Ocean Circulation May Have Released CO2 at End of Ice Ages  New
research suggests oceans play a critical role in climate by
regulating greenhouse gas levels iceberg in the Southern Ocean
Flickr/Liam Quinn  At the end of each ice age, the ocean exhales
carbon dioxide. Scientists believe this explains the difference
in atmospheric CO2 concentrations between ice ages, which have
lower concentrations of carbon dioxide, and warmer, more
CO2-saturated periods like the one we're living in now.  What
causes that carbon dioxide to exit the ocean when an ice age
ends, though, is still a puzzle oceanographers are trying to
decipher. The leading hypothesis now is that it wasn't primarily
ocean circulation but a change in the location or strength of
winds in the Southern Ocean near Antarctica that forced
upwelling of deep ocean water, which then released CO2 to the
atmosphere.  But research published yesterday in the journal
Nature rebuts this idea, suggesting that it was changes in ocean
circulation, not winds, that pre