Enhanced Atlantic Meridional Overturning Circulation supports the Last Glacial Inception
Enhanced Atlantic Meridional Overturning Circulation supports the Last Glacial Inception
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增强的大西洋经向翻转环流支持末次冰河起始
DOI：
10.1016/j.quascirev.2011.03.017
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发表时间：
2011
影响因子：
4
通讯作者：
L. Labeyrie
中科院分区：
文献类型：
--
作者：
A. Guihou;S. Pichat;A. Govin;S. Nave;E. Michel;J. Duplessy;P. Télouk;L. Labeyrie
大西洋经向翻转环流（AMOC）是气候系统的一个重要特征。然而，它在气候变化中的作用仍然受到很大限制，特别是在间冰期到冰期气候转变以及相关的全球变冷期间。本文首次根据沉积物（231 Pa/230 Th）记录重建了末次间冰期至随后的冰期（128，000 - 60，000年前）AMOC速率的垂直结构演变。我们显示了一个深AMOC在间冰期温暖海洋同位素阶段（MIS）5.5和一个较浅的冰川期间的冰川MIS 4。这两种模式之间的变化主要发生在冰期初期，即从MIS 5.5到MIS 5.4的转变。我们的数据表明，AMOC增强在这后一个过渡的中间沃茨，2500米以上的倾覆率的大幅度增加的结果。我们认为，这种AMOC模式需要一个加强的湾流北大西洋流系统，最终支持冰盖的增长提供热量和水分的北方高纬度地区。从MIS 5.4到MIS 5.1，AMOC在2000米以下基本上是连续的，并支持冰盖生长的时期。因此，在MIS 4开始时，由于冰盖的延伸和随后的深水形成的重组，触发了冰川AMOC。这项研究强调了中间沃茨作为气候变化过程中的主要参与者的作用。
The Atlantic Meridional Overturning Circulation (AMOC) is a key feature of the climate system. However, its role during climate change is still poorly constrained particularly during an Interglacial to Glacial climate transition and the associated global cooling. We present here the first reconstruction of the evolution of the vertical structure of the rate of the AMOC from the Last Interglaciation to the subsequent glaciation (128,000–60,000 years ago) based on sedimentary (231Pa/230Th) records. We show a deep AMOC during the interglacial warmth Marine Isotope Stage (MIS) 5.5 and a shallower glacial one during glacial MIS 4. The change between these two patterns occurred mostly during the glacial inception, i.e. the transition from MIS 5.5 to MIS 5.4. Our data show that AMOC was enhanced during this latter transition as a consequence of a large increase of the overturning rate of the Intermediate Waters, above 2500 m. We suggest that this AMOC pattern required a reinforced Gulf Stream-North Atlantic Current system that ultimately supported ice-sheet growth by providing heat and moisture to the Northern high latitudes. From MIS 5.4 to MIS 5.1, the AMOC was broadly continuous below 2000 m and supported periods of ice-sheet growth. As a result, a glacial AMOC is triggered at the beginning of MIS 4 due to the extension of ice-sheet and the subsequent reorganization of deep-water formation. This study highlights the role of intermediate waters as a major player during climate change.