1. Causal Loop Diagrams

2. Exponential growth of a bank account
Exponential growth of a bank account. The two positive connections between Bank balance and interest added for a positive feedback loop.

3. Causal Loop Diagrams

4. Earth’s Energy Balance
Earth’s Energy Balance. More absorbed sunlight increases Earth’s temperature. A warmer Earth sends off more heat radiation (a.k.a. longwave, infrared, or terrestrial) to space keeping our planet from getting too hot.
Earth’s albedo is the fraction of sunlight reflected back into space without being absorbed.

5. Connections (+ or - ??) Remember use nouns Absorbed Sunlight
Earth’s Mean Temperature
Planetary albedo
Earth’s Mean Temperature
Earth’s Mean Temperature
Emitted Infrared
Cloud Cover
Planetary albedo
Planetary albedo
snow Cover
Volcanic aerosol
Planetary albedo
Earth’s Mean Temperature
Water Vapor
Earth’s Mean Temperature
CO2
Knowing the “sense” of connections between two system components is essential to understanding overall system behavior.
If when the first increases the second also increases the connection is positive.
If when the first increases the second also decreases the connection is negative.

6. Connections (+ or - ??) Answers
Absorbed Sunlight
Earth’s Mean Temperature -
Planetary albedo
Earth’s Mean Temperature -
Earth’s Mean Temperature
Emitted Infrared
+ or -
Earth’s Mean Temperature
Cloud Cover +
Planetary albedo
snow Cover -
Earth’s Mean Temperature
Volcanic aerosol +
Earth’s Mean Temperature
Water Vapor +
Earth’s Mean Temperature
CO2
Remember use nouns

7. Example Draw a causal loop diagram to describe the following:
The sun becomes brighter causing Earth to warm. As the Earth warms it gives off more longwave radiation until it settles into a new equilibrium temperature.

8. Example - Draw a causal loop 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

9. Air Resistance

10. Connections (+ or - ??) Remember use nouns Size (area) of car
Air resistance force
Air resistance force
Air temperature
Speed of car
Air resistance force
Remember use nouns

11. Air resistance
Net downward Force
weight

12. Connections (+ or - ??) Remember use nouns Size of parachuet
Air resistance force
Altitude
Air resistance force
Air resistance force
Jumper’s speed
Size of parachuet
Net downward force
Altitude
Net downward force
Jumper’s speed
Net downward force
Remember use nouns

13. Draw a causal loop diagram to describe the following: As the sky diver falls she travels faster and faster until reaching a terminal velocity. Include diver’s speed, air resistance and net downward force in your diagram.

14. Gas pedal depression car’s speed
MPH above speed limit car’s speed

15. Home Heating

16. Home Heating

17. Home Heating