Wasting class time?

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Wasting class time?

• Please get out a piece of paper and read the
  board! ?

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Climate on a geologic scale
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First, try this

• Take the average of the following numbers 100,
  0
• Take the average of 100,100,100,100,100,100,100,10
  0,100, 0
• (thats 9 sets of 100)

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How does having more data affect an average?

• 2014 global average temperature
• 58.24 oF

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Observations?
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Three important inferences

• Climate change has been a natural cycle
• 100,000 year cycles between glacial maximum (ice
  age) and interglacial periods (maximum warmth)
• A change in global average of -3oC (about -5oF)
  can create an ice age
• Historically, the RATE has been slow enough that
  species could evolve to keep up with the changes.

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CO2 levels in the geologic record

• Response of ocean to increased radiation as
  Milakovitch cycles brought Earth closer to sun
  warm ocean releases CO2

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Milankovitch cycles create the 100,000 yr pattern

• Obliquity (Axial tilt)
• Eccentricity (orbit eliptical or circular)
• Precession (wobble on axis)
• Combination of these creates 100,000 year cycle
  of warming and cooling

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So where did this data come from? (since historic
records have only been kept since 1880)
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Studying geologic climate

• Historic records exist 130 years (since 1880)
• Inferred/Implied records
• Fossil records
• Tree rings relative amounts of oxygen isotopes
  (proxy methods)
• Ice cores - paleothermometers

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Tree rings isotopes of Oxygen
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Ice core sampling
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(No Transcript)
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Check for understanding

• Which is surprising to climatologists that the
  climate changes or the current rate of change?
• What is the name of the 100,000 year cycles of
  warming and cooling?
• How do climatologists study the ancient
  atmosphere? (name 4 ways)
• Why is a .7oC (1oF) change significant?

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Climate and civilization

• Human civilizations change when climate changes
• 20,000 ybp (years before present) ice age
  Bering strait freezes, people migrate to the
  Americas
• 8,000-7,000 ybp warming period Mesopotamia
  flourishing, Jericho established

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Mayan civilization collapses suddenly 950 CE
(common era used to be called AD)Leif Erikson
950 CE sails to Greenland
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Black Death in Europe famine 1315-1317 needed
to import grain from ChinaLittle Ice age
1550-1850 Irish Potato Famine
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Dust Bowl 1930s

• Mild but persistent La Nina conditions coupled
  with changes of sea surface temperatures poor
  farming practices

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Discuss with your neighbor

• How do humans depend on predictable climate?
  (any examples in the news right now?)
• Explain how climate has changed over geologic
  time on Earth.

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CO2 levels currently

• Mauna Loa Observatory - Hawaii
• CO2 at beginning of Industrial revolution 280
  ppm
• Current CO2 levels 398ppm
• (watch the movie when is CO2 highest? Where???
  Why???)