Post on 19-Jan-2016
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AP Environmental Science
Mr. Grant
Lesson 6
Our World At Seven Billion
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Objectives:
• Define the term IPAT Model.
• Perceive the scope of human population growth.
• Assess divergent views on population growth.
• Evaluate how human population, affluence, and technology affect the environment.
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IPAT Model: A formula that represents how humans’ total impact (I) on the environment results from the interaction among three factors: population (P), affluence (A), and technology (T).
I = P x A x T
Define the term IPAT Model.
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Perceive the scope of human population growth.
It would take 30 years, counting once each second, to count to a billion! It would take 210 years to count to 7 billion!
Populations continue to rise in most countries, particularly in poverty-stricken developing nationsGrowth in poorer
nations leads to stresses on society, the environment,
and people’s well-being
China’s stringent policies have greatly slowed growth there, but other countries may wish to slow
their growth without the measures used
by China
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India’s growth continues and if not changed will surpass China’s population
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Exponential population growth…
It took until 1800 to reach 1 billion
130 years later) we reached 2 billion
We added the most recent billion in 12
years
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Rates of growth vary from region to region.
Some countries are over 3%, while other country’s populations are shrinking
current world growth rate is 1.2%
At this rate, the human population of the planet would double in 58.3 years
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Assess divergent views on population growth - Malthus.
Thomas Malthus’s An Essay on the Principles
of Population (1798)
Humans will outstrip food supplies
War, disease, starvation reduce
populations
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Assess divergent views on population growth - Ehrlich.
Neo-Malthusians: population growth will increase faster than food production; cause famine and conflict
Paul Ehrlich’s Population Bomb (1968) predicted that civilization would end by the end of the 20th century
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Is population growth a problem?
Cornucopians argue that we
will continue to find new
resources and technology to support people
there are finite resources Quality of life will suffer with unchecked growth
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Is population growth a problem?
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Some governments fear falling populations.
Policymakers believe population growth increases
economic, political, and military strength
But growth is correlated with poverty, not wealth
Strong, rich nations have low growth rates
Weak, poor nations have high growth rates
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Evaluate how human population, affluence, and technology affect the environment.
x S
Total impact (I) on the environment
Population (P) = individuals need space and resources
Affluence (A) = greater per capita resource use
Technology (T) = increased exploitation of resources, but also pollution controls and
renewable energy
Sensitivity (S) = how sensitive an area is to human pressure (e.g., arid land vs.
rainforest)
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Population is one of several factors that affect the environment.
Humans use 25% of Earth’s net primary production
Technology has increased
efficiency and reduced our strain
on resources, resulting in
further population growth
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Human population growth and regulation
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Human population growth and regulation