CH08-1 Population Measuring its growth & impact 20Envi ronmental%20Science/course%20files/multimedia/l esson35/animations/3b_Cultural_Carrying_Capacity.html.

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Population

Measuring its growth & impact

http://www.montereyinstitute.org/courses/AP%20Environmental%20Science/course%20files/multimedia/lesson35/animations/3b_Cultural_Carrying_Capacity.html

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The Growing Human Population

The human population has grown slowly for most of human history.

The rapid increase in population size is a relatively recent phenomenon.

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Human Population through Time

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Why Has the Human Population Grown So Large?

The human population has skyrocketed in the last 200 years.

Global decline of death rates without a decrease in birth rates. result of increases in food supply and better medicine and sanitation.

Infant mortality in the U.S.

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The Ecology of Expanding the Earth’s Carrying Capacity

Technological advances lower environmental

resistance promote population

growth.

Technology increases the carrying capacity for humans.

Technology decreases the prospects of other species and may cause adverse effects in human populations as well.

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What Is the Earth’s Carrying Capacity for Humans?

Determining the Earth’s carrying capacity for humans is a task fraught with difficulty. Some people think we

have not reached the carrying capacity.

Others believe that the human population already exceeds the Earth’s long-term carrying capacity.

Economics, Diet, & Culture

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Too Many People, Reproducing Too Quickly

Population is at the root of virtually all environmental problems pollution resource depletion social and economic problems environmental problems and solutions

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Too Many People, Reproducing Too Quickly

The massive size of the human population causes environmental problems evident in urban and rural areas. shortages of resources environmental deterioration a host of possible social problems

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Reproducing Too Quickly

Social, economic, and environmental problems of cities and rural areas are aggravated by rapid population growth.

The large size of many populations makes it difficult for governments to keep up with current demands.

Continued rapid growth makes it nearly impossible to improve conditions and create a sustainable human presence.

CH08-10Fig. 8-4 Graph of global population

growth

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Understanding Populations and Population Growth

Measuring Population Growth – Growth Rates and Death Rates Global population growth is determined by

subtracting the crude death rate from the crude birth rate.

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Doubling Time

the time it takes a population to double in size. determined by dividing 70 by the growth rate.small growth rates can result in rapid doubling.Growth rates

developed countries are relatively low.

less developed nations, generally much higher.

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The Total Fertility Rate and Replacement-Level Fertility

Total fertility rate is the average number of children women are expected to have during their reproductive age span.

Replacement-level fertility occurs when couples produce exactly the number of children needed to replace themselves.

Zero population growth occurs when the death rate equals the birth rate and when the net migration is zero.

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Migration

The growth of a town, city, state, or region is determined by two factors:Growth rate (natural increase)Migration (the movement of people into

and out of the population)

Immigration, the movement of people from one region of a country to another, affects regional population growth.

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Population Histograms

Graphs of populations various age groups males and females provide useful information for planners.

A countries histogram may be Expansive Constrictive Stationary

Global population Expansive due to continued growth in the less

developed nations

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Exponential Growth

Human populations are growing exponentially.

Globally, the human population has “rounded the bend” of the exponential growth curve.

This means that even small percentage increases result in huge numbers of new world residents.

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Exponential Growth

Exponential growth is cause for great concern.

As our population increases, so do:

our demand for resources our waste production our environmental

damage

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The Future of World Population: Some Projections and Concerns

Predicting the future size of the world’s population is difficult.

It is likely that the population of the world will increase dramatically before it stabilizes.

This increase could bring about massive changes in the environment.

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Population Growth in the Less Developed World: Why Should We Worry?

Impacts: Social -- disease, war, equitable distribution of

resources Economic -- education, available resources,

sustainable development Environmental -- overuse of resources and pollution

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A World of Possibilities

The human population cannot grow indefinitely. Transition Options

Smooth transition to a stable population size. Periodic crashes that will eliminate large numbers

of people. Overshooting the carrying capacity

destroy their ability to support people populations may fall to much lower levels.

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Fig. 8-10 Patterns of population growth

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http://www.montereyinstitute.org/courses/AP%20Environmental%20Science/course%20files/multimedia/lesson36/animations/3b_Population_Crash.html

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A Bit of Good News…

⬈ Population growth is slowing⬈ 1960 – Average family had 5 kids⬈ 2005 – Average family has 3 kids⬈ Sustainable – Average family has 2 kids (ZPG)

⬈ 1994 – U.N. International Conference on Population & Development (ICPD) in Cairo, Egypt⬈ Multi-Faceted Approach

⬈ Equity for Women – Education, Social, Political, Economic⬈ Economic Equity between rich and poor

⬈ 2015 – affordable family planning and reproductive health care for all⬈ Sustainable Economic Development throughout the world