| 17 Dec 2025
Climate Controls on Snowfall at Coastal West Antarctic Ice Rises - Potential Ice Core Sites
Abstract. The West Antarctic Ice Sheet (WAIS) is a dynamic system where interactions between ice, ocean, and atmosphere drive significant ice mass loss, raising concerns of irreversible retreat and sea-level rise. Long-term observational records of variability and change along the WAIS coast are largely restricted to satellite observations, but more direct observations are needed, given this region’s present and future societal impact. Coastal ice rises, grounded domes of ice embedded in or along the margins of ice shelves, preserve in their accumulated snowfall high-resolution records of past climate variability that can be recovered by ice coring. These potential ice core sites offer unique opportunities to reconstruct key drivers of regional change, including modes of atmosphere-ocean variability described by the Southern Annular Mode (SAM), the Amundsen Sea Low (ASL), and El Niño–Southern Oscillation (ENSO)—and warrant exploration via climate reanalysis to assess the relative balance of climate controls at any potential ice core site. This study uses ERA5 and MERRA-2 reanalysis to evaluate the climate controls on interannual snowfall variability at thirteen WAIS coastal ice rises over the satellite era (1979–2022). Results highlight longitudinal differences in how interannual snowfall variability at coastal ice rises is influenced by SAM, ENSO, and Bellingshausen Sea atmospheric pressure anomalies. Snow accumulation (precipitation) as resolved in atmospheric reanalysis suggests that, as potential ice core sites, Dean Island and Guest Peninsula, located in the West Sector of the WAIS coast, are strongly influenced by broad Southern Hemisphere westerly wind anomalies suppressing local precipitation, making them ideal for isolating this mode of variability in paleoclimate reconstructions. In contrast, Farwell Island in the East Sector exhibits a positive relationship between precipitation and cyclonic activity associated with Bellingshausen Sea pressure variability, making it a key site for reconstructing the influence of synoptic-scale pressure systems on coastal accumulation in this region. These findings inform future ice core studies aimed at understanding WAIS climate dynamics, with implications for projections of Antarctic stability and global sea-level rise.
Overview Comments:
The authors use contemporary reanalyses to explore the relationship (primarily) between annual snowfall and the primary modes of variability affecting ice rise locations along with West Antarctic coast to the west of sites drilled by BAS. Ice core observations to extend the contemporary record of the “pole of variability” are really needed to provide a much longer-term perspective for this critical region for global sea level rise. The goal is to identify those sites that are more favorable to reconstructing specific modes going back decades to centuries (?) in the past. The challenges that reanalyses experience prior to 1979 (Bromwich et al. 2024) emphasize the need. The authors are suitably cautious about the fidelity of reanalyses along this coast post 1979 especially that has limited direct observations. Figure 3c verifies the need for caution, although the precipitation variations in Fig. 3d are very similar. Overall, I found this analysis interesting, significant, and well done apart from a few issues that need attention, constituting a minor-major revision.
Specific Comments: