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Beyond Earthly Skies

Snowball Earth: Refugia for Life

2 Sep 2013, 22:00 UTC
Snowball Earth: Refugia for Life
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At around 600 to 800 Mya, during the Neoproterozoic era, the Earth underwent at least two global-scale glaciation events, more commonly known as Snowball Earth events (Trindade and Macouin, 2007). During a Snowball Earth event, the ocean was completely covered by thick ice right down to the tropics. At low latitudes, the equilibrium ice cover over the ocean is estimated to be hundreds of metres thick and only got thicker at higher latitudes. The ice cover over the ocean would tend to flow from higher latitudes towards the Equator in the form of a global sea glacier (Goodman and Pierrehumbert, 2003; Pierrehumbert et al., 2011). Any unprotected area of open ocean surface is likely to be overrun by it.The existence of photosynthetic eukaryotic algae predates the Snowball Earth events of the Neoproterozoic era. At that time, life has yet to evolve from ocean to land and a completely ice covered ocean poses a problem for the survival of photosynthetic life. Nevertheless, a number of ways have been proposed that allow photosynthetic life to survive through a Snowball Earth event. It has been suggested that small pools of open water can exisit above geothermal hotspots on coastlines of volcanic islands (Hoffman ...

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