Carbon release from oceans leads to climate change

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Giving a fresh insight into how oceans affect climate change, a new study shows that carbon stored in deep in the Southern Ocean, re-connected with the atmosphere, drives a rise in atmospheric CO2 and climate change.

There were heavy concentrations of dissolved CO2 in surface waters of the Southern Atlantic Ocean which coincided with the rises in atmospheric CO2 at the end of the last ice age.

So, these regions acted as sources of CO2 to the atmosphere.

Currently, the oceans contain around 60 times more carbon than the atmosphere and that carbon can exchange rapidly between these two systems.

"The magnitude and rapidity of the swings in atmospheric CO2 across the ice age cycles suggests that changes in ocean carbon storage are important drivers of natural atmospheric CO2 variations," said Miguel Martinez-Boti from the University of Southampton.

While a reduction in communication between the deep-sea and the atmosphere in Southern Atlantic Ocean locks carbon away from the atmosphere into the abyss during ice ages, the opposite occurs during warm interglacial periods.

They studied the composition of the calcium carbonate shells of ancient marine organisms that inhabited the surface of the ocean thousands of years ago in order to trace its carbon content.

"Our new data confirms that natural variations in atmospheric CO2 between ice ages and warm inter-glacials are driven largely by changes in the amount of carbon stored in our oceans," pointed out Gavin Foster from the University of Southampton.

"These results will help to better understanding the dynamics of human-induced CO2 accumulation in the atmosphere since the ocean is an important carbon sink and the largest reservoir of carbon on our planet" concluded Patrizia Ziveri, professor at ICTA, UAB, Barcelona.

The study appeared in the journal Nature.