Carbon In the Atmosphere - My Life as a Greenhouse Gas
Part A: CO2 : It's a Gas!
View the image below; on which planet would you like to live?
With your group, compare the atmospheres of Mars, Earth, and Venus in the image above and then use the following questions to guide your discussion.
1. On which planet would it be possible for you to live? Why?
2. What relationship, if any, do you see between the amounts of carbon dioxide and the temperature in these three atmospheres?
3. You have probably heard about the greenhouse effect in previous science classes or in the media. Based on your current understanding of the greenhouse effect, which planet do you think has the strongest greenhouse effect? Why?
4. What if Earth's greenhouse effect amplified (became stronger)? Would Earth's atmosphere become more like Venus' or more like Mars'? Explain.
The greenhouse effect
If you would like to learn more about infra-red radiation, click on this link to a NASA video that explains infra-red radiation in greater depth: infra-red radiation
Scientists are now seeing an amplified greenhouse effect. What causes this amplified greenhouse effect, and could it have consequences for the Earth's System? How do they know? Before you begin exploring these questions, begin by first reviewing the greenhouse effect using the Greenhouse Effect Interactive developed by the Norwegian Center for Science Education. If you get most of the answers correct in the quiz at the end of the interactive, you are ready to continue with the lab investigation. Good luck!
Carbon Dioxide as a Greenhouse Gas
As you can see by the graph, above right, nitrogen and oxygen make up 99% of the atmosphere. While both nitrogen and oxygen are important in supporting life on Earth, they are not greenhouse gases and play almost no direct role in warming the atmosphere. The 1% slice of the pie chart is comprised of those gases found only in trace amounts.
Consider the table below and then answer the Checking In questions that follow:
The Case of the Dancing Molecules
Why do some gases in the atmosphere contribute to the greenhouse effect whereas others do not? For example, why isn't nitrogen or oxygen a greenhouse gas? If carbon dioxide is just a trace gas, how can it contribute to the greenhouse effect? It turns out that the ability of an atmospheric gas to trap infra-red radiation depends on how the radiation interacts with the structure of the molecule. To help you understand this important concept, first explore an interactive animation that compares the greenhouse warming potential of carbon dioxide to nitrogen. Then, watch a video of geoscientist, Dr. Scott Denning, using a molecular dance to explain this concept in greater depth.
When you enter the interactive, Molecules on the Move, do the following:
1. Follow the directions on in the pop-up screen before you begin the interactive animation.
2. Don't start adding in the molecules until you see how the solar and infrared radiation waves are behaving.
3. As you add the molecules, take notes on the similarities and differences in how carbon dioxide and nitrogen respond to solar radiation (yellow) and infrared radiation (red). Be prepared to share your notes with your partner or group.
Next, watch atmospheric scientist, Dr. Scott Denning, use his own personal dancing style to explain why greenhouse gases absorb infra-red radiation. As you watch and listen, note the following:
- How his molecular dance changes when he talks about the different molecules – nitrogen, carbon dioxide and water vapor.
- His explanation of the relationship between carbon dioxide, the greenhouse effect, and current atmospheric warming.