GEO ch. 8

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  1. Global climatic shifts have occurred throughout the earth's history
  2. Why Study Past Climates?
    • Test numerical climate models
    • find analogs for possible future climate changes
    • gain knowledge of past variations to help us understand climate system
    • examine possible human influences on climate
  3. How can we study past climates?
    • satellites
    • ground instruments
    • proxy data
  4. Types of proxy data
    • Historical data
    • Tree rings
    • Fossil pollen
    • Ice Cores
    • Ocean and lake sediments
    • Geology
  5. Historical data (proxy)
    Historical documents, ship logs, farmers logs, diaries, newspapers, official records, environmental disaster accounts
  6. Tree rings (proxy)
    Annual growth rings
  7. Fossil pollen (proxy)
    well preserved in anaerobic conditions pollen grains have distinctive shapes and can be arranged chronologically by depth
  8. Ice cores (proxy)
    ice accumulation in glaciers preserves dust, gas bubbles, isotopes
  9. Ocean and lake sediments (proxy)
    physical, chemical, and isotopic characteristics of sediments (and fossils)
  10. Geology (proxy)
    sedimentary rocks; erosional patterns; coastal landforms, coral reefs
  11. Pleistocene glaciation
    • currently in pleistocene epoch: characterized by several significant glacial events during periods of reduced insolation at the poles
    • last glacial event ended about 9000 years ago.
  12. Milankovitch Theory
    Combined effect of eccentricity and precession produces regular changes in the amount of solar radiation reaching earth surface
  13. Tilt
    • Natural changes in the earth's tilt affects amount of solar radiation reaching polar areas
    • less tilt equals less solar radiation reaching polar region in summer
  14. Eccentricity
    • Natural changes in shape of earth's orbit can affect the amount of solar radiation reaching polar areas
    • cycle of 100,000 years
  15. precession
    • determines time of year perihelion occurs
    • 21,000 year cycle
  16. Human impacts on greenhouse gas production
    • creation of artificial wetlands as a result of wet rice cultivation in the tropics
    • global Clearing of forests for agriculture
  17. potential climate change impacts
    • water resources¬†
    • agriculture
    • coastal erosion and or inundation
    • human health¬†
    • marine ecosystems
    • terrestrial ecosystems
    • endangered species
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GEO ch. 8
2015-10-11 10:13:56
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