UNIT FOUR: Matter and its Changes
 Chapter 12 Atoms and the Periodic
Table
 Chapter 13 Compounds
 Chapter 14 Changes in Matter
 Chapter 15 Chemical Cycles and
Climate Change
Chapter Fifteen: Chemical Cycles and
Climate Change
 15.1 Chemical Cycles
 15.2 Global Climate Change
Section 15.2 Learning Goals
 Define climate change and describe factors
that influence global climate change.
 Explain the greenhouse effect.
 Research and discuss public policy
initiatives designed to combat negative
effects of global climate change.
Investigation 15B
Oceans and the Carbon Cycle
 Key Question:
 What role do the oceans play in the carbon cycle?
15.2 Global climate change
 Global climate change refers to changes
in the factors used to describe a climate
(such as temperature, precipitation, or
wind) that last for two or more decades.
 Since the Sun and the oceans affect
weather patterns, changes in the Sun’s
intensity or in ocean circulation can
cause climate change.
15.2 Global climate change
 Greenhouse gases
“blanket” our planet by
trapping heat from the
Sun that Earth’s average
temperature is hospitable
for living things.
 These gases are water
vapor, carbon dioxide,
methane, nitrous oxide,
ozone, and carbon
compounds produced by
industry.
15.2 The greenhouse
effect
 The greenhouse
effect is the
warming of Earth
that results when
greenhouse gases
trap heat emitted
from the planet’s
surface.
15.2 Upsetting the balance
 Excess carbon dioxide, produced by
many combustion reactions since the
Industrial Revolution, is one of the main
causes of global warming.
15.2 Understanding climate change
 Two scientists, Revelle and
Keeling, collected data on
atmospheric levels of CO2
at Mauna Loa Observatory
(MLO) in Hawaii over about
a 30-year period.
 Other scientists have
analyzed gas bubbles
trapped in glacial ice.
15.2 Today and the future

Currently, the amount of carbon dioxide in
our atmosphere is 35 percent more than it
was 200 years ago.

There are several indicators of global
warming:
1.
2.
3.
4.
Warming temperatures
Rising sea level
Decreasing ice coverage
Increasing water vapor in atmosphere
Investigation 15C
Natural Resources
 Key Question:
 How fast are we using nonrenewable resources?
Harvesting the Wind
There is a new kind of farm that
is unlike any other—it doesn’t
produce food—it produces
energy from wind. As wind
turbine technology has
improved over the past 30
years, the cost per kilowatthour of electricity generated by
wind has decreased
dramatically.