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C. How Sea Ice May Have Affected Past Climate Changes

Narrator: This is Science Today. Researchers at the University of California's Scripps Institution of Oceanography are studying how variations in Antarctic sea ice may have lowered atmospheric carbon dioxide levels during the last ice age. Ralph Keeling, who led the study, says carbon dioxide-rich waters in the deep ocean primarily return to the surface around Antarctica. Since these waters were mostly covered with ice during glacial periods, this could have prevented the carbon dioxide from escaping.

Keeling: In a sense, you could think of our study as invoking a mechanism as simple as putting a cap on a soda bottle. You trap the carbon dioxide by preventing it from leaking out and if the deep ocean really only comes into contact with the atmosphere in a few places, particularly around Antarctica, then you don't have to cover very much of the ocean's surface with this cap to affect the retention in the deep water.

Narrator: This retention may have influenced very abrupt climate changes in the past.

Keeling: There does seem to be a unifying theme in this work that maybe Antarctic sea ice is a major influence on past climates.

Narrator: For Science Today, I'm Larissa Branin.