Energy flows and feedback processes: A systems perspective Left Figure: 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 by permission of the American Meteorological Society. Permission granted by Jinny Nathans, program officer, on 6/8/2015 Right Figure from: Ruzek, M. Earth System Science in a Nutshell, Starting Point. Retrieved June 10, 2016, from http://serc.carleton.edu/introgeo/earthsystem/nutshell/index.html.

Blue slides will have corresponding questions in the student handout 2 A red star on a slide indicates that advancing will give an answer or partial answer to the questions on the next slide so advance to the next slide carefully. The number inside the red start is the suggested time in minutes that students should be given to answer the question on their own. Looking at student progress around the class should give a better indication on whether it is time to advance to the next slide or not.

Learning Objectives By the end of the unit, students will be able to: Identify causal connection polarities between system components, with a focus on Earth's energy balance and the Earth system. Analyze system diagrams related to the Earth system. Create systems diagrams of feedback processes within the Earth system. Build a system diagram to describe the inter-connections and feedbacks between climate change mitigation policy, science education, public awareness, and the media.

From a previous lesson Your prediction: If rising CO2 increases temperature, how will this change evaporation (and H2O) in the atmosphere? How do you think Earth’s temperature will respond? Take a minute to jot down your ideas in the space below, compare with your neighbor and revise as appropriate, and then be prepared to share with the class. Think, pair, share We revisit these connections in slides 8 and 9 so the discussion should be short but long enough to get students thinking about this important feedback process.

Example of a system diagram related to atmospheric water This slide is intended to clarify what a system diagram looks like and to provide motivation for learning more.

What do you know? Have you ever learned how to create and use systems diagrams (causal loop diagrams)? ____Yes ___No If yes, how would you rate your understanding of creating and using them? Very poor 1 2 3 4 5 Expert

Systems Diagrams Our goal today is to learn how to create and analyze systems diagrams, with emphasis on Earth’s climate system as well as their generic applicability. Your lecture discussion may also touch on the utility of System Diagrams. Systems diagrams are an essential component of the systems thinker toolkit. They are useful for explaining the mechanism behind feedback processes and identifying whether the feedback loop structure is a positive or negative feedback loop. They can also be used, along with concept maps, and concept sketches, to communicate the expected behavior of conceptual models.

Review slide Review this figure of important global scale energy flows in the climate system. Left side highlights the flow of solar radiation, right side highlights the flow of longwave radiation, and the middle shows the flux of latent heat of and sensible heat from the surface to the atmosphere. Figure: 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 by permission of the American Meteorological Society. Permission granted by Jinny Nathans, program officer, on 6/8/2015 Earth’s Energy Balance is used here to develop and explain causal loop diagrams.

Connections (+ or - ??)** Put a + or – near the tip of the arrow to indicate whether the connection between the two climate system variables is positive or negative. 2 The advice to use nouns, like Earth’s surface temperature, as opposed to verbs, like warming, helps make connections clears. System variables should be nouns (Earth’s Temperature rather than warming.) ** A connection is positive if when the first increases the second also increases, and a connection is negative (opposite) if when the first increases the second decreases.

Connections (+ or - ??)* put a + or – near the tip of the arrow to indicate whether the connection between the two climate system variables is positive or negative. Students check their own work. use nouns * A connection is positive if when the first increases the second also increases, and a connection is negative (opposite) if when the first increases the second decreases.

A system diagram 1 What are the missing connections? + or -

A system diagram: identifying feedback structure Students check their own work. Here we also introduce the polarity of this loop as being positive ++++=+ See Appendix 1 for further discussion of water vapor feedback.

Slides on clouds and climate from Appendix 2 could be inserted here but would likely make this lesson exceed a normal 50 minute session. Remove this slide. It is a bold note for the instructor for optional material on clouds.

A Challenge Draw a systems diagram to describe the following: 1 Draw a systems diagram to describe the following: The Sun becomes brighter, causing Earth to warm. Warmed Earth gives off more longwave radiation until it settles into a new equilibrium temperature. Your diagram should have the Sun’s brightness as an external driver to Earth’s temperature and Earth’s Temperature connected with emitted longwave (infrared*) radiation. * Infrared radiation emitted from Earth or its atmosphere is also referred to as longwave or terrestrial radiation. Give students 1 to 2 minutes to try and draw a system diagram. Encourage them to compare with their neighbor. Walk around the room to see if students come up with anything like the diagram structure on the next slide. The next slide can be used as an intermediate step encouraging students to continue thinking.

A first challenge: diagram structure 1 Draw a systems diagram to describe the following: The sun becomes brighter causing Earth to warm to a new equilibrium temperature. sunlight ? Earth’s mean temperature ? ? ? Emitted infrared energy When identifying whether the connection between two variable is positive or negative ask yourself what happens to the second variable when the first increases. If it also increases then the connection is positive and if it decreases the connection is negative. When establishing the polarity of the connect, it doesn’t matter whether you actually think that the first variable will increase in a particular situation. Determining the polarity of all connections in this way will then give you insight into wheter the loop is a positive or negative feedback structure. Notice that the sun is not within the feedback loop structure. What are the missing connections? + or – and is the loop a positive or negative feedback loop

A first Challenge: completed diagram Draw a systems diagram to describe the following: The sun becomes brighter causing Earth to warm to a new equilibrium temperature. sunlight + Earth’s mean temperature - - + Emitted infrared energy Students check their own answers. This is a negative feedback loop + - =- Notice that the sun is not within the feedback loop structure. This negative feedback loop is always present in the Earth System and helps limit (or balances) the runaway effects of positive feedback processes.

Albedo Review Student may need a refresher on albedo here. “Albedo-e hg.svg” (at right) by Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany, Own work, share alike, attribution required (Creative Commons CC-BY-SA-2.5), http://commons.wikimedia.org/wiki/File:Albedo-e_hg.svg

Ice albedo feedback process Description: As Earth’s temperature increases from increased solar radiation output there will be less snow and ice cover globally. This decreases the planetary albedo causing even more sunlight to be absorbed by the climate system resulting in amplified warming. Again solar output (or intensity) is an external driver and will not be within the loop structure. A systems diagram capturing the essence of the feedback process is shown on the next slide. Student may need a refresher on albedo here. “Albedo-e hg.svg” (at right) by Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany, Own work, share alike, attribution required (Creative Commons CC-BY-SA-2.5), http://commons.wikimedia.org/wiki/File:Albedo-e_hg.svg

1.5 Ice albedo feedback. Diagram Structure What is the polarity (sign) of each connection? 1. 2. 3. 4. 5. The next slide has answers and also a new question about the loop polarity.

0.5 What are the polarities of each connection? What is the sign (polarity) of this feedback loop? 1. + 2. - 3. + 4. - 5. + + + - Students check answers and then answer one last question. Here students get confused by trying to look at the whole loop before identifying the connection. For example, students clearly see that if Earth’s mean temperature increases then Snow cover will decrease. Wrong***They then often want to say that if snow cover decreases then the albedo decreases. This is true but can often give a wrong sign of the Snow cover Global Albedo connection and hence yield an incorrect systems diagram. Correct** To determine the Snow cover Global Albedo connection Students should ask themselves; what happens to the Global Albedo as Snow cover increases (forgetting completely about any previous connections)? Clearly it increases also, so the connection is positive. The positive connection indicates a positive correlation between two variables. Alternatively one could ask; what happens to the Global Albedo as Snow cover decreases? The Global albedo also decreases and since both decrease the correlation is still a positive correlation. This alternative approach is needlessly confusing. In effect we break the system down into its conncetions to synthesize the overall system behavior. - +

Is this a positive or negative feedback loop? 1. + 2. - 3. + 4. - 5. + What is the sign of this feedback loop? Positive When the number of negative connections in a causal loop is even, then the loop is positive. If odd, then the loop is negative. + + - + Students Self assess their answers - +

It is important to realize that the negative feedback loop between Earth’s temperature and emitted terrestrial radiation is always present. This limits limits/balances the positive feedback.

The terms positive and negative feedbacks have no reference to the value (good or bad) of the feedback. They are often referred to as amplifying and balancing feedbacks. Sometimes the results of positive feedbacks are characterized as “spiraling out of control” or the “snowball effect”.

25 minute mark

Pair up with a neighbor or two and exchange your ideas. The figure above shows 5 components of a systems diagram intended to show the interconnections between key factors driving climate change policy. Take a minute to think about the possible connections between these components and whether the connection are positive or negative. Pair up with a neighbor or two and exchange your ideas.   Be prepared to share your ideas with the class. This slide is intended to get students thinking about the connection between climate change education and public policy. Spend no more than two minutes of this slide.

Then compare your answers with those of your nearest neighbors Suggested time on this slide is 2 minutes As a start, think about whether the connections shown above are positive or negative, and whether the loop structure is a positive or negative feedback loop. Then compare your answers with those of your nearest neighbors and be prepared to share your results with the class.

How did you do? Suggested time on this slide 1 minute. Make sure student understand the connections. Informed population can increase letters to legislators, climate change rallies, demonstrations, marches Pressure on policy makers ultimately adds to climate change mitigation policy Climate change mitigation policy can, in part, be directed towards increased science education And climate change science education can inform the public

Add the connections shown above (CE and EA). Media coverage is central to climate change mitigation policy development and can be considered as a form of education but is considered separate here. 2 minutes on this think, pair, share. Add the connections shown above (CE and EA). Think about whether the connections shown above are positive or negative, and whether the additional loop structure is a positive or negative feedback loop. Compare your answers with those of your nearest neighbors and be prepared to share your results with the class.

Two feedback loops shown above ABCDA (outside perimeter) 1 minute discussing answers Emphasize that a loop AECDA does not exist because you cannot go against the arrows as you traverse a feedback loop. All feedback loops follow the causal connection arrows in the forward direction. Two feedback loops shown above ABCDA (outside perimeter) ABCEA (right hand loop)

ABCDA (outside perimeter), Five loops ABCDA (outside perimeter), ABCEA (not shown with loop symbol-- perimeter of right side), ABEA , BCEB , and BEB All are positive in this example. Clearly media coverage can be considered a form of climate science education. This additional connection (ED) has been omitted for simplicity. It is important to emphasize to students that positive feedback loops amplify change. So if the Public becomes better informed the feedback processes tend to amplify the number of informed people. However, if the public is misinformed the same feedback processes can amplify this misinformation. Also emphasize that this is a simplistic view of processes related to the creation of climate change mitigation policy but does include key aspects and could be expanded upon.

How would you rate your understanding of creating and using systems diagrams now? Very poor 1 2 3 4 5 Expert What about today’s lesson has been most helpful? What suggestions do you have for improvements in today’s lesson?  

Quiz Question Arctic sea ice grows in the winter as the ocean loses heat energy to the atmosphere. It retreats in the summer as the ocean gains heat energy from the sun and atmosphere. For this question, we focus on the winter months where heat loss from the ocean is slowed by sea ice cover. This insulates the ocean. A system diagram showing the connections between Arctic sea ice cover, insulation provided for the ocean by the sea ice, and ocean heat loss is given below. What is the polarity of each connection in the diagram below? Is this feedback loop positive or negative? _____ 3. _____ 4. ______

Other reading related to System Diagrams Systems Diagrams: Understanding How Factors Affect One Another. By Ruth Hall http://www.mindtools.com/pages/article/newTMC_04.htm Guidelines for Drawing Causal Loop Diagrams By: Daniel H. Kim The Systems Thinker, Vol. 3, No. 1, pp5-6 (Feb 1992). http://www.cs.toronto.edu/~sme/SystemsThinking/GuidelinesforDrawingCausalLoopDiagrams.pdf Folk Tales, Foreign Policy, and the Value of Systems Thinking By Karl North | January 30, 2014