Abstract
The response of the dynamic marginal marine environment in East Antarctica to climate change in the 21st century has implications for global sea level and climate. However, the processes that govern the coupled ice-ocean-atmosphere system at the margin of the East Antarctic Ice Sheet are not yet well-constrained. To identify the processes and feedbacks that drive the Antarctic system’s response (and contribution) to changes in global mean climate state during the Holocene this thesis analyzes a marine sediment core, RS15-GC57, collected from the northeastern margin of Victoria Land. The diatom assemblage, bulk sediment geochemistry, and magnetic properties of RS15-GC57 are interpreted in the context of modern oceanographic observations to reconstruct Holocene oceanographic variability at the intersection of the East Antarctic Ice Sheet, the Ross Sea, and the Southern Ocean.
The most prominent shared feature in proxy records from core RS15-GC57 is a rapid shift from a stable mid-Holocene to a more variable late-Holocene environment at 3.45 ± 150 ka. The timing of this transition, constrained using novel ramped pyrolysis 14C dating methodology, is coincident with the transition from warm Hypsithermal conditions to cooler, more variable, Neoglacial conditions recorded in sediment cores from Adélie Land and the Antarctic Peninsula. Interpreted in the context of modern oceanographic observations and recently published models of the impact of AIS discharge, the results of this thesis suggest that the retreat of the Ross Ice Shelf may have warmed the circum-Antarctic during the mid-Holocene.
Feedbacks associated with enhanced sea ice and Antarctic Bottom Water production after the stabilization of the Ross Ice Shelf at ~3.5 ka may be linked to late Holocene cooling observed in marine records from Antarctica and global proxy reconstructions. Fluctuations in the proxies for productivity and oceanography in RS15-GC57 indicate multi-centennial Late-Holocene warm (1.5 – 0.75 ka) and cool events (0.7 ka to the present). Similar intervals occur in the Ross Sea, East Antarctica, and the Antarctic Peninsula indicating a circum-Antarctic response to changes in meridional (katabatic) and zonal (easterly and westerly) wind stress, Antarctic Bottom Water production, and upwelling of Modified Circumpolar Deep Water. The paleoceanographic reconstruction presented in this thesis indicates that, to improve projections of further climate change, global climate models require accurate representation of the Antarctic marginal marine environment.