The Earths Atmosphere

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The Earths Atmosphere
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The Modern Atmosphere (500 mya to the present)

• Nitrogen, N2 (78)
• Oxygen, O2 (21) 99.9
• Argon, Ar (0.9)
• Trace gases
• water vapor (0-4)
• carbon dioxide (.036), methane (greenhouse
  gases)
• nitrogen oxides, sulfur oxides (acid rain and
  more)
• many other trace gases
• particulate (dust)

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Atmospheric Pressure
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The Vertical Thermal Structure of the Atmosphere
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Temperature Inversions
When warmer air overlies cooler air, pollutants
and fog are trapped beneath the inversion.
Common Winter Radiation Inversion in Valleys
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Temperature Inversions
Common Summer Inversion in Los Angeles
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The Importance of Stratospheric Ozone

• Ozone formed naturally in stratosphere (after
  photosynthesis became common)
• UV radiation (sun) --gt mutations
• plankton reduced (food chain base), crops decline
• weaker immune systems, skin cancer
• Stratospheric ozone (O3) absorbs UV rays

light
?
O2 ? 2 O then O O2 ? O3
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The Importance of Stratospheric Ozone

• CFCs
• link to ozone hole established in 1970s
• Chloroflourocarbons (refrigerants, aerosols)
• one Cl can decompose more than 100,000 O3
• Montreal Protocol, 1987 U.N. agreement on ban
• up to 10 years for rising CFC gases to reach
  stratosphere once in the stratosphere, CFCs can
  last up to 50-100 years

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NASA Ozone Watch Images Data Animations
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Global Warming (Human-accelerated Greenhouse
Effect)

• The Greenhouse Effect
• Greenhouse Gases
• The Global Warming Hypothesis
• Observed Warming and Rising CO2
• The Effects of Global Warming

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The Greenhouse Effect
Water Vapor Carbon Dioxide Methane
Greenhouse Gases
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The Greenhouse Effect

• Keeps Earths average temperature 90º F warmer
  (59º F 16 ºC average now)
• Human role? A heated
  debate

Venus 480ºC thick carbon
dioxide
Mars -62 ºC little carbon dioxide
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Global Energy Balance
NO. Why not?
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b
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Global Surface Temperature Increase
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Note that very recent rate of increase greatly
exceeds anything in last 1000 years.
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650,000 years of climate and CO2
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Changes in Solar Radiation
Milankovitch Cycles explain much (60) of the
changes

• 21,000 year cycle perihelion shifts throughout
  the year
• 41,000 year cycle /- 1.5 change in Earth's
  tilt
• 100,000 year cycle Orbital eccentricity of the
  elliptical orbit of the Earth

The most recent ice age lasted 100, 000 years. We
are currently in an interglacial period
(Holocene).
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Climate models suggest that the changes are just
beginning now and will accelerate.
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The Global Warming Hypothesis

• Human-induced rise in CO2 levels is theorized to
  lead to unnatural warming of atmosphere.
• Likely effects
• Increased storminess
• Rising sea level (1-3 ft. in 100 years - IPCC,
  2001)
• Loss of arable land (some areas hotter, others
  cooler)
• Extinction of thousands of species
• Loss of nearly all coral reef
• Possible effects even include climate flip-flop
  wherein dangerous rapid cooling sets in!

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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 mean sea level.
IPCC Report, 2007
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So is Global Warming Really Happening? How much?
GLOBAL average temperatures will likely rise by
2.2-10F (1.4-5.8C) by the year 2100, according
to the most authoritative report yet produced by
the UN Intergovernmental Panel on Climate Change
(IPCC). These are massive increases over the .5C
rise seen over the last 100 years.
Source UN IPCC, 2001
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So is sea level rise happening? How much?
GLOBAL average sea levels will likely rise by .5
- .9 meters (1.5 2.7 feet) by the year 2100,
according to the most authoritative report yet
produced by the UN Intergovernmental Panel on
Climate Change (IPCC). When added to storm surges
and high tides, these small changes may have
large effects.
Source UN IPCC, 2001
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Where is CO2 released?
Total carbon release in metric tons, Source OECD