Retreat of Southern Hemisphere Sea Ice, 130 000 to 116 000 years BP

A major retreat in Northern Hemisphere sea ice since 1978 has enabled climate and sea ice models to be evaluated for their ability to replicate retreat data. This has helped ensure that we have high confidence in Arctic sea ice predictions. In the Southern Hemisphere, there has been no similar sea retreat since 1978, which has meant that models cannot be tested against retreat data. This lack of sea ice retreat data has thus been a major contributor to the current lack of confidence in Southern Hemisphere sea ice forecasts. Here we propose to address this lack of data which covers a retreat of the Southern Hemisphere sea ice. We have found a period during the Last Interglacial (LIG) between 130,000 and 116,000 years Before Present (BP), when there was a substantial retreat in Southern Hemisphere sea ice. By reconstructing and modelling a retreat during this LIG period, under a climate which was similar to that of today, this proposal aims to transform understanding of the structure and causes of a major Southern Hemisphere retreat event. The project will be the first ever quantitative investigation of a large Southern Hemisphere sea ice retreat, and will be be of considerable importance to both the sea ice and palaeoclimate science communities. We will generate a new LIG sea ice dataset, using a robust new statistical approach. This will draw from, and build upon, the core expertise of our science team members. Our new Southern Hemisphere sea ice data data will then be used to help establish the cause of the LIG retreat and to test current climate and sea ice models. In addition to identifying the most likely cause of the decrease in sea ice during the LIG, this project will establish for the first time the degree of confidence that the sea ice community can have in our UK model-based predictions of a future retreat in Southern Hemisphere sea ice.