Download 6-4 Charting a Course for the Future

Biology
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Ozone Depletion
What are two types of global change of
concern to biologists?
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6-4 Charting a Course
for the Future
Researchers are gathering data to monitor
and evaluate the effects of human activities
on important systems in the biosphere. Two
of these systems are:
• the ozone layer high in the atmosphere
• the global climate system
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Ozone Depletion
Exposure to UV can:
• cause cancer
• damage eyes
• decrease organisms' resistance to disease
• damage plant leaf tissue and phytoplankton in the
oceans
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Ozone Depletion
Early Evidence
In the 1970s, scientists discovered a hole in the
ozone layer over Antarctica.
After it was first discovered, the ozone hole grew
larger.
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Ozone Depletion
One Solution
CFCs (chlorofluorocarbons) were once widely used:
• as propellants in aerosol cans
• as coolant in refrigerators, freezers, and air
conditioners
• in the production of plastic foams
The U.S. and other nations began reducing the use of
CFCs in 1987, and eventually banned them.
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Ozone Depletion
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Global Climate Change
Global Climate Change
The term used to describe the increase in the
average temperature of the biosphere is
global warming.
One sign of global warming is melting polar
ice.
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Global Climate Change
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Global Climate Change
Evidence of Global Warming
The geological record shows that Earth’s climate
has changed repeatedly during its history.
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6-4 Charting a Course for the Future
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6-4 Charting a Course for the Future
The Value of a Healthy
Biosphere
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The Value of a Healthy
Biosphere
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6-4
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An increase in the average temperature of the
biosphere is called
a. the greenhouse effect.
b. global warming.
c. ozone depletion.
d. climate control.
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The geological record indicates that Earth’s
climate has
a. remained essentially the same throughout
history.
b. been constant until humans have influenced
the environment.
c. changed dramatically every 150 years.
d. repeatedly changed over its history.
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A possible effect of global warming is
a. extinction of organisms in areas where they
once thrived.
b. an increase in global surface temperature of
20 Celsius degrees.
c. a sharp decrease in the temperature of the
waters off the coast of California.
d. complete elimination of the protective ozone
layer in the atmosphere.
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Depletion of Earth’s protective ozone layer
results in
a. a decrease in the amount of heat that
reaches the surface.
b. a decrease in the amount of UV radiation
that reaches the surface.
c. an increase in the amount of rainfall.
d. an increase in the amount of UV radiation
that reaches the surface.
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The most likely cause of ozone depletion is the
a. addition of carbon dioxide to the
atmosphere.
b. increase in UV radiation from the sun.
c. addition of chemicals developed for use in
refrigeration and aerosol cans.
d. increase in the amount of smog produced
by automobiles.
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