Researchers from the University of Southampton have uncovered a significant and unexpected change in the Southern Ocean, revealing a marked increase in surface water salinity and a rapid decline in sea ice since 2015.

Utilizing advanced European satellite data, the team observed a sudden rise in surface salinity south of 50° latitude, which coincided with a steep decrease in sea ice around Antarctica.

Since 2015, Antarctica has lost a volume of sea ice equivalent to the size of Greenland, representing one of the largest environmental changes observed globally in recent decades.

This rapid decline in sea ice contradicts traditional expectations that man-made climate change would maintain Antarctic sea ice cover.

The findings challenge previous scientific projections that anticipated sustained sea ice cover due to enhanced surface freshening and stronger ocean stratification, which have not materialized.

Co-author Aditya Narayanan emphasized that the swift reduction in sea ice could further accelerate global warming by decreasing the reflective surface area that cools the planet.

Dr. Alessandro Silvano warned that the increasing salinity allows heat from the deep ocean to rise, further melting sea ice and creating a dangerous feedback loop that could permanently alter the Southern Ocean and impact global climate.

The re-emergence of the Maud Rise polynya in the Weddell Sea, a large area of open water not seen since the 1970s, indicates the unusual conditions now present in the Southern Ocean.

This increase in salinity is linked to the re-emergence of the Maud Rise polynya, highlighting the dramatic shifts occurring in this critical marine environment.

The study underscores the urgent need for ongoing satellite and in-situ monitoring to better understand the dynamics of the ice-ocean system and forecast future changes.

Overall, the study's findings, published in the Proceedings of the National Academy of Sciences, document a significant shift in the Southern Ocean, raising alarms about its implications for global climate patterns.