The Antarctic Ice Sheet (AIS) has the potential to exert a major control on future global sea level. Here, we gain insight into the response of the Antarctic Ice Sheet (AIS) to changing climate through assessment of ice-sheet behavior during and since the Last Glacial Maximum (LGM) along the western coast of McMurdo Sound. We examine whether expansion of grounded ice in this sector of the Ross Embayment during the last glaciation was caused by increased flux from East Antarctic outlets and local glaciers or was produced by marine influences, such as lowered sea level or reduced melting of submarine grounded ice. During the LGM, grounded ice derived from the Ross Sea deposited a well-defined drift sheet along the Royal Society headlands on the western coast of McMurdo Sound. Twenty-six new radiocarbon dates of subfossil algae within this drift sheet suggest that the ice sheet was at its maximum extent by at least ∼18.4 ka and maintained this position for about five thousand years. Cross-cutting relationships show that local alpine glaciers did not contribute to the grounded ice but rather fluctuated asynchronously. This same relationship held true during the penultimate glaciation, dated to roughly 137–191 ka with Be exposure ages. An explanation for this out-of-phase relationship is that different mechanisms controlled their respective extents. Because they lack significant surface melting ablation zones, the local alpine glaciers, which largely terminate on land, were driven by changes in accumulation. These glaciers likely expanded during warmer times when accumulation was higher. In contrast, marine factors, such as global sea-level change and/or subglacial melting, controlled ice fluctuations in the Ross Embayment, including McMurdo Sound, leading to advance during the LGM.

中文翻译：

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南极洲皇家学会山脉当地冰川与邻近罗斯海冰之间的相互作用

南极冰盖（AIS）有可能对未来全球海平面发挥重大控制作用。在这里，我们通过评估麦克默多海峡西海岸末次盛冰期 (LGM) 期间及之后的冰盖行为，深入了解南极冰盖 (AIS) 对气候变化的响应。我们研究了末次冰期期间罗斯海湾这一区域的接地冰的扩张是否是由于东南极出口和当地冰川通量增加造成的，或者是由海洋影响造成的，例如海平面降低或海底接地冰融化减少。在末次盛冰期期间，来自罗斯海的接地冰沿着麦克默多海峡西海岸的皇家学会岬角沉积了清晰的漂移片。该漂移片内亚化石藻类的 26 个新放射性碳测年结果表明，冰盖在至少 ∼18.4 ka 时达到最大范围，并保持这一位置约五千年。交叉关系表明，当地的高山冰川对接地冰没有贡献，而是异步波动。同样的关系在倒数第二次冰期期间也成立，大约可追溯到 137-191 ka，铍暴露年龄。对这种异相关系的解释是不同的机制控制着各自的程度。由于缺乏明显的表面融化消融区，当地的高山冰川主要终止于陆地，是由积累的变化驱动的。这些冰川可能在温暖时期扩张，此时冰川积累量较高。相比之下，全球海平面变化和/或冰下融化等海洋因素控制了包括麦克默多海峡在内的罗斯海湾的冰层波动，导致末次盛冰期期间冰层前进。