Snowball Earth

Topics: Snowball Earth, Earth, Glacier Pages: 4 (1391 words) Published: March 9, 2011
The Snowball Earth Hypothesis

The concept of Earth being in an extreme climatic state which resulted in the covering of the Earth’s surface and oceans in glaciers and ice sheets about 600 million years ago in the Neoproterozoic era, which lasted for about ten (10) million years or more, is considered to be the Snowball Earth hypothesis ( Hoffman and Schrag, 2000). This theory suggests that an uncontrollable positive feedback of the ice-albedo caused the complete freezing of the Earth including the tropical and equatorial latitudes (Allen and Etienne, 2008). The ending of this extreme state and the climatic reversal is said to be brought about by high levels of carbon dioxide emitted into the Earth’s atmosphere from volcanoes over long periods of time. In support of the Snowball Earth theory, there has been evidence in the deposition and composition of rocks, the alignment of minerals in rocks to the magnetic field, and the composition of the oceans from the Neoproterozoic era. However, there have been several factors and evidence such as sedimentary rock deposition and the fossils of several microscopic organisms which indicated that during the event of this extreme glaciation, there were some oceans that remained unfrozen.

Based on W. Brian Harland’s conclusion from the magnetic orientation of the mineral grains in the glacial rocks which are predated to the Neoproterozoic era, the relatively horizontally alignment with the magnetic field was due to their close proximity to the equator. During the Neoproterozoic era all the continents were clustered together near the equator. Because of the position of continents near the equator, the ice albedo feedback increased tremendously causing the rapid decrease in the surface temperatures as was explained by Mikhail Budyko by using equations based on the interactions of the solar radiation with the Earth to control climate (Hoffman and Schrag, 2000). The cold temperatures sustained and stabilized the snow...
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