Filchner–Ronne Ice Shelf

• At the end of the southern summer, Antarctica’s sea ice hit its annual minimum.
• By at least one measure, which tracks the area of ocean that contains at least 15% of sea ice, it was a little above the record low of 2023.
• But something has changed in how the Southern Ocean works and the area covered by sea ice has decreased dramatically.

The southernmost shelf sea

• The annual freeze-thaw cycle of Antarctic sea ice is one of the defining properties of our planet.
• Time to take our medicine

  The voyage was led by a team of scientists who coordinate Italy’s longstanding research in the Southern Ocean.

• Continental shelf seas around Antarctica are special because of the presence of sea ice – but this varies in space and time.
• It shows that by the end of summer, the Ross Sea region holds only a few patches of sea ice.
• The region is the southernmost open water on the planet and acts as a gateway to seawater flowing in and out under the largest (by area) ice shelf on the planet – the Ross Ice Shelf.

The state of sea ice

• This reinforced our understanding of the importance of the spatial variability of sea ice.
• At the late-summer sea-ice minimum, the Ross Sea is largely free of ice, while the Weddell Sea stays filled with ice.

• They took me beyond anything imagined from data and models.
• However, it is clear that Antarctic ocean data collection systems need to expand when and where they collect information.

The future is robotic

• We deployed 11 relatively simple Argo floats that will drift around the region for years, surfacing to send back data on temperature, salinity and in some cases oxygen.
• We also sent three robotic ocean gliders on their data-collecting missions independent of the ship.

• The data provide evidence of warmer water lying just beneath the edge of the continental shelf, highlighting the fragility of the system.
• There is a growing sense that the Ross Sea sector will become more important in the coming decade.

• Craig Stevens receives funding from the New Zealand Ministry for Business, Innovation and Employment (MBIE), Antarctica New Zealand Antarctic Science Platform (ASP-ANTA1801), MBIE Strategic Science Investment Fund and the New Zealand Royal Society Te Apārangi Marsden Fund.
• The observations and collaboration described here were made possible through long-term funding for the work from both the Italian PNRA (Programma Nazionale di Ricerche in Antartide) and the NZ Antarctic Science Platform.