Environmental Science: Toward a Sustainable Future

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Environmental Science Toward a Sustainable
Future

• The Atmosphere Climate, Climate Change, and
  Ozone Depletion and Atmospheric Pollution

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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 The day-to-day variations in
  temperature, air pressure, wind, humidity, and
  precipitation mediated by the atmosphere in a
  given region.

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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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Climate

• Defined as the average trend in temperature and
  rainfall that produces a unique assemblage of
  plants and animals

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Climates in the Past
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Global Climate Change

• The Earth as a greenhouse
• The greenhouse gases
• Evidence of climate change
• Anthropogenic pollutants and other forms of
  impacts on naturals environments that can be
  traced back to human activities

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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
  (11-year sunspot cycle)
• Seems low sunspot, lower temp.
• 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 sinks (oceanic absorption)
• Forests CO2 source when burned
• 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
Billion metric tons
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Impacts of Global Warming

• Melting of polar ice caps and glaciers
• Flooding of coastal areas due sea levels rising
• Thermal expansion of oceans
• Ocean currents shifting (ENSO)

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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
• 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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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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Radiation and Importance of the Shield

• Stratosphere provides 99 shield from UV
  radiation to troposphere
• 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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TOMS Total Ozone Mapping Spectrometer Dobson
Unit (DU) a measure of the total amount of ozone
in a column of the atmosphere (total column
ozone) from ground level to the top of the
atmosphere, based on analysis of absorbed
ultraviolet light. The number of Dobson units
corresponds directly with the thickness of the
ozone layer. While measurements vary widely
according to time and place, a typical reading
for a healthy polar ozone layer might be in the
300-450 Dobson unit range.
Ozone Hole 11 million sq.mi.
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1997 The ozone hole is indicated by ozone values
less than 220 Dobson Units (the violet colors).
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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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Pollutants and Atmospheric Cleansing

• Air pollutants gases and aerosols in the
  atmosphere that have harmful effects
• Level of air pollution determined by
• The amount of pollutants entering the air
• The amount of space into which the pollutants
  dispersed
• Mechanisms that remove pollutants from the air
  (i.e. wind speed direction, precipitation)

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The Appearance of Smog
Smoke Fog Smog
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Impacts of Smog Temperature Inversion
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Air Pollution Effects

• Adversely affects human health
• Damages crops and forests
• Highly corrosive

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Major Air Pollutants and Their Sources

• Suspended particulate matter
• Volatile organic compounds (VOCs)
• Carbon monoxide
• Nitrogen oxides

• Sulfur oxides
• Heavy metals
• Ozone
• Air toxics

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Major Air Pollutant Sources
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Major Air Pollutants Primary (see next slide)

• Primary pollutants derived directly from burning
  fuels and wastes
• Particulates (dust, fuel combustion)
• Hydrocarbons (CFCs)
• Carbon monoxide (looks like O2)
• Nitrogen oxides (industries)
• Sulfur dioxides (contributes to acid rain)

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Major Pollutants Secondary (see next slide)

• Secondary air pollutants derive from reactions
  that occur between primary pollutants and other
  atmospheric chemicals
• Ozone
• PANs (peroxyacetyl nitrates)
• Acids sulfuric and nitric

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Major Sources of SO2 Emitters
All sources are coal-burning power plants
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Impacts of Air Pollutants on Human Health

• Chronic gradual deterioration of a variety of
  physiological functions over a period of years
  Ex lead poisoning leads to neurological damage
• Acute life-threatening reactions within a period
  of hours or days Ex asthmatics or elderly
• Carcinogenic cancer-causing Ex lung cancer

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Impacts of Air Pollutants on the Environment

• Plants
• Necrotic kills plant cells
• Chlorotic destroys chlorophyll, reducing
  photosynthesis
• Increases susceptibility to disease and pests

Ozone most serious pollutant
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Ozone Impact on Crop Yields
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Impacts of Air Pollutants on the Environment

• Forests
• Leaching of nutrients
• Release of aluminum into solution
• Rapid changes in soil chemistry
• Reduced growth and diebacks of plants and animals
• Increased soil erosion, flooding, sedimentation
  in waterways

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Impacts of Air Pollutants on the Environment

• Materials
• Loss of color
• Oxidation
• Corrosion
• Decreased real estate values (degrades building
  materials)

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Effects of Acid Deposition

• Alteration of plant and animal reproduction
• Leaching of other toxic elements, e.g., aluminum
• Eutrophic to oligotrophic conditions
• Total loss of biota from aquatic ecosystems
• Alterations of food chains

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Bringing Air Pollution under Control

• Clean Air Act identifies most widespread
  pollutants e.g., particulates, SO, CO, NO, lead
  criteria pollutants
• National Ambient Air Quality Standards (NAAQS)
  set levels that protect environmental and human
  health

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Bringing Air Pollution under Control

• NAAQS also set national ambient air quality
  standards
• National Emission Standards for Hazardous Air
  Pollutants set national emission standards for
  hazardous air pollutants

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Title IV Clean Air Act 1990

• Reduce SO emissions 50 below 1980 levels
• Improve methods of reducing SO emissions
• Allow emissions allowances and trading
• Emissions purchases
• Reduce NO emissions

Title X Clean Air Act 1990

• Addresses acid rain deposition

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Industrys Response to Clean Air Act - 1990

• Fuel switching
• Scrubbers
• Emissions allowance trading
• Using low-sulfur coals