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The Greenhouse Effect, Who needs It

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Earth Without an Atmosphere. Let's calculate the theoretical temperature of Earth's surface ... Shortwave energy passes through atmosphere and heats surface ... – PowerPoint PPT presentation

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Title: The Greenhouse Effect, Who needs It


1
The Greenhouse Effect,Who needs It?
2
The Greenhouse Effect
  • What is it?
  • How does it work?
  • Is it a bad thing?
  • What does it have to do with global change?

3
The Greenhouse Effect
  • Air inside a greenhouse is warmer than air
    outside even though there is no internal heat
    source.
  • Earths surface is warmer than it should be.
  • How warm should Earths surface be?

generalhorticulture.tamu.edu/.../Temp/temp.html
4
Earth Without an Atmosphere
  • Lets calculate the theoretical temperature of
    Earths surface
  • Conservation of Energy
  • First consider
  • Conservation of Mass

5
Conservation of Mass
In Out Change in Storage
In
How is change in storage measured?
Change in Storage
Out
6
Conservation of Energy
  • Energy in Energy out Change in Stored Energy

How is this energy stored?
HEAT!!
TEMPERATURE!!
7
Conservation of Mass and Energy
8
Conservation of Energy
The ideal Earth/Atmosphere is in radiative
equilibrium with the sun!
IN OUT 0
IN OUT
9
In Energy from the Sun
Gallons per Minute Cubic Feet per Second
Joules per Second Watt
10
Energy from the Sun
Energy Flow ??T4
Tsun 10,400 degrees F
Energy Flow 74,000,000
11
Energy from the Sun
Energy Flow 74,000,000
Area of Sun 6,000,000,000,000,000,000 m2
12
Energy from the Sun
60 Watts
400,000,000,000,000,000,000,000,000 Watts 400
Septillion Watts !!!!
13
Energy from the Sun
Cross-section Area of Earth 1.27 x 1014 m2
1.75 x 1017 Watts
Total energy in
1.27 x 1014 m2
x
14
30 Reflected
1.75 x 1017 Watts
1.23 x 1017 Watts
15
Conservation of Mass and Energy
1.23 x 1017 Watts
1.23 x 1017 Watts
16
Temperature of Earth
Tearth 255 K -18 Celcius -0.4 Farhenheit
17
Temperature of Earth
Predicted Temperature of Earth -0.4 F
Actual Average Temperature of Earth 63 F
Was our energy balance wrong?
18
What is the Greenhouse Effect
  • 63.4 Fahrenheit !!!

19
The Greenhouse Effect
  • What is it?
  • How does it work?
  • Is it a bad thing?
  • What does it have to do with global change?

20
How does the Greenhouse Effect work?
  • Everything with a temperature Radiates energy
  • Radiant energy travels in waves
  • The hotter the source the shorter the wavelength

21
Energy Travels in Waves
Sun
Earth
http//en.wikipedia.org/wiki/Electromagnetic_spe
ctrum
22
Energy Particle Interaction
or reflected
Energy can be absorbed
Response depends on wavelength and particle size
23
Greenhouse Gases Interact with Energy
Infrared Energy
Visible Energy
http//ess.geology.ufl.edu/ess/Notes/050-Energy_Bu
dget/absorbspec.jpeg
24
How Does the Greenhouse Effect Work?
  • Shortwave energy passes through atmosphere and
    heats surface
  • Earth radiates longwave energy into atmosphere
  • Atmosphere absorbs some longwave energy
  • Atmosphere radiates longwave energy back to
    surface causing further heating

63.4 F
25
The Greenhouse Effect
  • What is it?
  • How does it work?
  • Is it a bad thing?
  • What does it have to do with global change?

26
What are we worried about?
  • Without the Greenhouse Effect the planet would be
    TOO COLD !!!

27
Goldilocks' Effect
60oF /-20oF
-50oF /-130oF
840oF
/-80oF
Too Cold Just Right Too Hot
On Mars, the atmosphere is too thin and does not
trap enough heat On Venus, the atmosphere is too
thick and traps too much heat. Interesting,
Mercury which is closer to the sun is cooler!
28
Increasing Greenhouse Gases Cause an ENHANCED
GREENHOUSE EFFECT
29
The Big Question
  • The global climate is warming
  • Greenhouse gases keep Earths surface warm
  • Greenhouse gas concentrations are rising and
    enhancing the Greenhouse Effect
  • Are increases in greenhouse gases responsible for
    recent warming?

30
The Greenhouse Effect
Short Wave Radiation Is Passes Through Atmosphere
Some Long Wave Radiation Is Trapped,
Further Warming the Earth
The Earth Warms
31
Short to Longwave Conversion
What comes IN and what goes OUT controlled by
gases in the atmosphere
32
Ozone Absorbs Short Wave Radiation Carbon
Dioxide Adsorbs Long Wave Radiation
33
Goldilocks' Effect
Earth
Mars
Venus
60oF /-20oF
-50oF /-130oF
840oF
/-80oF
Too Cold Just Right Too Hot
On Mars, the atmosphere is too thin and does not
trap enough heat On Venus, the atmosphere is too
thick and traps too much heat. Interesting,
Mercury, which is closer to the sun, is cooler
than Venus!
34
What is the Evidence For Global Warming?
35
The Keeling Curve CO2 Record on Mauna Loa, Hawaii
36
(No Transcript)
37
Industrial Revolution
38
CO2
Changes in Many Parameters Exhibit Trends
Consistent with Fossil Fuel Burning as Primary
Cause of Increasing CO2
O2
Emissions
Isotope Signature
39
A Number of Factors Push on the Climate System
40
Instrumental Records
  • Increase of 0.73 0.2 C (1.3 0.4 F) in the
    20th century.
  • 11 of last 12 years are warmest in last 100 years

Brohan, P. et al., 2006, J. Geophysical Research
41
Rate of Warming Is Increasing
Source IPCC 2007 Report
42
Warming is Significanton 1000 Year Time Scale
43
Climate change over longer timescales Ice Core
Records
44
Global Palmer Drought Index Increase In
Frequency of Droughts
Source IPCC 2007 Report
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