Air%20Issues

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Air Issues

• Atmosphere basics
• Air pollution
• Climate change

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Composition of atmosphere

• 78 nitrogen
• 21 oxygen
• 1 everything else

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Structure of atmosphere

• Mesosphere and thermosphere
• 52-120 km
• Stratosphere
• 12-52 km
• temperature increases upward
• important ozone layer (19-26 km)
• Troposphere
• ground to 12 km
• temperature decreases upward

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Focus on troposphere

• Our weather
• Pollution that affects humans
• Usual conditions vs. inversions
• (change in temperature going upward)

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Usual conditions pollution rises
Inversion pollution is trapped
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Air pollution

• Outdoor air pollution
• Indoor air pollution

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Criteria air pollutants (Clean Air Act, EPA)

• Carbon monoxide
• NOx or nitrogen dioxide
• SO2 (sulfur dioxide)
• tropospheric ozone (O3)
• particulate matter (PM)
• lead (Pb)
• Lets look at sources of each of these.

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Carbon monoxide (CO)

• Incomplete combustion of
• coal
• gasoline (catalytic converters help here)
• Why is it harmful to humans?

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Nitrogen oxides (many forms)

• NOx
• Incomplete burning of gasoline
• Contributes to acid rain
• Part of ozone problem in summer in cities

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Tropospheric Ozone

• Secondary pollutant
• Monitor VOCs (volatile organic compounds)
• solvents and vehicle emissions particularly
  important
• Often a summer-time problem

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Sulfur dioxide (SO2)

• Burning of coal
• Volcanic emissions (natural)
• Effects damages plant chlorophyll, irritates
  throat and lungs causes acid rain

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Particulate matter

• Incomplete combustion of fossil fuels
• Dust from fields, construction, etc.
• Size of particles important
• What ARE those particles?

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Lead

• Primary source from leaded gasoline
• Metal processing industries
• Effects central nervous system and bioaccumulates

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Criteria Air pollutants Primary sources to atmosphere
Carbon Monoxide
Sulfur Dioxide
Nitrogen Dioxide
Tropospheric Ozone
Particulate Matter
Lead

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Secondary pollutants

• Created by a reaction
• Includes smog and tropospheric ozone

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Smog

• Photochemical smog (LA smog)
• Industrial smog (London smog)

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Photochemical smog (1)

• Car exhaust
• Hydrocarbons and NOx plus solar radiation
  produces toxic chemicals, particularly ozone
• Higher ozone concentrations in late summer
  afternoons

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Photochemical smog (2)

• Effects of ozone
• Solutions

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Ozone (O3)

• Stratosphere good troposphere bad
• Part of summertime smog
• Charlotte area (and many other urban areas) are
  in non-attainment for ozone levels

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Industrial smog

• Older industrial cities
• Often associated with coal burning
• Particulates, sulfur dioxide and stagnant air

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Acid deposition

• Sulfuric and nitric acids
• Travel long distances
• Some solutions industrial scrubbers, catalytic
  converters

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Indoor air quality

• Increasing awareness
• Developing countries particulate matter and
  carbon monoxide
• Industrialized nations cigarette smoke, radon,
  mold, VOCs
• Solutions?

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Global air issues

• Stratospheric ozone depletion
• Climate change

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Stratospheric Ozone Depletion

• What does stratospheric ozone do?
• What is happening?

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mid 1990s
1970s
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Antarctic Researchers

• Routinely monitor atmosphere above Antarctica
• Significant depletion started in 1980

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Rowland and Molina

• Predicted CFCs would destroy ozone (1974)
• CCl2F2 UV Cl CClF2
• Cl O3 ClO O2
• ClO O O2 Cl

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What can we do?

• Phase out manufacturing of CFCs done
• Phase out use of CFCs spray cans, styrofoam
  products, refrigerants done
• Can this happen on a global basis?

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Montreal Protocol (1987)

• Major reduction in production of CFCs and halons
• Initially signed by 25 nations, eventually
  ratified by over 150 nations
• CFC production in industrial nations to be cut by
  50
• Halon production frozen at 1986 levels
• SUCCESS

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Climate Change

• NATURAL TEMPERATURE VARIABILITY INCLUDING GREEN
  HOUSE EFFECT
• HUMAN IMPACT ON TEMPERATURES
• ADAPTATION, MITIGATION, SUFFERING

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Natural Temperature Variability

• Seasons
• Latitudes - altitudes
• Milankovitch cycles
• El Nino cycles

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How do we know temperatures from long ago?

• Human records actual measurements
• Proxies ice cores, sediment cores for example

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Greenhouse effect

• What is it?
• Is it bad or good that Earth has a greenhouse
  effect?
• Greenhouse gases

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Sources of greenhouse gases

• Carbon dioxide burning fossil fuels and
  forests, making cement
• Methane decomposition of organic matter in
  swampy environments frozen in tundra and ocean
  floor stomachs of cows
• Nitrous oxides bacterial decomposition of
  manure soil denitrification some organic
  fertilizers
• Halocarbons (including CFCs) chemical cooling
  agent foaming agent propellant (phased out by
  Montreal Protocol)

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Relative strength of GHG (from IPCC, 2007)
Carbon Dioxide 1
Methane 25
Nitrous oxide 300
1 CFC replacement 15,000
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Future of global warming?

• Computer modeling
• United Nations IPCC

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Intergovernmental Panel on Climate Change

• Established in 1988

• 2,000 scientists from many nations

• Four assessment reports (latest in 2007)

• Policy-relevant but policy neutral

• Won the Nobel Peace Prize (along with Al Gore)

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IPCC Fourth Assessment Report Conclusions
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IPCC Fourth Assessment Report Conclusions
Global atmospheric concentrations of carbon
dioxide, methane, and nitrous oxide have
increased markedly as a result of human
activities since 1750 and now far exceed
pre-industrial values determined from ice cores
spanning many thousands of years.
Today 385 ppm Preindustrial 280 ppm
Highest in 650,000 years
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IPCC Fourth Assessment Report Conclusions
Warming of the climate system is unequivocal, as
is now evident from observations of increases in
global average air and ocean temperatures,
widespread melting of snow and ice, and rising
global average sea level.
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Future?

• Sea level change (3-20 ft rise)
• Coral reef bleaching
• Changes in locations of plants and animals
• Melting of ice caps and glaciers

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Sea Ice in Arctic Ocean 1979 and 2003
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Alaskan glacier1914 and 2004
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Solutions?

• Adaptation
• Mitigation
• Suffering is inevitable, but how much?

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Evaluating Solutions
The Need for Adaptation
We are already committed to a certain amount of
warming
Resources must be devoted to adapting to altered
future conditions
Focus on mitigation cannot ignore need for
adaptation
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Mitigation?

• Limit dependence on fossils fuels
• Plant trees
• Kyoto Protocol and beyond