Reasons for our planet’s earliest ice age may have been uncovered, according to geologists last week. It seems that Earth’s earliest ice ages could have been caused by an atmospheric rise in oxygen, which in turn, reacted with methane, a greenhouse gas, and chilled the earth.

“This singular event had a profound effect on the climate, and also on life,” said Alan J. Kaufman, a geology professor at the University of Maryland.

Kaufman, along with colleague James Farquhar and a team of scientests hailing from the United States, Canada, Germany and South Africa, have discovered that the initial oxygenation of the Earth’s atmosphere occurred alongside Earth’s first widespread ice age.

Using 2.3 billion-year-old rocks from South Africa, the team used sulfur isotopes to analyze increases in atmospheric oxygen levels that simultaneously occurred with ice formation and shifting carbon dioxide patterns.

“The sulfur isotope change we recorded coincided with the first known anomaly in the carbon cycle,”  Kaufman explained. “This may have resulted from the diversification of photosynthetic life that produced the oxygen that changed the atmosphere.” The rise in oxygen stimulated the rise in our ozone layer, decreasing UV rays and allowing organisms that usually harbour themselves near the ocean floor to move to the surface – and in turn, delivering oxygen.

The Great Oxidation Event transformed the Earth’s atmosphere, climate, and the life that populated its surface.

The study is published in the May issue of Geology.
Image courtesy of ohiomm.com

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