We review successes and challenges from five recent subglacial bedrock drilling campaigns intended to find evidence for Antarctic Ice Sheet retreat during warm periods in the geologic past. Insights into times when the polar ice sheets were smaller than present serve as guiding information for modeling efforts that aim to predict the rate and magnitude of future sea level rise that would accompany major retreat of the Antarctic Ice Sheet. One method to provide direct evidence for the timing of deglaciations and minimum extent of prior ice sheets is to extract subglacial bedrock cores for cosmogenic nuclide analysis from beneath the modern ice sheet surface. Here we summarize the lessons learned from five field seasons tasked with obtaining bedrock cores from shallow depths (<120 m beneath ice surface) across West Antarctica since 2016. We focus our findings on drilling efforts and technology and geophysical surveys with ground-penetrating radar. Shallow subglacial drilling provides a high risk, high reward means to test for past instabilities of the Antarctic Ice Sheet, and we highlight key challenges and solutions to increase the likelihood of success for future subglacial drilling efforts in polar regions.

Measurements of snow accumulation are critical for reliable prediction of future ice mass loss and hence projections of sea level change. However, there are currently very few published in situ measurements of snow accumulation in the Pine Island–Thwaites glacier catchment of the Amundsen Sea Embayment, and none from low elevation sites west of 100.77° longitude. Here measurements of snow accumulation over an 11 month period in 2016 are reported for six sites in the Pine Island–Thwaites glacier catchment. The average accumulation rates of 0.10±0.01 to 1.26±0.22 m w.e. yr-1 are comparable with those derived from airborne radar for the period 1985–2009, suggesting very high rates of snowfall, particularly in the vicinity of the grounding line.

Recent changes along the margins of the Antarctic Peninsula, such as the collapse of the Wilkins Ice Shelf, have highlighted the effects of climatic warming on the Antarctic Peninsula Ice Sheet (APIS). However, such changes must be viewed in a long-term (millennial-scale) context if we are to understand their significance for future stability of the Antarctic ice sheets. To address this, we present nine new cosmogenic 10Be exposure ages from sites on NW Alexander Island and Rothschild Island (adjacent to the Wilkins Ice Shelf) that provide constraints on the timing of thinning of the Alexander Island ice cap since the last glacial maximum. All but one of the 10Be ages are in the range 10.2–21.7 ka, showing a general trend of progressive ice-sheet thinning since at least 22 ka until 10 ka. The data also provide a minimum estimate (490 m) for ice-cap thickness on NW Alexander Island at the last glacial maximum. Cosmogenic 3He ages from a rare occurrence of mantle xenoliths on Rothschild Island yield variable ages up to 46 ka, probably reflecting exhumation by periglacial processes.

We present two 10Be exposure ages from erratic boulders at Cape Adare, northern Victoria Land. The exposure ages obtained suggest that Cape Adare was covered by ice during the last glacial period, and the younger age points to deglaciation around 16.2 ka. Comparison of our younger 10Be exposure age with published radiocarbon dates for Adélie penguin occupation at Cape Adare suggests that the onset of penguin colonization (at 2–3 kyr before present) lagged behind the deglaciation by at least 11.5 kyr. These observations indicate that penguin colonization did not occur until several thousand years after ice free ground became available.

Asterozoans (Echinodermata) of Late Miocene age (6.02 ± 0.12 Ma) are preserved as external moulds in water-lain tuffs of the James Ross Island Volcanic Group (JRIVG), James Ross Island, Antarctic Peninsula. The asterozoans are complete, and appear to represent specimens suffocated after having been pinioned by rapid sedimentation on the distal fringe of an erupting sub-aqueous tuff cone. Although the coarse nature of the host sediments has obliterated the fine morphological detail of the specimens, at least one suggests evidence of entrainment by a turbidity current. A second shows evidence of detachment of the distal tip of one of its arms. In addition to fossil discoveries from glaciomarine sediments, the volcanic tuffs of the JRIVG represent a new source of fossil data that can be used to interpret the ecology and environment of the Antarctic marine shelf biota during the Neogene.