Download Climate Change

Climate Change
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Weather vs. Climate
• Weather is the atmospheric conditions at a
given place at a given time.
– Example: On Sunday it was 72 degrees
Fahrenheit and mostly sunny in Sacramento.
• Climate is the average weather of a place
over a long period of time.
– Example: Sacramento has hot dry summers
and cool wet winters. (Mediterranean climate)
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Climate
• Temperature and precipitation are how we
measure climate.
• Climate information preserved in the
geologic record only tells us about
temperature.
• We infer precipitation from temperature.
– Warmer climates are usually wetter
– Colder climates are usually drier
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Plate Tectonics & Climate
• On longer time scales (millions of
years) Plate Tectonics play a
major role in climate.
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Plate Tectonics & Climate
• Movement of
plates +
landmasses can
close or open new
pathways for
ocean currents
(Isthmus of
Panama)
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Plate Tectonics & Climate
• Building or
destruction of
topography changes
global air circulation
patterns (Himalayas)
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Plate Tectonics & Climate
• Changing ocean currents and
global air circulation patterns
can cause major changes to
climate.
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Climate
• What do we use to analyze climate?
– Ice Cores
– Tree rings
– Glacier length
– Ocean sediments
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Ice Cores
• Ice Cores are
pieces of ice
that are drilled
out of glaciers,
ice sheets and
shelves
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Tree Rings
• Growth rings form
every year. They
often reflect the
conditions in which
the tree grew.
• Thicker rings indicate
more sun and rain.
• What would thinner
rings mean?
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Glacier Length
• Longer and larger
glaciers mean a
colder climate.
• Shorter and
smaller glaciers
mean a warmer
climate.
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Ocean Sediments
• Tiny fossil sea
animals, called
foraminifera are found
in the material at the
bottom of the ocean.
• By analyzing the
fossils scientist can
determine the
temperature of the
ocean at the time the
sea animal died.
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Earth’s History
• We will use years before present (b.p.),
measured from 1950, to describe Earth’s
history.
• Using the next slide answer the following:
– Which way is time flowing on the diagram?
• From Left to Right
• From Right to Left
– Did modern humans (homo sapiens) live at
the same time as sabertooth tigers?
– Do wooly mammoths live today?
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Average Global Temperature
• Average Global Temperature is the
average temperature of all locations on the
surface of Earth.
– Today’s average global temperature is
approximately 59° Fahrenheit (14° Celsius)
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Global Warming
• Global Warming is when the Average
Global Temperature goes up.
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Ice Age vs Glaciation
• Ice Ages are periods of time when large portions
of the Earth’s surface are covered with ice
sheets.
• Ice Ages last 10-100’s of millions of years.
• Glaciations last 10’s of thousands of years.
• We are dealing with glaciations (short ice ages)
• The time period between ice ages/glaciations is
called an interglacial period.
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Ice volume
• Ice volume is the
amount of Ice on the
surface of the Earth.
– Glaciers
– Sea Ice
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Greenhouse Effect/
Gases
• Greenhouse gases
trap heat in the
Earth’s atmosphere.
• This trapping of heat
is called the
Greenhouse Effect.
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Carbon Dioxide (CO2)
• CO2 is a greenhouse
gas.
• Sources of CO2 are:
– Volcanoes
– Forest Fires
– Factories & Cars
(Burning of Fossil
Fuels)
– Other Natural Sources
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Insolation
• Insolation is the amount of energy from the
Sun reaching the Earth.
• The solar energy is measured in watts per
square meter (W/m2).
• Insolation is dependent on the changes of
the Earth’s orbit (Eccentricity, Tilt, and
Precession).
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Changes in the Earth’s Orbit :
Eccentricity
Near-circular Orbit =
Mild winters but
cool summers.
Favors Ice Age
Eccentric Orbit =
Cold winters but
hot summers.
Favors Interglacial
Period
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Changes in the Earth’s Orbit :
Tilt
• Small Axis Tilt: Mild
winters but cool
summers. Favors Ice
Age
• Large Axis Tilt: Cold
winters but hot
summers. Favors
Interglacial Period
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Changes in the Earth’s Orbit :
Precession
Precession is the
"wobble" of the Earth's
rotational axis. One
complete wobble takes
26,000 years.
Precession changes the
pole star as seen from
Earth.
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Industrial Revolution
• The time period in
which machine power
replaced human and
animal power in the
production of goods.
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Biodiversity
• Number and variety of species on Earth.
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Biome
• Area on the Earth with a particular climate.
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