Glacial Episodes: Understanding Positive Feedback

What are glacial episodes an example of?

a. positive feedback
b. negative feedback
c. the “Daisy model”
d. the Gaia hypothesis

Answer:

The correct answer is a. Glacial episodes are an example of positive feedback.

Glacial episodes serve as a prime example of positive feedback in the Earth's climate system. During a glacial period, positive feedback mechanisms come into play, amplifying the initial cooling effect and leading to more severe glacial conditions.

One of the key positive feedback processes during a glacial episode is the ice-albedo feedback. As temperatures drop, ice sheets and glaciers expand, increasing the Earth's overall albedo or reflectivity. This higher reflectivity causes more sunlight to be reflected back into space, further cooling the planet and promoting the growth of ice sheets. This cycle continues, with the cooling effect reinforcing itself and leading to more extensive glaciation.

Another positive feedback mechanism during glacial episodes involves the storage of carbon dioxide in the oceans. As the climate cools and ice sheets expand, atmospheric carbon dioxide levels decrease due to increased absorption by the colder oceans. This reduction in greenhouse gas concentration further contributes to cooling the Earth and perpetuates the glacial conditions.

In summary, glacial episodes exemplify the concept of positive feedback, where initial changes in the climate system are intensified and amplified by self-reinforcing mechanisms. Understanding these feedback processes is crucial for comprehending the dynamics of Earth's climate and predicting future climatic changes.