Climate Change May be Caused More by Ocean Circulation Than the Atmosphere

Climate change isn't just caused by our atmosphere; it's also caused by the world's oceans. Now, scientists have taken a closer look at the circulation of the ocean and have examined what role it plays in regulating Earth's climate.

The ocean circulation is responsible for pulling in heat and carbon dioxide in the Atlantic and moving them through the deep ocean from north to south. The system then releases it all in the Pacific. This conveyor belt-like system could potentially be responsible for global climate changes.

In this case, the scientists found that the major 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.  It's possible that this switch occurred at the same time as a major expansion in the volume of the glaciers in the northern hemisphere as well as a substantial fall in sea levels. This may have caused global climate change at the time.

"We argue that it was the establishment of the modern deep ocean circulation-the ocean conveyor-about 2.7 million years ago, and not the 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 of the new study, in a news release.

In fact, the new study reveals that changes in heat distribution between the ocean basins are important for understanding future climate change. That said, scientists can't predict precisely what effect the carbon dioxide currently being pulled into the ocean will have on climate. Yet because more carbon dioxide has been released in the past 200 years than any recent period in geological history, it's likely that interactions between carbon dioxide, temperature changes and precipitation, and ocean circulation will result in profound changes.

"Our study suggests that changes in the storage of heat in the deep ocean could be as important to climate change as other hypotheses-tectonic activity or a drop in carbon dioxide level-and likely led to one of the major climate transitions of the past 30 million years," said Yair Rosenthal, co-author of the new study.

The findings are published in the journal Science.