Institute of Geosciences, Kiel University, Ludewig-Meyn-Straße 10, 24118, Kiel, Germany.
GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstraße 1-3, 24148, Kiel, Germany.
Nat Commun. 2019 Feb 4;10(1):586. doi: 10.1038/s41467-019-08408-6.
A significant reduction in the Atlantic Meridional Overturning Circulation and rapid northern Hemisphere cooling 8200 years ago have been linked to the final melting of the Laurentide Ice Sheet. Although many studies associated this cold event with the drainage of Lake Agassiz-Ojibway, recent model simulations have shown that the Hudson Bay Ice Saddle collapse would have had much larger effects on the Atlantic Meridional Overturning Circulation than the lake outburst itself. Based on a combination of Mg/Ca and oxygen isotope ratios of benthic foraminifera, this study presents the first direct evidence of a major Labrador shelfwater freshening at 8.5 ka BP, which we associate with the Hudson Bay Ice Saddle collapse. The freshening is preceded by a subsurface warming of the western Labrador Sea, which we link to the strengthening of the West Greenland Current that could concurrently have accelerated the ice saddle collapse in Hudson Bay.
8200 年前，北大西洋经向翻转环流的显著减少和北半球的快速降温与拉布拉多冰盖的最终融化有关。尽管许多研究将这一寒冷事件与阿加西湖-奥杰布瓦湖的排水联系起来，但最近的模型模拟表明，哈得逊湾冰鞍崩塌对北大西洋经向翻转环流的影响将远远大于湖泊的爆发本身。本研究结合底栖有孔虫的 Mg/Ca 和氧同位素比值，首次提供了 8.5kaBP 拉布拉多陆架水显著淡化的直接证据，我们将其与哈得逊湾冰鞍崩塌联系起来。这种淡化之前是拉布拉多西海的次表层变暖，我们将其与加强的西格林兰流联系起来，这可能同时加速了哈得逊湾的冰鞍崩塌。
