What caused the ice ages? Tiny ocean fossils offer key evidence

Liz Fuller-Wright, Office of Communications

Since the discovery that atmospheric carbon dioxide (CO2) concentrations were lower during past ice ages, the cause has been a mystery. Now, the fossils of ocean algae reveal that a weakening in upwelling in the Antarctic Ocean, the ocean around Antarctica, kept more CO2 in the deep ocean during the ice ages. This brings scientists closer to a complete explanation for the climate cycle between the ice ages and warm periods such as today. This also suggests that upwelling will strengthen under human-driven global warming, altering the concentration of atmospheric CO2, global climate and ocean ecosystems.