Climate Change and Ozone Depletion

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Chapter 20

• Climate Change and Ozone Depletion

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• Scientists know with virtual certainty that
• Human activities are changing the composition of
  Earth's atmosphere. Increasing levels of
  greenhouse gases like carbon dioxide (CO2) in the
  atmosphere since pre-industrial times are
  well-documented and understood.
• The atmospheric buildup of CO2 and other
  greenhouse gases is largely the result of human
  activities such as the burning of fossil fuels.
• An unequivocal warming trend of about 1.0 to
  1.7F occurred from 1906-2005. Warming occurred
  in both the Northern and Southern Hemispheres,
  and over the oceans.
• The major greenhouse gases emitted by human
  activities remain in the atmosphere for periods
  ranging from decades to centuries. It is
  therefore virtually certain that atmospheric
  concentrations of greenhouse gases will continue
  to rise over the next few decades.
• Increasing greenhouse gas concentrations tend to
  warm the planet.

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What's Not Certain? Important scientific
questions remain about how much warming will
occur, how fast it will occur, and how the
warming will affect the rest of the climate
system including precipitation patterns and
storms. Answering these questions will require
advances in scientific knowledge in a number of
areas.
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PAST CLIMATE AND THE GREENHOUSE EFFECT

• Over the past 900,000 years, the troposphere has
  experienced prolonged periods of global cooling
  and global warming.
• For the past 1,000 years, temperatures have
  remained fairly stable but began to rise during
  the last century.

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How Do We Know What Temperatures Were in the Past?

• Scientists analyze tiny air bubbles trapped in
  ice cores learn about past
• troposphere composition.
• temperature trends.
• greenhouse gas concentrations.
• solar, snowfall, and forest fire activity.

Figure 20-3
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The Natural Greenhouse Effect

• Three major factors shape the earths climate
• The sun.
• Greenhouse effect that warms the earths lower
  troposphere and surface because of the presence
  of greenhouse gases.
• Oceans store CO2 and heat, evaporate and receive
  water, move stored heat to other parts of the
  world.
• Natural cooling process through water vapor in
  the troposphere (heat rises).

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Major Greenhouse Gases

• The major greenhouse gases in the lower
  atmosphere are water vapor, carbon dioxide,
  methane, and nitrous oxide.
• These gases have always been present in the
  earths troposphere in varying concentrations.
• Fluctuations in these gases, plus changes in
  solar output are the major factors causing the
  changes in tropospheric temperature over the past
  400,000 years.

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FACTORS AFFECTING THE EARTHS TEMPERATURE

• Some factors can amplify (positive feedback) and
  some can dampen (negative feedback) projected
  global warming.
• There is uncertainty about how much CO2 and heat
  the oceans can remove from the troposphere and
  how long the heat and CO2 might remain there.
• Warmer temperatures create more clouds that could
  warm or cool the troposphere.

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FACTORS AFFECTING THE EARTHS TEMPERATURE

• Aerosol and soot pollutants produced by human
  activities can warm or cool the atmosphere, but
  such effects will decrease with any decline in
  outdoor air pollution.
• Warmer air can release methane gas stored in
  bogs, wetlands, and tundra soils and accelerate
  global warming.

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EFFECTS OF GLOBAL WARMING

• A warmer climate would have beneficial and
  harmful effects but poor nations in the tropics
  would suffer the most.
• Some of the worlds floating ice and land-based
  glaciers are slowly melting and are helping warm
  the troposphere by reflecting less sunlight back
  into space.

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Changing Ocean Currents

• Global warming could alter ocean currents and
  cause both excessive warming and severe cooling.

Figure 20-12
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EFFECTS OF GLOBAL WARMING

• A warmer troposphere can decrease the ability of
  the ocean to remove and store CO2 by decreasing
  the nutrient supply for phytoplankton and
  increasing the acidity of ocean water.
• Global warming will lead to prolonged heat waves
  and droughts in some areas and prolonged heavy
  rains and increased flooding in other areas.

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Effects on Biodiversity Winners and Losers

• Possible effects of global warming on the
  geographic range of beech trees based on
  ecological evidence and computer models.

Figure 20-13
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Beech
Future range
Overlap
Present range
Fig. 20-13, p. 478
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EFFECTS OF GLOBAL WARMING

• In a warmer world, agricultural productivity may
  increase in some areas and decrease in others.
• Crop and fish production in some areas could be
  reduced by rising sea levels that would flood
  river deltas.
• Global warming will increase deaths from
• Heat and disruption of food supply.
• Spread of tropical diseases to temperate regions.
• Increase the number of environmental refugees.

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Some impacts from increasing temperatures are
already happening. Ice is melting worldwide,
especially at the Earths poles. This includes
mountain glaciers, ice sheets covering West
Antarctica and Greenland, and Arctic sea ice.
Researcher Bill Fraser has tracked the decline
of the Adélie penguins on Antarctica, where their
numbers have fallen from 32,000 breeding pairs to
11,000 in 30 years. Sea level rise became
faster over the last century. Some butterflies,
foxes, and alpine plants have moved farther north
or to higher, cooler areas. Precipitation (rain
and snowfall) has increased across the globe, on
average. Spruce bark beetles have boomed in
Alaska thanks to 20 years of warm summers. The
insects have chewed up 4 million acres of spruce
trees.
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Other effects could happen later this century, if
warming continues.  Sea levels are expected to
rise between 7 and 23 inches by the end of the
century, and continued melting at the poles could
add between 4 and 8 inches. Hurricanes and other
storms are likely to become stronger. Species
that depend on one another may become out of
sync. For example, plants could bloom earlier
than their pollinating insects become active.
Floods and droughts will become more common.
Rainfall in Ethiopia, where droughts are already
common, could decline by 10 percent over the next
50 years. Less fresh water will be available.
If the Quelccaya ice cap in Peru continues to
melt at its current rate, it will be gone by
2100, leaving thousands of people who rely on it
for drinking water and electricity without a
source of either. Some diseases will spread,
such as malaria carried by mosquitoes.
Ecosystems will changesome species will move
farther north or become more successful others
wont be able to move and could become extinct.
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Removing and Storing CO2

• Methods for removing CO2 from the atmosphere or
  from smokestacks and storing (sequestering) it.

Figure 20-15
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Spent oil reservoir is used for Crop field
Coal power plant
Tanker delivers CO2 from plant to rig
Tree plantation
Oil rig
CO2 is pumped down from rig for deep ocean
disposal
Abandoned oil field
Crop field
Switchgrass
CO2 deposit CO2 is pumped down to reservoir
through abandoned oil field
Spent oil reservoir is used for CO2 deposit
CO2 pumping
CO2 deposit
Fig. 20-15, p. 482
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International Climate Negotiations The Kyoto
Protocol

• Treaty on global warming which first phase went
  into effect January, 2005 with 189 countries
  participating.
• It requires 38 participating developed countries
  to cut their emissions of CO2, CH4, and N2O to
  5.2 below their 1990 levels by 2012.
• Developing countries were excluded.
• The U.S. did not sign, but California and Maine
  are participating.
• U.S. did not sign because developing countries
  such as China, India and Brazil were excluded.

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Solving the problem sustainably

• Redesigning human systems according to sound
  principles of sustainability could help alleviate
  the problem of global warming.
• Population stabilization can help reduce our
  demand for fossil fuels and other
  greenhouse-enhancing activities such as
  deforestation.
• Restoring forests, especially in the tropics,
  could have a profound effect on global carbon
  dioxide levels.

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Solving the problem sustainably

• Recycling and energy efficiency greatly reduce
  energy demand and cut greenhouse gas emissions.
• Renewable energy technologies can provide us with
  much-needed power, with little or no impact on
  global climate.
• Solving the problem of global warming will
  require the efforts of all sectors of society and
  every country on Earth.

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OZONE DEPLETION IN THE STRATOSPHERE

• Less ozone in the stratosphere allows for more
  harmful UV radiation to reach the earths
  surface.
• The ozone layer keeps about 95 of the suns
  harmful UV radiation from reaching the earths
  surface.
• Chlorofluorocarbon (CFCs) have lowered the
  average concentrations of ozone in the
  stratosphere.
• In 1988 CFCs were no longer manufactured.

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Ultraviolet light hits a chlorofluorocarbon (CFC)
molecule, such as CFCl3, breaking off a chlorine
atom and leaving CFCl2.
Once free, the chlorine atom is off to attack
another ozone molecule and begin the cycle again.
A free oxygen atom pulls the oxygen atom off
the chlorine monoxide molecule to form O2.
The chlorine atom attacks an ozone (O3) molecule,
pulling an oxygen atom off it and leaving an
oxygen molecule (O2).
The chlorine atom and the oxygen atom join to
form a chlorine monoxide molecule (ClO).
Stepped Art
Fig. 20-18, p. 486
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Natural Capital Degradation
Effects of Ozone Depletion
Human Health
Worse sunburn
More eye cataracts
More skin cancers
Immune system suppression
Food and Forests
Reduced yields for some crops
Reduced seafood supplies from reduced
phytoplankton
Decreased forest productivity for UV-sensitive
tree species
Wildlife
Increased eye cataracts in some species
Decreased population of aquatic species
sensitive to UV radiation
Reduced population of surface phytoplankton
Disrupted aquatic food webs from reduced
phytoplankton
Air Pollution and Materials
Increased acid deposition
Increased photochemical smog
Degradation of outdoor paints and plastics
Fig. 20-21, p. 488
Global Warming
Accelerated warming because of decreased ocean
uptake of CO2 from atmosphere by phytoplankton
and CFCs acting as greenhouse gases
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Case Study Skin Cancer

• Structure of the human skin and relationship
  between radiation and skin cancer.

Figure 20-22
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This long-wavelength (low-energy) form of UV
radiation causes aging of the skin, tanning, and
sometimes sunburn. It penetrates deeply and may
contribute to skin cancer.
This shorter-wavelength (high-energy) form of UV
radiation causes sunburn, premature aging, and
wrinkling. It is largely responsible for basal
and squamous cell carcinomas and plays a role in
malignant melanoma.
Ultraviolet A
Ultraviolet B
Thin layer of dead cells
Hair
Squamous cells
Epidermis
Basal layer
Sweat gland
Melanocyte cells
Dermis
Basalcell
Blood vessels
Squamous Cell Carcinoma
Melanoma
Basal Cell Carcinoma
Fig. 20-22, p. 489
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