Greenhouse Effect & Global Warming The Earth s Atmosphere

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Greenhouse Effect Global Warming
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The Earths Atmosphere

• 2 elements Nitrogen (N2) and Oxygen (O2) make up
  99 of the volume of clean, dry air.
• Remaining 1 of gases are inert gaseous elements
  like Argon. These gases are sometimes called
  Trace gases and are often referred to as the
  Greenhouse Gases- ( they function much like the
  glass plates found on a greenhouse used for
  growing plants.) http//www.rcn27.dial.pipex.com/c
  loudsrus/images/atmosc20compos.jpg

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Earths Atmosphere

• composed of gases (like CO2 and CH4 ) of just the
  right types in the right amounts to warm the
  earth to temperatures suitable for life.
• The effect of the atmosphere to trap heat is the
  "greenhouse effect."www.solcomhouse.com

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The Goldilocks Principle

• "Venus is too hot, Mars is too cold, and Earth is
  just right.
• Earth has an average surface temperature
  comfortably between the boiling point and
  freezing point of water, and is suitable for our
  life.
• This cannot be explained by simply suggesting
  that our planet orbits at just the right distance
  from the sun to absorb just the right amount of
  solar radiation.
• Our moderate temperatures are also the result of
  having just the right kind of atmosphere.

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Goldilocks

• A Venus-type atmosphere would produce hellish,
  Venus-like conditions on our planet a Mars
  atmosphere would leave us shivering in a
  Martian-type deep freeze. http//www.ucar.edu/lear
  n/1_3_1.htm

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Our atmosphere is Just Right

• Parts of our atmosphere (greenhouse gases-like
  CO2) act as an insulating blanket of just the
  right thickness, trapping sufficient solar energy
  to keep the global average temperature in a
  pleasant range.
• The Martian blanket is too thin, and the Venusian
  blanket is way too thick!

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Global Insulators

• Greenhouse gases, like water vapor (H20 ), carbon
  dioxide (CO2) and methane (CH4), all act as
  effective global insulators.
• Lets see How

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Energy from the Sun

• Absorbed by land, oceans, and vegetation at the
  surface, visible light is transformed into heat
  and re-radiates in the form of invisible infrared
  radiation.
• If this was ALL that happened, then during the
  day earth would heat up, but at night, all the
  accumulated energy would radiate back into space
  and the planet's surface temperature would fall
  far below zero very rapidly!
• This doesn't happen b/c the earth's atmosphere
  contains molecules (CO2) that absorb the heat and
  re-radiate the heat in all directions. This
  reduces the heat radiated out to space
• These greenhouse gases serve to hold heat in
  like the glass walls of a greenhouse, and are
  responsible for the fact that the earth enjoys
  temperatures suitable for life.

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Carbon dioxide (CO2)A Greenhouse Gas

• CO2 is made up of 1 carbon atom with an oxygen
  atom bonded to each side. When its atoms are
  bonded tightly together, the carbon dioxide
  molecule can absorb infrared radiation and the
  molecule starts to vibrate.
• The vibrating molecule will emit the radiation
  again, and it will likely be absorbed by yet
  another greenhouse gas molecule. This
  absorption-emission-absorption cycle serves to
  keep the heat near the surface, effectively
  insulating the surface from the cold of space.
• For demo go to http//www.ucar.edu/learn/1_3_1.h
  tm

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What do Greenhouse gases have in common?

• Carbon dioxide, water vapor, methane , nitorus
  oxide, and a few other gases are greenhouse
  gases. They all are molecules composed of more
  than two component atoms, bound loosely enough
  together to be able to vibrate with the
  absorption of heat. The major components of the
  atmosphere Nitrogen and Oxygen are two-atom
  molecules too tightly bound together to vibrate
  and thus they do not absorb heat and contribute
  to the greenhouse effect.

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Greenhouse effect

• Natural situation in which HEAT is retained in
  Earths atmosphere by Carbon dioxide, Methane,
  Water Vapor and other gases. (pg. 87)

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Climates Past

• Our evolutionary origins lie in the warm
  equatorial Africa, but our ancestors battled the
  cold, harsh, and unforgiving climate of the last
  ice age in order to spread across the planet.

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Climate History

• We know that the earth's climate has changed over
  time. Throughout the earth's history, there have
  been periods of glaciation followed by warming
  trends in which the glaciers retreated toward
  higher altitudes and latitudes. Today's concerns
  focus on the current and projected rate of
  climate change based, in large part, on human
  activities.
• Some 10,000 years age, the ice age ended. We
  developed agriculture, civilization, industry,
  and technology generally in a global climate that
  was warm, pleasant, and mostly predictable.
  Regional climates have changed, sometimes
  drastically and disastrously for local human
  populations, but by and large the global climate
  has not dealt any significant long-term blows to
  the spread and development of human civilization.

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Fossil Fuels

• One of the most significant accomplishments of
  our species is the discovery of fossil fuels and
  the means of turning the energy trapped within
  them into heat, transportation, and the basis for
  manufacturing and construction

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Changing the world forever?

• On an ancient warmer Earth with a high
  concentration of carbon dioxide in the
  atmosphere, photosynthetic organisms (algae and
  higher plants) absorbed carbon dioxide , and used
  it to produce abundant organic material. When
  these organisms died, they were buried deep
  within the earth and slowly turned into coal and
  oil.
• Since the 1800s, we've been burning vast
  quantities of these fossil fuels to power our
  developing technological and global civilization.
  
• So, we've been releasing the CO2 trapped in the
  fuels in the form of energy-rich organic
  molecules back into the atmosphere, increasing
  the atmospheric concentration of CO2 .

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So What?

• Since the 1800s, CO2 concentrations worldwide
  have increased from approximately 280 ppm (or
  0.028) to around 365 ppm (0.0365). The increase
  might seem trivial, but it also means that some 3
  gigatons (3 billion metric tons) of CO2 are
  being added to the atmosphere every year!
• Knowing that CO2 is a GREENHOUSE gas, what might
  Increased Concentrations of this gas do to our
  climate?

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CO2

• CO2 is a powerful greenhouse gas!
• We can therefore conclude that the earth's
  temperature should go up as CO2 concentrations
  increase.

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Climatologists have detected a steady but small
increase in global average temperatures over the
last few decades, based on weather data collected
all around the world. Six of the last ten were
the hottest years on record.
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Global Warming

• An increase in the Average Temperature of the
  Earth (pg. 159) http//www.weatherquestions.com/gl
  obal_warming_Jones.jpg

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• Why is the carbon cycle so important when looking
  at climate change issues?

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• What major events in human history are thought to
  be factors in changing the earth's atmosphere?

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