Causal Loop Diagrams Causal loop diagrams can be very helpful for explaining the mechanism behind feedback loops and identifying whether the feedback loop structure is a positive or negative feedback loop.

Earth’s Energy Balance is used here to develop and explain causal loop diagrams.

Connections (+ or - ??)* Absorbed SunlightEarth’s Mean Temperature Emitted Infrared Earth’s Mean Temperature Cloud Cover Earth’s Mean Temperature Volcanic aerosol Earth’s Mean Temperature CO2 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 Earth’s Mean Temperature Water Vapor Planetary albedoEarth’s Mean Temperature

Connections (+ or - ??) Absorbed SunlightEarth’s Mean Temperature Emitted Infrared Earth’s Mean Temperature Cloud Cover* Earth’s Mean Temperature Volcanic aerosol Earth’s Mean Temperature CO2 use nouns * The effect of cloud cover is complicated because they reduce sunlight be day but provide warming at night. High thin ciro stratus clouds also influence the Earth system differently than low thick stratus clouds. Earth’s Mean Temperature Water Vapor Planetary albedoEarth’s Mean Temperature or

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.

Answer 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 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 the runaway effects of positive feedback processes.

Ice albedo feedbck process Draw a causal loop diagram capturing the essence of the feedback process decribed below. As Earth’s temperature increases from an increase in solar 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.

What are the polarities of each connection?

What are the polarities of each connection? What is the sign of this feedback loop?

What is the sign of this feedback loop?

Air Resistance

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

Connections (+ or - ??) Size (area) of carAir resistance force Air temperature Air resistance force** Speed of car Remember use nouns **Warmer air is thinner air Air resistance force + + -

weight Air resistance Net downward Force

Connections (+ or - ??) Size of parachuetAir resistance force AltitudeAir resistance force Jumper’s speed Remember use nouns Air resistance force

Connections (+ or - ??) Size of parachuetAir resistance force AltitudeAir resistance force Jumper’s speed Remember use nouns Air resistance force Note: our text uses For an opposite connection o

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, weight, and net downward force in your diagram.

Whenever the number of negative (opposite) connection is odd The loop is a negative feedback loop.