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Global Change
Learning Objectives
After reading this chapter, students should be able to:
• Understand the major global environmental problems.
• Know about anthropogenic greenhouse gases.
• Know about fundamental components of the Earth system.
• Differentiate between global warming and the greenhouse effect.
• Know how the stratospheric ozone layer is affected by anthropogenic gases.
• Know the effect of deforestation on biodiversity.
• Understand the relationship between surface temperature and atmospheric CO2
concentration.
• Know how reduced solar luminosity would have affected the early Earth.
• Know what the Gaia hypothesis is.
• Know how past surface temperatures are determined.
Review Questions
1.)
a. What is meant by “anthropogenic greenhouse gases”?
Humans cause changes to the environment that are called “anthropogenic.”
Humans have generated local pollution ever since they first developed agricultural
b. Name three such gases that are currently increasing in concentration in Earth’s
atmosphere.
There are 4 greenhouse gases discussed in the textbook:
1- Carbon dioxide (CO2)
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2.)
a. What are the four fundamental components of the Earth system?
The Earth system is composed of four parts:
i. The atmosphere: A thin layer of gases that surrounds Earth
3.) Explain the difference between global warming and the greenhouse effect.
Greenhouse gases are gases that warm a planet’s surface by absorbing outgoing
4.)
a. By how much has Earth’s atmospheric CO2 concentration increased since the year
1800?
b. How do we know this?
Keeling’s data show that the mean atmospheric CO2 level for today is around 389
c. What are thought to be the primary causes of this increase?
5.) Cite two ways in which chlorofluorocarbons can affect the environment.
6.)
a. How far back in time do direct measurements of Earth’s surface temperature
extend?
Since 1861 scientists have made accurate atmospheric temperature measurements
using thermometers.
b. Why is it difficult to determine accurately the long-term temperature trend?
7.) How might the burning of coal have had opposing effects on climate during the
20th century?
8.) Why is stratospheric ozone important to humans?
9.) To what two global environmental problems does tropical deforestation
contribute?
10.) How are hydrogen isotopes used to infer polar temperature records?
11.) How is past surface temperature
a. Determined from the Vostok ice core?
The temperature changes, ΔT, were determined from measured values of the
deuterium content of the Vostok ice core. The section of the Vostok ice core
b. Related to atmospheric CO2 content?
Vostok results showed that atmospheric CO2 and CH4 concentrations have
varied in concert with surface temperature. As levels of the greenhouse gases
12.) Why is iridium a good indicator of impacts by extraterrestrial bodies?
13.)
a. How has solar luminosity changed during the past 4.6 billion years?
When the Sun first formed 4.6 billion years ago, it is believed to have been
b. What is the fundamental cause of this change?
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14.) What is the Gaia hypothesis, and what does it say about the importance of life
on this planet?
Critical Thinking Problems
1.) Which of the three modern global change problems discussed in this chapter–
global warming, ozone depletion, or loss of biodiversity–do you consider to be
the most serious? Give reasons for your answer. If you wish, include information
drawn from other sources.
There are different opinions for this problem; one can argue that any one of them
is the most significant problem. We have listed reasons students could use for all
three of these problems below.
Students can argue that global warming is the most serious problem because:
• It affects the greatest number of people
Students can argue that loss of biodiversity is the most serious problem because:
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• There is potential for recovery for the other problems: the ozone layer could
2.) How do global warming, ozone depletion, and loss of biodiversity compare with
other environmental and social problems that the world faces today? You may
wish to list the major problems, as you see them, in decreasing order of
importance. Justify your answer with an explanation.
As in the first problem there are different views on this question.
Global warming, ozone depletion, and loss of biodiversity are more important
than the other environmental and social problems because:
• They are too large in scale to consider secondary to any other problems. These
three affect the entire planet and could alter the future of human life on Earth
Resource Guide
Video/Film:
An Inconvenient Truth
Al Gore (2 hours, color)
This is by far the most up-to-date and powerful movie about the perils of global warming.
Although Gore himself is politically controversial, the science in this movie is for the
most part very good. A “must show” if you are teaching this course.
The Pleasure Planet: Can the Earth Be Saved?