© 2010 Pearson Education Canada 6 Human Population PowerPoint ® Slides prepared by Thomas Pliske, Heidi Marcum, and Nicole Lantz.

© 2010 Pearson Education Canada

6Human Population

PowerPoint® Slides prepared by Thomas Pliske, Heidi Marcum, and Nicole Lantz

This lecture will help you understand:

• The scope of human population growth• The effect of population, affluence and

technology on the environment• Fundamentals of demography • The demographic transition• Factors that affect population growth• The HIV/AIDS pandemic

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Housekeeping items• I couldn’t find anything about ‘Black Earth’ corn.

• In addition to nitrogen, phosphorus plays an exceptionally important role in DNA and RNA.

• A reminder that I have passed out hard copies of the life-cycle analysis instructions (a copy of which is also on the web site). The instructions for the other three assignments – out of the four, you do two of your choice – are also up on the web site: the campus research project, the outreach to schools project, and the media analysis. The life cycle is due on March 16th (or earlier, if you so choose).

• A reminder that Ian Roberts from Marine Harvest Canada (the largest aquaculture company in Canada) will be speaking tonight from 7 to 8 in Building 356, Room 109.

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Case study: China’s one-child policy

In 1979, the government instituted a one-child policy, drastically decreasing the growth rate (now 0.6%)

Unintended consequences: • Killing female infants • Unbalanced sex ratio• Black-market trade in teenage girls

“As you improve health in a society, population growthgoes down. You know I thought it was…before I learnedabout it, I thought it was paradoxical.” – Bill Gates, Microsoft Corp.

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Human population: approaching 7 billion

• It would take 30 years, counting once each second, to reach 1 billion

• Populations continue to rise in most countries• Particularly in developing nations

• Although the rate of growth is slowing, we are still increasing in absolute numbers. Can anyone explain how this is possible?

For a look at exponential growth, see http://www.singularitysymposium.com/exponential-growth.html

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The human population is growing nearly as fast as ever

• It took all of human history to reach 1 billion• In 1930, 130 years later, we reached 2 billion, and

added the most recent billion in 12 years

FIGURE 6.26-6

Rates of growth vary with region• At today’s 2.1% annual growth rate, the

population will double in 33 years• If China’s rate had continued at 2.8%, it would

have had 2 billion people in 2004.

FIGURE 6.36-7

Perspectives on human population have changed over time

• Population growth results from technology, sanitation, food

• Death rates drop, but not birth rates• Some people say growth is no problem

• New resources will replace depleted ones• But, some resources (i.e., biodiversity) are

irreplaceable• Quality of life will suffer with unchecked growth

• Less food, space, wealth per person

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Perspectives on human population have changed over time

• 1700s – more children meant better support in old age (this is still the case in many societies) and more labour for factory work

• 1766: Thomas Malthus – growing population is eventually checked by limits on births or increases in deaths. This didn't happen -- why?

• 1968: Paul Ehrlich (of “Population Bomb” fame) – population is growing too fast and must be controlled

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Is population growth really a “problem” today?

• Sheldon Richman – humans find potential stuff and human intelligence turns it into resources

• Humankind will always be able to save itself with a “technological fix”

• Yet not all resources can be replaced or reinvented once they are depleted (e.g. extinct species, land)

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Some governments fear falling populations

• Policymakers believe growth increases economic, political, military strength

• They offer incentives for more children

• 60% of European nations think their birth rates are too low

• In non-European nations, only 8% feel their birth rates are too low

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Population growth affects the environment

• The IPAT model: I = P x A x T x S• Our total impact (I) on the environment results

from the interaction of population (P), affluence (A) and technology (T), with an added sensitivity (S) factor

• Population = individuals need space and resources• Affluence = greater per capita resource use• Technology = increased exploitation of resources• Sensitivity = how sensitive an area is to human

pressure

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Computer simulations predict the future• Status quo leads to

• Sudden food & population decrease

• Pollution increase

• Sustainability leads to• Food & population

stabilize • Pollution decrease

FIGURE 6.5

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Demography is the study of human population

Demographers study• Population size • Density and distribution• Age structure• Sex ratio • Birth, death,

immigration, and emigration rates

FIGURE 6.7

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Population size and density• Population size is only one factor• Highest population density is in temperate, subtropical,

and tropical climates

FIGURE 6.8

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Population distribution• Humans are unevenly distributed around the globe

• Unpopulated areas tend to be environmentally sensitive (high S value in the IPAT equation)

FIGURE 6.9

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Age structure affects future population dynamics

• Having many individuals in young age groups results in high reproduction and rapid population growth

FIGURE 6.10

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China’s reproductive policy

•Consider China’s reproductive policy.

•Do you think a government should be able to enforce strict penalties for citizens who fail to abide?•If you disagree with China’s policy, what alternatives can you suggest?•How will Canada deal with the challenges of an aging population?

weighing

the issues

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Sex ratios

• Naturally occurring sex ratios for humans slightly favour males (100 females born to 106 males)

• In China, 120 boys were reported for 100 girls

• Cultural gender preferences, combined with the government’s one-child policy, led to selective abortion of female fetuses

• Had the undesirable social consequences of many single Chinese men

• Teenage girls were kidnapped and sold as brides

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Population growth depends on various factors

• Whether a population grows, shrinks, or remains stable depends on:

• Rates of birth, death, and migration• Birth and immigration add individuals• Death and emigration remove individuals

• Technological advances led to dramatic decline in human death rates

• Widening the gap between birth rates and death rates resulting in population expansion

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Low growth does not mean fewer people

FIGURE 6.13

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Total fertility rate influences population growth

• Total fertility rate (TFR) = average number of children born per female member of a population during her lifetime

• Replacement fertility = the TFR that keeps the size of a population stable

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Factors affecting total fertility rate

• Increasing urbanization decreases TFR• Children go to school, and increase costs

• With social security, elderly parents need fewer children to support them

• Greater education allows women to enter the labor force, with less emphasis on child rearing

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Life expectancy is increasing

• Natural rate of population change = due to birth and death rates alone

• In countries with good sanitation, health care, and food, people live longer

• Life expectancy = average number of years that an individual is likely to continue to live

• Increased due to reduced rates of infant mortality

• Urbanization, industrialization, and personal wealth

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The demographic transition• Demographic transition = a model of economic

and cultural change to explain the declining death and birth rates in industrializing nations

• high birth and death rates change to low birth and death rates

• As mortality (particularly, infant mortality) decreases, there is less need for large families (i.e. “insurance births”)

• Parents invest in quality of life

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The demographic transition’s four stages

Population growth is seen as a temporary phenomenon

FIGURE 6.14

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Is the demographic transition universal?

• It has occurred in Europe, U.S., Canada, Japan, and other nations over the past 200-300 years

• But, it may or may not apply to all developing nations

• The transition could fail in cultures that • Place greater value on childbirth• Grant women fewer freedoms

For people to attain the material standard of living of NorthAmericans, we would need the natural resources of four and a half more Earths. So, even with fewer people....

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The status of women greatly affects population growth rates

• 2007: 54% of married women worldwide reported using modern contraception to plan / prevent pregnancy

• Social empowerment of women reduces unintended pregnancy

• Increasing female literacy is strongly associated with reduced birth rates

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Female literacy is associated with birth rates

FIGURE 6.156-29

Family planning reduces unintended pregnancy

Blue = family planning accessible

Red = family planning not accessible

FIGURE 6.16

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Population policies and family planning programs are working around the globe

• These policies lower population growth rates in all types of nations

• Programs for population control:• India – incentives for a “two-child norm”• Thailand – family planning education and increased

availability of contraceptives• 1994: U.N. platform for governments to offer universal

access to reproductive health care within 20 years.

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Abstaining from the real world?Funds for international family planning

•In the past, the U.S. government has withheld funds from the U.N. Population Fund because its programs provide education in family planning, HIV/AIDS prevention, and teen pregnancy prevention.

•What do you think of the U.S. decision?•What conditions, if any, should Canada place on the use of funds for international aid in the area of family planning?

weighing

the issues

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• Poorer societies have higher growth rates than wealthier societies

• Consistent with the demographic transition theory• They have higher fertility and growth rates, with

lower contraceptive use• 99% of the next billion people added will be born in

poor, less developed regions that are least able to support them

• Poverty often results in environmental degradation (e.g. soil degradation, hunting of large mammals)

Poverty is strongly correlated with population growth

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Consumption from affluence creates environmental impacts

Affluent societies have enormous resource consumption and waste production

People use resources from other areas, as well as from their own

Individuals’ ecological footprints are huge

The addition of 1 Canadian to the world has as much environmental impact as 6 Chinese, or 12 Indians or Ethiopians, or 40 Somalians.

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The wealth gap and population growth contribute to conflict• The richest 20% use

86% of the world’s resources

• Leaves 14% of the resources for 80% of the world’s people to share

FIGURE 6.19

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HIV/AIDS impacts African populations• 2006: 40 million infected worldwide, 27 million in sub-

Saharan Africa• Low rates of contraceptive use spread the disease• Also spreading in Caribbean, Southeast Asia, eastern Europe,

central Asia• 14 million children have

lost one or both parents

FIGURE 6.20 6-36

HIV/AIDS and population

What sorts of problems would you predict might occur in the surviving population after a major disease, such as AIDS, kills a high percentage of the population?

weighing

the issues

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Severe demographic changes have widespread repercussions

• Demographic fatigue = governments face overwhelming challenges related to population growth.

• With the added of stress of HIV/AIDS; governments are stretched beyond their capabilities

• Problems grow worse

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The U.N. has articulated sustainable development goals for humanity

• Millennium Development Goals = by 2015 achieve goals for sustainable development

• Does not include population control

• Earth does not hold enough resources to sustain 6.8 billion of us at the North American standard of living

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Conclusion• The human population is larger than at any time in the

past• However, the rate of growth has decreased because of:

• Demographics• Better rights for women

• How will the population stop rising?• demographic transitions• governmental intervention• disease • social conflict

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QUESTION: ReviewWhat has accounted for the majority of the world’s population growth in recent years?

a) Women are having more babies

b) Death rates have dropped due to technology, medicine, and food

c) More women are using contraceptives

d) Nothing, the population has dropped in recent years

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QUESTION: Review

According to the I = P x A x T formula, what would happen if China’s 1 billion people had a lifestyle like Canadians?

a) Their population would automatically drop

b) Their population would automatically increase

c) Their affluence and technology would increase

d) Their impact on the environment would even out

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QUESTION: Review

How have humans been able to raise the environment’s carrying capacity for our species?

a) Through technology

b) By eliminating limiting factors

c) Through increased consumption

d) Spending more money on non-essential resources

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QUESTION: Review

Areas that lack significant numbers of people, and have a low population density are…

a) No longer available

b) Best able to support higher densities of people

c) Sensitive areas least able to support high densities of people

d) Located around tropical and grassland areas

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QUESTION: ReviewDescribe the relationship between growth rates and population size.

a) Falling growth rates automatically mean a smaller population

b) Falling growth rates automatically mean a larger population

c) Falling growth rates means we no longer have a population problem

d) Falling growth rates does not mean a smaller population, but that rates of increase are slowing

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QUESTION: Weighing the Issues

Would you rather live in a country with a larger population or smaller population?

a) Small population, so there will be more resources for me

b) Small population, so there will be more resources for others, including wildlife

c) Large population, so I can find a date

d) Large population, because people are our biggest resource

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QUESTION: Interpreting Graphs and Data

a) High birth and death rates rise cause population increases

b) High birth and death rates, but population is stable

c) High birth rates with low death rates cause population to increase

d) Low birth and death rates cause the population to decrease

What happens during the “pre-industrial”stage of the demographictransition?

FIGURE 6.14

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QUESTION: Interpreting Graphs and Data

According to this age pyramid, Madagascar’s future population will be…?

a) Balancedb) Largerc) Much largerd) Smallere) Much smaller

FIGURE 6.10

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QUESTION: Interpreting Graphs and DataAccording to these graphs, which countries had access to family planning?

a) Iraq and Pakistanb) Malawi and Haitic) Malawi and Kenyad) Kenya and Bangladesh

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