Exploring Antarctic Sea Ice Dynamics and Ocean Interactions

Onboard the Polarstern, our bathymetry team collaborates with physical oceanographers to explore the Antarctic deep sea and continental shelf. We've tracked water masses, revealing a decline in Antarctic deep water compared to long-term data from the Hybrid Antarctic Float Observing System (HAFOS), active since 2002. We've also refined the outflow paths of cold water from the Larsen Ice Shelf, which significantly impacts global ocean currents and sea ice melting.

Antarctic sea ice, once considered stable, has seen a sharp decline in the north-western Weddell Sea since 2017, likely due to warmer surface waters. Our SWOS (Summer Weddell Sea Outflow Study) results show regional variability in ice thickness, with up to four meters on the western continental shelf due to tidal deformation, while ice from the Ronne and Filchner shelves is less deformed.

Surprisingly, we observed strong surface melting, affecting snow cover and upper ice layers, resembling Arctic conditions with melt ponds. Despite few melt ponds, the ice was often snow-free with bluish or greyish surfaces. Novel measurements revealed sweet meltwater under the ice, influencing biological colonization and ocean-ice interactions by insulating the ice from ocean heat.

Future analyses will explore the role of organisms in and under the ice in the Southern Ocean's carbon cycle. These studies will follow the expedition's conclusion in the Falkland Islands in April 2026, after which the Polarstern will return to Bremerhaven.