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Recent glacier changes and climate trends on South Georgia

机译：南乔治亚州最近的冰川变化和气候趋势

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Frontal positions for a sample of 36 out of a potential ca. 160 glaciers on the subantarctic island of South Georgia have been mapped, georeferenced in ArcGIS and analysed for 20th century fluctuations from a variety of satellite, aerial and oblique photographs, ground surveys and historical sources. Of these glaciers, 2 are currently advancing, 28 are retreating and 6 are stable or show a complex, ambiguous response. Most glaciers on the north-east coast of the island attained more advanced positions during the late 19th century. Since then, smaller mountain and valley glaciers have progressively receded. Although showing more variable behaviour, larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. Since then, however, most glaciers have receded; some of these retreats have been dramatic and a number of small mountain glaciers will soon disappear. The response of these glaciers can be related to the direct effects of synoptic-scale warming on glacier mass balance, particularly since the 1950s. However, individual long-profile geometry also appears to be a significant influence on the response and sensitivity characteristics of these glaciers. Thus the delayed and varied behaviour of the larger glaciers may in part reflect their longer response time compared to small glaciers, but the combination of both larger and higher-elevation basins, potentially exposed to enhanced orographic-driven accumulation, is a critical factor that cannot be discounted, especially for the few calving glaciers that have recently advanced. Our observations indicate that glacier recession on the windward south-west coast, where precipitation is significantly higher, is less widespread.
机译：潜在位置中约有36个样品的正面位置。已经绘制了南乔治亚南部亚热带岛屿上的160个冰川，并在ArcGIS中进行了地理参考，并分析了20世纪来自各种卫星，航空和斜向照片，地面勘测和历史资料的波动。这些冰川中，有2个正在前进，28个正在后退，6个稳定，或显示出复杂，模糊的响应。在19世纪后期，该岛东北海岸的大多数冰川获得了更高级的地位。从那时起，较小的山脉和山谷冰川逐渐退去。尽管表现出更多的可变性，但更大的潮水和产冰谷和出口冰川在1980年代之前通常仍处于相对较先进的位置。从那以后，大多数冰川消退了。这些退缩中有一些是引人注目的，许多高山冰川将很快消失。这些冰川的响应可能与天气尺度变暖对冰川质量平衡的直接影响有关，特别是自1950年代以来。但是，单个长剖面的几何形状似乎也对这些冰川的响应和敏感性特征产生重大影响。因此，与小冰川相比，大冰川的延迟和变化行为可能部分反映了它们更长的响应时间，但是大盆地和高海拔盆地的组合（可能会暴露于地形驱动的增强堆积）是一个无法克服的关键因素。可以打折，尤其是对于最近发展起来的少数冰河冰川而言。我们的观察结果表明，在西南风顺风地区，降水量明显较高，冰川退缩不那么普遍。

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