Rapid Melting of Antarctic Sea Ice Increases Ocean Salinity

Scientists have announced that rapid melting of Antarctic sea ice since 2016 has led to a sharp increase in salinity across a vast layer of the Southern Ocean, reversing a decades-long freshening trend. According to a study published on Wednesday, the change in this layer surrounding Antarctica, spanning depths from 2,300 to 4,000 feet, has the potential to impact global climate systems.

Bishakhdatta Gayen, a co-author from the University of Melbourne and the Centre for Atmospheric and Oceanic Sciences in Bengaluru, noted that this layer, known as Antarctic Intermediate Water, spreads toward the Indian, Pacific, and Atlantic oceans. This current transports heat, carbon, oxygen, and nutrients toward the tropics and beyond the equator. The study combined six independent data sets obtained from Argo floats to monitor changes between 2004 and 2024.

Antarctic sea ice reached its highest level in satellite records in 2014, but showed a record decline within two years. In 2023, it recorded a new low, remaining approximately 1 million square miles below the 1981-2010 average. While having less freshwater during the melting season increases the salinity of Antarctic Intermediate Water, changes in this layer's density, thickness, and salinity affect the movement of heat between the ocean surface and deep waters.