West Antarctic Ice Sheet retreat in the Amundsen Sea driven by decadal oceanic variability
West Antarctic Ice Sheet retreat in the Amundsen Sea driven by decadal oceanic variability
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DOI：
10.1038/s41561-018-0207-4
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发表时间：
2018-10-01
影响因子：
18.3
通讯作者：
Stammerjohn, Sharon
中科院分区：
文献类型：
--
作者：
Jenkins, Adrian;Shoosmith, Deb;Stammerjohn, Sharon
近几十年来，西南极冰盖阿蒙森海部分的质量损失有所增加，这表明持续的海洋强迫或对过去气候异常的持续，可能不稳定的反应。然而，长时间的卫星记录似乎与这两个过程都不相容，揭示了加速和间歇性变薄的周期性间断。在这里，我们使用2000年至2016年在Dotson冰架附近进行的海洋温度，盐度，溶解氧和电流测量来确定净基底融化的时间变化。一个十年周期主导着海洋记录，通过与海洋温度的非线性关系，融化在凉爽和温暖的极端之间变化了大约四倍。2009年左右达到顶峰的温暖阶段与冰架变薄和接地线的撤退相吻合，在2011年后的凉爽阶段重新前进。这些观测结果表明，冰的不连续退缩如何与海洋变化有关，并且十年极端事件的强度和时间比长期平均状态的变化更有影响力。融化对温度变化的非线性反应加剧了阿蒙森海冰架对这种变化的敏感性，这可能解释了该地区冰盖的脆弱性，因为亚表层海洋温度相对较高。
Mass loss from the Amundsen Sea sector of the West Antarctic Ice Sheet has increased in recent decades, suggestive of sustained ocean forcing or an ongoing, possibly unstable, response to a past climate anomaly. Lengthening satellite records appear to be incompatible with either process, however, revealing both periodic hiatuses in acceleration and intermittent episodes of thinning. Here we use ocean temperature, salinity, dissolved-oxygen and current measurements taken from 2000 to 2016 near the Dotson Ice Shelf to determine temporal changes in net basal melting. A decadal cycle dominates the ocean record, with melt changing by a factor of about four between cool and warm extremes via a nonlinear relationship with ocean temperature. A warm phase that peaked around 2009 coincided with ice-shelf thinning and retreat of the grounding line, which re-advanced during a post-2011 cool phase. These observations demonstrate how discontinuous ice retreat is linked with ocean variability, and that the strength and timing of decadal extremes is more influential than changes in the longer-term mean state. The nonlinear response of melting to temperature change heightens the sensitivity of Amundsen Sea ice shelves to such variability, possibly explaining the vulnerability of the ice sheet in that sector, where subsurface ocean temperatures are relatively high.