The polar retrospective – Looking beneath Antarctica’s icy coastline | Polarjournal
Well researched on the surface, but still full of unanswered questions underwater: these are the Antarctic coastal regions. New studies are now providing some relief. Picture: Michael Wenger

The polar retrospective picks up on events of the past week related to the Arctic and Antarctic and focuses on one or more aspects. Last week, a series of new research findings literally dove into the icy waters along the Antarctic coasts, offering a better picture of the continent’s complex interactions with the surrounding Southern Ocean and the impact of some previously little-noticed currents on ice shelf melting and heat transport.

Recent research shed light on the complex interactions between the Antarctic Slope Undercurrent (ASC), ice shelves, and ice sheet stability. The ASC, a current flowing eastward beneath the Antarctic ice shelf, transports both heat and potential meltwater. One of the recent studies used simulations to investigate the dynamics of the undercurrent along the West Antarctic coast. The results suggest that meltwater beneath the ice shelf strengthens the eastward undercurrent, which could enhance the supply of warm circumpolar deep water (CDW) to the ice shelves and accelerate basal melt rates. However, the ASC may also play a role in transporting meltwater away from the ice shelf, which could mitigate some of the warming effects of CDW. This complicated dance between heat input and meltwater transport requires further research.

Two additional studies examined the processes that drive instability in critical sections of the Antarctic. One of them looked at the seasonal evolution of the Antarctic slope current system mentioned above, but this time off the coast of Dronning Maud Land in East Antarctica. This work highlights the fluctuations in warm water transport towards the continent, which influences ice shelf melt rates.

The largest contiguous ice shelf lies in the Ross Sea and covers an area larger than France. But the seemingly endless and stable ice surface is threatened from below, especially by warmer deep water and the topography of the seabed plays a major role in the process. Photo: Michael Wenger

In a third study related to the Antarctic coast, the researchers mapped the intricate grounding zone of the Ross Ice Shelf, where the ice turns into a floating ice shelf. Their work revealed channels and crevices through which warmer water can penetrate and accelerate the melting of the ice from below. The researchers focused particularly on the role of bathymetric ridges. “These ridges can act as natural buffers and slow the retreat of the ice shelf,” explains Dr. Alastair Graham, lead author of the study mapping the Ross Ice Shelf, “But once these natural protective mechanisms are overcome, rapid disintegration can occur.”

All of the studies emphasize Antarctica’s potential to contribute significantly to global sea level rise. One of the main problems involves the ongoing ice loss from ice shelves such as the Ross Ice Shelf, which acts as a plug for the glacier area behind it and which, in a melting event, threatens low-lying coastal areas worldwide and requires adaptation measures. This comprehensive data will allow scientists to refine their climate models, with improved model accuracy crucial for predicting future changes in the Antarctic and their far-reaching consequences.

The urgency is clear: the ongoing study of Antarctica’s ice sheets, ocean currents and their underlying relationships provides important clues to understanding how these vast ice masses will respond to continued warming. Accurate modeling and comprehensive climate risk assessments are urgently needed to develop global strategies to mitigate climate change and support the resilience of vulnerable communities worldwide.

Dr. Michael Wenger, Polar Journal AG

Links to the studies

Wiens et al (2024) Geophys Res Let 51(7), Ross Ice Shelf Displacement and Elastic Plate Waves Induced by Whillans Ice Stream Slip Events; https://doi.org/10.1029/2023GL108040

Lauber et al (2024) J J Geophys Res Oceans 129(4), Observed Seasonal Evolution of the Antarctic Slope Current System off the Coast of Dronning Maud Land, East Antarctica; https://doi.org/10.1029/2023JC020540

Si et al (2024) Scie Adv 10(16), Antarctic Slope Undercurrent and onshore heat transport driven by ice shelf melting; DOI: 10.1126/sciadv.adl0601

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