Causal Loop Diagrams

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.

Causal Loop Diagrams

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.

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.

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

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.

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

Air Resistance

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

Air resistance Net downward Force weight

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

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.

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

Home Heating

Home Heating

Home Heating