Topic Guide: The Greenhouse Effect
In this
activity you will form groups, conduct research into greenhouse gases and
the greenhouse effect, and report back to your lab section in the form of
a presentation. At the end of this activity you will find suggestions for
the format of the presentation. You will use the data you investigate as evidence
for your statements. Please use these suggestions and the “How to make
a class presentation” (Resource 1) as guidelines for your presentation.
Overview:
The greenhouse
effect is responsible for warming the earth by about 330C. Without it, the earth would be covered
in ice. This effect depends strongly on concentration of “greenhouse
gases” in the atmosphere. The sources and sinks of these gases is the
subject of intense research by climate scientists. It is vital that we understand
whether human activities are modifying the greenhouse effect or modifying
other processes that control the balance of atmospheric greenhouse gases.
Many scientists warn us that success or failure to understand these processes
could have serious consequences for the life on our planet. What do you think?
Key processes and concepts to review before beginning:
Resources:
The greenhouse effect is a phrase
that describes how water vapor, carbon dioxide, and other gases in the atmosphere
aid in the maintenance of the Earth's surface temperature
After completing this investigation you should be able
to:
Background information:
Browse the links listed below to answer the questions posed below. You will not have time to read all of the resources in detail, but be sure to browse them sufficiently so that you can find the information for later review and your position papers. Be sure that you save some time to explore the data on the WorldWatcher CD (under Data, below). You may wish to assign various members of your group to different questions.
Methane: http://icp.giss.nasa.gov/research/methane/
http://www.ngdc.noaa.gov/paleo/globalwarming/greeneffect.html
http://www.ec.gc.ca/pdb/ghg/ghg_home_e.cfm
http://www.yourplanet.org/terms/details.php3?term=Greenhouse+Gases
http://www.agu.org/eos_elec/99148e.html
http://www.epa.gov/globalwarming/emissions/index.html
http://yosemite.epa.gov/oar/globalwarming.nsf/content/index.html
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What special property do these gases possess?
How do the greenhouse gases act to affect the climate?
What is the general trend in the concentration of these
greenhouses gases for the last 150 years?
The concentration of which greenhouse gases have increased
in the last 100 years or so due to human activity?
What specific activities have caused these gases to increase?
What is the general trend in the concentration of these
greenhouses gases for the last 150 years?
http://asd-www.larc.nasa.gov/erbe/components2.gif
How does the increase in greenhouse gases affect the Earth's
energy budget?
http://www.eia.doe.gov/oiaf/1605/ggrpt/index.html#gases
http://www.eia.doe.gov/oiaf/1605/ggrpt/other_gases.html#hydro
http://www.mct.gov.br/clima/ingles/convencao/guia.htm
What are engineered gases?
What are CFCs? Are they covered under the Kyoto Protocol?
Why does the CFC graph only show an increase from approximately
1950 on?
Why were PFCs developed?
Do PFCs have an adverse affect on ozone? What is the problem
with PFCs?
Data:
Access the energy balance dataset
on the WorldWatcher CD. First, look at data
included in the energy balance dataset, specifically that of the greenhouse
effect and the greenhouse increase.
Greenhouse Increase Data
Open the greenhouse increase data. The greenhouse increase is the amount the surface temperature is warmer due to the atmosphere.
Step through the data in the animation, months January to
September. Do you notice a difference in the pattern between the Northern
and Southern Hemispheres?
What is it? For the Northern Hemisphere, especially note the differences between the patterns in January and those of July.
Is the difference as clear for the Southern Hemisphere?
Greenhouse Effect Data
Look at the greenhouse effect data. The greenhouse effect is the percentage the surface temperature is warmer because of the atmosphere.
Step through the data in the animation, months January to September. Do you notice a difference in the pattern between the Northern and Southern Hemispheres?
What is it? For the Northern Hemisphere, especially note the differences between the patterns in January and those of July.
Is the difference as clear for the Southern Hemisphere?
Precipitable Water Vapor Data
Look at WorldWatcher’s precipitable water vapor data that can be found in the Atmosphere database under Water Vapor. Water vapor in the atmosphere is the main greenhouse gas.
Before opening the precipitable water vapor data, make
a prediction about the relationships that you expect to discover.
Open the dataset and look at the data. Did you find the expected relationship?
What are the differences and similarities between this
dataset and the Greenhouse effect data?
Clouds make large changes in the Earth’s albedo. The effect of warming on cloud cover has been a subject of intense debate, but has been reasonably well resolved by understanding the effect of high clouds and low clouds, which will have opposite effects on the albedo. So, these two large effects tend to cancel each other out, but the cancellation is, inevitably, imperfect. This introduces a potential source of error into the models, depending on how well the effect of clouds is computed.
Look at the Earth Atmosphere reflectivity (albedo) data on the WorldWatcher CD. In the database there are three sets of data, Earth Atmosphere reflectivity, Earth Atmosphere reflectivity (clear sky), and Earth Atmosphere reflectivity (Clouds only). What relationships do you see?
Look at the two datasets, Earth Atmosphere reflectivity (clear sky) and Earth Atmosphere reflectivity (clouds only).
Other WorldWatcher suggestions:
Scientists have worked hard to create models that predict changes due to global warming.
Click on “Activities” on the “Welcome to WorldWatcher” screen. When the window comes up, double click on the small icon next to “Global Warming Project Resources.” When the resulting window appears, double click on “Predicted Global Warming Scenario”. Here you can see a model that predicts changes in global temperature and precipitation. This would be very helpful in speculating about the possible global warming effects on a particular region. Where did this model come from? Don’t hesitated to email the CD authors if necessary. http://www.worldwatcher.northwestern.edu/
Now you can use an Internet browser (either Internet Explorer or Netscape) to access the World Wide Web. Listed below are several web sites covering the various issues concerning the albedo. Remember that the albedo is the fraction of solar energy reflected at the earth’s surface. Perfect reflection would be an albedo of 1, while perfect absorption would be an albedo of 0.
http://www-cger.nies.go.jp/grid-e/gridtxt/grid7.html
http://climate.gsfc.nasa.gov/radiation.html
http://www.eumetsat.de/en/area2/cgms/ap4-08.htm
http://cires.colorado.edu/~julienne/EOS.html
http://cires.colorado.edu/~julienne/albedo2.abs.html
http://stress.swan.ac.uk/~mbarnsle/research/brdf.htm
What role do clouds play on solar heating?
What are several of the variables that affect albedo?
How does albedo affect the amount of incoming radiation that is reflected back into space?
What effect does changing albedo have on the Earth's climate?
How do dimethylsulphide (DMS) emissions from the ocean
affect cloud formation?
Background information: Please take some time to learn more about the background information available for the topic of greenhouse gases and the greenhouse effect. If you learn something new and interesting, please share it with the lab in your presentation.
http://www.science.gmu.edu/~zli/ghe.html
http://icp.giss.nasa.gov/research/methane/greenhouse.html
http://www.mct.gov.br/clima/ingles/convencao/guia.htm
Information for your Earth Summit country:
http://www.epa.gov/globalwarming/emissions/international/index.html
International greenhouse gas emissions website
Your presentation should include a brief overview explaining the significance of greenhouse gases and the greenhouse effect and how studies of greenhouse gases and the greenhouse effect relate to climatic issues of today. You should then choose as many of the following topics as is necessary to explain the concept. Choose topics that you think might be relevant to understanding climate change. Your presentation should include interesting findings from your investigations, backed up with data. You must use the physical data in your presentation.
You may choose from the following
list of topics, or investigate a topic of your own. The topics in the list
are examples of investigations that could be made using the data available
at the URL’s listed above.
Data driven topics:
Overview type topics:
