Over recent decades Antarctic sea-ice extent has increased, alongside widespread ice shelf thinning and freshening of waters along the Antarctic margin. In contrast, Earth system models generally simulate a decrease in sea ice. Circulation of water masses beneath large-cavity ice shelves is not included in current Earth System models and may be a driver of this phenomena. We examine a Holocene sediment core off East Antarctica that records the Neoglacial transition, the last major baseline shift of Antarctic sea ice, and part of a late-Holocene global cooling trend. We provide a multi-proxy record of Holocene glacial meltwater input, sediment transport, and sea-ice variability. Our record, supported by high-resolution ocean modelling, shows that a rapid Antarctic sea-ice increase during the mid-Holocene (∼ 4.5 ka) occurred against a backdrop of increasing glacial meltwater input and gradual climate warming. We suggest that mid-Holocene ice shelf cavity expansion led to cooling of surface waters and sea-ice growth that slowed basal ice shelf melting. Incorporating this feedback mechanism into global climate models will be important for future projections of Antarctic changes.

中文翻译：

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海洋冰盖退缩推动中全新世南极海冰增加

在最近的几十年中，南极海冰的面积增加了，同时南极边缘的冰架普遍变薄和水质变淡。相反，地球系统模型通常模拟海冰的减少。当前的地球系统模型不包括大腔冰架下面的水团的循环，并且可能是这种现象的驱动因素。我们研究了南极东部全新世沉积岩芯，记录了新冰期转变，南极海冰的最后一个主要基线偏移以及全新世晚期全球冷却趋势的一部分。我们提供全新世冰川融水输入，沉积物传输和海冰变化的多代理记录。我们的记录在高分辨率海洋模拟的支持下显示，在全新世中期（〜 4.5 ka）是在冰川融水输入增加和气候逐渐变暖的背景下发生的。我们认为，全新世中期的冰架腔扩张导致地表水冷却和海冰生长，从而减慢了基础冰架融化。将这种反馈机制纳入全球气候模型对于南极变化的未来预测非常重要。