Around 2.7 million years ago, cooling ice build-up in the northern hemisphere coincided with a shift in ocean circulations. Today’s oceanic circulation pulls heat and carbon dioxide north to south through the Atlantic until both are released in the south Pacific.
‘It was the establishment of the modern deep ocean circulation and not a major change in carbon dioxide concentration in the atmosphere that triggered an expansion of the ice sheets in the northern hemisphere,’ says Stella Woodard, researcher at Rutgers’ Department of Marine and Coastal Sciences.
The findings are based on ocean sediment core samples between 2.5 million to 3.3 million years old, and provide scientists with a deeper understanding of the mechanisms of climate change today.
‘Our study suggests that changes in storage of heat in the deep ocean could be as important to climate change as other hypotheses – tectonic activity or a drop in the carbon dioxide level – and likely led to one of the major climate transitions of the past 30 million years,’ said Yair Rosenthal, co-author and professor of marine and coastal sciences at Rutgers.