1. What is the Greenhouse Effect? (Slide 2)
The Greenhouse Effect refers to the trapping and build-up of heat in the atmosphere (troposphere) near the Earth’s surface. Without this effect, the Earth would be about 30° C or 60° F cooler. The current average temperature of the Earth is estimated to be around 59° F. Some of the heat flowing back towards space from the Earth’s surface is absorbed and re-radiated by water vapor, carbon dioxide, and several other gases (greenhouse gases).
Is the Greenhouse Effect an advantage to humans? (If there were no greenhouse effect, the earth would be too cold to support life) (Slide 3)
2. What are greenhouse gases?
Gases that absorb infrared radiation in the atmosphere can be classified as greenhouse gases. Greenhouse gases include, but are not limited to, water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone (O3), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). (Slides 4-5)
Note: An interesting demonstration of how the temperature changes by the addition of CO2 can be found on the You Tube video “The Greenhouse Gas Experiment” by Erik Christensen (www.youtube.com/watch?v=kwtt51gvaJQ)
Show the NASA video on the Earth’s Greenhouse Effect on the MEECS Climate Change Resource DVD. Reinforce the main points that: (Slide 6)
• What are the two most abundant greenhouse gases? (Water vapor and carbon dioxide)
• How do these two gases react to the solar energy coming into the earth’s atmosphere? (Water vapor and carbon dioxide allow solar energy to penetrate earth’s atmosphere but prevent much of the long wave radiation emitted by the surface of the earth from escaping to space)
• This trapping of long wave energy is called the Greenhouse Effect. What does it do to the temperature of the earth? (Enhances the surface temperature of the earth)
• Are all gases are greenhouse gases? (No)
Distribute the Earth’s Greenhouse Effect student activity. Consider showing the video again to help students complete the activity.
3. Greenhouse gases in Michigan
Give students a copy of Greenhouse Gases (student resource) to prepare for the next activities.
Show the pie chart of Michigan Greenhouse Gases per Sector in Michigan and give students Sources of Greenhouse Gases based on the Michigan’s Greenhouse Gas Inventory student activity. (Slide 7)
Ask the following questions:
• What sector emits the most greenhouse gas? (Energy Use) (Slide 8)
• What types of activities come under this category? (Electricity use, residential and commercial industrial fuel use, transportation, fossil fuel industry)
• Which of these are common activities in your daily life and that of your family?
• What is the largest contributor of greenhouse gases? (Carbon dioxide released from the combustion of fossil fuels) (Slide 9)
Using the chart, complete the activity by adding the percentages to the boxes. Circle those sources you have used or seen used. (Slide 10)