Ocean circulation, a major factor in climate change

Washington: It isn't just the atmosphere, but the circulation of the oceans plays an equally important role in regulating the Earth's climate, new research shows.

The study revealed that the cooling of Earth and continental ice build-up in the Northern Hemisphere 2.7 million years ago coincided with a shift in the circulation of the ocean - which pulls in heat and carbon dioxide in the Atlantic and moves them through the deep ocean from north to south until it's released in the Pacific.

The ocean conveyor system changed at the same time as a major expansion in the volume of the glaciers in the northern hemisphere took place along with a substantial fall in sea levels.

It was the Antarctic ice, researchers argued, that cut off heat exchange at the ocean's surface and forced it into deep water.

This led to global climate change at the time and it could be said that the formation of the ocean conveyor cooled the earth and created the climate we live in now.

"We argue that it was the establishment of the modern deep ocean circulation - the ocean conveyor - about 2.7 million years ago, and not a major change in carbon dioxide concentration in the atmosphere that triggered an expansion of the ice sheets in the northern hemisphere," said Stella Woodard, lead author and a post-doctoral researcher at Rutgers University in the US.

The new findings, based on ocean sediment core samples between 2.5 million to 3.3 million years old, provide scientists with a deeper understanding of the mechanisms of climate change today.

The changes in heat distribution between the ocean basins is important for understanding future climate change, the team concluded.

The study was published in the journal Science.