The polar ocean and glacial cycles in atmospheric CO2 concentration

The oscillations during the past 2.5 million years between ice ages and interglacials were probably triggered by orbital changes, but the observed amplitude and timing of these climate cycles still awaits a full explanation. One notable correlation links lower partial pressure (or concentration) of CO2 with ice ages: changes in CO2 concentration may cause some of the ice-age cooling, but what causes the loss of CO2 is unknown. Daniel Sigman, Mathis Hain and Gerald Haug review the evidence in support of the hypothesis that the Southern Ocean is an important driver of these glacial/interglacial changes in partial pressure of CO2.