Establishing lichenometric ages for nineteenth‐ and twentieth‐century glacier fluctuations on south georgia (south atlantic)
Establishing lichenometric ages for nineteenth‐ and twentieth‐century glacier fluctuations on south georgia (south atlantic)
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建立南乔治亚州（南大西洋）十九世纪和二十世纪冰川波动的地衣年龄
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Thorne
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作者：
S. Roberts;D. Hodgson;Samantha Shelley;Jessica Royles;H. Griffiths;T. Deen;M. Thorne
抽象的。南格鲁吉亚的小型山地冰斗中的冰川对南大西洋气候的变化反应迅速而敏感。其冰川消退的时间和速度可以用来检查的影响，十九和二十世纪的气候变化对冰川动力学和陆地生态系统的南格鲁吉亚。作为在南格鲁吉亚的奥拉夫王子港（POH）进行的一项勘察研究的一部分，我们测量了地衣的大小。em Th.亚属在两个小冰斗周围的无冰冰碛脊上。我们的目标有两个：首先，提供地衣殖民化的年龄估计，因此，冰碛脊的冰川消退，第二，研究应用地衣测量更广泛地提供南格鲁吉亚冰川消退年龄的限制的潜力。在南格鲁吉亚没有地衣年龄大小（测年）曲线的情况下，我们使用最近对亚南极群岛和南极半岛西部的研究中的长期Ruppicarpon地衣生长率来计算可能的年龄估计。这些数据表明，冰从最外面的两个冰碛中撤退发生在“小冰河时代”结束（后C。1870年）和世纪初的南格鲁吉亚。最内层冰碛的地衣殖民化可能与20世纪后半叶的冰川退缩有关，这与c. 1950.在POH中确定的可能的十九和世纪冰川退缩的模式需要通过建立南格鲁吉亚的物种和特定地点的地衣年龄大小（测年）曲线，并通过将地衣测量法应用于南格鲁吉亚的其他山脉冰斗来进一步测试。
Abstract. Glaciers in small mountain cirques on South Georgia respond rapidly and sensitively to changes in South Atlantic climate. The timing and rate of their deglaciation can be used to examine the impact that nineteenth‐ and twentieth‐century climate change has had on the glacial dynamics and terrestrial ecosystems of South Georgia. As part of a reconnaissance study in Prince Olav Harbour (POH), South Georgia, we measured the size of lichens (Rhizocarpon Ram. em Th. Fr. subgenus. Rhizocarpon group) on ice‐free moraine ridges around two small mountain cirques. Our aims were twofold: first, to provide age estimates for lichen colonization, and hence, deglaciation of the moraine ridges, and second, to examine the potential of applying lichenometry more widely to provide deglacial age constraints on South Georgia. In the absence of lichen age‐size (dating) curves for South Georgia, we use long‐term Rhizocarpon lichen growth‐rates from recent studies on sub‐Antarctic Islands and the western Antarctic Peninsula to calculate likely age estimates. These data suggest ice retreat from the two outermost moraines occurred between the end of the ‘Little Ice Age’ (post c. 1870) and the early twentieth century on South Georgia. Lichen colonization of the innermost moraines is probably related to glacier retreat during the second half of the twentieth century, which has been linked to a well‐defined warming trend since c. 1950. Patterns of possible nineteenth‐ and twentieth‐century glacial retreat identified in POH need to be tested further by establishing species‐ and site‐specific lichen age‐size (dating) curves for South Georgia, and by applying lichenometry to other mountain cirques across South Georgia.