Reconstructions of Antarctic sea-ice at the peak of the last interglacial (marine isotope stage 5e)

海冰在调节全球海洋生态系统、海洋环流和人为气候变化方面发挥着基础性作用。预计未来几十年，南半球和北半球的海冰都将消退。这种不确定性的产生是因为南半球最近没有发生过限制模型的海冰消退事件。为了帮助解决这个问题，我们最近发布了一份基于冰芯数据的对最后一次间冰期海冰范围的新评估。这一重建表明南极冬季海冰覆盖面积可能减少65%(+/-)7%(Holloway等人)。2016)(图1)。有趣的是，这表明最后一次间冰期可能是预测到21世纪末南半球海冰(高达58%)缩小(高达58%)的极好和独特的类似物(Stocker等人，2013年)。(2016)海冰减少65%的计算完全基于冰芯数据。因此，这一拟议的撤退迫切需要对照海洋核心数据进行核对，因为这些数据可以更直接地测量海冰边缘过去的位置。一些现有的基于微化石的南大洋重建包含有证据表明，在最后一次间冰期的顶峰期间，海洋表面温度变暖，海冰面积大大减少(Allen&Peck，提交和参考文献)。其中)。但这些以前的研究都是关于太北的海洋沉积物岩心，无法准确地限制海冰边缘的位置，而且它们没有足够的年代学控制或样本分辨率，无法准确确定最后一次间冰期海冰最小值的时间和大小。

Sea-ice plays a fundamental role in regulating global marine ecosystems, ocean circulation and anthropogenic climate change. Sea-ice is predicted to retreat in both the Southern and Northern Hemispheres over the coming decades. This uncertainty arises because there has not been a recent sea-ice retreat event in the Southern Hemisphere to constrain models. To help tackle this problem, we have recently published a new assessment of last interglacial sea-ice extent, based on ice core data. This reconstruction indicates a likely 65% (+/-)7% reduction in Antarctic winter sea-ice cover (Holloway et al. 2016) (Figure 1). Intriguingly, this suggests that the last interglacial is potentially an excellent and unique analogue for the predicted shrinking of Southern Hemisphere sea-ice (up to 58%) by the end of the 21st century (Stocker et al., 2013).However, the Holloway et al. (2016) calculation of a 65% reduction in sea ice is based solely on ice core data. This proposed retreat therefore urgently requires checking against marine core data, since these allow a more direct measurement of the past position of the sea-ice edge. Some existing microfossil based Southern Ocean reconstructions contain evidence of warmer sea surface temperatures and greatly reduced sea-ice extent during the peak of the last interglacial (Allen & Peck, submitted and refs. therein). But these previous studies are on marine sediment cores located too far north to accurately constrain the position of the sea-ice edge, and they have insufficient chronological control, or sample resolution, to accurately resolve the timing and magnitude of the last interglacial sea-ice minimum.