Paris, France | AFP | Wednesday, March 18, 2026 – The mysterious evolution of Antarctic sea ice in recent years is explained by contact with warm waters from the ocean depths, following the weakening of the cold water layer that protected it, according to a study published Wednesday.
While Arctic sea ice is steadily declining, Antarctic sea ice behaves completely differently: it expanded gradually over several decades before experiencing a rapid decline at the end of 2015 and strong annual fluctuations since then.
An international team of researchers, publishing in the journal Nature Climate Change, tried to understand what has happened in recent years.
“A protective layer of cold water beneath the Antarctic ice sheet prevented warmer water from deeper underground from rising and melting the ice from below,” explains Theo Spira of the University of Gothenburg (Sweden), lead author of the study.
“But during the winter of 2015, unusually strong storms in the Southern Ocean reduced the effect of the protective layer of cold water,” he adds.
Normally, water masses of different salinity or temperature do not mix easily, a phenomenon called ocean stratification. But the layer of cold water protecting the ice sheet was gradually reduced between 2005 and 2015 as the ocean warmed at depth, allowing warmer water to approach the surface.
« The storms of 2015 stirred up the ocean, and the warmer water mixed with the layer of cold water, eroding the protective ice, which melted at a record rate, » Theo Spira points out. That year, unusually strong winds swept across the Antarctic continent.
The authors emphasize the importance of understanding these changes because the Antarctic sea ice plays a « critical » role for the planet, both for the global climate and for its ability to reflect solar energy (albedo effect), ocean currents, and local ecosystems.
source : tahiti infos
