May 8, 2009

Oxygen spike may have caused ice age

Earth's earliest ice age could have been caused by an atmospheric rise in oxygen reacting with methane, a greenhouse gas, a geologist in Maryland said.

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 and a team of international scientists found evidence the oxygenation of Earth's atmosphere coincided with the first widespread ice age on the planet 2 1/2 billion years ago.

They theorize the earliest ice age was created from oxygen escaping from developing oceans and filling up the atmosphere, where there had been no oxygen. The oxygen then reacted with methane, a powerful greenhouse gas, to form carbon dioxide, which is 62 times less effective at warming the surface of the planet.

With less warming potential, surface temperatures may have plummeted, resulting in globe-encompassing glaciers and sea ice Kaufman said.