“We think we may have found the answer. Increased circulation in the Southern Ocean allowed carbon dioxide to leak into the atmosphere, working to warm the planet,” said Princeton University’s Professor Daniel Sigman, co-author of the study. For years, researchers have known that growth and sinking of phytoplankton pumps carbon dioxide deep into the ocean, a process often referred to as the ‘biological pump.’ “The biological pump is driven mostly by the low latitude ocean but is undone closer to the poles, where carbon dioxide is vented back to the atmosphere by the rapid exposure of deep waters to the...