Name______________ Period___ Date_______

Feedback Practice

There are a number of examples of how both positive and negative feedback mechanisms might operate in the physical environment. No-one can be sure which of these effects is likely to be most influential, and consequently we cannot know whether or not the Earth will manage to regulate its temperature, despite human interference with many natural processes.

1. Label each example overleaf as either positive or negative feedback

2. Draw diagrams of one example of positive feedback and one example of negative feedback using the examples given, to show how feedback affects a system. Include feedback loops on your diagrams.

Examples of possible positive and negative feedback in physical systems

1. As carbon dioxide levels in the atmosphere rise:

• Temperature of Earth rises

As Earth warms:

• the rate of photosynthesis in plants increases

• more carbon dioxide is therefore removed from the atmosphere by plants, reducing the greenhouse effect and reducing global temperatures

 Draw a Diagram of the feedback Loop

2. As Earth warms:

• Ice cover melts, exposing soil or water

• Albedo decreases

• More energy is absorbed by Earth’s surface

• Global temperature rises

• More ice melts

Draw a Diagram of the feedback Loop

 

3. As Earth warms, upper layers of permafrost melt, producing waterlogged soil

above frozen ground:

• Methane gas is released in anoxic environment

• Greenhouse effect is enhanced

• Earth warms, melting more permafrost

 Draw a Diagram of the feedback Loop