Deep sea geological records indicate that Antarctic ice-sheet growth and decay is strongly influenced by the Earth’s astronomical variations (known as Milankovitch cycles), and that the frequency of the glacial–interglacial cycles changes through time. Here we examine the emergence of a strong obliquity (axial tilt) control on Antarctic ice-sheet evolution during the Miocene by correlating the Antarctic margin geological records from 34 to 5 million years ago with a measure of obliquity sensitivity that compares the variance in deep sea sediment core oxygen-isotope data at obliquity timescales with variance of the calculated obliquity forcing. Our analysis reveals distinct phases of ice-sheet evolution and suggests the sensitivity to obliquity forcing increases when ice-sheet margins extend into marine environments. We propose that this occurs because obliquity-driven changes in the meridional temperature gradient affect the position and strength of the circum-Antarctic easterly flow and enhance (or reduce) ocean heat transport across the Antarctic continental margin. The influence of obliquity-driven changes in ocean dynamics is amplified when marine ice sheets are extensive, and sea ice is limited. Our reconstruction of the Antarctic ice-sheet history suggests that if sea-ice cover decreases in the coming decades, ocean-driven melting at the ice-sheet margin will be amplified.

深海地质记录表明，南极冰盖的生长和衰落受到地球天文变化（称为米兰科维奇循环）的强烈影响，并且冰川-冰川间周期的频率会随时间变化。在这里，我们通过将34到500万年前的南极边缘地质记录与可比较深海方差的倾斜敏感性测量值相关联，来检验中新世期间对南极冰盖演化的强烈倾斜（轴向倾斜）控制的出现倾斜时标上的沉积物核心氧同位素数据随计算的倾斜强迫的变化而变化。我们的分析揭示了冰盖演化的不同阶段，并暗示了当冰盖边缘延伸到海洋环境时，对倾斜强迫的敏感性会增加。我们之所以会发生这种情况，是因为子午线温度梯度中的倾斜驱动变化会影响南极洲周向环流的位置和强度，并增强（或减少）整个南极大陆边缘的海洋热量传输。当海洋冰盖广泛而海冰受到限制时，由倾斜驱动的海洋动力学变化的影响会放大。我们对南极冰盖历史的重建表明，如果未来几十年海冰覆盖率下降，那么冰盖边缘的海洋驱动融化将被放大。当海洋冰盖很宽且海冰受到限制时，由倾斜驱动的海洋动力学变化的影响会放大。我们对南极冰盖历史的重建表明，如果未来几十年海冰覆盖率下降，那么冰盖边缘的海洋驱动融化将被放大。当海洋冰盖广泛而海冰受到限制时，由倾斜驱动的海洋动力学变化的影响会放大。我们对南极冰盖历史的重建表明，如果未来几十年海冰覆盖率下降，那么冰盖边缘的海洋驱动融化将被放大。