Ice ages are triggered by Antarctic sea ice rising, study finds

For a cooler climate, order it on the rocks.

By Rae Hodge, CNET

Researchers from the University of Chicago have mapped out a climate-change chain reaction that starts with a rise in Antarctic sea ice and ends with an ice age. In a study this month, researchers presented a new model detailing how increased sea ice changes the ocean's circulation, and blocks the ocean from exchanging carbon dioxide with the atmosphere. More carbon dioxide in the ocean and less in the air would lead to a reverse greenhouse effect.

"One key question in the field is still what caused the Earth to periodically cycle in and out of ice ages," said Malte Jansen, UChicago assistant professor, in a Monday release. "We are pretty confident that the carbon balance between the atmosphere and ocean must have changed, but we don't quite know how or why." 

The researchers say understanding the outsized role played by carbon storage in the ocean can help scientists more accurately simulate future environmental change. 

While slight changes in Earth's orbit led to some cooling of the planet, Jansen said that wouldn't have been enough to start an ice age. Instead, massive accompanying changes would have had to happen to the planet's climate system.