Evolution of prehistoric Antarctic ice sheet holds lessons for the future
Antarctica plays a significant role in Earth’s oceanic and climate systems. Understanding the evolution of the Antarctic ice sheet in particular can provide invaluable information on future global sea fluctuations, ocean circulation and climate. With the support of the Marie Curie-Skłodowska Actions (MCSA) programme, the EU-funded WAMSISE project examined the record of ice sheet evolution on West Antarctic continental margins from the middle Miocene to present, seeking to clarify the factors behind major sedimentary changes and their global implications. “The research developed under WAMSISE focused on the middle Miocene ice sheet oscillation over the Ross Sea continental shelf,” explains project coordinator Robert Larter.
International Ocean Discovery Program presents rare opportunity
WAMSISE took advantage of the new International Ocean Discovery Program (IODP) drilling results and the invitation for MSCA fellow, Lara Pérez, to participate in an IODP expedition to the Scotia Sea. “We had the huge opportunity to work on records from a slightly earlier time than originally proposed that were recovered in the Ross Sea on IODP Expedition 374,” notes Larter. IODP Expedition 374 had recovered an expanded early to middle Miocene (18 to 14 million years ago) record from a drill site on the Ross Sea continental shelf. “Pérez took on the challenge to correlate this record with those from legacy Deep Sea Drilling Project sites drilled in the 1970s on other parts of the Ross Sea continental shelf, thus revealing the geographic patterns of sedimentation related to the earliest ice sheet advances onto the continental shelf in the region,” reports Larter. In the IODP expedition 382 to the Scotia Sea, Pérez correlated the drilling results to seismic profiles. “This provides insights into the history of development of the Antarctic Circumpolar Current and export of Antarctic Bottom Water through the Scotia Sea,” Larter explains. Expedition results were set out in the paper ‘Miocene to present oceanographic variability in the Scotia Sea and Antarctic ice sheets dynamics: Insight from revised seismic-stratigraphy following IODP Expedition 382’.
New perspectives on Antarctic ice sheets dynamics
WAMSISE’s research suggests that the ice sheet advanced on the continental shelf in short time intervals, prior to the Miocene Climate Optimum. “This was followed by widespread marine-based ice sheet advance across the Ross Sea during the Middle Miocene Climate Transition around 14 million years ago,” highlights Pérez. Additionally, research showed a link between the regional variability of the bottom-water flows and the Antarctic ice sheets dynamics from the late Miocene to the present. Based on seismic-stratigraphic analyses and core-log-seismic correlations in the Ross Sea, WAMSISE’s MSCA fellow led work on a multiauthor paper describing how regional transition from growth of isolated ice caps to widespread ice sheets occurred through the Miocene.
Reconstructing the past: significance of CO2 concentrations
“Studies in the Ross Sea provide a clearer picture of how the Antarctic ice sheets behaved the last time atmospheric CO2 concentrations were at the levels expected to be reached in the next few decades,” outlines Larter. The ice extent fluctuated, then probably driven by variations in insolation attributed to orbital variations, but there were long periods when the ice sheets were less extensive than today, particularly over much of West Antarctica. “These results are a cautionary warning about the potential consequences of continued warming,” concludes Larter.
Keywords
WAMSISE, Miocene, International Ocean Discovery Program, West Antarctic continental margins, Ross Sea continental shelf, ice sheets
