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1. A global database of marine isotope substage 5a and 5c marine terraces and paleoshoreline indicators

   https://doi.org/10.5194/essd-13-3467-2021  

   Thompson, Schmitty B.; Creveling, Jessica R. (January 2021, Earth System Science Data)

   Abstract. In this review we compile and document the elevation, indicative meaning, and chronology of marine isotope substage 5a and 5c sea level indicatorsfor 39 sites within three geographic regions: the North American Pacific coast, the North American Atlantic coast and the Caribbean, and theremaining globe. These relative sea level indicators, comprised of geomorphic indicators such as marine and coral reef terraces, eolianites, andsedimentary marine- and terrestrial-limiting facies, facilitate future investigation into marine isotope substage 5a and 5c interstadial paleo-sealevel reconstruction, glacial isostatic adjustment, and Quaternary tectonic deformation. The open-access database, presented in the format of theWorld Atlas of Last Interglacial Shorelines (WALIS) database, can be found at https://doi.org/10.5281/zenodo.5021306 (Thompson and Creveling, 2021). 

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2. Late Pleistocene sea-level constraints across Antarctica

   https://doi.org/10.1016/j.quascirev.2024.108879  

   Simms, Alexander R; Ishiwa, Takeshige; Hodgson, Dominic A; Tamura, Toru; DeWitt, Regina (October 2024, Quaternary Science Reviews)

   Global sea levels during the last interglacial (LIG), 129,000–116,000 years ago, may have reached as much as 5–10 m higher than present. However, the elevation of the LIG highstand varies locally due to tectonics, subsidence, steric effects, and glacial isostatic adjustment (GIA). The variability brought upon by GIA can be used to constrain the past distribution of ice sheets including the source of higher sea levels during the LIG. In spite of its importance for fingerprinting the source of additional meltwater at the LIG, little is known about the elevation of LIG sea levels across Antarctica. In this study we review the geologic constraints on the elevation of the LIG highstand across Antarctica. We find that although several Late Pleistocene sea-level constraints are available across the continent very few of them provide definitive LIG ages. Arguably the most probable LIG sea-level indicators come from East Antarctica but most of them have age constraints approaching the limits of radiocarbon dating (>~45 ka) with many likely dating to Marine Isotope Stage 3, not the LIG. For West Antarctica, Late Pleistocene sea level constraints are confined to a few poorly or completely undated possible examples from the Antarctic Peninsula. Our review suggests that much more work is needed on constraining the elevation of the LIG highstand across Antarctica. 

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3. Constraining the contribution of the Antarctic Ice Sheet to Last Interglacial sea level

   https://doi.org/10.1126/sciadv.adf0198  

   Barnett, Robert L; Austermann, Jacqueline; Dyer, Blake; Telfer, Matt W; Barlow, Natasha L M; Boulton, Sarah J; Carr, Andrew S; Creel, Roger C (July 2023, Science Advances)

   Polar temperatures during the Last Interglacial [LIG; ~129 to 116 thousand years (ka)] were warmer than today, making this time period an important testing ground to better understand how ice sheets respond to warming. However, it remains debated how much and when the Antarctic and Greenland ice sheets changed during this period. Here, we present a combination of new and existing absolutely dated LIG sea-level observations from Britain, France, and Denmark. Because of glacial isostatic adjustment (GIA), the LIG Greenland ice melt contribution to sea-level change in this region is small, which allows us to constrain Antarctic ice change. We find that the Antarctic contribution to LIG global mean sea level peaked early in the interglacial (before 126 ka), with a maximum contribution of 5.7 m (50th percentile, 3.6 to 8.7 m central 68% probability) before declining. Our results support an asynchronous melt history over the LIG, with an early Antarctic contribution followed by later Greenland Ice Sheet mass loss. 

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4. Total isostatic response to the complete unloading of the Greenland and Antarctic Ice Sheets

   https://doi.org/10.1038/s41598-022-15440-y  

   Paxman, Guy J. G.; Austermann, Jacqueline; Hollyday, Andrew (July 2022, Scientific Reports)

   Abstract The land surface beneath the Greenland and Antarctic Ice Sheets is isostatically suppressed by the mass of the overlying ice. Accurate computation of the land elevation in the absence of ice is important when considering, for example, regional geodynamics, geomorphology, and ice sheet behaviour. Here, we use contemporary compilations of ice thickness and lithospheric effective elastic thickness to calculate the fully re-equilibrated isostatic response of the solid Earth to the complete removal of the Greenland and Antarctic Ice Sheets. We use an elastic plate flexure model to compute the isostatic response to the unloading of the modern ice sheet loads, and a self-gravitating viscoelastic Earth model to make an adjustment for the remaining isostatic disequilibrium driven by ice mass loss since the Last Glacial Maximum. Feedbacks arising from water loading in areas situated below sea level after ice sheet removal are also taken into account. In addition, we quantify the uncertainties in the total isostatic response associated with a range of elastic and viscoelastic Earth properties. We find that the maximum change in bed elevation following full re-equilibration occurs over the centre of the landmasses and is +783 m in Greenland and +936 m in Antarctica. By contrast, areas around the ice margins experience up to 123 m of lowering due to a combination of sea level rise, peripheral bulge collapse, and water loading. The computed isostatic response fields are openly accessible and have a number of applications for studying regional geodynamics, landscape evolution, cryosphere dynamics, and relative sea level change. 

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5. Three-dimensional glacial isostatic adjustment modeling reconciles conflicting geographic trends in North American marine isotope stage 5a relative sea level observations

   https://doi.org/10.1130/G51257.1  

   Thompson, Schmitty B.; Creveling, Jessica R.; Latychev, Konstantin; Mitrovica, Jerry X. (June 2023, Geology)

   Glacial isostatic adjustment (GIA) simulations using earth models that vary viscoelastic structure with depth alone cannot simultaneously fit geographic trends in the elevation of marine isotope stage (MIS) 5a relative sea level (RSL) indicators across continental North America and the Caribbean and yield conflicting estimates of global mean sea level (GMSL). We present simulations with a GIA model that incorporates three-dimensional (3-D) variation in North American viscoelastic earth structure constructed by combining high-resolution seismic tomographic imaging with a new method for mapping this imaging into lateral variations in lithospheric thickness and mantle viscosity. We pair this earth model with a global ice history based on updated constraints on ice volume and geometry. The GIA prediction provides the first simultaneous reconciliation of MIS 5a North American and Caribbean RSL highstands and strengthens arguments that MIS 5a peak GMSL reached values close to that of the Last Interglacial. This result highlights the necessity of incorporating realistic 3-D earth structure into GIA predictions with continent-scale RSL data sets. 

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