Snowball Earth




Global glaciations occurred due to the long periods of isolation andextreme environments on a snowball earth (Hoffman &amp Schrag,2000). The plate tectonics viewpoint explains how the planet’sthin, rocky skin was broken into giant pieces. Subsequently, thelatter segments moved atop a distinct mass of hotter rock below.During a global glaciation, shifting tectonic plates wouldcontinually build volcanoes and release carbon dioxide into theatmosphere (Hoffman &amp Schrag, 2000). Furthermore, some physicaland chemical mechanisms would drive the earth into a deep-freeze. Forexample, liquid water required to erode sedimentary rocks and burythe carbon would be trapped within the mass of ice (Hoffman &ampSchrag, 2000). Consequently, the carbon dioxide would accumulate tohigh levels. Contrariwise, a low concentration of carbon dioxide wassufficient to cause a deep-freeze on the earth.

On the other hand, the earth could have reversed the deep-freeze andentered a global hothouse state. In this regard, extreme greenhouseconditions would have led to the development of thick sequences ofcarbonate rocks. Such hot and humid conditions would be particular tothe transient aftermath of a snowball earth (Hoffman &amp Schrag,2000). An ultrahigh level of carbon dioxide would be needed in theatmosphere to raise temperatures if the earth froze over. Notably,the temperatures had to match the melting point at the equator. Theonset of melting was accompanied by the replacing of high-albedo icewith low-albedo seawater (Hoffman &amp Schrag, 2000). Consequently,the runway freeze would be reversed. Similarly, resumed evaporationwarms the atmosphere because water vapor acts as a powerfulgreenhouse gas (Hoffman &amp Schrag, 2000). Subsequently, a massivereservoir of atmospheric moisture could create and enhanced watercycle. Torrential rainfall would also eliminate some of theatmospheric carbon dioxide in the form of carbonic acid (Hoffman &ampSchrag, 2000). Therefore, the snowball earth could enter into aglobal hothouse state.


Hoffman, P. F., &ampSchrag, D. P. (2000). Snowball earth. Scientific American,282(1), 68-75.

Snowball Earth


Manytheories exist about the how the earth evolved. During evolution, icecovered the earth in a period known as the Neoproterozoic Era(Hoffman and Schrag, 1999). During this time, the intensity of theice was so high that the tropics froze over. Complex animals are saidto have evolved in the heat wave after the Neoproterozoic Era. Thispaper answers questions about the Neoproterozoic Era, CO2 emissions,and effects of expanding glaciers.

Cluesthat Ice may have Completely Covered the Earth

Thepresence of thick layers of ancient rock is one early clue that iceonce covered the earth (Hoffman and Schrag, 1999). Some of theserocks are visible on hills that are near the Namibian northwestcoast. There is dirt on the rocks that was left behind after the icemelted (Hoffman P. and Schrag, 1999). There is glacial debris thatoccurred near the sea level in the tropics. All these are testimoniesof the Neoproterozoic Era.

Explainthe effect of decreased Carbon Dioxide (CO2) level in the atmosphereon the climate.

Carbondioxide gas is responsible for keeping the earth warm and thereforeif the degree of this gas was to drop, the earth would freeze(Hoffman and Schrag, 1999). A drop in CO2 levels in the atmospherewould allow invasion of ice sheets like the ones in Greenland andAntarctica (Hoffman and Schrag, 1999).

Albedoand effects of expanding Glaciers

Seaice and continental glaciers have higher albedo as compared tosea-water and vegetation (Hoffman and Schrag, 1999). Expandingglaciers would cause a rise in the earth’s albedo. The amount ofsolar radiation absorbed by the earth would reduce as the sunlightwould instead strike the large surface of the expanding glaciers(Hoffman and Schrag, 1999).


Fromthe observations made in the article, it is clear that there havebeen significant changes in the earth’s temperature over time.


HoffmanP. F. and Schrag D.P. (1999). . Scientific American Inc