Last Interglacial Antarctic – Southern Ocean climate

Abstract:

Evidence from multiple paleoclimate proxy records suggests that the Last Interglacial (LIG, ~130 to 115 thousand years before present) was characterised by high-latitude air and sea surface temperatures (SSTs) slightly warmer than present, and by mean global sea level a few metres higher. Therefore, the LIG is considered to be a good analogue for oceanographic/climatic conditions that may be experienced in the near future, and the modelled response of the LIG Antarctic Ice Sheet could provide insights into the probability of rapid sea level rise driven by Antarctic ice loss. Paleoclimate reconstructions needed to force LIG Antarctic Ice Sheet simulations are largely obtained from proxies in ice cores or marine sediment cores. In the Southern Hemisphere, existing temperature reconstructions suffer from very high variance among a low number of individual records, with very few data from south of 50°S. While several recent syntheses have focused on the LIG climatic optimum, conditions prior to ~130 ka have received less attention but are needed to force transient Antarctic Ice Sheet models. Here we review existing temperature reconstructions and examine in detail their sources of variance. We also extend the synthesis of Southern Ocean SST back to 200 ka, thus providing a longer temperature time series for ice sheet simulations. Finally, we compare our LIG Southern Ocean SSTs with climate model output to assess how well climate model output may be able to fill the geographic gaps in paleoclimate reconstructions.