Climate Change II

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Climate Change II

• November 7, 2007

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Milankovitch Cycle

• Produces variations in solar radiation received
  at Earths surface
• Changes in shape (eccentricity) of the Earths
  orbit around the sun
• Precession of the Earths axis of rotation, or
  wobbling
• Changes in the tilt (obliquity) of the Earths
  axis
• When taken into account, the present trend should
  be towards cooler summers over the higher
  latitudes of the Northern Hemisphere
• http//www.educnet.education.fr/svt/anim/ticeparis
  nov2003/hf/tp_o18/milanko.swf

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The Earths orbit and tilt combine to create the
seasons.
Orbital View
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Arctic Climates

• Arctic region warmed 9F since 1987
• This has led to a freshening of northern oceans
• Greenland ice melting at 1m/year
• Permafrost is melting
• Increased precipitation in Arctic/Antarctic areas
• What does this mean for ice sheets?

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Three States of Water
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Thermohaline Circulation Revisited

• Antarctic component
• Sea ice formed of freshwater makes ocean saltier
  heat released
• The saltier water sinks becoming the deep ocean
  portion of the conveyor belt
• 4 areas of sinking water 2 off Antarctica and 2
  in North Atlantic

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Thermohaline Circulation
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Carbon Cycle Feedback Mechanism(Billions of
Metric Tons)
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Clouds Feedback Mechanism

• Net warming effect
• Cirrus (ice)
• Expected to increase
• Net cooling effect
• Stratus (water)

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Global Warming

• Warmer air temperatures mean higher rates of
  evaporation
• Therefore rainfall must also increase
• Increase in intensity of precipitation
• Increase in hurricanes
• Happy plants happy bugs
• Desertification reductions in convection

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Temperature ºC
Solar Radiation
Carbon Dioxide ppm
Methane ppb
Dust Flux
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