Ice age onset tied to declining CO2 levels

Ancient geological formations are giving further evidence that the temperatures on the surface of the earth are controlled by the amount of carbon dioxide in the atmosphere.

Around 460 million years ago, the Appalachian mountains had just pushed up volcanic soils from beneath the ocean to the surface. The silicate rock reacted with air and moisture and captured CO2 in the atmosphere. The result? In 7 to 8 million years, the Ordovician ice age began.

"We are seeing a mechanism that changed a greenhouse state to an icehouse state, and it's linked to the weathering of these unique volcanic rocks," said Seth Young, a postdoctoral student at OSU in a prepared statement.

It's the opposite of what's happening now, according to most scientists who've studied global warming. Increased levels of CO2 caused by burning fossil fuels are causing temperatures on the earth to climb.

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