1] Department of Environmental Studies, Macalester College, 1600 Grand Avenue, Saint Paul, Minnesota 55105, USA [2] Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, Massachusetts 02543, USA.
1] Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, New York 10964, USA [2] Department of Earth and Environmental Sciences, Columbia University, New York, New York 10027, USA.
Nat Commun. 2014 Dec 18;5:5817. doi: 10.1038/ncomms6817.
The strength of Atlantic meridional overturning circulation is believed to affect the climate over glacial-interglacial and millennial timescales. The marine sedimentary (231)Pa/(230)Th ratio is a promising paleocirculation proxy, but local particle effects may bias individual reconstructions. Here we present new Atlantic sedimentary (231)Pa/(230)Th data from the Holocene, the last glacial maximum and Heinrich Stadial 1, a period of abrupt cooling ca. 17,500 years ago. We combine our results with published data from these intervals to create a spatially distributed sedimentary (231)Pa/(230)Th database. The data reveal a net (231)Pa deficit during each period, consistent with persistent (231)Pa export. In highly resolved cores, Heinrich (231)Pa/(230)Th ratios exceed glacial ratios at nearly all depths, indicating a significant reduction, although not cessation, of overturning during Heinrich Stadial 1. These results support the inference that weakened overturning was a driver of Heinrich cooling, while suggesting that abrupt climate oscillations do not necessarily require a complete shutdown of overturning.
大西洋经向翻转环流的强度被认为会影响冰期-间冰期和千年时间尺度的气候。海洋沉积物的 (231)Pa/(230)Th 比值是一种很有前途的古环流示踪剂，但局部颗粒效应可能会使个别重建产生偏差。在这里，我们呈现了来自全新世、末次冰盛期和 Heinrich 冰期 1 的新的大西洋沉积物 (231)Pa/(230)Th 数据，Heinrich 冰期 1 是约 17500 年前突然冷却的时期。我们将我们的结果与这些时期发表的数据相结合，创建了一个空间分布的沉积物 (231)Pa/(230)Th 数据库。这些数据显示，每个时期都存在净 (231)Pa 亏损，这与持续的 (231)Pa 输出一致。在高分辨率的岩芯中， Heinrich 时期的 (231)Pa/(230)Th 比值几乎在所有深度都超过了冰期的比值，表明尽管大西洋经向翻转环流没有完全停止，但 Heinrich 时期的翻转环流显著减弱。这些结果支持了这样的推断，即翻转环流减弱是 Heinrich 冷却的驱动因素，同时表明突然的气候振荡不一定需要翻转环流的完全停止。
