Antarctic Seawater Salinity Rising as Sea Ice Melts, Scientists Puzzled
The salinity of seawater in the Antarctic region is increasing and sea ice is gradually disappearing, but scientists are not yet sure of the reasons behind this phenomenon, which requires further research.
According to a report from Live Science, since 2015, Antarctic sea ice has been steadily decreasing, contrary to earlier model predictions. By 2023, the area covered by Antarctic sea ice had shrunk by a record-breaking 600,000 square miles (1.55 million square kilometers) compared to the expected average. In July of that year, during the peak of winter, a portion of sea ice larger than Western Europe was missing in the region, with no signs of recovery.
This reduction in sea ice is the most significant environmental change on Earth in recent decades and is expected to have chain reactions on global climate patterns.
Currently, scientists are linking the trend of decreasing Antarctic sea ice with a sudden rise in seawater salinity around the Antarctic continent, yet the exact cause of this sea surface salinity increase remains unclear.
Lead scientist Alessandro Silvano from the University of Southampton expressed surprise at the findings, stating, “We were amazed. This is a counterintuitive result because we usually associate ice melting with freshening of seawater.” He added, “This indicates more profound structural changes in the Southern Ocean—not just in the ice, but also in the underlying ocean.”
The University of Southampton mentioned in a press release that researchers, using data from European satellites, found that the sea surface salinity south of the 50th parallel suddenly rose. Simultaneously, sea ice around Antarctica decreased rapidly, and a large hole in sea ice known as the Maud Rise polynya in the Weddell Sea reappeared.
Silvano explained, “The increase in surface seawater salinity makes it easier for heat from the deep sea to rise, leading to the melting of sea ice below. This is a dangerous feedback loop—reduced sea ice leads to increased heat, which in turn reduces sea ice further.”
He continued, “The reappearance of the Maud Rise polynya demonstrates how abnormal the current situation is. If this high salinity, low ice condition persists, it could permanently reshape the Southern Ocean and the Earth. Its impact is already global—intensified storms, warming oceans, and shrinking habitats for penguins and other iconic Antarctic wildlife.”
With the assistance of the European Space Agency’s new satellite technology, this research marks the first real-time monitoring of sea ice changes in the Southern Ocean.
One of the authors of the study, Professor of Physical Oceanography at the University of Southampton, Alberto Naveira Garabato, emphasized, “These new findings indicate that our current understanding may not be sufficient to accurately predict future changes.”
Garabato added, “This underscores the urgent need for ongoing satellite and in-situ monitoring so that we can better comprehend the driving factors behind recent and future changes in the ice-ocean system.”
The research findings were published on June 30 in the Proceedings of the National Academy of Sciences, shedding light on the complexities of Antarctic sea ice dynamics and the pressing need for continued monitoring and research in the region.