CLIMATE CHANGE

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CLIMATE CHANGE
Pg. 70 What is climate? - The general atmosphere
conditions of a country or region. a.)
temperature b.) winds c.) moisture d.)
duration of seasons What creates climate? 1)
amount of solar radiation (insolation) received
and/or retained on planet Earth. Remember
the weather unit?
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CLIMATE CHANGE
Pg. 70 HOW CAN SOLAR RADIATION BE AFFECTED 1.)
Volcanic Activity - Ben Franklin realized could
affect weather (1784)! a.) Ash and dust block
sun b.) Gas sulfur dioxide reacts to form
sulfuric acid in atmosphere block sun OR CO2
can. ADD c.) Paradox/conundrum Add to
Greenhouse gases/effect. Is it possible that
volcanic activity can have two effects? Three
biggie eruptions Tambora 1815, El Chichon
1982, Mt. Pinatubo 1991
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CLIMATE CHANGE

• Pg. 70
• HOW CAN SOLAR RADIATION BE AFFECTED
• (CONTINUED)
• 2) Impact dust and debris block incoming sun
• energy (insolation)

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CLIMATE CHANGE
Pg. 70 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) 3) Orbital Variations -
Milankovitch SUPPLEMENTAL How much solar
radiation reaches earth and at what lat. and
season a) Eccentricity -changing from circular
to more elliptical 1.) more
ellipticalless insolation 2.) 100,000 year
cycle which seems to match glacial advance and
retreat times based on oxygen isotope record in
the ice sheets.
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CLIMATE CHANGE
Pg. 70 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) 3) Orbital Variations
Milankovitch SUPPLEMENTAL b) Tilt- varies from
21.5 to 24.5 degrees 1.) 41,000 year
cycle. 2.) during great tilt angles increased
seasonal extremes. This would include
greater snow meltless ice 3.) Lower
tiltwarmer wintermore precip. to form more
snow/ice. BUT the summer would be cooler when
most melting would occur.
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CLIMATE CHANGE
Pg. 70 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) 3) Orbital Variations
Milankovitch SUPPLEMENTAL c) Wobble
(Precession)- spinning top analogy tilt is the
same but it wobbles.19,000-23,000 year
cycle. 1.) Currently the wobble has Earth closer
to sun during wintermild winter compared to
southern hemisphere 2.) If pointing away
(winter) while a long ways away super cold then
pointing toward (summer) while close. BIG
seasonal contrast. Conundrum?
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CLIMATE CHANGE
ADD SUMMARY Like precession, axial tilt could
cause warmer winters, that relate to more
moisture available (more snowfall), and cooler
summers, more snow/ice lasts through the summer
months.
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CLIMATE CHANGE
Pg. 70 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) BUT WAIT!!!!!!!
Milankovitch problems? These orbital variations
seem to effect the hemispheres differently
(sometimes at least). So. The idea is that if
there is more heat in the system (Earth) the
oceans and atmosphere will distribute this for a
net increase in temps. on Earth. This theory is
highly substantiated by oxygen isotope record.
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CLIMATE CHANGE

• Pg. 70-71
• HOW CAN SOLAR RADIATION BE AFFECTED
• (CONTINUED)
• Ocean/atmosphere system - Generally warm water
• moves to poles and cold water to EQ
• a.) Tectonics affect by moving continents
• b.) Ocean currents (thermohyline conveyor) can
  also change by changing salinity of water (St.
  Lawrence)
• DRAWING FOR ST. LAWRENCE EXAMPLE
• RESULTS???
• El Nino (short term change) warm water makes it
  to coast of Peru and Ecuador kills fish creates
  lots of rainfall which results in flooding and
  mass wasting

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CLIMATE CHANGE
Pg. 71 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) 5) GREEN HOUSE - HUMAN
AFFECT Incoming sunlight is short wavelength
(UV) and CAN penetrate the atmosphere. Earths
surface emits long wavelength energy (infrared)
and CANNOT penetrate the atmosphere.
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CLIMATE CHANGE
Pg. 71 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) 5) GREEN HOUSE Greenhouse
Gases (continued) Carbon Dioxide -the biggie.
Methane - cows and swamp gas (organic
decay) melting of methane hydrates on ocean
floor? Ozone - forms in upper atmosphere. 3
oxygens hooked together. Absorb long
wavelength. Nitrous Oxide agriculture-fertilize
rs and fossil fuel combustion
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CLIMATE CHANGE
Pg. 71 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) LETS FOCUS ON CARBON
DIOXIDE SINKS where CO2 is stored Organic
material lots stored in permafrost Rocks
Coal and limestone Ocean Water and sediments
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CLIMATE CHANGE
Pg. 71 HOW CAN SOLAR RADIATION BE
AFFECTED (CONTINUED) LETS FOCUS ON CARBON
DIOXIDE SOURCES Volcanoes, ocean water and
organics Burning Fossil fuels significant source
Weathering of Limestone Other organics warm
up permafrost meltingincrease in decomposition
of organicsrelease of carbon dioxide and methane
RESEARCH LINK ON PERMAFROST AND CARBON
SEQUESTERING Creates positive feedback CARBON
CYCLE LINK
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CLIMATE CHANGE
Pg. 72 Today we produce an unnatural abundance
of CO2 and methane by burning fossil fuels
and weathering (increasing temps increases
weathering rates) of limestone ADD Isnt this
part of the carbon cycle? The problem is
what??? And that leads to. Add more to
atmosphere THAN CAN BE TAKEN OUT BY NATURAL
PROCESSES and will let solar radiation in but
not out!warming
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CLIMATE CHANGE
Pg. 72 IS GLOBAL WARMING REAL??? MANY SAY YES
Some say No WE CAN MEASURE IT- are
measurements accurate and representative??? a.)
Earths average surface temperature gt 1
degree F in past 100 years But. ND pg. 295
Fig. 10.39 b.) Models suggest an increase in
warming in past 20 years is attributed to human
activities
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CLIMATE CHANGE
Pg. 72 IS GLOBAL WARMING REAL??? MANY SAY YES
Some say No CONTINUED c.) In the 20th century
the 10 warmest years were between 1985-2000!
But. d.) Since industrial revolution 30gt
in greenhouse gases ADD CALCULATIONS/MODELS 1.)
Suggest human activity caused a 0.4C global
temp. change 2.) Only a small increase in
greenhouse gases could tip the scales toward
disaster. Why beg the issue?
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CLIMATE CHANGE

• Pg. 73
• HAS THE EARTH WARMED AND COOLED IN THE PAST??
• YES - HOW DO WE KNOW???
• Use the geologic record stored in rocks,
  sediment,
• fossils, and topography
• Topography shorelines record changes in sea
  level
• a.) lake shorelines record changes in climate
  patterns
• b.) Dune fields in Nebraska now stabilized
• c.) Glacial topography and evidence in areas
  where none
• exist today (NY and Midwest)

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CLIMATE CHANGE
Pg. 73 HOW DO WE KNOW??? continued 2) Sediment
ocean sediment record change (fossils) a.)
Lake and bog sediment record vegetation changes
(pollen). b.) Gives a pretty detailed account
of climatic changes c.) plants are sensitive
to climatic change BUT remember they are robust
in terms of extinction
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CLIMATE CHANGE

• Pg. 73
• HOW DO WE KNOW??? continued
• Fossils - cool weather fossils found in warmed
• location etc. dinos in Arctic

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CLIMATE CHANGE
Pg. 73 HOW DO WE KNOW??? continued 4) Rocks -
Tell story of changes in the past a.) Tillite
and Coal very important b.) Limestone and
reefs c.) Halite and Gypsum ADD EACH ARE
EVIDENCE OF WHAT???? LOCAL EXAMPLES a.)
????? b.) ????? c.) ?????
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CLIMATE CHANGE

• Pg. 73
• HOW DO WE KNOW??? continued
• Last 1,000 years historic records provide a
  unique
• look at past climate
• 1) grain and grape crops (tax records)
• 2) advance and retreat of mountain glaciers in
  Europe
• 3) paintings frozen canals etc.
• 4) sea ice records from around Iceland
• ADD HOW COULD EACH OF THE ABOVE HELP???
• 1.)
• 2.)
• 3.)
• 4.)

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CLIMATE CHANGE
Pg. 74 From 1000 - 1300 a.) Medieval Maximum
(Optimum) -times are good and warm. b.)
Iceland and Greenland were settled (farming)
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CLIMATE CHANGE
Pg. 74 From 1400-1900 a.) Little Ice
Age b.) Cold in Europe reduced crops
famine c.) Iceland and Greenland
abandoned d.) Canada had build up of snow
fields and the beginnings of icesheets
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CLIMATE CHANGE
Pg. 74 From 1645-1715 a.) Maunder Minimum
especially cold! b.) Usually attributed to
decreased sunspot activity.