Average age of a woman at birth of first child

• Availability of legal abortions

• Availability of reliable birth control methods

• Religious beliefs, traditions, and cultural norms

Several Factors Affect Death Rates

Population increase is

due to decline in

crude death rate

Migration Affects an Area’s Population Size

Why migrate???

• Economic improvement

• Religious freedom

• Political freedom

• Wars• Environmental refugees-40

million in 2008, water and food shortage, drought

Several Factors Affect Death Rates

• Life expectancy- globally, increased from 47 to Life expectancy- globally, increased from 47 to 69 years from 1955-2010. by 2050…74 years69 years from 1955-2010. by 2050…74 years

• Japan has longest life expectancy of 83 and US Japan has longest life expectancy of 83 and US is 78 (50is 78 (50thth of all nations) of all nations)

• Infant mortality rate- reflects country’s level of Infant mortality rate- reflects country’s level of nutrition and health carenutrition and health care

• Why are people living longer and fewer infants dying?Why are people living longer and fewer infants dying?– Increased food supply and distributionIncreased food supply and distribution– Better nutritionBetter nutrition– Medical advancesMedical advances– Improved sanitationImproved sanitation

• U.S. infant mortality rate high due to

–Inadequate health care for poor women during pregnancy and their infants

–Drug addiction among pregnant women

–High birth rate among teenagers

Legal Immigration to the U.S. between 1820 and 2003

• Immigration Reform and Control Act of 1986: granted legal status to illegal immigrants if they showed they lived in the country several years.

• 36% of US growth is due to legal/illegal immigration

• Many Americans believe all immigration should be reduced.

• Opposition-• It would diminish the historical role of the US

being a place of opportunity for the poor and oppressed

• Take away cultural diversity• Most immigrants pay taxes, start new

businesses and create jobs• Take menial and low paying jobs• Proponents-• Allow immigrants if they can support

themselves• By lowering immigration, the US could stabilize

its population and reduce its ecological footprint

Populations Made Up Mostly of Young People Can Grow Rapidly

• Age structure categories

–Pre-reproductive ages (0-14)

–Reproductive ages (15-44)

–Post-reproductive ages (45-over)Males vs. females

Generalized Population Age Structure Diagrams

Nearly 27% of people on planet were under 15 in 2010

Population Structure

by Age and Sex in

Developing and

Developed Countries

We Can Use Age-Structure Information to Make Population and Economic Projections

• Baby boomers

• Job market when they retire-job shortage

The Fastest Growing Age Group Is…The Fastest Growing Age Group Is…

SENIORS!SENIORS!• The global populations of seniors is projected to triple by 2050 The global populations of seniors is projected to triple by 2050

in which 1 of every 6 people will be 65 or older.in which 1 of every 6 people will be 65 or older.• This graying of the population is due to declining birth rates This graying of the population is due to declining birth rates

and longer life expectancies due to medical advancementsand longer life expectancies due to medical advancements.

Populations Made Up of Mostly Older People Can

Decline Rapidly

• Slow decline– Manageable

• Rapid decline-Japan, Russia, Germany, Hungary, Greece, Italy– Severe economic problems (less in work force,

fewer children to care for grandparents, more spent on medical care, pension funds, and shortages of health-care workers

Fig. 11.20, p. 249

194541.9 workers

40

30

20

10

0

195016.5

20751.9

1945 2000 2050 2075

Nu

mb

er o

f w

ork

ers

sup

po

rtin

gea

ch S

oci

al S

ecu

rity

ben

efic

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27 million killed by 2009

Many young adults die: loss of most productive workers

Sharp drop in life expectancy

International community called upon to– Reduce the spread of HIV through

education and health care– Financial assistance and volunteers to

provide education, healthcare, teachers, social workers

Populations Can Decline from a Rising Death Rate: The AIDS

Tragedy

Slowing the Human Population Growth

• Demographic Transition: As countries become industrialized

–Death rate declines

–Then birth rate declines

–4 majors stages…

Four Stages of the Demographic Transition

• US is in the early phase of stage 4 • Most of the less developed countries will make

a demographic transition over the next few decades due to technology and family planning

• Some fear these countries will stay in stage 2 due to extreme poverty, and rapid population growth. Many lack basic services such as food, health care and education. Countries are in civil war, and are training grounds for terrorist groups

• Somalia- 3% population growth, TFR=6.5 and 45% of population under 15.

• Haiti- foreign debt, lack of skilled workers, large number of people in poverty, and the 7.0 earthquake in Jan 2010

Planning for Babies Works

• Family Planning– Responsible for a 55% drop in TFRs– In developing countries– Expansion of program

• Include teenagers, sexually active unmarried women, and men

• Slow and stabilize population growth– Invest in family planning– Reduce poverty– Elevate the social and economic status

of women

• Bangladesh- TFR dropped from 6.0 in 1960 to 2.7 in 2010.

• Family planning and economic development are responsible for the drop.

• Thailand’s TFR dropped from 6.4 to 1.8

• The best way to slow and stabilize population growth are through

1. promoting economic development

2. elevating the social and economic status of women

3. Encouraging family planning

Empowering Women Can Slow Population

Growth• Education-fewer children

• Paying jobs

• Human rights without suppression

• “For poor women the only holiday is when you are asleep”

Women account for 2/3 of all

hours worked, but only get 10%

of world's income

Fig. 11.28, p. 256

4:45 A.M.Wake,wash, andeat

5:00 A.M.-5:30 A.M.Walk tofields

3:00 P.M.-4:00 P.M.Collectfirewood

4:00 P.M.-5:30 P.M.Pound andgrind corn

5:30 P.M.-3:00 P.M.Work infields

5:30 P.M.-6:30 P.M.Collectwater

6:30 P.M.-8:30 P.M.Cook forfamily andeat

8:30 P.M.-9:30 P.M.Washdishesand children

9:30 P.M.Go to bed

Women• Make up 70% of the world’s poor• 64% are illiterate (and 5-7 children)• 60-80% of work associated with

growing food, gathering wood and hauling wood and water

• In most societies, they have fewer rights and educational and economic opportunities

• (Sharbat Gula 1985 and 2002)• (Afghanistan refugee who crossed

over into Pakistan)

Slowing growth in India• 1952- the first national family planning

program began• 2nd largest population today, but projected

to be the largest by 2015• 32% of its population is under 15• 4th largest economy, growing middle class• Faces poverty, malnutrition and

environmental problems• ¼ of urban population lives in slums• 2/3 of population lives in rural areas• Nearly ½ are unemployed or

underemployed• ¾ live on less than $2.25 a day

• Most poor couples believe they need several children to work and care for them in old age

• Cultural preference for male children• Only 48% use some form of birth control• 17% of world’s population, 2.3% of land

and 2% of forests• Soil erosion and overgrazing of ½ of

croplands• 2/3 water is polluted• Sanitation often inadequate• Economic growth= larger ecologic

footprint but possible a slower population growth

What does it mean to grow exponentially?

• Youtube. The most important video you’ll ever see

Population Calculations

Global population

growth rate = CBR-CDRCBR-CDR

1010

If there were 20 people born per 1,000 people and 8 deaths per 1,000, the global population growth rate would be 1.2% 20-8

10

In 2011, the population growth rate of the ….

world was 1.09%

Zimbabwe = 4.3%

Japan = -0.1%

US = 0.9%

China= 0.5%

India = 1.3%

• To calculate the population growth rate for a single nation, we take immigration and emigration into account.

• Nat. pop = (CBR + immigr) – (CDR+ emigr)

growth rate 10

Fig. 11.3, p. 240

<1%

1-1.9%

2-2.9%

3+%

Data notavailable

Annual worldpopulation growth

Population Growth Rate

• If we know the growth rate of a population and assume that growth rate is constant, we can calculate the number of years it takes for a population to double. Doubling Time

• Rule-of-70 - way to calculate the approximate number of years it takes for the level of a population growing at a constant rate to double.

• States that the approximate number of years n for a variable growing at the constant growth rate of r percent, to double is:

n = 70/r

For example, a city with an annual population growth rate of 5% will double its population in approximately 14 years. 70 =14

5 If the growth rate were 7%, it would double its population in approximately ? years.

10

• Remember that a population growing at 2 percent per year, regardless of the size

will double in 35 years. Whether the population is 500,000 or 50,000, it will still

double in the same amount of time.

• It is almost certain that the Earth’s population will not double again. Most demographers believe that the human

population will be somewhere between 8.1 billion and 9.6 billion in 2050 and stabilize

by 2100.

• New Zealand has a population of 4.3 million people, a TFR of 2.1 and a net migration rate of 2 per 1,000. How many people will New Zealand gain next year as a result of immigration? (assume the TFR and net migrations stays the same)

• Net migration = # of immigrants

rate # of people in pop

A TFR of 2.1 for a developed country suggests that the country is at replacement-level fertility and thus the population is stable.

• The migration rate suggest that• 2__ = __ x_ _

1000 4,300,000

So, X= 8,600 people/year

Since there is no growth due to biological replacement and a net migration of 8,600 people, the rate of increase is

8,600 people/year = 0.2%

4,300,000 people

How many years will it take the population to double at this rate?

• T= 70 T= 70 = 350 years

r 0.2/yr

• A metropolitan region of 100,000 people has 2,000 births, 500 deaths, 200 emigrants, and 100 immigrants over a 1 year period. Calculate its population growth rate.

• Net increase = 2,100• Net decrease= 700

• Total change in population= 1400• Total number in population = 100,000• = 0.014 = 1.4%

• In 2010, the population of Upper Fremont was 200,000 and growing at a rate of 2% each year.

• If the rate of population growth remains constant, calculate the population in 2045.

• Determine the doubling time of the population by dividing 70 by 2 to get 35 years. Since one 35-year period passes between 2010 and 2045, the population would have doubled once from 200,000 to 400,000.

• The population of Lower Fremont was 20,000 in 1968. In 2010 the population was 160,000. Assuming the growth is exponential, calculate the average annual percentage rate of population growth since 1968.

• 2010-1968 = 42 years• The population has doubled 3 times

since 1968. 20,000 → 40,000 → 80,000 → 160,000

• 42/3 = 14 years• T= 70/r and r= 70/t• 70/14 = 5%

• In 2010, the CBRin East Fremont was 25 and the CDR was 11. Calculate the percentage growth rate of East Fremont in 2010. If the population was 15,000 in 2010, and the population growth rate remains constant, when will the population reach 30,000?

__CBR-CDR__ 14 = 1.4%

10 10

70/1.4 = 50 years

50 years + 2010 = 2060

Population Density

• New York City has 8,175,113 people within 305 mi2.

• Calculate the density of the population in mi2 and km2. 1 km2 = 0.386 mi2

• 8,175,113 people = 26,804 people/ mi2

305 mi2

26,804 people x 0.386 mi2 = 10,346 people

1 mi2 1 km2 km2

The population of Atlanta is 420,003 and covers an area of 131 square miles.Calculate the density of the population inin mi2 and km2

420,003 people = 3206 people/ mi2

131 mi2

3206 people x 0.386 mi2

mi2 1 km

= 1238 people/km2

How many times more dense is NYC than ATL?

10,346 people/mi2 = 3.2 times

3,206 people/ mi2

• The tiny country of Monaco has the world's highest population density. With an area of 3/4 of a square mile and a total population of 32,000, Monaco has a density of almost 43,000 people per square mile.

• However, since Monaco and other microstates have very high densities due to their extremely small size, Bangladesh is often considered the most densely populated country, with more than 2,200 people per square mile.

States by density: New Jersey, Rhode Island, Massachusetts- density

States: California, Texas, New York by population

Cities: New York, LA, Chicago by population

““People are People are everywhere. everywhere. Some people Some people say there are say there are too many of too many of

us, but no one us, but no one wants to wants to leave.”leave.”

The End

If the world had 100 people…

• http://www.100people.org/statistics_detailed_statistics.php?section=statistics

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