A system is a set of interconnected parts that form a whole. An open system exchanges matter, energy, and information with its surroundings, while a closed system exchanges only energy. Feedback occurs when a system's output is used as its input and can be either negative, stabilizing systems, or positive, driving large-scale changes through reinforcing loops.

1. SYSTEMSSCIENCE

2. SYSTEM
• A set of connected, interacting
parts forming a complex whole

3. OPEN SYSTEM
• Able to exchange matter, energy and
information with their surroundings
• Constantly changing though processes
and relative outcomes relatively
constant
• Most common
• Ex: Ecosystems, living organisms, ocean,
etc.

4. CLOSED SYSTEM
• Exchanges energy but not matter with
its surroundings
• Water and Nitrogen cycles are pretty
close to being closed systems
• The Earth is a pretty much a closed
system; receives energy from sun but
does not really exchange matter with
the universe

5. FEEDBACK
• Occurs when the output of the system is
used as an input in that system
• Two types: Negative & Positive

6. NEGATIVE FEEDBACK
• Tend to stabilize a system around a mean/average condition
• Ex: Climate control/HVAC in your house
Increased surface
temperature
Increased ocean
evaporation
Increased cloud cover
More sun reflected
back to space
Decreased surface
temperature
Decreased ocean
evaporation
Decreased cloud
cover
Less sun reflected
back to space

7. POSITIVE FEEDBACK
• Increase a departure from the mean
• Tend to drive large scale changes to the climate and environment
Increased surface
temperature
Increased melting fo
permafrost
Increased surface
temperature
Increased ice melting
Decreased albedo
(reflected sun)
More heat retainedRelease of methane
Enhanced greenhouse
effect