Unit 3: Energy Flows and Feedback Processes

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Illustration of earth's energy balance in Watts per square meter.

Provenance: From Figure 1 of the article "Earth's Global Energy Budget" (by Trenberth, Fasullo, and Kiehl page 311-324 of Volume 90 Issue 3 (March 2009) BAMS). Used with permission of the American Meteorological Society.
Reuse: If you wish to use this item outside this site in ways that exceed fair use (see http://fairuse.stanford.edu/) you must seek permission from its creator.

By the end of the unit, students will be able to:

1. Identify causal connection polarities between system components with a focus on Earth's energy balance and the Earth system.
2. Analyze system diagrams related to the Earth system.
3. Create systems diagrams of feedback processes within the Earth system.
4. Build a system diagram to describe the inter-connections and feedbacks between climate change mitigation policy, science education, public awareness, and the media.

This unit is an interactive lecture that should work well with most class sizes and assumes a 50 minute in-class session. It is designed for introductory undergraduate geoscience students familiar with radiation from the Earth and Sun, Earth's global mean radiative equilibrium temperature, and the greenhouse effect (these topics are emphasized in Units 1 and 2 of this module). We begin with a discussion of a "question for thought" proposed in a previous class and then explore system diagrams and feedback processes in the context of Earth's Energy Balance. The homework assignments for this unit can be used as a wrap-up of ideas presented here, or to help set the stage for future small group collaboration and in-class discussion in Units 4 and 6 of this module.

The instructor uses this Unit 3 Power Point (PowerPoint 2.6MB Nov18 16) presentation on systems diagrams in an interactive lecture setting. An outline for it includes:

• Last time
• What do you know?
• Why use systems diagrams?
• Review of Earth's global mean annual Energy Budget
• Causal connections between climate system components
• Turning connections into causal loop diagrams
• A simple yet important example
• Ice albedo feedback
• An interdisciplinary feedback structure: Climate Change mitigation policy
• Metacognition wrap-up
• Take-home assignment

During the interactive lecture students work through the mini-activity included in the Unit 3 student handout (Microsoft Word 2007 (.docx) 989kB Nov15 16), also available as a PDF (Acrobat (PDF) 1024kB Nov15 16). The Unit 3 Power Point (PowerPoint 2.6MB Nov18 16) presentation has slides with a yellow background format for informational slides and blue background format for student activities that correspond to the student handout. Preview the notes section of each slide on tips for successfully using this presentation in an interactive lecture format.

In the take-home assignment for this unit, Large Eruption, Part A (Microsoft Word 2007 (.docx) 162kB Nov18 16)---also available as a PDF (Acrobat (PDF) 310kB Nov18 16)---students work on their own to learn about how volcanoes may effect climate and society. This will prepare them for the small in-class group work scheduled for the first part of the module's capstone assessment in Unit 6. At least 5 calendar days should be given between unit 3 and unit 6 class sessions to allow students ample time to complete this assignment. This short PowerPoint presentation for Large Eruption, Part A (PowerPoint 1.8MB Nov15 16) will help you introduce this take-home activity.

The Unit 3 Power Point (PowerPoint 2.6MB Nov18 16) presentation on systems diagrams is designed for a 50 minute interactive lecture, and can be used as a stand-alone unit, but naturally blends with Units 2 and 4 of this module. Review the notes section of each slide for ideas on how to use this presentation in your class. Also, make sure to allow students ample time to think through the questions posed to them, but also be mindful of keeping a good pace to continually engage all students. A pink slide is included (slide 23) to identify the suggested 25 minute mark. The 25 minute mark is identified in case you need to do the first half of this unit in one class and the second half in a following class.

There are 5 Appendices (PowerPoint 1.3MB Nov15 16) related to the primary presentation that may be useful. It is recommended that students have access to all PowerPoint presentations after the class session as a reference for self-assessment and review. After reviewing the material, you may want to add material from Appendix 1 (more on water vapor feedback), Appendix 2 (ocean temperature CO₂ uptake), or Appendix 3 (clouds and climate). Appendix 4 has possible answers to some interdisciplinary systems diagrams and could be used by students to self-assess their results for this activity, as possible exam questions, or used in conjunction with 1 minute in-class student presentations of their results for these diagrams. Appendix 5 contains an additional example, CO₂ weathering feedback.

Leave yourself about 12 minutes at the end of the unit to introduce the Large Eruption Part A assignment (Microsoft Word 2007 (.docx) 162kB Nov18 16) (also available in PDF (Acrobat (PDF) 310kB Nov18 16)) using associated PowerPoint (PowerPoint 1.8MB Nov15 16). Make sure to include a due date for this assignment. It is best to have students turn this in at the beginning of class on the day for Unit 6 of this module. This assignment prepares students for the first part of Unit 6 which is an in-class small group activity.

You may want to alter the instructions of the Large Eruption assignment (Microsoft Word 2007 (.docx) 162kB Nov18 16) to have students submit several key PowerPoint slides of their research findings to you a day before the Unit 6 in-class presentation, and use them to make a composite summary presentation of their work available for student use during the Unit 6 in-class session to show key graphs or images related to their particular volcano.

The Unit 3 Student Handout (Microsoft Word 2007 (.docx) 989kB Nov15 16) is completed by each student during the interactive lecture session. Answers to questions are included in the Unit 3 Power Point (PowerPoint 2.6MB Nov18 16) on the slide following the question slide. Students are encouraged to self-assess themselves, but make sure they have time to answer before showing them the answer slide. Unit 3 Student Handout (Microsoft Word 2007 (.docx) 989kB Nov15 16) can be collected and given low stakes credit for thoughtful completion. A rubric is included within the Unit 3 Student Handout for students to self-assess themselves and/or to provide criteria for low stakes credit on this activity. Unit 3 Student Handout (Microsoft Word 2007 (.docx) 989kB Nov15 16) provides a low stakes assessment of learning goals 1 through 4 above.

Slide 30 provides an opportunity for metacognitive reflection and a student assessment of what worked well and not so well for them during the interactive lecture. Slide 31 (in both the student handout and PowerPoint) could be used as a low stakes graded assessment.

Appendix 4 and 5 of the Appendices (PowerPoint 1.3MB Nov15 16) has additional ideas for a low stakes graded assessment or for an in class discussion. These can be used to assess learning goals 2 and 3 above.

Possible exam questions with answers are included here:

• ExamQuestions -- private instructor-only file
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  . The exam questions offer assessment of learning goals 1 through 3 above.

• System diagrams:
• PowerPoint introducing causal loop diagrams for Earth's energy balance
• How to draw and use causal loop diagrams (more info)
• Systems Diagram overview from Mind Tools
• Folk Tales, Foreign Policy, and the Value of Systems Thinking, by Karl North, January 30, 2014
• Hey New York Times, A causal loop diagram is not a Power Point fail