Identify greenhouse gases and describe how they trap infrared radiation to affect Earth's temperature
Explain how surface reflectivity affects solar energy absorption and contributes to global temperature changes.
Make evidence-based predictions about future global temperatures using greenhouse gas and albedo data, recognizing positive feedback loops.
Distinguish which atmospheric gases absorb infrared radiation and describe how greenhouse gas concentration changes affect surface temperature.
Compare how different surfaces reflect or absorb sunlight and explain how decreasing Arctic sea ice creates a reinforcing cycle that amplifies warming.
If you need help, please watch the class recording.
Identify greenhouse gases and describe how they trap infrared radiation to affect Earth's temperature
Explain how surface reflectivity affects solar energy absorption and contributes to global temperature changes.
Make evidence-based predictions about future global temperatures using greenhouse gas and albedo data, recognizing positive feedback loops.
Distinguish which atmospheric gases absorb infrared radiation and describe how greenhouse gas concentration changes affect surface temperature.
Compare how different surfaces reflect or absorb sunlight and explain how decreasing Arctic sea ice creates a reinforcing cycle that amplifies warming.
If you need help, please watch the class recording.
In your own words, answer at least 1 question:
What are greenhouse gases?
What are some examples of greenhouse gases?
How do greenhouse gases work?
What questions do you have about greenhouse gases?

Background:
Earth’s atmosphere is made of up many gases, mostly nitrogen N₂ and oxygen O₂ gases, but also carbon dioxide CO₂, water vapor H₂O, and methane CH₄, among other compounds.
A greenhouse traps heat by allowing sunlight to enter through transparent walls but preventing the resulting infrared radiation from escaping back out.
Gases that absorb and reemit infrared light are greenhouse gases. Gases that do not interact with infrared light are not greenhouse gases.
The greenhouse effect makes temperatures favorable for life on Earth but makes other planets, like Venus, uninhabitable.
Which of the following student responses best summarizes these ideas?

Electromagnetic energy such as visible light and infrared radiation can be represented two ways:
As waves (with properties like wavelength and frequency that explain how it travels and bends)
As photons (tiny packets of energy that explain how light interacts with matter and causes chemical reactions).
You will see both models being used.
Which of the following student responses best summarizes these ideas?
Part 1: Greenhouse Gases
Open the Molecules and Light Simulation.
In this simulation, you will observe how different wavelengths of the electromagnetic spectrum interact with different molecules of gas.
Greenhouse gases will absorb electromagnetic energy and re-emit the energy back towards Earth's surface.
Try passing photons of infrared and visible light through molecules of each of the gases listed in the table below by clicking on the flashlight's green button. Identify if the molecule reacts to the photons.
Gas | Infrared | Visible |
|---|---|---|
Nitrogen N2 | ||
Oxygen O2 | ||
Carbon Dioxide CO2 | ||
Methane CH4 | ||
Water H2O |
What type of light caused the molecules to react?
Based on your observations, which gases are greenhouse gases?
Part 2: Greenhouse Effect
Open the Greenhouse Effect Simulation.
Click on the Photons module.
Set the greenhouse gas concentration to none.
Uncheck "Cloud."
Observation: With no greenhouse gases in the atmosphere or no clouds, what happened to the temperature of the Earth?
Move the greenhouse gas concentration slider upward and stop at the middle.
Observation: How are the photons behaving due to the increase in greenhouse gases?
Observe the surface temperature with the slider still at the middle.
Conclusion: Which of the following is correct?
Reset the simulation. Under Greenhouse Gas Concentration, click on the calendar. Set the conditions to Ice Age. Note the greenhouse gas concentrations in the table below.
You do not need to include the units.
PPM = Parts Per Million
PPB = Parts Per Billion
Run the simulation until the temperature stabilizes. Record the surface temperature in the table below.
Complete the table below by running the simulation for the remaining time periods (1750, 1950, 2020).
Time Period | CO2 | CH4 | N2O | Temperature |
|---|---|---|---|---|
Ice Age | ||||
1750 | ||||
1950 | ||||
2020 |
From Ice Age to 2020, the global average temperature due to the of greenhouse gas concentrations.
Part 3: Albedo
FYI: Pronounced al·bee·dow
Switch to the Layer Model module in the PhET simulation.
Move the Surface Albedo slider to 0 (low albedo).
How do the sunlight photons interact with the surface?
How does the temperature change?
Move the Surface Albedo slider all the way up to 0.9 (high albedo).
How do the sunlight photons interact with the surface?
How does the temperature change compared to when the albedo was lower?
Based on what you have observed, which of the following student responses best explains albedo?
Which 2 surfaces would have the lowest albedo?

The surfaces in the previous question would most of the Sun's energy.
Which 2 surfaces would have the highest albedo?

The surfaces in the previous question would most of the Sun's energy.
Modern Earth has an average albedo of 0.3.
What was Earth's albedo different during the last Ice Age?

Consider the effect of decreased Arctic sea ice:

This is an example of a feedback loop because less sea icethe overall cycle.
Part 4: Prediction & Reasoning
If greenhouse gases continue to increase AND Arctic albedo continues to decrease, predict what will happen to global temperatures over the next 50 years.
Justify in your own words: How will greenhouse gases and albedo contribute to the prediction you selected?