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 that of 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. Human activity is increasing the amount of greenhouse gases in the atmosphere - especially carbon dioxide. This is amplifying the greenhouse effect. What causes this amplified greenhouse effect, and could it have consequences for the Earth's System? How do scientists 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! Note: It may take some time for this interactive to load.
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 infrared radiation depends on how the radiation interacts with the structure of the molecule. First, watch a video of geoscientist Dr. Scott Denning using his own personal dancing style to explain why greenhouse gases absorb infrared radiation (IR). Then, use the animation of Greenhouse Gas Molecules below to deepen your understanding of greenhouse gas molecules and the greenhouse effect. As you view the video and the animation, make note of the following:
- How the molecular structure of a greenhouse gas is related to its ability to absorb infrared radiation.
- The relationship between infrared radiation re-emitted to Earth and the greenhouse effect.