Estimating Greenland tidewater glacier retreat driven by submarine melting
Estimating Greenland tidewater glacier retreat driven by submarine melting
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DOI：
10.5194/tc-13-2489-2019
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
D. Slater;F. Straneo;D. Felikson;C. Little;H. Goelzer;X. Fettweis;J. Holte
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文献类型：
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作者：
D. Slater;F. Straneo;D. Felikson;C. Little;H. Goelzer;X. Fettweis;J. Holte
摘要。北大西洋通过格陵兰岛潮水冰川崩解前沿的海底融化对格陵兰冰盖产生的影响，被认为是冰川广泛退缩、动态质量损失以及冰盖对海平面上升有贡献的关键驱动因素。尽管其至关重要，但过程的复杂性和规模问题阻碍了在冰盖规模模型中体现海底融化影响的努力。在此，我们提出将潮水冰川末端位置参数化为海底融化的简单线性函数，而海底融化又被估计为冰下排泄量和海洋温度的函数。利用1960 - 2018年期间涵盖整个冰盖及周边海洋的末端位置、冰下排泄量和海洋温度数据集，对这种关系进行了测试、校准和验证。我们证明了数十年的潮水冰川末端位置变化与海底融化之间存在具有统计学意义的联系，并表明当考虑一群冰川时，所提出的参数化具有预测能力。考虑了一个21世纪的示例性预测，结果表明在低排放的RCP2.6情景下，格陵兰岛的潮水冰川将不会进一步大幅退缩。相比之下，在高排放的RCP8.5情景下，会导致中位数为4.2千米的退缩，四分之一的潮水冰川退缩超过10千米。我们的研究对潮水冰川对海底融化的敏感性进行了长期且涵盖整个冰盖的评估，并提出了一种将海洋作用力纳入格陵兰冰盖模型的实用且经经验验证的方法。
Abstract. The effect of the North Atlantic Ocean on the Greenland Ice Sheet through submarine melting of Greenland's tidewater glacier calving fronts is thought to be a key driver of widespread glacier retreat, dynamic mass loss and sea level contribution from the ice sheet. Despite its critical importance, problems of process complexity and scale hinder efforts to represent the influence of submarine melting in ice-sheet-scale models. Here we propose parameterizing tidewater glacier terminus position as a simple linear function of submarine melting, with submarine melting in turn estimated as a function of subglacial discharge and ocean temperature. The relationship is tested, calibrated and validated using datasets of terminus position, subglacial discharge and ocean temperature covering the full ice sheet and surrounding ocean from the period 1960–2018. We demonstrate a statistically significant link between multi-decadal tidewater glacier terminus position change and submarine melting and show that the proposed parameterization has predictive power when considering a population of glaciers. An illustrative 21st century projection is considered, suggesting that tidewater glaciers in Greenland will undergo little further retreat in a low-emission RCP2.6 scenario. In contrast, a high-emission RCP8.5 scenario results in a median retreat of 4.2 km, with a quarter of tidewater glaciers experiencing retreat exceeding 10 km. Our study provides a long-term and ice-sheet-wide assessment of the sensitivity of tidewater glaciers to submarine melting and proposes a practical and empirically validated means of incorporating ocean forcing into models of the Greenland ice sheet.