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1. Formation of sea ice ponds from ice-shelf runoff, adjacent to the McMurdo Ice Shelf, Antarctica

   https://doi.org/10.1017/aog.2020.9  

   Macdonald, Grant J.; Popović, Predrag; Mayer, David P. (September 2020, Annals of Glaciology)

   null (Ed.)

   Abstract Ponds that form on sea ice can cause it to thin or break-up, which can promote calving from an adjacent ice shelf. Studies of sea ice ponds have predominantly focused on Arctic ponds formed by in situ melting/ponding. Our study documents another mechanism for the formation of sea ice ponds. Using Landsat 8 and Sentinel-2 images from the 2015–16 to 2018–19 austral summers, we analyze the evolution of sea ice ponds that form adjacent to the McMurdo Ice Shelf, Antarctica. We find that each summer, meltwater flows from the ice shelf onto the sea ice and forms large (up to 9 km 2 ) ponds. These ponds decrease the sea ice's albedo, thinning it. We suggest the added mass of runoff causes the ice to flex, potentially promoting sea-ice instability by the ice-shelf front. As surface melting on ice shelves increases, we suggest that ice-shelf surface hydrology will have a greater effect on sea-ice stability. 

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2. The Ronne Ice Shelf survived the last interglacial

   https://doi.org/10.1038/s41586-024-08394-w  

   Wolff, Eric W; Mulvaney, Robert; Grieman, Mackenzie M; Hoffmann, Helene M; Humby, Jack; Nehrbass-Ahles, Christoph; Rhodes, Rachael H; Rowell, Isobel F; Sime, Louise C; Fischer, Hubertus; et al (January 2025, Nature)

   Abstract The fate of the West Antarctic Ice Sheet (WAIS)¹is the largest cause of uncertainty in long-term sea-level projections. In the last interglacial (LIG) around 125,000 years ago, data suggest that sea level was several metres higher than today^2–4, and required a significant contribution from Antarctic ice loss, with WAIS usually implicated. Antarctica and the Southern Ocean were warmer than today^5–8, by amounts comparable to those expected by 2100 under moderate to high future warming scenarios. However, direct evidence about the size of WAIS in the LIG is sparse. Here we use sea salt data from an ice core from Skytrain Ice Rise, adjacent to WAIS, to show that, during most of the LIG, the Ronne Ice Shelf was still in place, and close to its current extent. Water isotope data are consistent with a retreat of WAIS⁹, but seem inconsistent with more dramatic model realizations¹⁰in which both WAIS and the large Antarctic ice shelves were lost. This new constraint calls for a reappraisal of other elements of the LIG sea-level budget. It also weakens the observational basis that motivated model simulations projecting the highest end of projections for future rates of sea-level rise to 2300 and beyond. 

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3. Enigmatic surface rolls of the Ellesmere Ice Shelf

   https://doi.org/10.1017/jog.2022.3  

   Coffey, Niall B.; MacAyeal, Douglas R.; Copland, Luke; Mueller, Derek R.; Sergienko, Olga V.; Banwell, Alison F.; Lai, Ching-Yao (January 2022, Journal of Glaciology)

   Abstract The once-contiguous Ellesmere Ice Shelf, first reported in writing by European explorers in 1876, and now almost completely disintegrated, has rolling, wave-like surface topography, the origin of which we investigate using a viscous buckling instability analysis. We show that rolls can develop during a winter season (~ 100 d) if sea-ice pressure (depth-integrated horizontal stress applied to the seaward front of the Ellesmere Ice Shelf) is sufficiently large (1 MPa m) and ice thickness sufficiently low (1–10 m). Roll wavelength initially depends only on sea-ice pressure, but evolves over time depending on amplitude growth rate. This implies that a thinner ice shelf, with its faster amplitude growth rate, will have a shorter wavelength compared to a thicker ice shelf when sea-ice pressure is equal. A drawback of the viscous buckling mechanism is that roll amplitude decays once sea-ice pressure is removed. However, non-Newtonian ice rheology, where effective viscosity, and thus roll change rate, depends on total applied stress may constrain roll decay rate to be much slower than growth rate and allow roll persistence from year to year. Whether the viscous-buckling mechanism we explore here ultimately can be confirmed as the origin of the Ellesmere Ice Shelf rolls remains for future research. 

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4. The scientific response to Antarctic ice-shelf loss

   https://doi.org/10.1038/s41558-018-0290-y  

   Ingels, Jeroen; Aronson, Richard B.; Smith, Craig R. (October 2018, Nature Climate Change)
5. Ice-Shelf Meltwater Overturning in the Bellingshausen Sea

   Ruan, X. (January 2021, Journal of geophysical research)

   null (Ed.)

   Hydrographic data are analyzed for the broad continental shelf of the Bellingshausen Sea, which is host to a number of rapidly thinning ice shelves. The flow of warm Circumpolar Deep Water (CDW) onto the continental shelf is observed in the two major glacially carved troughs, the Belgica and Latady troughs. Using ship-based measurements of potential temperature, salinity, and dissolved oxygen, collected across several coast-to-coast transects over the Bellingshausen shelf in 2007, the velocity and circulation patterns are inferred based on geostrophic balance and further constrained by the tracer and mass budgets. Meltwater was observed at the surface and at intermediate depth toward the western side of the continental shelf, collocated with inferred outflows. The maximum conversion rate from the dense CDW to lighter water masses by mixing with glacial meltwater is estimated to be 0.37 ± 0.1 Sv in both depth and potential density spaces. This diapycnal overturning is comparable to previous estimates made in the neighboring Amundsen Sea, highlighting the overlooked importance of water mass modification and meltwater production associated with glacial melting in the Bellingshausen Sea. 

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