Southern Ocean Becoming Less Salty

Expanding sea ice in Antarctica may be related to water in the Southern Ocean freshening -- a possible consequence is loss of effectiveness in one of our biggest natural tools to combat climate change.

A team of German researchers examined the relationship between sea ice and Southern Ocean salinity. Their complete findings are available in the journal Nature. A sea-ice conveyor belt transports frozen sea ice from the Antarctic coast to the edge of the ice where it melts.

Antarctic sea ice expansion, in contrast to the loss of sea ice in the Arctic, has been watched with some confusion. Part of the ice melts every year -- bigger swaths of ice mean a larger volume of ice is cyclically melting.

Frozen sea ice contains less salt than surrounding sea water, a change that occurs during the freezing process. When the ice melts, would move along the sea-ice conveyor belt, away from the salt that was left behind when it froze.

The sea ice travels about 1,000 kilometers. This process results in increasing saline water near the Antarctic coast but fresher water near the ice melt.

"The amount of freshwater released from the sea ice into the open ocean surface waters and the Antarctic Intermediate Water has increased significantly in past decades. For the first time, we have been able to quantify these changes, which are presumably caused by stronger southerly winds during this period," lead author and doctoral student in the Environmental Physics group and the Center for Climate Systems Modeling at ETH Zurich Alex Haumann said via Science Daily.

Increased amounts of fresh water lead to a more stable stratification of the ocean, which causes the ocean to absorb less heat. That's a scary change considering that the Southern Ocean currently absorbs about three quarters of the globe's excess heat and about half of human created carbon dioxide.

A decreased ability to absorb heat and carbon dioxide is a huge cause for concern given that studies outlining the dangers of climate change are being published with regularity. It's possible that the expansion of sea ice is already a symptom of climate change.