Holocene climate variability in northwestern Ross Sea area, East Antarctica

In this study, particular attention has been paid to sea ice evolution in northwestern Ross Sea since seasonal sea ice variability is crucial to accurately reconstruct the main paleoclimatic variations and to confidently predict future climate changes. Indeed, sea ice influences global climate dynamics through several physical oceanic and atmospheric processes such as albedo, energy balance, latitudinal thermal gradient and bottom water formation. This study is part of the ESF PolarCLIMATE HOLOCLIP (Holocene climate variability at highsouthern latitudes: an integrated perspective) Project that aims to bring together the sediment core, the ice core and the modelling scientific communities with the intention of understanding the processes linking different components of the Antarctica climate system. Diatom analyses were carried out on three sediment cores collected from the northwestern Ross Sea and covering the Holocene period. Core c20 from Cape Hallett and core c43 from Wood Bay were both collected at coastal sites, while core cJ5 from Joides Basin area was retrieved in a more open environment. Diatom counts suggest that in coastal sites the sea ice duration increased over the last 4 ka BP (thousand of years before present), while in the open ocean site conversely sea ice increased between 10-6 ka BP and subsequently slightly decreased between 6-1 ka BP. Diatom records in c20 and c43 cores are similar to other coastal core records from East Antarctica, while cJ5 diatom record shows more similar environmental conditions to the core from the Polar Front Zone. Since integrating proxies from different realms (marine and glacial) could provide us a more complete view of the climate and environmental changes occurring during the Holocene, a comparison was performed between the sea ice diatom Fragilariopsis curta relative abundances in the three sediment cores and the sea-salt Na records (a potential proxy of sea ice extend/persistence) from Talos Dome and Taylor Dome ice cores. Significant positive correlations indicate that the two coastal cores and Taylor Dome bear more local to regional signal, while core cJ5 and TALDICE conversely bear a more global signal.