Let ’ s review last week: sometimes Venus, Earth and
Mars are called the Goldilocks planets

Temp at surface
Venus
880 F
Earth
59 F
Mars
-58 F
Pressure at surface
Atmosphere composition
Dist. from sun
One word description?
~ 90 atmospheres 1 atmosphere
(14.7 lbs/sq in)
CO
2 and sulfuric acid clouds
Nitrogen, oxygen, water vapor clouds,
0.7 A.U.
1 A.U.
0.007 atmospheres
CO
2
, nitrogen
1.5 A.U.
Let ’ s look at atmosphere more carefully:

Venus
Carbon Dioxide:
96%
Nitrogen: 3.5%
Earth
Nitrogen: 78%
Oxygen: 21 %
Argon: 0.9%
Water: > 1%
Carbon Dioxide:
0.004% *
Mars
Carbon Dioxide:
95%
Nitrogen: 3%
Argon: 2%

Solar radiation comes in
How did Venus get so hot?
A planet with an atmosphere
The greenhouse gases reradiate. Some of the energy goes towards the surface.
Greenhouse gases
Planetary radiation goes out, but gets absorbed
Planetary surface

In class, or lab exercise: Greenhouse effect
Go to http://phet.colorado.edu/en/simulation/greenhouse

How do greenhouse gases naturally get into the atmosphere?
Water: evaporation
CO
2
: vaporization of rocks, release from volcanos, vaporization of biotic material
(like fossil fuels), respiration
Methane: release from earth, biology (bacteria, cows, rice)

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3. Earth developed an oxygen atmosphere from plant life
What is happening to the atmosphere today ?
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“ Warming of the climate system is unequivocal, and since the
1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased .
”
* Intergovernmental Panel on Climate Change: A total of 209 Lead
Authors and 50 Review Editors from 39 countries and more than
600 Contributing Authors from 32 countries contributed to the preparation

Articles published in peer review journals support idea that this is happening, and that it is caused by humans
Peer review, or refereed: article has been anonymously approved by another expert in the field before publication

These temperatures are derived from different methods

CO2 levels in ppm (parts per million)

Class exercise with Mauna Loa (top of volcano in Hawaii) data:
Plotting some data on the CO
2 concentration in the atmosphere
Date CO
2
(ppm)
Each team will plot one year ’ s worth of CO
2 data

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2005
Group #
______
2006 2007 2008 2009 2010 2011 2012

Keeling Mauna Loa CO2 Data (2005-2011)
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370 янв.05
янв.06
янв.07
янв.08
янв.09
янв.10
янв.11
янв.12
Time

Various effects of climate change today

Summary of effects:
Shrinking ice sheets
Declining arctic ice
Melting glaciers
Sea level rise
Global temperature rise
Warming oceans

Currently, 30% of both the US House and Senate are on record as denying climate change, or its importance.
Solution requires many nations to address the problem:
China in particular

•
Buy more fuel efficient cars and trucks, do less driving, do more car pooling, use
CFL (compact fluorescent) light bulbs, use solar cooker…
•
Develop Solar power on homes
•
Burn less coal (which creates much of our electricity)
•
Develop alternative energy: wind, nuclear
•
What are your ideas?

Earth ’ s temperature is increasing because carbon dioxide concentration is increasing.
All evidence is that this is caused by human activity.
Lecture tutorial, Greenhouse effect
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Index: Change in earth ’ s temperature
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