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Potential sea-level rise from Antarctic ice-sheet instability constrained by observations

机译：受观测限制的南极冰盖不稳定性引起的潜在海平面上升

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摘要

Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI)(1), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence(2-4) that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions(5-8), the centennial to millennial contribution could be several metres. Physically plausible projections are challenging(9): numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive(2,3,10) to generate large ensembles for uncertainty assessment, and lower-resolution model projections(11) rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments9 (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.
机译：位于海平面以下基岩上的南极冰盖的大部分可能容易受到海冰盖不稳定性（MISI）（1）的影响，这是由海洋或大气变化触发的接地线的自我维持性退缩。越来越多的证据表明（2-4）MISI可能在整个阿蒙森海上游（ASE）进行，该海冰所含冰量相当于全球海平面上升的一米以上。如果在其他地区触发（5-8），则百年至千禧年的贡献可能会达到几米。物理上合理的预测是具有挑战性的（9）：具有足够空间分辨率来模拟接地线过程的数值模型在计算上过于昂贵（2,3,10），以至于无法生成用于不确定性评估的大型集合，而较低分辨率的模型预测（11）依赖于仅受当前更改宽松约束的参数设置。在这里，我们预计，在ASE占主导地位的情况下，到2100年，南极冰盖将贡献相当于30 cm的海平面，到2200年（95％的分位数）将贡献72 cm的海平面。我们基于过程的统计方法给出了偏斜和复杂的概率分布（单模，在2100时为10厘米；两种模在2200时为49厘米和6厘米）。滑动对基础摩擦的依赖性是一个未知的关键：非线性关系有利于贡献更大。结果取决于在气候情景A1B下基于预计触发因素对MISI风险的评估（参考资料9），尽管对这些因素的敏感性受到制冰速度和程度的理论和地形限制。我们发现，这些限制因素，校准成功以模拟观测到的ASE损失以及在某些盆地中评估风险较低的因素共同限制了贡献。我们的评估表明，在当前对物理机制和潜在触发因素的理解下，低分辨率模型和物理论证9（到2100年达到一米，到2200年达到大约一米）的上限估计是难以置信的。

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  • 来源
    《Nature》 |2015年第7580期|115-118|共4页
  • 作者

    Ritz Catherine; Edwards Tamsin L.; Durand Gael; Payne Antony J.; Peyaud Vincent; Hindmarsh Richard C. A.;

  • 作者单位

    CNRS, LGGE, F-38041 Grenoble, France|Univ Grenoble Alpes, LGGE, F-38041 Grenoble, France;

    Open Univ, Fac Sci, Dept Environm Earth & Ecosyst, Milton Keynes MK7 6AA, Bucks, England|Univ Bristol, Dept Geog Sci, Bristol BS8 1SS, Avon, England;

    CNRS, LGGE, F-38041 Grenoble, France|Univ Grenoble Alpes, LGGE, F-38041 Grenoble, France;

    Univ Bristol, Dept Geog Sci, Bristol BS8 1SS, Avon, England;

    CNRS, LGGE, F-38041 Grenoble, France|Univ Grenoble Alpes, LGGE, F-38041 Grenoble, France;

    British Antarctic Survey, Nat Environm Res Council, Cambridge CB3 0ET, England;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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