Accumulation and marine forcing of ice dynamics in the western Ross Sea during the last deglaciation

TitleAccumulation and marine forcing of ice dynamics in the western Ross Sea during the last deglaciation
Publication TypeJournal Article
Year of Publication2015
AuthorsHall, BL, Denton, GH, Heath, SL, Jackson, MS, Koffman, TNB
JournalNature Geoscience
Pagination625 - 628
Date PublishedJan-07-2016

The grounding line of the ice sheet in the Ross Sea, Antarctica, retreated between the Last Glacial Maximum and the present. However, the timing of the retreat and the interplay of factors controlling ice stability in this region1 remain uncertain. Here we use 180 radiocarbon dates to reconstruct the chronology of moraine construction on the headlands adjacent to western McMurdo Sound. On the basis of these dates we then assess the timing of ice expansion and retreat in the Ross drainage system that is fed from both the East and West Antarctic ice sheets. We find that grounded ice in the western Ross Sea achieved its greatest thickness and extent during the last termination, between 12,800 and 18,700 years ago. Maximum ice thickness at our site coincides with a period of high accumulation as recorded by the West Antarctic Ice Sheet Divide ice core2. Recession of the ice sheet from the headland moraines began about 12,800 years ago, despite continued high accumulation and the expansion of land-based glaciers at this time. We therefore suggest that the grounding-line retreat reflects an increased marine influence as sea levels rose and the ocean warmed. We suggest that future instability in the ice sheet grounding line may occur whenever the ocean forcing is stronger than forcing from accumulation.  

Short TitleNature Geosci