Feedback Loop in Environmental Systems

Feedback loops for Global Warming

Positive feedback loops

• Positive feedback is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance.

• That is, A produces more of B which in turn produces more of A. 

• Positive feedback tends to promote the triggering mechanism.

Negative feedback loops

• Negative feedback occurs when some function of the output of a system, process, or mechanism is fed back in a manner that tends to reduce the fluctuations in the output.

• A system in which the results of a change act to reduce or counteract it has negative feedback.

• Negative feedback tends to promote a settling to equilibrium.

Multiple Choice

Earth warms, which increases evaporation of water from oceans, which adds additional water vapor to atmosphere. In this case, water vapor is a greenhouse gas.

• Positive Feedback Loop

• Negative Feedback Loop

Multiple Choice

On a hot day, people turn on their air conditions. The air conditions are run with electricity which is generated in a power plant by burning natural gas. The exhaust from the power plant is CO2. With more CO2, the atmosphere heats up more and people turn their air conditions up.

• Positive Feedback Loop

• Negative Feedback Loop

Multiple Choice

Earth warms and algae populations will increase. The algae will use CO2, thus depleting CO2 from the atmosphere.

• Positive Feedback Loop

• Negative Feedback Loop

Multiple Choice

Earth warms and water evaporates from the ocean. The moisture condenses to form clouds. The clouds reflect sunlight back into space.

• Positive Feedback Loop

• Negative Feedback Loop

Multiple Choice

Earth warms and glaciers and ice caps melt and dark terrestrial land is exposed. The dark land absorbs sunlight.

• Positive Feedback Loop

• Negative Feedback Loop