Bathtub Water Level Model

Cloud – input/output that doesn’t affect model

Converter – constant used within the model

Flow – causes conditions to change

Stock – tells what conditions are

Link – connects two parts of a model

Key to Symbols

Water Supply

Water LevelSewer

Faucet Drain

Water pressure “Cloggage”

Compound Interest Model

Cloud – input/output that doesn’t affect model

Converter – constant used within the model

Flow – causes conditions to change

Stock – tells what conditions are

Link – connects two parts of a model

Key to Symbols

Interest Rate

Earning InterestBank Balance

The R means that this is a self-reinforcing or “positive” feedback loop which makes the result exponential

R

Compound Interest ModelCan be represented by a relatively simple equation

Where:A – Final amountP – Principle amountr – Interest Ratet – Time (years)

Can also be shown graphically

Rule of thumb:10X more CPUfor a doubling ofresolution

Increased Resolution RequiresIncreased Computing Resources

1980’s

1990’s2000’s

Sources• Slide 1 and 2

– “An Introduction to Systems Thinking”, High Performance Systems, Inc.• Slide 3

– http://www.crackerjackgreenback.com/the-basics/compound-interest-a-lesson-from-benjamin-franklin/

• Slide 4– http://co2now.org/Know-the-Changing-Climate/Climate-System/ipcc-faq-clim

ate-change-weather.html

• Slide 5– http://www.atmosp.physics.utoronto.ca/people/guido/research.html

• Slide 6– http://serc.carleton.edu/eslabs/weather/5c.html

• Slide 7– http://serc.carleton.edu/eet/envisioningclimatechange/teaching_notes.html