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

海冰对全球气候、南极冰盖以及南大洋的所有生命都非常重要。然而，南半球的海冰覆盖面积预计将在下个世纪急剧减少；2200人的降幅可能高达58%。预测海冰消失的模型是基于这些模型，从未与南半球海冰的消退进行过验证。自1978年以来，北半球海冰的一次重大退缩使气候和海冰模型能够因其复制退缩数据的能力而受到评估。这有助于确保我们对北冰洋海冰预测有很高的信心。在南半球，自1978年以来就没有发生过类似的海退，这意味着无法用海退数据对模型进行测试。因此，缺乏海冰消退数据是目前对南半球海冰预报缺乏信心的主要原因。在这里，我们建议解决南半球海冰消退数据的缺乏问题。我们发现，在距今13万年至11.6万年之间的最后一次间冰期(LIG)，南半球的海冰出现了大幅退缩。通过重建和模拟LIG期间在与今天相似的气候下的撤退，这一提议旨在改变对南半球重大撤退事件的结构和原因的理解。该项目将是有史以来第一次对南半球大型海冰消退进行定量调查，对海冰和古气候科学界都具有相当重要的意义。我们将使用一种强大的新统计方法生成一个新的LIG海冰数据集。这将借鉴和发展我们科学团队成员的核心专业知识。我们新的南半球海冰数据将被用来帮助确定LIG退缩的原因，并测试当前的气候和海冰模型。除了确定LIG期间海冰减少的最可能原因外，该项目还将首次建立海冰界对我们基于英国模型的南半球海冰未来消退预测的信心程度。

Sea ice is of huge importance to global climate, the Antarctic ice sheet, and to all life in the Southern Ocean. However the area covered by sea ice in the Southern Hemisphere is predicted to drastically decrease over the next century; the decrease by 2200 could be as much as 58%.The models, on which predictions of sea ice loss are based, have never been tested against a documented retreat of Southern Hemisphere sea ice. 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.