This document discusses population growth and its impact on the environment. It covers topics like population biology patterns, public health contributions to population growth, depletion of global resources from population increase, and climate change effects. Prospects for population control are also examined, noting challenges faced at the 1994 Cairo conference. Discussion questions at the end explore issues like how public health measures impact population growth and factors determining the carrying capacity of Earth.

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CHAPTER 25
Population:
The Ultimate
Environmental
Health Issue

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2021
by
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Learning,
LLC
an
Ascend
Learning
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Population Biology
 Population biology is a science in itself.
 S curve and J curve express two general patterns of population growth.
 Carrying capacity is the number of organisms that can be supported
without degrading environment.
 Thomas Malthus predicted, in about 1800, that population growth would
outgrow food supply.
 Paul Ehrlich published The Population Bomb in 1968.
 Population growth has slowed, but many negative effects of
overpopulation are occurring.

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Public Health and Population Growth
 Public health has contributed to population growth by reducing death rates,
especially among children, in developing countries.
 Birth rates tend to fall as a result of falling death rates, which is known as
“demographic transition.”
 Excess population settles in cities, increasing homelessness, shantytowns, and
poor sanitation.
– Conditions threaten to reverse all the progress in public health made through earlier
efforts.
 HIV/AIDS shortens life expectancies in Africa.

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Depletion of Global Resources
 Fresh water
– Uses include drinking, cooking, washing, agriculture.
– It is unevenly distributed.
– Small percentage of Earth’s water is suitable for human use.
 Fuel
– Deforestation leads to degradation of land.
 Arable land
– Amount of land under cultivation is declining.
 Food from the sea
– There is a decline of fish and shellfish harvests.

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Ascend
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Climate Change
 Climate change is perhaps the most threatening effect of population growth.
 Greenhouse effect is from burning fossil fuels.
 Earth’s temperature has risen by over 1 degree Fahrenheit during the 20th
century.
– Prediction is for 3–7 degree rise by 2100.
 The U.S. has 4.3% of the world’s population but contributes 15.5% of
greenhouse gases.
– China, with 18.2% of the world’s population, has become the leading emitter,
with 29% of greenhouse gases.
 No international plan for improvement has been reached.

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Prospects for Population Control
 United Nations conference in Cairo in 1994 established:
– Opposition to contraception by Catholics and Muslims
– Rich and poor countries blame each other
– 20-year Programme of Action
• Education for women
• Empowerment of women to choose to have fewer children
 Population stabilization comes with modernization and economic viability.
 The United Nations conducted the ICPD Beyond 2014 Global Survey.
– Although progress has been made in some countries, it is uneven, and the
agenda remains unfinished.

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Discussion Question 1
 Choose three or more public health measures discussed previously in the book.
 How do these measures lead to increases or decreases in population growth?

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Discussion Question 2
 What are three or more factors that may determine the carrying capacity of the
earth?
 Explain the effect of each factor.

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Discussion Question 3
 Imagine an island inhabited by a human population that is self-sufficient and
has no interaction with the rest of the world.
 Describe conditions that would cause a J-type crash of the island’s population.
 How could this be prevented?

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Discussion Question 4
 Visit the website of the Population Reference Bureau, www.prb.org.
 Find the most recent “World Population Data Sheet.” Choose a developed
nation and a developing nation to compare with respect to: birth rate, death
rate, infant mortality rate, rate of population growth, and/or other data indicators
of interest to you.
 What do these data tell you about the health of the populations of these
countries?

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Discussion Question 5
 Visit the website of the Millennium Ecosystem Assessment,
www.millenniumassessment.org.
 This is a massive United Nations-sponsored analysis of the state of the
world’s environment.
 What does it say about the ability of the world to provide food and
water for its population in the next century?