It is popularly believed that 700million year ago, during the late Neoproterozoic era the earth was completely covered with ice. The period which, preceded the Cambrian explosion, when earth grew more rapidly than during any other period in the planet’s history, was a critical moment in the planet’s evolutionary history. The rock samples from this era show large variations in the quantity of carbonates. The carbonate variations suggest that life was prevalent on the planet immediately before and after the glacial period and total halting of photosynthesis during the glacial age.
The theory, commonly known as the Snowball Earth Theory has been contradicted by three Canadian Researchers. On Wednesday, they revealed a climate model published in the journal Nature that did not support the earlier contentions made by scientists regarding the earth’s condition during the glacial age. Their new model, christened the Slushball Earth Theory claimed that the complex carbon cycles occurring in the oceans prevented the earth from being completely frozen. The oceans near the equator during the period were only partly frozen.
The new model showed that oxygen in the atmosphere diffuses into the ocean as temperature drops. The added oxygen would trigger oxidation of organic carbon in the ocean turning it into carbon dioxide which when released into the atmosphere would produce the greenhouse effect.
This process has been termed by the scientists as ‘negative feedback’ the process by which the natural cooling of the atmosphere is reversed by the carbon cycle. The is reverse to what is happening at present owing to man made greenhouse gas emissions that is instead melting ice at the poles.
Source:cbc
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