Holocene glacier fluctuations in Patagonia are modulated by summer insolation intensity and paced by Southern Annular Mode-like variability
Holocene glacier fluctuations in Patagonia are modulated by summer insolation intensity and paced by Southern Annular Mode-like variability
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DOI：
10.1016/j.quascirev.2019.05.029
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发表时间：
2019-09-15
影响因子：
4
通讯作者：
Schaefer, Joerg M.
中科院分区：
文献类型：
--
作者：
Reynhout, Scott A.;Sagredo, Esteban A.;Schaefer, Joerg M.
高山冰川是气候变化的敏感指标，它们在山区的普遍存在使它们成为全球陆地气候重建的宝贵代表。然而，相对于北方半球的冰川变化，整个全新世南美洲中纬度地区冰川变化的时间和程度仍然受到很大的限制。在这里，我们报告了一个新的Be-10表面膨胀为基础的冰碛年表记录了一系列逐渐减少广泛的冰川冰川进展的冰川塔（阿根廷，南纬49.3度/西经73.0度），最高膨胀率为17，600 +/- 900，13，500 +/- 500，9700 +/- 400，6900 +/- 200、6100 +/- 300、4500 +/- 200和530 +/- 60岁BP。全新世冰川扩张幅度的下降与全新世期间当地夏季日照强度的逐渐上升相平行，而在百年至千年的时间尺度上，在推断出的负南方环形模式（SAM）样状态期间发生了个别进展。这些观测结果表明，（一）夏季日照强度调制反相趋势冰川范围在极地半球在全新世，和（二）百年尺度的“SAM样”的温度和降水异常步调整个巴塔哥尼亚冰川波动。鉴于整个全新世推断的“SAM样”异常的持续性，现代测量的趋势，积极的SAM指数条件可能标志着南半球中纬度地区的气候发生根本性转变，值得考虑预测未来的气候。(C)2019由Elsevier Ltd.出版
Alpine glaciers are sensitive indicators of changes in climate, and their ubiquity in mountainous regions make them valuable proxies for terrestrial climate reconstructions worldwide. However, the timing and extent of glacier change across the South American mid-latitudes through the Holocene are still poorly constrained relative to their counterparts in the Northern Hemisphere. Here we report a new Be-10 surface exposure-based chronology of moraines recording a series of progressively less-extensive glacier advances of Glaciar Torre (Argentina, 49.3 degrees S/73.0 degrees W) since the Last Glacial Maximum, with expansions culminating at 17,600 +/- 900, 13,500 +/- 500, 9700 +/- 400, 6900 +/- 200, 6100 +/- 300, 4500 +/- 200, and 530 +/- 60 yr BP. The declining magnitude of Holocene glacier expansions parallels a gradual rise in local summer insolation intensity during the Holocene, while individual advances occurred during inferred negative Southern Annular Mode (SAM)-like states at centennial to millennial timescales. These observations suggest that (i) summer insolation intensity modulated antiphased trends in glacier extent in the polar hemispheres during the Holocene, and that (ii) centennial-scale 'SAM-like' temperature and precipitation anomalies paced glacier fluctuations throughout Patagonia. Given the persistence of the inferred 'SAM-like' anomalies throughout the Holocene, the modern measured trend towards positive SAM index conditions could mark the onset of a fundamental shift in the climate of the Southern Hemisphere midlatitudes that warrants consideration in projections of future climate. (C) 2019 Published by Elsevier Ltd.