Rapid thinning of lake-calving Yakutat Glacier and the collapse of the Yakutat Icefield, southeast Alaska, USA
Rapid thinning of lake-calving Yakutat Glacier and the collapse of the Yakutat Icefield, southeast Alaska, USA
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美国阿拉斯加东南部的雅库塔特冰川快速变薄和雅库塔特冰原的崩塌
DOI：
10.3189/2013j0g12j081
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发表时间：
2013
影响因子：
3.4
通讯作者：
C. Larsen
中科院分区：
文献类型：
--
作者：
B. Trüssel;R. Motyka;M. Truffer;C. Larsen
美国阿拉斯加州雅库塔特湖裂冰川（337 km ~ 2）及其母冰原（810 km ~ 2）正在经历强烈的变薄，在目前的气候条件下最终将消失。数字高程模型的比较显示，雅库塔特冰川以4.76 ± 0.06 m w.e.a−1（2000-07）和3.66 ± 0.03 m w.e.a−1（2007-10）的面积平均速率变薄。与此同时，邻近的雅库塔特冰原陆地终止冰川以较低但仍然相当大的速度变薄（在同一时期分别为3.79和2.94 m w.e.a-1），表明湖泊崩解动力学有助于推动质量损失增加。雅库塔特冰川终止于哈勒昆湖，十多年来一直维持着一个103公里长的漂浮舌头，它在2010年开始分解成大型扁平冰山。这种漂浮的舌头在温带的冰川上很少见。我们推测，这种差异可能是由于缺乏水下融化的情况下，湖裂冰川。浮舌冰损失的总体质量平衡和海平面上升的贡献进行了评估。雅库塔特冰原在小冰期后的崩塌部分是由邻近冰川的定时崩解退缩、雅库塔特冰川的湖泊崩解退缩、气候变暖以及通过表面降低的正反馈机制驱动的。
Abstract Both lake-calving Yakutat Glacier (337 km2), Alaska, USA, and its parent icefield (810 km2) are experiencing strong thinning, and under current climate conditions will eventually disappear. Comparison of digital elevation models shows that Yakutat Glacier thinned at area-averaged rates of 4.76 ± 0.06 m w.e.a−1 (2000–07) and 3.66 ± 0.03 m w.e.a−1 (2007–10). Simultaneously, adjacent Yakutat Icefield land-terminating glaciers thinned at lower but still substantial rates (3.79 and 2.94 m w.e.a−1 respectively for the same time periods), indicating lake-calving dynamics helps drive increased mass loss. Yakutat Glacier terminates into Harlequin Lake and for over a decade sustained a ∼3 km long floating tongue, which started to disintegrate into large tabular icebergs in 2010. Such floating tongues are rarely seen on temperate tidewater glaciers. We hypothesize that this difference is likely due to the lack of submarine melting in the case of lake-calving glaciers. Floating-tongue ice losses were evaluated in terms of overall mass balance and contribution to sea-level rise. The post-Little Ice Age collapse of Yakutat Icefield was driven in part by tidewater calving retreats of adjacent glaciers, the lake-calving retreat of Yakutat Glacier, a warming climate and by the positive feedback mechanisms through surface lowering.