Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand.
Proc Natl Acad Sci U S A. 2012 Oct 2;109(40):16052-6. doi: 10.1073/pnas.1205385109. Epub 2012 Sep 17.
Retreat of the Last Glacial Maximum (LGM) Antarctic ice sheet is thought to have been initiated by changes in ocean heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the Antarctic ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-Antarctic terrestrial and marine geological data for constraint, then perturb the system with sea level and ocean heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to ocean forcings, in agreement with empirical data. Most significantly, we find that although ocean warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments-a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets.
末次冰盛期（LGM）南极冰盖的退缩被认为是由北半球海洋热量和均衡海平面变化引发的，随着大气温度升高，北部冰盖融化。然而，到目前为止，冰动力学的空间变化在多大程度上可能调节了南极冰盖的衰减模式和时间，这一点还没有得到太多关注，尽管人们越来越认识到，动态效应解释了现代冰盖观测到的质量平衡变化的相当一部分。在这里，我们使用分辨率为 5 公里的全大陆数值冰盖模型来评估控制冰盖流动的机制差异是否可以解释大陆不同地区地质年代学研究之间的差异。我们首先使用泛南极陆地和海洋地质数据来模拟 LGM 平衡冰盖的几何形状和流动特征，然后通过海平面和海洋热通量的增加来对系统进行扰动，以研究冰盖的脆弱性。我们的结果表明，东部威德尔海、阿蒙森海、罗斯海中部和阿梅里槽的快速流动冰川对海洋强迫的响应最快，这与经验数据一致。最重要的是，我们发现，尽管海洋变暖与海平面上升主要导致局部冰川加速，但来自邻近地区的冰的同时减少导致整个冰川流域的广泛变薄——这一发现对现代冰盖目前观测到的动态变化具有重要影响。
