APR 01, 2014 12:00 AM PDT

Reduced Southern Ocean Convection Raises Climate Regulation Concerns

WRITTEN BY: Jen Ellis
Polynyas may sound to you like a new kind of plastic, or something you slept through in geometry class. They are really openings in sea ice occurring near Antarctica, and the lack of them in recent times is both a byproduct of climate change and the potential harbinger of further problems in absorbing the planet's heat and carbon dioxide output. So says a team of researchers from the University of Pennsylvania and McGill University, in a study published in Nature Climate Change.

The concern is the interaction between the Antarctic Bottom Waters and the Southern Ocean that surrounds Antarctica.

The Atlantic Bottom Waters is a powerful, deep ocean current originating from near the coast of Antarctica and heading north toward the equator. This current filled with dense salty water is thought to effectively hide heat and carbon from the atmosphere-which is an important factor in regulating the climate, given that the Southern Ocean is thought to absorb around 60% of the earth's man-made heat and between 40% and 50% of the man-made carbon dioxide.

The Atlantic Bottom Waters have been shrinking over the last few decades, and the research team suspected that man-made climate change could be a least part of the reason why. Polynyas enter into the equation because they are part of an effective mixing mechanism between the Atlantic Bottom Waters and the Southern Ocean, and their absence may be related to climate change.

Polynyas were last observed in 1976 in the Weddell Sea. They are a byproduct of warm water that is forced up toward the surface of the Southern Ocean meeting very salty and cold water at the Weddell Sea's surface. The heavier salty water sinks as the lighter warm water rises, creating a convective mixing process that is believed to feed the Atlantic Bottom Waters.

The inability to observe polynyas in recent times led scientists to assume that both polynyas and that type of open-sea convection was not common. However, modeling performed by the research team indicated that convection was a much more common process in pre-industrial times.

This suggests that the Atlantic Bottom Waters are likely to continue to shrink, and that with less overall mixing the oceans will continue to stratify, thus reducing the ability of the Southern Ocean to absorb and disperse heat and carbon dioxide.

How is climate change to blame? The team suggests that climate change has increased the precipitation in the Antarctic, providing more fresh water at the surface. This effectively dilutes the salt content of the surface water, making it less likely to sink and mix. Heat that is already in the deeper ocean may be partially trapped there with less of a dispersing current, effectively reducing the ability of the ocean to absorb more heat.

Data has shown a freshening of the Southern Ocean surface waters, and more intense gradients of salinity and corresponding density are appearing in the ocean depths, lending credence to this theory.

It remains to be seen how climate change will continue to affect these currents and the corresponding dissipation of heat and carbon dioxide, but it certainly bears further watching as we struggle to control the variables that produce man-made climate change.
About the Author
You May Also Like
AUG 23, 2022
Technology
An Environmentally Friendly Air Conditioner
AUG 23, 2022
An Environmentally Friendly Air Conditioner
It’s getting harder and harder to beat the summer heat. Across the globe, temperatures are rising. While global te ...
AUG 26, 2022
Technology
Recycling PPE to Make Stronger Concrete
AUG 26, 2022
Recycling PPE to Make Stronger Concrete
When you’re done wearing that face mask, where does it go?  The use of personal protective equipment (PPE) sk ...
AUG 29, 2022
Chemistry & Physics
Plastics Created from Carbon Dioxide Instead of Petroleum
AUG 29, 2022
Plastics Created from Carbon Dioxide Instead of Petroleum
In a recent study published in Reaction Chemistry & Engineering, a team of researchers from Japan discuss how artifi ...
AUG 30, 2022
Chemistry & Physics
This Day in Science History 8/30/1871: Birth of Ernest Rutherford Who Laid the Groundwork for Nuclear Physics
AUG 30, 2022
This Day in Science History 8/30/1871: Birth of Ernest Rutherford Who Laid the Groundwork for Nuclear Physics
On August 30, 1871, Ernest Rutherford, who would later establish the groundwork for nuclear physics and be knighted as S ...
SEP 07, 2022
Health & Medicine
What's in Fake Meat & Is it Healthy?
SEP 07, 2022
What's in Fake Meat & Is it Healthy?
Animal agriculture has a massive impact on our world. There are huge environmental consequences to our planet, in part b ...
SEP 08, 2022
Chemistry & Physics
Boiling Away Forever Chemicals
SEP 08, 2022
Boiling Away Forever Chemicals
Forever chemicals are in hot water. In a paper published on August 18 in Science, researchers at the University of Calif ...
Loading Comments...