Draft 1. Did Snowball Earth Occur?

This topic submitted by Lisa Headen and Chelsea Dorman on 3/9/04 .

Global Climate Change -Western Program-Miami University

Abstract

The primary purpose of our research is to find out if Snowball Earth actually occurred. Evidence of a climate change like this can be found in geological records. We plan on looking at these geological records to determine whether or not a period of global glaciation was possible. If it was possible, we would like to know what factors caused it. This would be useful in the future so that we can compare the current climate of the earth to what led to Snowball Earth and look for correlations. In addition, if Snowball Earth did occur it would greatly impact the life on the planet.

Introduction

The snowball earth theory suggests that the earth was once completely frozen over. It would have been caused by the breakup of a single landmass during the Neoproterozoic period. This breakup increased the amount of rainfall, which decreased the earthÕs temperature and formed ice. As ice formed it increased the albedo of the earth, cooling temperatures even further. In theory, this continued until the earth was completely frozen over.
In doing our research we hope to find out how probable it was that the earth was once completely covered in ice, and if so could it happen again? We predict that Snowball Earth could have occurred. Based on this prediction we will look at what caused the glaciation in the first place. We predict that it was influenced by factors such as the strength of the sun being weaker, the earth having a greater axial tilt than it does today, and the magnetic pole wandering. Since there is no good experimental way for us to test if the earth could ever be frozen we will rely primarily on evidence that has been found of the history of the earth that suggests it was frozen.

Relevance

There has been evidence found around the globe that both supports and refutes Snowball Earth. We propose looking at data gathered from geologic records of various locations, as well as other peopleÕs conclusions to determine whether or not this occurred. The results of our research will provide important implications. It would show us how global warming or cooling can quickly spiral to an extreme. This could be related to the current temperatures of the earth to see if we are in danger of this happening. In addition, if Snowball Earth had occurred it would have had a significant impact on the life that developed on the planet.

References

Websites

BBC News "'Snowball Earth' Theory Melted" Available from website http://news.bbc.co.uk/2/hi/uk_news/scotland/1857545.stm
This website gives evidence against the idea of the snowball earth theory.

Hoffman, Paul and Daniel Schrag. "Snowball Earth." Available from website http://www.sciam.com/article.cfm?articleID=00027B74-C59A-1C75-9B81809EC588EF21&pageNumber=1&catID=2
This website gives extensive information on snowball earth.

Hoffman, Paul and Daniel Schrag. "The Snowball Earth." Available from website http://www-eps.harvard.edu/people/faculty/hoffman/snowball_paper.html

"Snowball Earth" Available from website http://www.uwsp.edu/geo/faculty/hefferan/Geol106/CLASS4/snowball_earth.htm
This is a class website giving basic information about what the theory is and how to find more information about it.

Wikipedia, "Snowball Earth." Available from website http://en.wikipedia.org/wiki/Snowball_Earth
This website gives basic information about the idea of snowball earth.

Library / Articles

Beyth, M.; Avigad, D.; Wetzel, H.-U.; Matthews, A.; Berhe, S.M. "Crustal exhumation and indications for Snowball Earth in the East African Orogen: north Ethiopia and east Eritrea" Precambrian Research Volume: 123, Issue: 2-4, June 10, 2003. pp. 187-201.
This article uses information about crustal deposits to support the idea of a snowball earth.

Evans D.A.D. "A fundamental Precambrian-Phanerozoic shift in earth's glacial style?" Tectonophysics, 6 November 2003, vol. 375, no. 1, pp. 353-385(33)
This article gives possible explainations for the cause of snowball earth.

GoddÚris, Y.; Donnadieu, Y.; NÚdÚlec, A.; DuprÚ, B.; Dessert, C.; et. al. "The Sturtian ÔsnowballÕ glaciation: fire and ice." Earth and Planetary Science Letters Volume: 211, Issue: 1-2, June 15, 2003. pp. 1-12.
This article explains how magma events affected the outcome of snowball earth.

Hoffman, Paul F.; Schrag, Daniel P. "The snowball Earth hypothesis: testing the limits of global change" Terra Nova Volume: 14, Issue: 3, June 1, 2002. pp. 129-155.
This article provides us with a basic understanding of the processes and ideas behind the snowball earth theory.

Hoffman, Paul F. "The break-up of Rodinia, birth of Gondwana, true polar wander and the snowball Earth." Journal of African Earth Sciences Volume: 28, Issue: 1, January, 1999. pp. 17-33.
This article talks about how the tilt of the earth may have been the catalyst for the snowball earth phenomena.

Maloof, Adam C.; Kellogg, James B.; Anders, Alison M.
"Neoproterozoic sand wedges: crack formation in frozen soils under diurnal forcing during a snowball Earth." Earth and Planetary Science Letters Volume: 204, Issue: 1-2, November 30, 2002. pp. 1-15.
This article explains how the temperature of the earth affects the sand deposited at any given time.

Meert, J.G.; van der Voo, R. "The Neoproterozoic (1100-540 Ma) glacial intervals: No more snowball Earth? Reply" Earth and Planetary Science Letters Volume: 131, Issue: 1-2, March, 1995. pp. 123-125.
This article gives information about why the snowball earth theory is incorrect.

Miller, Nathan R.; Alene, Mulugeta; Sacchi, Rosalino; Stern, Robert J.; Conti, Anna; Krûner, Alfred; et. al. "Significance of the Tambien Group (Tigrai, N. Ethiopia) for Snowball Earth events in the Arabian Nubian Shield." Precambrian Research Volume: 121, Issue: 3-4, March 25, 2003. pp. 263-283.
This article looks at sediment deposition in the Arabian area as a sign of global temperature.

Tajika, Eiichi. "Faint young Sun and the carbon cycle: implication for the Proterozoic global glaciations." Earth and Planetary Science Letters Volume: 214, Issue: 3-4, September 30, 2003. pp. 443-453.
This article talks about how the change in carbon could lead to a global decline in temperature leading to global ice cover.

Young, Grant M. "Stratigraphic and tectonic settings of Proterozoic glaciogenic rocks and banded iron-formations: relevance to the snowball Earth debate." Journal of African Earth Sciences Volume: 35, Issue: 4, November, 2002. pp. 451-466.
This article looks at the composition of rocks, specifically the iron deposits as a sign of temperature and composition of the atmosphere.

Materials and Methods

We plan on doing our research by looking at published information, such as journal articles on Snowball Earth. There are several studies of geologic records that have concluded that layers identified in the earth's crust are sufficient evidence of the occurrence of global glaciation. However, there are also studies that say this same evidence shows that global glaciation never did occur. Therefore, when we are looking at these studies it is important for us to look at what specifically led to these conclusions, and then evaluate how valid this is.
Our timeline of carrying out this project consists of primarily doing research and then spending the final two weeks drawing our conclusions and writing a report about our findings.

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