Bendle Jacob M, Palmer Adrian P, Thorndycraft Varyl R, Matthews Ian P
Centre for Quaternary Research, Geography Department, Royal Holloway, University of London, Egham, TW20 0EX, Surrey, UK.
Sci Rep. 2019 Mar 11;9(1):4133. doi: 10.1038/s41598-019-39750-w.
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.
南半球中纬度地区冰消期的开始归因于在新仙女木事件1期（HS-1；18-14.6千年前）大西洋经向翻转环流（AMOC）放缓时气候异常向南传播。然而，由于缺乏高分辨率的陆地档案，关于以前冰盖对亚千年古气候变化响应的推断受到限制。在这里，我们使用一个持续约1000年、逐年解析的湖泊沉积物记录，来研究前巴塔哥尼亚冰盖的卡雷拉将军湖-布宜诺斯艾利斯冰叶（南纬46.5°）冰消期的退缩动态。我们将18.0±0.14 cal ka BP时冰川退缩的开始归因于西风急流突然向南迁移，这增强了冰盖表面的太阳辐射接收（以及消融）。我们推断，从17.77±0.13 cal ka BP开始的加速退缩代表了南半球对与北半球气候异常通过海洋双极跷跷板百年尺度传播相关的海洋-大气逐渐变暖的滞后响应。到17.38±0.12 cal ka BP时，冰川边缘已退缩到一个不断加深的冰前湖中，引发了持续的崩解损失和更快的冰川消退。
