| 27 Nov 2025
Assessing the potential for an ice core in the southern Antarctic Peninsula to elucidate Holocene climate history
Abstract. Connecting the West Antarctic Ice Sheet to the southern Antarctic Peninsula, northern Ellsworth Land is a region of enigmatic glacial history now experiencing significant cryospheric change. Large portions of the Bellingshausen-Sea-draining basins have experienced extreme ice thinning and grounding-line change over the satellite observation period. However, the Holocene glacial history of northern Ellsworth Land, which would help to frame the contemporary changes being observed, is poorly constrained. High-resolution ice cores are crucial for reconstructing this past ice-sheet change. We identify a new deep ice-core drilling site at the triple-ice divide point between the Amundsen, Bellingshausen, and Weddell seas (74°34'37" S, 86°54'16" W) that could be utilised to address this knowledge gap. Using a transient ice-thinning model, constrained by shallow-ice-core data and dated englacial radar stratigraphy, we estimate records of accumulation and derive a preliminary age-depth scale for the proposed coring site. Inclusion of dated radar stratigraphy in the model improves our constraints on the long-term climate history, and highlights that these data are not compatible with a steady-state assumption. We also show that there has been a significant change in the accumulation rate regime or ice thickness throughout the Holocene. A deep ice core at this site would provide a climate record up to ∼30 ka with a resolution of 0.58 ka/m at 60 m above the ice-bed interface. An analysis of the model sensitivity to basal melting shows that a record beyond the onset of the Holocene could still be recovered under high basal-melt-rate scenarios. We thus conclude that an ice core at this site would yield a valuable high-resolution climate record and provide precise constraints to reconstruct climatic changes and glacial retreat during the Holocene, to help resolve the onset of the extensive dynamic thinning observed today.
Competing interests: At least one of the (co-)authors is a member of the editorial board of The Cryosphere.
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Review of "Assessing the potential for an ice core in the southern Antarctic Peninsula to elucidate Holocene climate history" by H. Davis et al.
This article investigates the potential for an ice core in the Northern Ellsworth Land, at a triple ice divide point between the Amundsen, Bellinghausen and Weddell seas (so called ABW site, 1,200 m ice thickness). This is done with a conjunction of age modeling, radar observations and shallow ice coring. Two IRHs could be traced down to ABW, dated 2.62 and 4.72 ka. Another IRH dated at 6.94 ka could be traced elsewhere in this region but not down to ABW. The model of Martín et al. (2015) was used to evaluate the age-depth relationship at ABW and elsewhere along the radar profiles. It is a 1D model with a steady velocity profile but with a transient surface accumulation forcing. The model is actually able to invert the surface accumulation rate needed to fit some age markers. The accumulation is therefore inverted at ABW for the last ~5 ka with a linear by parts assumptions (there are actually two segments) and before that, it is forced with the Wais Divide scenario. It is found a very strong decrease in accumulation since ~5 ka ago, but the authors also suggest a possible ~600 m Holocene ice thinning explaining these age observations. The maximum age of the ABW profile is also evaluated depending on various estimates of the basal melt rate. It is found that the ABW record probably extends back to at least the onset of the Holocene and possibly back to the Last Glacial Period (LGP), with an acceptable vertical resolution. A spatialisation of this basal age estimate is done along the available radar profiles.
The manuscript is well written and I enjoyed reading it. The figures are generally pleasant and informative, the structure is clear, the references are appropriate.
Major comments
The modeling part is based on the inverse model by Martín et al. (2015). While I appreciate the quality of this model, I think it is only half appropriate in this study. Indeed, as the authors point out, there are two possible explanations of this un-steady age-depth profile: either a change of surface accumulation rate or a change of ice thickness (or a combination of both). While the Martín et al. (2015) model well explores the first option, it is not appropriate to explore the second option. A rough 600 m estimate of a possible ice thickness change is done by keeping the same a-dH/dt term but assuming a is constant. But this is not accounting for the coupling of ice thickness change with ice flow! I put it as a challenge to the authors if they can come up with a more quantitative estimate of ice thickness change, possibly with a figure illustrating possible scenarios.
Minor comments