The Carbon Cycle: What Goes Around, Comes Around
Part C: Systems Thinking and The Carbon Cycle
Think of a complex system like a large high school. What if one day every student that walked through the doors received a laptop for their own personal use in class with unlimited access to wireless? How might this one change cause other components of the high school system to change? Think about it!
The Connections GameUnderstanding Complex Systems
How can we demonstrate that parts of a system are interconnected and that changes to one part of the system can cause changes to other parts of the system? To help us understand this concept, we are going to play the Connections Game, developed by systems thinkers Rob Quaden, Alan Ticotsky and Debra Lyneis in The Shape of Change. In the Connections Game, you and your fellow students will each be playing one component of a system. What will happen to other components of the system if one component should change?
Connections Game Materials:
A number card large enough to be visible to other students.
Connection Game Instructions: (adapted from The Shape of Change)
1. Demonstration: Understanding the term "equidistant" is critical to playing this game. The teacher will ask two students to help demonstrate what it means to be equidistant from two other players. Can one person move and still be equidistant from the other two people?
2. Your teacher will give each student a number card.
3. Stand in a large circle with your numbers held in front of you so others can see.
4. Look around the room and randomly choose the numbers of two other players. These will be your SECRET equidistant partners. DO NOT tell anyone who they are!
5. When your teacher gives a signal, move to a point that is equidistant from your two partners. Do this with NO talking.
6. Keep playing the game until all players are equidistant from their two partners and the movement stops.
Discussion:Think of the people in the Connections Game circle as a complex system.
- How did the system behave when you tried to stay equidistant from your two secret partners?
- How did one person's change in position affect others in the group?
- Could a change in one part of the Connection Game system cause a cascade of changes in other parts of the system? If so, how?
- How will understanding how a Connection Game system behaves help you understand how a very complex system like the carbon cycle might behave if changes occurs anywhere within the carbon cycle system?
Connection Circles - Identifying Causal Connections in The Global Carbon Cycle
Part 1: Identifying Causal Connections.(adapted from The Shape of Change)
Now that you know a change in behavior in one part of a system can cause multiple changes in other parts of a system, the next step in systems thinking is to look for causal connections Cause and effect relationships between parts of a system. A change in one part of a complex system can cause changes in other parts of the system. between these changes. Causal connections are another way to describe "cause and effect" relationships. Systems thinkers use Connection Circles as a graphic tool to identify and understand changes and their causal connections in complex systems. When thinking about causal connections, it is helpful to think about them in "If....then " statements. The "If.........." represents the cause; the "then......." represents the effect.
With a partner or group, read the "If...then" statements below. Complete each causal connection. Keep in mind that there will be several possibilities for each of these "If...then" statements. In addition, think about these causal connections in terms of the carbon. When you are done, share your causal connections with the rest of the class. The first one has been done for you as an example:
- Example: If the human global population continues to increase, then..... more fossil fuel hydrocarbons will need to be burned for energy.
- If every country planted more forests, then ..........
- If cars and factories burn more hydrocarbon fuel, then ..............
- If wildfires burn for many days over large tracts of land, then ...............
- If phytoplankton populations increase, then ......................
In pairs or larger group, examine the Arctic causal loop diagram and answer the following questions.
1. What story does this causal feedback loop diagram itell about what is currently happening in the Arctic?
2. Think of rising temperatures as the original element in the Arctic feedback loop. Does melting ice "amplify" or "dampen" rising Arctic temperatures? Why?
3. Why is this feedback drawn as a circle?
4. If CO2 levels continue to increase, how might this affect this feedback causal loop? Why?
Part 2. Using Connection Circles in A Case Study: The Effects of Pine Bark Beetle Infestation on the Carbon Cycle.
As you use the Connection Circle in the case study below, you will find that these "If..then" statements will interconnect in many ways. Lets begin the first of several Connection Circles you will create throughout this module by exploring the effect of a pine bark beetle infestation on the carbon cycle.
In this activity, you will use the systems thinking tool "Connection Circles" to identify causal connections between the pine bark beetle infestation and three important processes in the carbon cycle:
- decomposition Decomposition is the natural process of dead organisms being rotted or broken down into smaller bits. When soil invertebrates, fungi and bacteria carry out decomposition, they also respire releasing CO2 to the surrounding soil and air.
- soil respiration Soil respiration refers to respiration carried out by organisms living in the soil - including bacteria, fungi, worms, beetles etc.
To learn about the pine bark beetle infestation and its severity, view the New York Times slideshow Attacks on a Protective Canopy. Then read the article Climate Change Sends Beetles Into Overdrive! As you read, keep the following questions in mind: What are the important elements of the pine bark beetle infestation story? Using the questions below as a guide, list as many elements as you can.
- What does the infestation do to forests?
- What causes the infestation and why is it getting worse?
- What changes have been observed in the Pine Bark Beetle infestation?
- What are scientists observing and thinking about?
- What is the relationship between temperature, the beetle infestation and climate?
Materials you will need:
- Pencils and colored pencils
- A Connections Circle diagram or draw one on your own. Note: larger paper is best.
- Access to the Carbon Cycle interactive in Lab 2-B or if unavailable, a hard copy of the carbon cycle image and transcript.
- Pine Bark Beetle Infestation story "Element Strips"
PINE BARK BEETLE INFESTATION
A WARMING CLIMATE
CO2 IN ATMOSPHERE
BEETLES REPRODUCE 2X PER YEAR
LESS WATER FOR TREES MAKES THEM VULNERABLE TO SUMMERTIME WATER STRESS
FORESTS MAY TURN INTO GRASSLANDS AND SHRUBS
PROCESS OF PHOTOSYNTHESIS
PROCESS OF DECOMPOSITION OF DEAD TREES
PROCESS OF SOIL RESPIRATION
BEETLES INCREASE THEIR GEOGRAPHIC RANGE
Setting up your Pine Park Beetle Infestation Connection Circle(Adapted from The Shape of Life)
1. Draw a large circle on a piece of paper or use a connection circle template.
2. Cut out the "elements of the story" strips and spread them out on the table.
3. Put "Pine Bark Beetle Infestation" at the top outside of the circle.
4. Next, place the "CO2 in the atmosphere increases" and "Warming Atmosphere" strips on opposite sides of "Pine Bark Beetle Infestation"
5. Finally, place the other strips around the outside edge of the remaining circle.
Identifying Causal Connections in your Connections Circle.
Refer to your Carbon Cycle Interactive for help if you need to.
1. Starting at the "Pine Bark Beetle Infestation element" use an arrow to draw your first causal connection. As you draw arrows, think about the casual connections in terms of increases and decreases. Example: If this process increases, then this will cause an (increase or decrease) in another process. Make sure you draw your arrows from the "cause" to the "effect."
2. Continue identifying causal connections until you have drawn at least seven arrows.
Part 3: Identifying feedback loops
Identifying feedback loops in the carbon cycle allows us to understand why the carbon cycle is behaving a certain way and how it might behave in the future. Feedback loops can often tell us the cause of changes we see in the carbon cycle.
There are two basic types of feedback loops you will be looking for in this activity:
- Amplifying feedback loop An amplifying feedback loop amplifies the original element by increasing, speeding up or reinforcing the original element. This is also called a positive feedback loop.
- Dampening feedback loop. A dampening feedback loop slows down or reduces the original element. This is also called a negative feedback loop.
1. Carefully examine the arrows in your Pine Bark Beetle connection circle. Choose one element (for example photosynthesis) and start to look for arrows that "loop back" to your beginning element. This is a feedback loop. For each loop that you find, trace it with a different color marker.
2. Choose one loop and draw it on a separate piece of paper. Indicate whether each arrow leads to an increase (+) or a decrease (-) in the next element. Follow the same process for any other loops you have found on your connection circle.
3. Next, you will identify each loop as either an amplifying feedback loop or a dampening feedback loop.
- In an amplifying feedback loop, the final arrow leading back to the originating element amplifies that element. In the Arctic example, the rising temperature was amplified by the melting sea ice and
- In a dampening feedback loop, the final arrow leading back to the originating element dampens or slows down that original element.
Hint: There can be both (-) and (+) arrows in a feedback loop, but the last arrow is the most important.
4. Do any of your feedback loops share a common element? If so, try to draw them side by side and connected.
Share your connection circle and feedback loops with other groups or the class.
- Are the Connection Circles in the classroom all the same? Identify some similarities and some differences.
- Compare your feedback loops you found in the Pine Bark Beetle Infestation connection circle. Does the feedback loop amplify the initial change or dampen it? What makes you think so?
- What do the feedback loops tell you about how the Pine Park Beetle Infestation is impacting carbon cycle processes?
Positive and Negative Feedback Loops: The language of scientists.
A positive feedback loop A positive feedback creates conditions that amplifies, increases or speeds up a process or variable. Positive feedbacks tend to destabilize a system. is an amplifying feedback. Other words and phrases associated with positive feedback loops are amplifying, vicious circle, snowball effect, domino effect, feeds back in on itself, run-away change, and self-reinforcing loop.
A negative feedback loop A negative feedback loop creates conditions that dampens or slows down a process or variable. Negative feedbacks tend to stabilize or balance a system. is a dampening feedback. Other words and phrases associated with negative feedback loops are dampening, balancing, restores balance, and reducing.
Stop and Think
- Re-examine your Pine Bark Beetle feedback loops again. Are they negative or positive feedback loops? How do you know?
- Write a statement that describes what happens in the feedback loop(s).
Complex systems such as ecosystems and the carbon cycle have multiple positive and negative feedbacks operating at the same time.
- The influence of some feedbacks dominate the influence that other feedbacks have on the system
- Some feedbacks operate at different time scales - days, years, decades, centuries etc.
- Some feedbacks operate at different spatial scales - local, regional, continental, hemispheric, global
Look at the different causal feedback loops you have identified in your pine bark beetle activity. Hypothesize as to how these feedback loops might differ from each other in terms of their influence on the system, and/or the time scales and spatial scales on which they operate.
Articles and videos on pine bark beetles, forests and carbon cycles:
Feedback loops in other systems: There are many examples of feedback loops (causal loop diagrams) available on the Internet. For example, you might want to explore causal loops in a political system, an economic system, a business system, history or human behavior - the list goes on and on. Research a causal loop that interests you and bring a causal loop diagram to class with a title and brief written explanation. Contribute your causal loops to a feedback wall. Looking at many different examples will help you and your classmates understand feedback loops.