The impact of dynamic topography change on Antarctic ice sheet stability during the mid-Pliocene warm period
The impact of dynamic topography change on Antarctic ice sheet stability during the mid-Pliocene warm period
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DOI：
10.1130/g36988.1
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发表时间：
2015-10-01
期刊：
影响因子：
5.8
通讯作者：
Raymo, Maureen E.
中科院分区：
文献类型：
--
作者：
Austermann, Jacqueline;Pollard, David;Raymo, Maureen E.
南极冰盖在上新世中期暖期（MPWP）的演变仍然不确定，并为我们理解冰盖对现代全球变暖的响应具有重要意义。在MPWP期间，东南极冰盖（EAIS）的海洋部分退缩的程度特别有争议，地质观测和地球化学分析被引用来论证上新世中期变暖引起的相对较小或显著的冰盖退缩。海洋冰盖的稳定性与其接地线处的基岩高程密切相关，以前的冰盖建模假设MPWP期间的南极基岩高程与今天相同，但对地壳对冰负荷的响应进行了校正。然而，在过去的300万年里，各种过程可能已经扰动了基岩高程，最显著的是地幔对流或动态地形驱动的地壳垂直偏转。在这里，我们提出了地幔对流的模拟是一致的，与广泛的现今观测，并使用它们来预测动态地形的变化和重建基岩高程在MPWP。我们将这些海拔到模拟的南极冰盖在MPWP，并发现动态地形变化的校正有显着的影响，在海洋为基础的威尔克斯盆地内的EAIS的稳定性，在该部门的冰缘后退相当进一步内陆（200 - 560公里）相对于模拟，不包括这种校正基岩海拔。
The evolution of the Antarctic ice sheet during the mid-Pliocene warm period (MPWP) remains uncertain and has important implications for our understanding of ice sheet response to modern global warming. The extent to which marine-based sectors of the East Antarctic Ice Sheet (EAIS) retreated during the MPWP is particularly contentious, with geological observations and geochemical analyses being cited to argue for either a relatively minor or a significant ice sheet retreat in response to mid-Pliocene warming. The stability of marine-based ice sheets is intimately linked to bedrock elevation at their grounding lines, and previous ice sheet modeling assumed that Antarctic bedrock elevation during the MPWP was the same as today with the exception of a correction for the crustal response to ice loading. However, various processes may have perturbed bedrock elevation over the past 3 m.y., most notably vertical deflections of the crust driven by mantle convective flow, or dynamic topography. Here we present simulations of mantle convective flow that are consistent with a wide range of present-day observables and use them to predict changes in dynamic topography and reconstruct bedrock elevations during the MPWP. We incorporate these elevations into a simulation of the Antarctic ice sheet during the MPWP and find that the correction for dynamic topography change has a significant effect on the stability of the EAIS within the marine-based Wilkes Basin, with the ice margin in that sector retreating considerably further inland (200-560 km) relative to simulations that do not include this correction for bedrock elevation.