Interactions and Feedback
Part C: Ice-Albedo Feedback
A positive feedback loop creates conditions that speeds up a process and/or amplifies the effect. Other words and phrases associated with positive feedback loops are vicious circle, snowball effect, domino effect, feeds back in on itself, run-away change, and self-reinforcing loop.
A negative feedback loop creates conditions that makes the process slow down and/or dampens the effect. Other words and phrases associated with negative feedback loops are balancing, restores balance, and reducing.
Connection Circles: Identifying Causal Connections
(adapted from The Shape of Change)
Causal connections are another way to describe "cause and effect" relationships. Systems thinkers use Connection Circles as a graphical 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. As you use the Connection Circle in the activity below, you will find that these "If...then" statements will interconnect in many ways.
Because of their high reflectivity, snow and ice are instrumental in regulating Earth's temperature. If climate warms, then snow and ice will melt. Then what? Let's explore.
Materials you will need:
- Pencils and colored pencils or markers
- A Connections Circle diagram or draw one on your own. Larger paper is best.
- Ice-Albedo Feedback "Element Strips"
SEA ICE MELTS
A WARMING CLIMATE
CO2 IN ATMOSPHERE
GLACIERS & ICE SHEETS GROW
DARKER GROUND/WATER IS EXPOSED
GREATER HEAT ABSORPTION
ALBEDO (REFLECTIVITY) INCREASES
ALBEDO (REFLECTIVITY) DECREASES
OCEAN TRADE ROUTES OPEN
SEA LEVEL RISES
FRESH DRINKING WATER SUPPLY DECREASES
Setting up your Ice-Albedo Feedback Connection Circle.(Adapted from The Shape of Life)
- Draw a large circle on a piece of paper or use a connection circle template.
- Cut out the "elements of the story" strips and spread them out on the table.
- Put "Sea Ice Melts" at the top outside of the circle.
- Place the other strips around the outside edge of the remaining circle.
- Starting at the "Sea Ice Melts" element, draw an arrow to your first causal connection. Make sure you draw your arrows from the "cause" to the "effect."
- Continue identifying causal connections until you have drawn at least seven arrows.
- Carefully examine the arrows in your Ice-Albedo Feedback Connection Circle. Choose one element (for example, "albedo decreases") 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 pencil or marker.
- 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.
- Next, you will identify each loop as either an "amplifying feedback loop" or a "dampening feedback loop." Here is how you tell the difference:
- In an amplifying feedback loop, the final arrow leading back to the originating element is a (+) arrow representing an increase or "amplification."
- In a dampening feedback loop, the final arrow leading back to the originating element is an (-) arrow representing a decrease or dampening effect.
Hint: There can be both (-) and (+) arrows in a feedback loop, but the last arrow is the most important.
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 the feedback loops you found in the Ice-Albedo Feedback Connection Circle. Does the feedback loop amplify the initial change or dampen it? What makes you think so?