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Environmental Science: Toward a Sustainable Future Richard T. Wright
The Atmosphere: Climate, Climate Change, and Ozone Depletion
PPT by Clark E. Adams
Chapter 20
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El Niño: What Happened?
Jet streams shifted from normal course
Cause unknown
April May
June
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El Niño: What Happened?
Development of warm water in the eastern Pacific over time
Reversal in trade winds that normally blow from an easterly direction
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El Niño: What Happened?
Warm water spread to the east Global patterns in moisture and
evaporation changed = climate shifts
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The El Niño Effects: Fig. 20-1
Landslides on the California coast Mildest hurricane season in many years Rain five times normal in an East Africa
drought region Record crop harvests in India, Australia,
and Argentina
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La Niña: What Happened?
Easterly trade winds reestablished with greater intensity
Upwelling of colder water from ocean depths
Jet streams are weakened Global patterns in moisture and
evaporation return to “normal”
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The Atmosphere: Climate, Climate Change, and Ozone Depletion
Atmosphere and weather Climate Global climate change Response to climate change Depletion of the ozone layer
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Atmosphere and Weather
Atmospheric structure Weather
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Atmospheric Structure
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Weather: Solar Energy Balance
Most solar energy absorbed by atmosphere, oceans, and land
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Weather: Convection Cell
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Tornadoes
Cold low-pressure air mass collides with a warm high-pressure air mass
http://www.photolib.noaa.gov/nssl/nssl0065.htm
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Fujita Scale Measures the Intensity of Tornadoes F-0: 40–72 mph, chimney damage, tree
branches broken F-1: 73–112 mph, mobile homes pushed off
foundations or overturned F-2: 113–157 mph, considerable damage,
mobile homes demolished, trees uprooted
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Fujita Scale Measures the Intensity of Tornadoes F-3: 158–205 mph, roofs and walls torn down,
trains overturned, cars thrown F-4: 207–260 mph, well-constructed walls
leveled F-5: 261–318 mph, homes lifted off foundation
and carried considerable distances, autos thrown as far as 100 meters
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Climate
Ocean and atmosphere Climates in the past
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Climate
Defined as the average trend in temperature and rainfall that produces a unique assemblage of plants and animals
On the next slide identify climates A to E, e.g., low average rainfall and high average temperature = hot desert
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Identify Climates A to E
Precipitation
Tem
pera
ture
Low High
High
A
B
C
D
E
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Climates in the Past
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Past Climates
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Ocean and Atmosphere
Covers 75% of the Earth’s surface Major source of water to hydrologic cycle Major source of heat to atmosphere Stores and conveys heat
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The Ocean Conveyor System
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The Ocean Conveyor System
Thermohaline circulation: effects that temperature and salinity have on density of water Conveyor system moves water masses from
the surface to deep oceans and back again Cool northern waters more dense and sink to
depths of 4,000 m = North Atlantic Deep Water (NADW)
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The Ocean Conveyor System
Deep water spreads southward to south Africa and joined by cold Antarctic waters
Spread northward into Indian and Pacific oceans as deep currents
Current slows down, warms up, becomes less dense, rises to the surface, and moves back to North Atlantic
Produces a warm climate in Europe
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The Ocean Conveyor System
Factors that could alter the conveyor system Appearance of unusually large quantities of
freshwater – melting icebergs Global warming
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Global Climate Change
The Earth as a greenhouse The greenhouse gases Evidence of climate change
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The Earth as a Greenhouse
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Factors Affecting Global Temperatures
Cloud cover: cooling Changes in Sun’s intensity: cooling or
warming Volcanic activity: cooling Sulfate aerosols: cooling
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Greenhouse Gases: CO2 Emissions from Fossil Fuel Burning 35% higher than before industrial
revolution Oceans = CO2 sink Forests = CO2 source 24 billion metric tons CO2 added each year
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Other Greenhouse Gases and Sources
Water vapor Methane Nitrous oxide CFCs and other
halocarbons
Hydrologic cycle Animal husbandry Chemical
fertilizers* Refrigerants*
* = Long residence times and contribute toozone depletion
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Atmospheric CO2 Concentrations
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Global Surface Temperatures
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Global Carbon Cycle
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Impacts of Global Warming
Melting of polar ice caps Flooding of coastal areas Massive migrations of people
inland
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Impacts of Global Warming
Alteration of rainfall patterns Deserts becoming farmland and
farmland becoming deserts Significant losses in crop yields
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Evidences of Climatic Change
17 of the hottest years on record have occurred since 1980 (Fig. 20-5)
Wide-scale recession of glaciers Sea level rising
Predicted mean global temperature changeby 2100 is between 1.5 and 4.5oC
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Reducing CO2 Emissions (True or False) Reducing use of fossil fuels Adopt a wait-and-see attitude Develop alternative energy sources Plant trees Examine other possible causes of global
warming
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Reducing CO2 Emissions (True or False) Make and enforce energy conservation
rules Rely on the government Adopt the precautionary principle Raise the minimum driving age to 18 years
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Key Findings of the 2000 U.S. Climate Change Assessment (Table 20-3)
Increased warming Differing regional impacts Vulnerable ecosystems Widespread water concerns Agriculture largely unaffected Forest growth to increase Coastlines – rising sea levels
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Responses to Climate Change
Response 1: mitigation = reduce CO2 emissions
Response 2: adaptation = accepting and learning to live with the consequences of climate change
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Framework Convention on Climate Change (FCC) Relied on voluntary approach to reduce
CO2 emissions Developing countries continue toward
developed nation status using fossil fuels
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Framework Convention on Climate Change (FCC) To achieve a 7% reduction by 2010
requires a 25% reduction of present use By 2010 CO2 emissions will have
increased by 30%
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Framework Convention on Climate Change (FCC)
Bottom line: need 60% reduction (144 ppm) in CO2 emission worldwide NOW to stabilize greenhouse gas concentrations at today’s levels
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Depletion of Ozone Layer
Radiation and importance of the shield Formation and breakdown of the shield Coming to grips with ozone depletion
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Good Ozone!
Bad Ozone!
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Electromagnetic Spectrum
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Radiation and Importance of the Shield
Skin cancer (700,000 new cases each year)
Premature skin aging Eye damage Cataracts Blindness
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Formation of the Ozone Shield
Reaction #1: UV light + O2 O + O
Reaction #2: Free O + O2 O3
Reaction #3: Free O + O3 O2 + O2
Reaction #4: UV light + O3O + O2
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Chlorofluorocarbons (CFCs)
Organic molecules in which both chlorine and fluorine atoms replace some of the hydrogen atoms
Sources: refrigerators and air conditioners production of plastic foam cleaner for electronic parts pressurizing agent in aerosol cans
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Breakdown of Ozone Shield
Reaction #5: CFCl3 + UV Cl + CFCl2
Reaction #6: Cl + O3 ClO + O2
Reaction #7: ClO + ClO 2 Cl + O2
Which reaction releases Cl from CFCs?Which reaction generates more Cl?Chlorine is a catalyst that destroys the production of ________?
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Montreal Protocol
1987 – scale back CFC production by 50% by 2000
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Coming to Grips with Ozone Depletion: Montreal Protocol
1990 – amendment to completely phase out ozone-destroying chemicals by 2000
1992 – amendment to completely phase out ozone-destroying chemicals by 1996
Why the rush?
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Ozone Hole: 11 million sq.mi.
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The Clean Air Act of 1990: Title IV
Restricts production, use, emissions, and disposal of ozone-depleting chemicals
Regulates the servicing of refrigeration and air-conditioning units
“Protecting Stratospheric Ozone”
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End of Chapter 20