Efforts to improve sea level forecasting on a warming planet have focused on determining the temperature, sea level and extent of polar ice sheets during Earth’s past interglacial warm periods1–3. About 400,000 years ago, during the interglacial period known as Marine Isotopic Stage 11 (MIS11), the global temperature was 1 to 2 degrees Celsius greater2 and sea level was 6 to 13 metres higher1,3. Sea level estimates in excess of about 10 metres, however, have been discounted because these require a contribution from the East Antarctic Ice Sheet3, which has been argued to have remained stable for millions of years before and includes MIS114,5. Here we show how the evolution of 234U enrichment within the subglacial waters of East Antarctica recorded the ice sheet’s response to MIS11 warming. Within the Wilkes Basin, subglacial chemical precipitates of opal and calcite record accumulation of 234U (the product of rock–water contact within an isolated subglacial reservoir) up to 20 times higher than that found in marine waters. The timescales of 234U enrichment place the inception of this reservoir at MIS11. Informed by the 234U cycling observed in the Laurentide Ice Sheet, where 234U accumulated during periods of ice stability6 and was flushed to global oceans in response to deglaciation7, we interpret our East Antarctic dataset to represent ice loss within the Wilkes Basin at MIS11. The 234U accumulation within the Wilkes Basin is also observed in the McMurdo Dry Valleys brines8–10, indicating11 that the brine originated beneath the adjacent East Antarctic Ice Sheet. The marine origin of brine salts10 and bacteria12 implies that MIS11 ice loss was coupled with marine flooding. Collectively, these data indicate that during one of the warmest Pleistocene interglacials, the ice sheet margin at the Wilkes Basin retreated to near the precipitate location, about 700 kilometres inland from the current position of the ice margin, which—assuming current ice volumes—would have contributed about 3 to 4 metres13 to global sea levels. Uranium isotopes in subglacial precipitates from the Wilkes Basin of the East Antarctic Ice Sheet reveal ice retreat during a warm Pleistocene interglacial period about 400,000 years ago.

中文翻译：

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在温暖的间冰期期间，南极洲东部威尔克斯盆地的冰退

改善地球变暖海平面预报的努力集中在确定地球过去间冰期暖期 1-3 期间极地冰盖的温度、海平面和范围。大约 40 万年前，在被称为海洋同位素阶段 11 (MIS11) 的间冰期期间，全球温度高出 1 至 2 摄氏度2，海平面高出 6 至 13 米1,3。然而，超过约 10 米的海平面估计值已被打折，因为这需要来自东南极冰盖 3 的贡献，据认为该冰盖在数百万年前一直保持稳定，包括 MIS114,5。在这里，我们展示了南极洲东部冰下水域中 234U 富集的演变如何记录冰盖对 MIS11 变暖的响应。在威尔克斯盆地内，蛋白石和方解石的冰下化学沉淀物记录了 234U（孤立的冰下水库中岩石-水接触的产物）的积累，比海水中发现的含量高 20 倍。234U 富集的时间尺度将这个水库的开始时间安排在 MIS11。根据在 Laurentide 冰盖中观察到的 234U 循环，其中 234U 在冰稳定期间积累，并因冰川消退而被冲入全球海洋 7，我们将我们的东南极数据集解释为 MIS11 威尔克斯盆地内的冰损失。威尔克斯盆地内的 234U 积累也在 McMurdo Dry Valleys 卤水8-10 中观察到，这表明卤水起源于相邻的东南极冰盖下方。盐水盐 10 和细菌 12 的海洋来源意味着 MIS11 冰损失与海洋洪水有关。总的来说，这些数据表明，在最温暖的更新世间冰期之一期间，威尔克斯盆地的冰盖边缘退缩到沉淀物位置附近，距离目前的冰边缘位置在内陆约 700 公里，假设目前的冰量将已使全球海平面升高约 3 至 4 米13。来自东南极冰盖威尔克斯盆地的冰下沉淀物中的铀同位素揭示了大约 40 万年前温暖的更新世间冰期期间的冰退。距目前冰缘位置约 700 公里的内陆，假设目前的冰量，全球海平面将增加约 3 至 4 米13。来自东南极冰盖威尔克斯盆地的冰下沉淀物中的铀同位素揭示了大约 40 万年前温暖的更新世间冰期期间的冰退。距目前冰缘位置约 700 公里的内陆，假设目前的冰量，全球海平面将增加约 3 至 4 米13。来自东南极冰盖威尔克斯盆地的冰下沉淀物中的铀同位素揭示了大约 40 万年前温暖的更新世间冰期期间的冰退。