Antarctic ice dynamics amplified by Northern Hemisphere sea-level forcing
Antarctic ice dynamics amplified by Northern Hemisphere sea-level forcing
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DOI：
10.1038/s41586-020-2916-2
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发表时间：
2020-11-26
期刊：
影响因子：
64.8
通讯作者：
Han, Holly K.
中科院分区：
文献类型：
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作者：
Gomez, Natalya;Weber, Michael E.;Han, Holly K.
北半球的海平面上升是由于阳光照射和温室气体强迫造成的北半球冰层的融化造成的，这被认为是南极冰盖(AIS)海洋部分的搁浅(1-3)。这种半球间的海平面强迫可能解释了全球冰盖在冰期周期中同步演变的原因。最近的研究表明，AIS在最后一次冰川消融(4-7年前)(大约在20,000至9,000年前)期间和之后经历了相当大的千年尺度的变化，这为这种海平面强迫提供了进一步的证据。然而，由于重力、变形和地球自转的影响，由于冰盖质量损失导致的全球海平面变化是非常不均匀的(8)，这表明AIS接地线对北半球海平面强迫的反应比以前模型(1，2，6)更复杂。在这里，使用一个冰盖模式与一个全球海平面模式相耦合，我们表明AIS动力被北半球海平面强迫放大。这种半球间相互作用的结果是，北半球大规模或快速的海平面强迫增强了冰川期间AIS的基准线推进和相关的质量增加，以及在冰川消融期间基准线的后退和质量损失。相对于没有这些相互作用的模型，我们的模型中包括了北半球海平面强迫，增加了最后一次冰川盛期(大约26,000到20,000年前)AIS的体积，触发了接地线的更早撤退，并导致了最后一次冰川消融过程中千年尺度的变化。这些发现与末次冰盛期和随后的冰盖退缩期间AIS范围的地质重建以及南极洲的相对海平面变化(3-7，9，10)是一致的。
Sea-level rise due to ice loss in the Northern Hemisphere in response to insolation and greenhouse gas forcing is thought to have caused grounding-line retreat of marine-based sectors of the Antarctic Ice Sheet (AIS)(1-3.) Such interhemispheric sea-level forcing may explain the synchronous evolution of global ice sheets over ice-age cycles. Recent studies that indicate that the AIS experienced substantial millennial-scale variability during and after the last deglaciation(4-7) (roughly 20,000 to 9,000 years ago) provide further evidence of this sea-level forcing. However, global sea-level change as a result of mass loss from ice sheets is strongly nonuniform, owing to gravitational, deformational and Earth rotational effects(8), suggesting that the response of AIS grounding lines to Northern Hemisphere sea-level forcing is more complicated than previously modelled(1,2,6). Here, using an ice-sheet model coupled to a global sea-level model, we show that AIS dynamics are amplified by Northern Hemisphere sea-level forcing. As a result of this interhemispheric interaction, a large or rapid Northern Hemisphere sea-level forcing enhances grounding-line advance and associated mass gain of the AIS during glaciation, and grounding-line retreat and mass loss during deglaciation. Relative to models without these interactions, the inclusion of Northern Hemisphere sea-level forcing in our model increases the volume of the AIS during the Last Glacial Maximum (about 26,000 to 20,000 years ago), triggers an earlier retreat of the grounding line and leads to millennial-scale variability throughout the last deglaciation. These findings are consistent with geologic reconstructions of the extent of the AIS during the Last Glacial Maximum and subsequent ice-sheet retreat, and with relative sea-level change in Antarctica(3-7,9,10).