Feedback cycle

A feedback cycle is some cyclic structure of cause and effect that causes some initial change in the system to run through a series of secondary effects, eventually influencing the initial change in some way.[1] There are two major types of feedback cycles or loops. The first is a negative feedback or a balancing loop. The second type is a positive feedback or reinforcing loop. Figures illustrating the different feedback cycles are shown below.

Positive Feedback Cycle

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Positive feedback cycles are cycles where some initial disturbance causes a series of secondary effects that, over the course of the cycle, return to cause some increase in the magnitude of the initial disturbance. This causes some initial change to grow larger and moves the system out of its original equilibrium state. This is the reason it is called a reinforcing loop, as changes move through the cycle to magnify and reinforce the initial change. Positive loops such as these tend to be destabilizing, pushing systems out of equilibrium and causing fairly drastic overall change from a disturbance.

In the climate system, positive feedback cycles are incredibly important. These positive climate feedbacks include cycles such as the ice-albedo feedback and carbon release. To learn more about these specific feedbacks, click here.

Negative Feedback Cycle

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Negative feedback cycles are cycles where some initial disturbance causes a series of secondary effects that, over the course of the cycle, return to minimize the magnitude of the initial disturbance. This causes some initial change to grow smaller, keeping the system from moving out of its equilibrium state. This is the reason it is called a balancing loop, as it moves to maintain the balance of a system. Negative loops such as these tend to be stabilizing, as they keep systems in a state of equilibrium by minimizing some initial effect to keep the system in the same initial state despite some "push".

In the climate system, negative feedback cycles are incredibly important. These negative climate feedbacks include cycles such as the loop of cloud creation caused by evaporation. To learn more about this and other specific feedback cycles, click here.

References

  1. Thwink. (November 29, 2015). Feedback Loop [Online]. Available: http://www.thwink.org/sustain/glossary/FeedbackLoop.htm
  2. 2.0 2.1 Created internally by a member of the Energy Education team.

Authors and Editors

Jordan Hanania, Kailyn Stenhouse, Jason Donev