The West Antarctic Ice Sheet: Instability, disintegration, and initiation of Ice Ages
The West Antarctic Ice Sheet: Instability, disintegration, and initiation of Ice Ages
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南极西部冰盖：不稳定、崩解和冰河时代的开始
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发表时间：
1975
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影响因子：
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通讯作者：
T. Hughes
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文献类型：
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作者：
T. Hughes
本文提出了一个冰期-间冰期全球气候循环受大西洋环境中冰冻圈、水圈和大气相互作用控制的模型。在该模型中，气候变化是由北美、欧洲和南极洲的雪原或冰盖中发展的不稳定性引起的。西南极冰盖（位于西半球的南极冰盖部分）的解体引发了一系列事件，最终导致全球冰河时代。10个独立的数据体可以解释为南极西部冰盖已经和正在解体的证据。南极洲罗斯海冰排水系统的动力学研究，以确定是什么控制南极西部冰盖的解体和恢复。它的结论是，解体是由冰流排水固有的不稳定的西南极冰盖和恢复是由出口冰川排水固有的稳定东南极冰盖控制。在这两种情况下，冰川的稳定性取决于冰盖和冰床之间的耦合程度。当这种耦合在冰盖边缘正常减弱时，冰排水通道就会形成，并可能导致冰流或出口冰川的激增。当这种耦合在平行于冰盖边缘的方向上减弱时，冰架就会形成，并可能导致漂浮的冰舌或冰架的快速接地线撤退。冰盖表面的拐点最大值在涌浪期间向内陆迁移，在涌浪结束后向海迁移。冰盖和冰架之间的过渡区在接地线向内陆撤退期间变宽，在接地线向海推进期间变窄。弯曲线和接地线的迁移联合收割机使冰盖在后退时形成凹面，在前进时形成凸面。冰流中的一系列涌动段分阶段降低冰盖，形成阶梯状冰流表面，导致接地线快速不连续撤退。快速冰川复苏后，激增可以截断前进冰盖冰架边界。今天，至少有一个西南极冰流是阶梯状的，至少有一个东南极出口冰川在罗斯海冰排水系统中被截断。如果这种情况是普遍的，那么西南极冰盖由于冰流涌动而沿着西普尔海岸沿着崩解，由于出口冰川增厚而沿着横贯南极山脉沿着恢复。这些过程之间的竞争将为冰河时代模型提供一个关键的测试，该模型预测，南极西部冰盖的逐步解体导致南极东部冰盖相邻部分的逐步增长。
An ice age model is proposed in which glacial-interglacial global climatic cycles are controlled by interactions between the cryosphere, hydrosphere, and atmosphere in the Atlantic environment. In the model, climatic change results from instabilities which develop in the snowfields or ice sheets of North America, Europe, and Antarctica. Disintegration of the West Antarctic ice sheet (that portion of the Antarctic ice sheet lying in the western hemisphere) initiates a chain of events which culminates in a global ice age. Ten independent bodies of data can be interpreted as evidence that the West Antarctic ice sheet has been and is disintegrating. The dynamics of the Ross Sea ice drainage system of Antarctica is examined to determine what controls disintegration and recovery of the West Antarctic ice sheet. It is concluded that disintegration is controlled by ice streams which drain the inherently unstable West Antarctic ice sheet and recovery is controlled by outlet glaciers which drain the inherently stable East Antarctic ice sheet. Glacial stability in both cases is determined by the degree of coupling between the ice sheet and its bed. Ice drainage channels develop when this coupling is weakened normal to the margin of an ice sheet and can lead to surges in ice streams or outlet glaciers. Ice shelves develop when this coupling is weakened parallel to the margin of an ice sheet and can lead to a rapid grounding line retreat of floating ice tongues or ice shelves. An inflection maximum on the ice sheet surface migrates inland during a surge and migrates seaward after the surge is spent. A transition zone between the ice sheet and the ice shelf widens during a grounding line retreat inland and narrows during a grounding line advance seaward. Inflection line and grounding line migrations combine to give the ice sheet a concave surface during retreat and a convex surface during advance. A train of surging segments in an ice stream lowers the ice sheet in stages, creating a terraced ice stream surface which causes rapid discontinuous retreats of the grounding line. Rapid glacial recovery following a surge can truncate the advancing ice sheet-ice shelf boundary. Today at least one West Antarctic ice stream is terraced and at least one East Antarctic outlet glacier is truncated in the Ross Sea ice drainage system. If this condition is general, the West Antarctic ice sheet is disintegrating along the Siple Coast as a result of surging ice streams and is recovering along the Transantarctic Mountains as a result of thickening outlet glaciers. The competition between these processes will provide a critical test of the ice age model, which predicts that progressive disintegration of the West Antarctic ice sheet results in progressive growth of adjacent parts of the East Antarctic ice sheet.