IISc study links shrinking Antarctic sea ice to a saltier Antarctic Intermediate Water
28 October 2026
Researchers at the Indian Institute of Science (IISc), Bengaluru, have found that a key Southern Ocean water mass is turning saltier. The water mass is Antarctic Intermediate Water (AAIW), which forms near Antarctica, sits hundreds of metres below the surface and spreads north into the Atlantic, Indian and Pacific Oceans. For decades AAIW had been growing fresher, but the trend reversed around 2015, when Antarctic sea ice began to fall sharply. With less sea ice melting, less fresh water reaches this layer, and warmer, saltier deep water is also rising. The team used temperature and salinity readings, including those from the Argo network of robotic floats, along with satellite records of sea ice. The study, by the Centre for Atmospheric and Oceanic Sciences (CAOS) with the universities of Melbourne and Southampton, appears in Nature Climate Change. A saltier AAIW can weaken ocean layering and let stored carbon escape more easily, adding to warming.
In plain words
AAIW Antarctic Intermediate Water — A water mass that forms in the Southern Ocean and spreads north at intermediate depth into three oceans.
CAOS Centre for Atmospheric and Oceanic Sciences — The IISc centre that carried out the study.
Argo Argo float network — A worldwide network of robotic floats that measure ocean temperature and salinity.
IISc Indian Institute of Science — Research university in Bengaluru, Karnataka.