Small Eddies in the Southern Ocean Cause Global Effects on Climate Change

Small eddies may actually impact global climate change. Scientists have found that the increasing strength of winds over the Southern Ocean is causing ocean eddies and mixing, which has extended its ability to absorb carbon dioxide and effectively delays the impacts of global warming.

"Considering the Southern Ocean absorbs something like 60 percent of heat and anthropogentic CO2 that enters the ocean, this wind has a noticeable effect on global warming," said Andy Hogg, the lead author of the new study, in a news release. "To put this in some kind of context, if theose small scale eddies did not increase with wind stress then the saturation of carbon dioxide in the Southern Ocean sink would occur twice as rapidly and more heat would enter our atmosphere and sooner."

Eddies dominate the circulation of the Southern Ocean. In order to see how this eddy field would change with stronger winds, the scientists used satellite observations. They found that the eddy field has increased in recent decades and that this increase can be attributed to the increase in winds around the Southern Ocean.

The winds themselves are a result of both the depletion ocean and global warming's effects on the Southern Annular Mode (SAM). The SAM is a measure of the position of a belt of westerly winds that circle Antarctica. A positive SAM means that the belt has moved closer to the Antarctic. A negative SAM means the wind belt has moved closer to the equator.

"Interestingly, we found that the movement and strength of the SAM played the largest role in increasing the energy of the eddies in the Southern Ocean over periods of less than a decade but there were clear delays between the timing of the SAM and its effect on the eddies," said Hogg. "The increase in kinetic energy of these eddies actually only became apparent a few years after a strong SAM event."

What's interesting is that if the winds continue to increase, then there will be increased energy in the eddies. This, in turn, will have large effects on the ability of the Southern Ocean to store carbon dioxide and heat. This may impact climate models and also may cause global warming to slow down.

The findings are published in the Journal of Geophysical Research: Oceans.

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