The Atmosphere

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The Atmosphere

• Composition - About 99 of the clean, dry air in
  the troposphere consists of (2) gases Nitrogen
  (79) Oxygen (20).
• Water vapor accounts for .01 to 5.
• Most of the atmosphere is held close to the earth
  by the pull of gravitational force, thus it gets
  thinner with increasing distance from the earth.

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The Atmosphere

• As the atmosphere absorbs heat from the earth, it
  expands and rises.
• When heat is radiated into space, air cools,
  becomes more dense, and flows toward the earth.
• Air quality degraded by multiple sources.
• Air pollution includes both aesthetic and human
  health problems.

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Primary Air Pollutants

• Five major materials released directly into the
  atmosphere in unmodified forms.
• Secondary air pollutants form under reaction of
  primary pollutants and water or sunlight.
• Carbon Monoxide - Produced when organic materials
  are incompletely burned.
• Single largest source is the automobile.
• Not a persistent pollutant.

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Primary Air Pollutants

• Hydrocarbons - Group of organic compounds
  consisting of carbon and hydrogen.
• Evaporated from automobile fuel or remnants of
  fuel incompletely burned.
• Catalytic converters used to burn exhaust gases
  more completely.

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Primary Air Pollutants

• Particulates Minute pieces of solid materials
  dispersed into the atmosphere (lt10 microns).
• Smoke, Asbestos, Dust, Ash
• Can accumulate in lungs and interfere with the
  ability of lungs to exchange gases.
• Sulfur Dioxide (SO2) Sulfur and oxygen compound
  produced when sulfur-containing fossil fuels are
  burned.
• Burning coal releases sulfur dioxide.

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Primary Air Pollutants

• Nitrogen Oxides (NO, NO2) - Formed when
  combustion takes place in the air.
• N and O molecules from the air may react with one
  another.

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Photochemical Smog

• A mixture of primary and secondary pollutants.
  Forms when primary pollutants interact under the
  influence of sunlight.
• Two most destructive components
• Ozone
• Peroxyacetyl Nitrates
• Large cities ringed by mountains tend to have
  trouble with photochemical smog.

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Photochemical Smog

• Thermal Inversions - Warm air becomes sandwiched
  between two layers of cold air and acts like a
  lid on the valley.
• Warm air cannot rise, causing smog accumulation.

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Global Warming and Climate Change

• Climatic records indicate over past 160,000 years
  a correlation between greenhouse gas
  concentration and global temperatures.
• UN established Intergovernmental Panel on Climate
  Change (IPCC)
• 1996 - Concluded climate change is occurring and
  it is highly probable human activity is
  importance cause of the change.

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Global Warming and Climate Change

• IPCC Conclusions
• Average temperature of the earth increased .5 to
  1.0 degrees Fahrenheit over the last 100 years.
• Strong correlation between temperature increase
  and amount of greenhouse gases in the atmosphere.
• Human activity greatly increases amounts of
  greenhouse gases in atmosphere.

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Greenhouse Effect

• Greenhouse gases allow sunlight to penetrate the
  atmosphere.
• Absorbed by earths surface.
• Reradiated as infrared energy (heat)
• Absorbed by gases.

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Greenhouse Effect

• Carbon Dioxide
• Fossil fuel burning, land clearing.
• Chlorofluorocarbons
• Refrigerants, cleaning solvents, propellants.
• Methane
• Breakdown of organic material by anaerobic
  material.
• Nitrous Oxide
• Biomass burning - Breakdown of nitrogen-rich
  products.

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Should the US Be Doing More to Combat Global
Warming?

• Yes Jerald L Schnoor. Global warming is real,
  human activities are to blame, and stabilizing
  the atmospheric carbon dioxide levels within the
  next century will require drastic action.
• No The Bush Administration. It is more useful
  to reduce greenhouse gas intensity or emissions
  per dollar of economic activity than to reduce
  total emissions.

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Schnoor

• The sources of greenhouse gasses include
• Fossil fuel burning
• Flood agriculture
• Use of nitrogen fertilizers
• The next 50 years can expect to see an additional
  warming of 2C (3.6 F)
• Average over the last 1000 years has been 0.6C
  (1.1 F)

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Schnoor (contd)

• Most of the effects so far have been on
  ecosystems not human health.
• Most of the warming over the last 50 years is
  probably due to the increase in greenhouse gas
  concentrations.
• In order to stabilize carbon dioxide
  concentrations at 550 ppm (double pre-industrial
  level) we must reduce global greenhouse gas
  emissions by 70.

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Schnoor Conclusion

• Global warming is a consequence of human
  enterprise growing too large with respect to
  natural cycles on Earth.

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Bush Administration

• Scientific knowledge about global warming is now
  sufficient to justify slowing the growth of
  greenhouse gas emissions.
• The summary of scientific knowledge about global
  warming significant uncertainties remain
• To address climate change effectively and
  economically we should immediately reduce
  greenhouse gas intensity.

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Effects of Global Warming

• Worsening Health Effects
• Rising Sea Level
• Disruption of Water Cycle

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Effects of Global Warming

• Changing Forests
• Geographic distributions of vegetation.
• Challenges to Agriculture
• Increased CO2 concentration likely to increase
  crop yields in some areas and decrease yields in
  other areas.
• Pest range expansion could increase
  vulnerability.
• Predictions based on computer models.

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Damage to Aquatic Life

• Acid Shock - Caused by sudden runoff of large
  amounts of highly acidic water, either following
  heavy snowmelt, or when heavy rains follow a
  prolonged draught.

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Addressing Climate Change

• Reductions in Greenhouse Gas emissions.
• Improved energy efficiency.
• Increased investments in renewable and
  longer-term technologies.