Changing Climates

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Changing ClimatesNaturally

• Changes in the millions of years
• Theory of plate tectonics
• glaciers in Australia, Africa
• atmospheric composition (degassing)
• Common fossil species on S. America/Africa

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• 2. Changes in the thousands of years
• Astronomical influences (Milankovitch theory)
• Eccentricity-change in earths orbit around the
  sun (100,000) either more elliptical or circular
• Precession-the wobbling of our axis, point
  towards Vega Star versus Polaris (N.
  Star)(23,000)
• Obliquity-change in the degree of tilt (ex 23.5
  to 22.0) (41,000)

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• 3. Changes over small time periods
• a) volcanic eruptions cooling for a few years
• SO2 acts as reflector, dust as well
• b) sun spots/solar variations more sunspots
  greater solar output (10-100 years) output
  changes approx. /- 0.01