Past and Present Climates

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Past and Present Climates

• Lynn Gribble
• 6/9/09

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Eco Tip 8 Water

• Up to 40 of bottled water comes from the same
  source as tap water, but is sold back to
  consumers at hundreds of times the cost.
• More than 17 million barrels of oil last year
  were used to produce and transport bottled water
• Enough fuel for more than 1 million U.S.
  cars for a year - and generated more than 2.5
  million tons of carbon dioxide.
• ( http//www.thinkoutsidethebottle.org/ )

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Climate

• Defn The collective state of the atmosphere for
  a given location over a specific amount of time
• Location global, hemispheric, continental,
  regional, city
• Time usually however long there is an accurate
  record
• Averages and extremes

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Climate Controls (Review)

• Latitude distance from equator associated with
  warmer climate
• Elevation higher altitudes associated with
  colder temps
• Topography vegetation modulates temperature
• Proximity to large bodies of water coastal
  cities vary less in temperature
• Prevailing atmospheric circulation

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Climate Zones

• Köppen Scheme classification scheme which
  separates the globe into 24 climate zones. (6
  main zones with sub-categories)

Figure 14-3
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Type A Tropical Humid

• High average temperature
• Small annual temperature range
• Abundant rainfall Figure
  14-4

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Type B Dry Climates

• Potential evaporation and transpiration exceeds
  precipitation
• Includes both warm climates and cold ones
  (desserts and poles)
  Figure 14-5

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Type C Moist Subtropical and Mid Latitude

• Humid and mild winters
• Warm average temperature
• Large annual temperature range Figure
  14-6

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Type D Severe Mid-Latitude

• Tend to be located in eastern regions of
  continents
• Great temperature range
• Usually have snow on the ground for extended
  periods
  Figure 14-10

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Type E Polar Climates

• Pole-ward of the Arctic and Antarctic circle
• Extremely cold with little precipitation (not
  considered dessert b/c precipgtevap) Figure 14-12

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Type FHighland

• Wide variety of climates due to wide variety of
  latitude, altitude, and exposure to solar energy
• Various precipitation based on orientation

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5 Minute Break!

• Exam 2 Thursday
• Onwards to Past Climate ?
• (For a really easy, fun read about the past, I
  recommend A Short History of Nearly Everything
  by Bill Bryson)

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Past Climate

• Historical Climate the period of the past in
  which humans have kept record of climate.
• Instrumental Climate the period of the past in
  which specialized scientific instruments were
  used to keep record of climate
• Paleo-climate climate records from pre-history

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Tree Rings

• Dendrochronology
• Tree ring width varies due to temperature and
  moisture changes
• Gives information about temperature and precip
  changes
• Qualitative (relative)

Figure 14-15
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Pollen Records

• Pollen Degrades slowly therefore this along with
  radio-carbon dating is a good proxy for climate
  records.
• Also different
• types of pollen
• Gives information
• about changing
• plant types

Figure 14-17
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Air Bubbles and Dust in Ice

• Accurate concentration of atmospheric gases from
  the past
• Dust indicates volcanic activity, and source
  regions for air masses and therefore circulation
  patterns

Figure 14-18
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Marine Sediments and Fossils

• Calcium Carbonate is useful for tracking relative
  amounts of oxygen isotopes (indicates relative
  cold or warm periods)
• Plant and animal fossils give good idea of
  climate based on the type of life that a given
  time period supported

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UAlbany studies in paleo-climate include

• John Delano (AGEO 105 Intro to Envi Sci)
• Early Earth Environments how these environments
  impacted the evolution of sustainable life
• Bombardment history
• Brad Linsley (AGEO 450 Climate Change)
• Generation of time series from Pacific Ocean
  corals and sediment cores
• Mathias Vuille
• Paleo-climatology in tropical mountain glaciers
  (Andes)
• Glacial recession prediction

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Change Mechanisms

• Volcanic Eruptions lead to cooler climates. Why?
  Ash and soot from eruption block sloar radiation
  causing cooling
• Asteroid Impacts , depending on impact location
  could cause extended darkness, global fires, acid
  rain, ozone loss, and huge tsunamis.
• Solar Variability 11 year sun spot cycle
• Fewer sunspots less energy, cooling
• "Little Ice Age (300 yrs ago) little to no
  sunspots

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Change Mechanisms

• Milankovitch Cycles
• Eccentricity Shape of earths orbit
• 100,000 year cycle
• Procession wobble around axis of rotation
• 23,000 year cycle
• Tilt/Obliquity change in angle of inclination
• 41,000 year cycle

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Change Mechanisms

• Milankovitch Cycles
• D\Media\Active_Figures\71_Orbital_Fluctuations\A_
  71.html

Figure 14-25A
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Change Mechanisms

• Changes in Ocean Currents
• Plate Tectonics continental movements
• Pangea Tropical , flat super continent
• (todays high latitude continents and mountains
  could contribute to cooling)
• The fact that natural factors caused climate
  changes in the past does not mean that the
  current climate change is natural. By analogy,
  the fact that forest fires have long been caused
  naturally by lightning strikes does not mean that
  fires cannot also be caused by a careless camper.
  

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So what does our past climate look like?