The onset of deglaciation in the Southern Hemisphere mid-latitudes has been attributed to the southward transmission of climate anomalies in response to slow-down of Atlantic meridional overturning circulation (AMOC) during Heinrich Stadial 1 (HS-1; 18–14.6 ka). However, inferences on the response of former ice sheets to sub-millennial palaeoclimate shifts are limited by a shortage of high-resolution terrestrial archives. Here we use a ~1000-year duration, annually-resolved lake sediment record to investigate the deglacial retreat dynamics of the Lago General Carrera–Buenos Aires ice lobe (46.5°S) of the former Patagonian Ice Sheet. We attribute the onset of glacier retreat at 18.0 ± 0.14 cal ka BP to abrupt southward migration of the Southern Westerly Winds that enhanced solar radiation receipt (and ablation) at the ice sheet surface. We infer that accelerated retreat from 17.77 ± 0.13 cal ka BP represents a lagged Southern Hemisphere response to gradual ocean-atmosphere warming associated with the centennial-scale transmission of Northern Hemisphere climate anomalies through the oceanic bipolar seesaw. By 17.38 ± 0.12 cal ka BP, the glacier margin had receded into a deepening proglacial lake, instigating sustained calving losses and more rapid ice recession.
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机译：南半球中纬度地区的冰消开始是由于海因里希第1阶段（HS-1; 18-14.6 ka）期间大西洋经向翻转循环（AMOC）变慢而引起的气候异常向南传播。但是，由于缺乏高分辨率的陆地档案，对前冰盖对亚千年古气候变化响应的推论受到限制。在这里，我们使用〜1000年的持续时间，每年解析的湖泊沉积物记录来调查前巴塔哥尼亚冰原的Lago General Carrera–Buenos Aires冰瓣（46.5°S）的冰川退缩动力学。我们将冰川退缩的开始时间定为18.0±0.14 cal BP，归因于南方西风的突然向南迁移，这增强了冰原表面的太阳辐射接收（和消融）。我们推断，从17.77±0.13cal ka BP加速退缩表示南半球对海洋逐渐变暖的滞后响应，这与北半球气候异常通过海洋双极跷跷板的百年尺度传播有关。到了17.38±0.12 cal ka BP时，冰川边缘已经退缩到一个加深的冰河湖中，从而导致持续的产犊损失和更快的冰期衰退。
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