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Global Climate Change

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Title: Global Climate Change


1
CLIMATE
2
SOME REVIEW
  • Weather is the condition in the atmosphere at a
    given place and time.
  • Climate describes the long-term pattern of
    weather at a given location. 
  • Weather and climate are key components of Earth's
    energy flow and cycles of matter, especially
    water, oxygen and carbon dioxide. 

3
CLIMATE
Generally based on temperature and moisture
patterns
4
Energy and the atmosphere
  • Heat energy enters the atmosphere from heat
    absorbed and radiated from the earth, from
    friction due to winds, volcanic activity and
    absorption of insolation.

5
Radiation
  • All bodies of matter radiate electromagnetic
    energy. The higher the temperature of the
    radiating body the more energy it will emit and
    the shorter the wavelength.

6
Energy can be transferred three ways
  • Radiation travels as electromagnetic waves and
    can even pass through empty space. 
  • Convection occurs in fluids (liquids and gases)
    and involves density-driven currents.  Warmer,
    less-dense fluids rise and cooler, more-dense
    fluids sink. Convection currents are most
    important in creating weather and moving tectonic
    plates.
  • Conduction involves heat energy moving between
    substances that are touching, such as your hand
    and a hot pot. 

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  • The electromagnetic spectrum describes all of the
    various types of radiant energy, each of which
    covers a specific range of wavelengths. (ESRT p.
    14)
  • The Sun's energy reaches Earth as incoming solar
    radiation (Insolation). Most of the insolation
    is visible light, with lesser amounts of infrared
    (heat) and ultraviolet waves.

9
INSOLATION
  • Incoming
  • solar
  • Radiation

10
ABSORBTION OF ENERGY
  • Dark-colored objects are good absorbers and
    radiators of heat, and poor reflectors. 
  • Light-colored objects are good reflectors, but
    poor absorbers or radiators.
  • Smooth surfaces are good reflectors and rough
    surfaces are good absorbers.

11
Energy Temperature
  • Kinetic energy is energy of moving things. The
    faster they move, the more KE they use.
  • Temperature is the "average kinetic energy" of an
    object. 
  • Potential energy is stored energy.  It increases
    with mass and as the object gets higher.

12
ALBEDO
  • The amount of insolation reaching Earth is
    balanced by the amount reflected back to space
    (albedo) and the terrestrial re-radiation, mostly
    as infrared waves.
  • Radiative balance (equilibrium) occur when the
    energy emitted by an object is equal to that
    absorbed by the object.

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15
Global and Regional Weather and Climate Systems
16
  • Local weather is a small part of global and
    regional weather patterns.
  • Global wind, pressure, and precipitation patterns
    result from differences in the amount of energy
    received at different latitudes and Earth's
    rotation.

17
  • Global climate patterns (ESRT p. 14) include wet
    conditions and calm winds centered around the
    equator (doldrums) east-to-west winds trade
    winds in the tropics zones of calm centered
    around 30 degrees north and south ("horse
    latitudes") west-to-east winds in the
    mid-latitudes ("prevailing westerly") and
    east-to-west winds at high latitudes ("polar
    easterlies").

18
Additional Climate and Weather Factors
  • Adiabatic Cooling As air rises, it cools because
    it expands and the pressure decreases.
  • Adiabatic Heating As air sinks, it warms as it
    contracts and the pressure increases.
  • Orographic effect As air rises up the windward
    side of a mountain, adiabatic cooling occurs, and
    as it sinks down the leeward side, adiabatic
    warming occurs. So the windward side has greater
    cloud cover and precipitation, and the leeward
    side often has a rain-shadow desert.

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20
Water Climate
  • Water has a higher specific heat value than
    rocks, so when the same amount of insolation
    strikes materials at a shoreline, the water will
    remain cooler and the beach will warm up more
    rapidly. 
  • These heating rate differences produce on-shore
    sea breezes during the day and off-shore land
    breezes  at night.

21
WARM AIR RISES
COOL AIR MOVES INLAND
22
COOL AIR OVER THE LAND PUSHES OUT TO SEA
WARM AIR RISES
23
  • Large bodies of water make cooler summers and
    warmer winters. 
  • On a regional scale, similar factors create the
    monsoons, with wet-seasons in summer and
    dry-seasons in winter. 

24
Global Climate Change
  • A long term perspective

25
Global WarmingTruth? Fiction? Both?
  • CO2 levels in the atmosphere rising
  • Average global temperature is rising
  • Polar ice caps and mountain glaciers are
    shrinking
  • Sea level is rising
  • Deserts are expanding
  • Weather is getting more severe

26
Is this normal?
  • How can we tell if the present change in climate
    is normal or something produced by humans?
  • Is the amount of present climate change normal or
    is it extreme?
  • Is there any way to answer these questions?

27
Changing Perspectives
  • Our perspective single human life.
  • We can expand to a few other generations based on
    research.
  • We need a longer time frame to evaluate global
    climate change.
  • Sohow do we do that???

28
The Geologic Record
  • The evidence contained in the ROCKS of the EARTH
    for the past 4.6 BILLION years
  • Provides us with longer perspective
  • Contains indirect evidence of climate
  • Contains direct evidence of climate
  • Gives us a history of global climate change on a
    scale of millions of years to billions of years.

29
Indirect Evidence
  • Evidence for
  • Aridity
  • Warm Climate
  • Cold Climate
  • Recorded by specific types of rocks

30
Examples Desert sandstones
31
Examples Reef Limestones
32
Examples Glacial Features
33
Direct Evidence
  • Ice Cores a core sample from glaciers that have
    trapped air bubbles from previous time periods
  • Can contain wind-blown dust, ash, bubbles of
    atmospheric gas and radioactive substances
  • Sediment Cores - long cylinders of sediment taken
    from beneath the surface of the (usually) ocean
    floor.

34
Ice Cores
35
Data from Ice Cores
  • Direct Evidence for last 100,000 years
  • Quantities of dust in each layer
  • Related to wet vs. dry climate
  • Air bubbles trapped in each layer
  • Samples of ancient air
  • Levels of CO2

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37
Sediment Cores
  • Deep Sea Drilling Project (DSDP)
  • Ocean Drilling Project (ODP)
  • Integrated Ocean Drilling Project (IODP)
  • Coring in lakes and bogs
  • contain microscopic fossils of marine animals,
    volcanic glass, sands originally from land cosmic
    material, and other unusual materials unique to a
    marine environment

38
  • The microfossils are important as time and
    environmental indicators they are very sensitive
    to slight changes in temperature and chemical
    changes in their environment.
  • Volcanic glass is an important "time marker" and
    records instantaneous geological events.
  • Sands can indicate the presence of ocean
    currents, tell of ancient shorelines, reveal a
    past dust storm, or record submarine slides which
    might indicate submarine earthquakes.
  • Deep-sea samples hold a permanent record of
    magnetic history revealing to scientists the
    ever-changing magnetic orientation of the poles.

39
SoWhat does theGeologic Record Tell Us?
  • The normal climate of the past 1.0 billion
    years was
  • Warmer than present
  • More uniform than present (less fluctuation)
  • Past 20 million years have been highly variable
    and generally much colder

40
Climate History20 Ma to Present
  • 20 Ma climate was somewhat moderate
  • Similar to present
  • 5 Ma coldest climate of past 65 million years
  • 2 Ma Great Ice Ages begin
  • At least 4 episodes of glacial advance melt
    back
  • 12,000 10,000 Modern Climate sets in

41
Recent Climate History
  • 7000-6000 BP - Warm Peak
  • 950-1300s Medieval Warm Spell
  • 1300s Cool and Wet
  • 1550 1850 Little Ice Age

42
Food For Thought
  • How many of the great events of recorded human
    history have been directly influenced by climate?

43
Recent Climate History
  • 7000-6000 BP - Warm Peak Great Ancient
    civilizations (e.g., Mesopotamia, Egypt)
  • 950-1300s Medieval Warm Spell Rise of
    modern European nation-states
  • 1300s Cool and Wet Bubonic Plague/Dark Ages
  • 1550 1850 Little Ice Age
  • First Settlers come to America many deaths
  • Washington crosses the Delaware
  • Winter at Valley Forge

44
So, are we to blame?
  • Paleoclimatic record reveals major shifts in
    climate through time
  • Is it coincidence or causation that climate is
    warming as we come out of last ice age?
  • Is it coincidence or causation that industrial
    revolution falls within this same time?

45
What factors cause changes in climate?
  • Long term vs. short term changes
  • Volcanic eruptions
  • Ex eruption of Krakatau in 1883
  • Yellowstone supervolcano 2 MYA, 1.3 MYA,
    630,000 YA
  • Earths orbital variations
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