Glacial-interglacial sea ice proxies from the Antarctic Peninsula using the James Ross Island ice core.

Abstract:

Ice core records from Antarctica have shown promise as highly-resolved indicators of regional sea ice change, but to date semi-quantified reconstructions do not extend back more than ~150 years. In this study the chemical composition of the James Ross Island ice core is presented as a potential sea ice proxy record spanning the full Holocene and into the last glacial interval. A CFA-TE method was used to analyse the chemical composition of the entire 363.9m core including final 5m which contains evidence of glacial age ice. MSA^- and major anions were measured at 4cm effective resolution, along with trace elements Na, Ca, K, Mg, Mn, H₂O₂, NO₃, total conductivity and dust at <0.5cm effective resolution. Seasonal signals from H₂O₂ in the upper 50m of the core support the use of non sea salt-SO₄^2- for determining seasonality in deeper sections. This multi-proxy analysis of the oldest ice core to date from the Antarctic Peninsula region allows the concurrent interpretation of sea ice changes and their environmental drivers. The potential dual influence of previous winter sea ice extent and air pathway source region on MSA concentrations in the core are interpreted with use of Na as a winter maximum indicator and Ca and dust signal strength showing changes in dust flux indicating potential source region variation.