Environmental Science: Toward a Sustainable Future Richard T' Wright

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Environmental Science Toward a Sustainable
Future Richard T. Wright
Chapter 20

• The Atmosphere Climate, Climate Change, and
  Ozone Depletion PPT by Clark E. Adams

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El Niño What Happened?
April
May

• Jet streams shifted from normal course
• Cause unknown

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 4072 mph, chimney damage, tree branches
  broken
• F-1 73112 mph, mobile homes pushed off
  foundations or overturned
• F-2 113157 mph, considerable damage, mobile
  homes demolished, trees uprooted

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Fujita Scale Measures the Intensity of Tornadoes

• F-3 158205 mph, roofs and walls torn down,
  trains overturned, cars thrown
• F-4 207260 mph, well-constructed walls leveled
• F-5 261318 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
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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 Earths 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 Suns 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 to ozone
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 change by 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 todays 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
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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
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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