GLOBAL CLIMATE CHANGE
WARM UP
Explain why, on a sunny day, the air inside of a
car is warmer than the air outside of a car.
VIDEOS
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Natl Geographic Global Warming 101
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What human activities are believed to be causing
global warming?
What evidence is there for global warming?
Bill Nye Climate Change 101
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Summarize the greenhouse effect process.
In addition to rising temperatures, what are other
consequences of increased levels of greenhouse
gases?
CARBON CYCLE REVIEW
THE GREENHOUSE EFFECT
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Global warming is closely related to a phenomenon known as
the greenhouse effect.
What is a greenhouse?
Greenhouses are structures made of glass or plastic that
provide a more consistent, warmer climate for plants to grow in.
Greenhouses create a sheltered environment for plants by
trapping incoming solar radiation.
The solar radiation is converted to
heat energy.
This way plants can thrive in spite
of cold temperatures outdoors.
WARMING PROCESSES:
THE GREENHOUSE EFFECT
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Greenhouse Effect simulation
On Earth, certain gases in the atmosphere play a role analogous to
the glass of a greenhouse.
These gases—including carbon dioxide, water vapor, and methane—
are therefore known as greenhouse gases.
Light energy comes through the atmosphere and is absorbed by
Earth and converted to heat energy at the Earth’s surface.
The infrared heat energy radiates back upward through the
atmosphere and into space.
Greenhouse gases act like a blanket, insulating the Earth and
delaying the loss of infrared heat energy to space.
Important to note: Without greenhouse gases in our atmosphere, the
average temperature on Earth would be only -19 C (-2 F) and life as
we know if would be impossible. The current average temperature on
Earth is about 57 F.
THE GREENHOUSE EFFECT
HOW HUMAN ACTIVITY ENHANCES THE
GREENHOUSE EFFECT
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Some greenhouse gases, such as CO2 and water vapor,
are naturally occurring.
Human activity is causing the levels of greenhouse
gases such as CO2, methane, and N2O in the
atmosphere to increase.
Human activities that lead to increases in the levels of
greenhouse gases include:
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Burning of fossil fuels for energy (power plants, cars, etc)
Deforestation
Raising of livestock ( methane)
Excessive use of fertilizer ( N2O)
HOW HUMAN ACTIVITY ENHANCES THE
GREENHOUSE EFFECT
GLOBAL WARMING AND
GLOBAL CLIMATE CHANGE
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Global warming is the increase in Earth’s
average temperature due to the build up of
greenhouses gases in the atmosphere.
Global climate change is a more general term
that refers to long-term changes in climate,
including average temperature and
precipitation.
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The enhanced greenhouse effect is believed to
result in increases in the intensity and frequency of
severe weather events such as droughts and floods
in addition to increases in average temperature.
EXIT SLIP
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What does the greenhouse effect have to do
with global warming?
WARM UP
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What scientific data support the view that
global warming is caused by human activity?
SCIENTIFIC EVIDENCE FOR GLOBAL WARMING
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The measurements of scientists working around
the world show that the amount of CO2 in the
atmosphere has increased sharply since 1800
(around the start of the Industrial Revolution).
Earth’s average temperature over that same time
period follows the same pattern of increases.
The observed warming is believed to be the result
of the enhanced greenhouse effect.
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In 2007, atmospheric CO2 levels were found to be 380
ppm, 35% higher than they were before the Industrial
Revolution and higher than they have been for over
400,000 years.
2007 was also the second hottest year on record.
EVIDENCE FOR GLOBAL WARMING
HOW DO WE DETERMINE THE CLIMATE AND
GHG LEVELS OF THE PAST?
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Systematic records of the weather have only been kept for a little
over one hundred years.
Records of weather and climate further back than 1880 come from
sources such as:
 Historical accounts
 Tree rings, pollen deposits, marine sediments, and ice cores
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Recent analysis of ice cores has revealed greenhouse gas levels as
well as temperature variability over the past 400,000 years.
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Atmospheric measurements
 Since 1958, the National Oceanic and Atmospheric
Administration (NOAA) has been recording both temperature and
GHG levels, finding steady increases in both CO2 levels and
temperature.
THE INFLUENCE OF COOLING FACTORS. . .
REASONS FOR SKEPTICISM?
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There is not a perfect correlation (relationship) between CO2 levels
and average global temperature year to year.
Calculations predict higher temperatures than have actually
occurred.
These calculations have not taken into full account the effect of
carbon sinks and cooling factors, however.
Carbon sinks are organisms or places that can store carbon,
including the forests, oceans, and soil.
Cooling factors include:
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Absorption of heat by the oceans
Reflection of solar radiation by:
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Clouds
Snow and ice
Sulfur dioxide and soot from air pollution
Global dimming (a decrease in the amount of sunlight reaching Earth)
VISIBLE SIGNS AND IMPACTS OF
GLOBAL CLIMATE CHANGE
Signs
Impacts
Increases in average temperature and
temperature extremes
More intense weather events, especially
hurricanes
Migration of organisms in search of habitat
with appropriate climate
Organisms becoming endangered or
extinct
Impact on human well being and economy
Rising sea levels due to melting of glaciers
and ice caps
Flooding in low lying areas
Increase in diseases such as malaria
Changes in habitat
Decreased precipitation
Increased drought
Desertification/difficulty raising crops
Decreased fresh water supply from rivers
and lakes
Shorter winters/changes in seasons
Migration of organisms in search of habitat
with appropriate climate
Organisms becoming endangered or
extinct
WHERE DO YOU FIT IN?
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The exact amount of climate change that is
caused by human activities in not clear.
It is clear, however, that increasing greenhouse
gas emissions result in warmer temperatures and
that human activities produce greenhouse gases.
Is it’s not too late to make lifestyle changes that
can have a positive effect on climate.
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Reducing travel in cars
Using products, especially food, that are produced
locally.
Conserving resources, including energy
EXIT SLIP
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Describe one way that global climate change
may impact humans (other than just an
increase in temperature).