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Snowball Earth - feedback diagram

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by

Emily S

on 24 January 2014

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Transcript of Snowball Earth - feedback diagram

Under the surface
Snowball Earth - feedback diagram
Earth's climate has self regulated through a number of negative and positive feedbacks.

This diagram will present the Snowball Earth theory through an example of positive and negative feedback.

Positive Feedback
At certain times in Earth's history, the planet has been covered in ice, known as 'Snowball earth'.
But how did it get so cold that even the tropics were frozen?





Negative Feedback
Evidence shows that early Earth was much warmer than it is today.
However, the sun is 20-30% brighter now than it was 4.5 millions years ago, so why was early earth so warm?
There were more greenhouse gases in the atmosphere years ago, warming the Earth.

The meant the Earth's temperature increased.
As the temperature of the Earth increased, so did the rate of chemical weathering.
Increased chemical weathering stores more carbon in sedimentary rocks
This lowered the amount of carbon in the atmosphere
This lowered the temperature of the Earth, counteracting the gradual brightening of the sun.
Ice has a high albedo, so it reflects radiation from the sun.
This, combined with the growth of continents, removing carbon dioxide from the atmosphere make the planet cooler.
This allows the ice cover to spread further from the poles towards the equator
As the ice spreads, it reflects more radiation, lowering the temperature further, so more ice forms.
This is an example of a positive feedback, which led to Snowball Earth, where the entire planet was covered in ice.
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