Explore the Greenhouse Effect
Once incoming solar energy reaches Earth’s atmosphere, what parts of the Earth system absorb and hold the energy, warming the planet? In this lab, you will explore some of the elements that absorb solar energy, the greenhouse gases (GHG). These gases include: carbon dioxide, methane, nitrous oxide, and water vapor. You will see that each greenhouse gas responds differently to electromagnetic radiation. This is an important asset of our current atmospheric composition. It allows some forms of solar radiation to pass through the “atmospheric window,” to the planet’s surface and also back out to space, while retaining other wavelengths of energy to warm the atmosphere and Earth’s surface. In this lab, you will further your understanding of the Earth’s energy balance that you investigated in the previous labs.
First, click the link How does the sun’s energy get into the climate system? to access the narrated video, describing the importance of the greenhouse effect in making the planet habitable, or able to support life. After viewing the video, discuss the question listed below with your classmates.
After viewing the video, discuss the following question with your parent, sibling, or someone else:
- How do greenhouse gases impact life on Earth?
What are the greenhouse gases?
Next, learn more about greenhouse gases and how they contribute to global warming by viewing a short animated presentation and reading a background article linked below. Click the link below to read the article.
- The NASA article, A blanket around the Earth gives detailed information about the greenhouse gases and explains the expanded greenhouse effect.
- “These gases absorb the infrared radiation emitted by the Earth and re-radiate the energy as heat back towards the Earth, causing a warming known as the greenhouse effect.”
Questions to Consider
Which of the above listed greenhouse gases (GHG) is most abundant in the atmosphere?
Which of the long-lived greenhouse gases (above) is the most important ?
- Not nitrogen and oxygen, all the others
- Water Vapor is the most abundant GHG and plays an important role in feedback mechanisms that either amplify (speed up) or dampen (slow down) climate change. However it is very short-lived in the atmosphere. Once it reaches a certain concentration, it quickly condenses into clouds and precipitates back out of the atmosphere.
- Nitrous Oxide, Chlorofluorocarbons
- Methane is a more potent greenhouse gas, but Carbon Dioxide lasts longer in the atmosphere and therefore it is more important.
Investigate the greenhouse effect
This is a graph of temperature and CO2 concentration.
A long-term record of the concentrations of these gases can be seen in the graphic below. Note the dramatic rise in the all three of the greenhouse gas concentrations in the most recent time period.
- Nitrous Oxide is in green
- Carbon Dioxide is the black line below Nitrous Oxide
- Methane is in blue
- Deuterium levels in arctic ice is the bottom black line and represents temperature.
The Atmosphere Today
Using the graph above, note the average global (land and ocean) temperature. Record the concentration of the three primary greenhouse gases, CO2, CH4, and N2O in the table below. Note that the N2O and CH4 concentrations are in parts per billion. CO2 is measured in parts per million. In other words, there is very little of these two gases in the atmosphere as compared to CO2.
The Atmosphere in 1850
Note the global temperature as well as the composition of the atmosphere. Record the composition of the atmosphere in the table.
Explore this website. https://www.n2olevels.org/ If the graph doesn’t fully load, reload the page. Scroll down and click on CO2 Levels, Methane Levels, Temperature Record, and Sea Levels.
The Atmosphere in 2100
What do you think the 2100 projection might be? Consider the following graphical projection. Add your projections to the table above.
Stop and Think
- Why are greenhouse gases (GHG) important to life on the planet?
- Which was the most potent (i.e., caused the greatest change in temperature) of the three greenhouse gases, how did you discover this? (Hint: note the concentrations of the gases.)
Altering the energy balance
Both instrumental and satellite data show that the years between 2000 to 2010 were the warmest decade of the past 150 years, and 2014 was warmest year on record since 1880. In fact, 9 of the 10 warmest years on record have occured during the 21st century. (Source: NOAA State of the Climate 2014) What could be causing the heating of the planet? Which parts of the balance have changed? This NASA video, Piecing Together the Temperature Puzzle, (5:48 minutes) explains the scientific understanding of how various elements of the Earth-Sun system, including changes in the solar cycle, alterations in snow and cloud cover, and rising levels of heat-trapping gases, may be contributing to these new records.
As you watch the video, consider how the individual changes in Earth’s climate are like a series of puzzle pieces that, when connected, begin to form a recognizable pattern. As you watch this video, you will also gain an appreciation for the contribution that NASA satellites have provided towards the solving of the global climate puzzle.
Preview the following discussion questions before watching the video.
Courtesy of NASA/Goddard Space Flight Center. Piecing Together the Temperature Puzzle
After completing this lab, discuss your thoughts about the material covered in this lab. Consider the following questions:
- Why do we study the planet as one interconnected system?
- How do we know that the Earth’s climate is changing, and what is the role of greenhouse gases in that change?
Another, more complex, greenhouse gas interactive can be accessed here: Greenhouse gas interactive. This JAVA applet has several layers of complexity and includes a visualization of molecular interactions with photons.