Western Mediterranean hydro-climatic consequences of Holocene ice-rafted debris (Bond) events
Western Mediterranean hydro-climatic consequences of Holocene ice-rafted debris (Bond) events
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DOI：
10.5194/cp-15-463-2019
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发表时间：
2019-03
影响因子：
4.3
通讯作者：
C. Zielhofer;Anne Köhler;S. Mischke;A. Benkaddour;Abdeslam Mikdad;W. Fletcher
中科院分区：
文献类型：
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作者：
C. Zielhofer;Anne Köhler;S. Mischke;A. Benkaddour;Abdeslam Mikdad;W. Fletcher
抽象的。杰拉德·C·邦德建立了一系列全新世的北大西洋冰筏碎片事件，这些事件是基于从北大西洋亚极地海洋岩芯中发现的石英和赤铁矿染色的颗粒。这些所谓的“邦德事件”记录了北大西洋9个大范围、长达数百年的冷却阶段，这些阶段可能与温盐环流减少有关。尽管全新世北大西洋冰筏碎片记录非常突出，但对这项研究有一些关键的科学评论：全新世邦德曲线尚未在北大西洋的其他海洋档案中复制，而且只有极少的古气候研究表明，所有个别邦德事件都在各自的记录中。因此，亚极地北大西洋和遥远地区之间持续的水文气候遥相关的证据尚不清楚。在这方面，西地中海区域为重建与北大西洋次极地的遥相关提供了关键的水文气候场所。特别是，西地中海冬季降水的变化可能是热带北大西洋外层大气-海洋耦合过程的结果。基于摩洛哥中部阿特拉斯Sidi Ali湖全新世δ18O的改进记录，我们将西地中海降水异常与北大西洋邦德事件联系起来，以确定西地中海冬季降水与北大西洋亚极地冷却阶段之间可能的遥相关。我们的数据显示，在全新世早期，西地中海冬季最小雨量和邦德事件有明显的相似之处，而在全新世晚期，情况则相反。有证据表明，整个大西洋大气-海洋系统发生了持久的水文气候变化，并对中全新世期间的外部强迫做出了反应。关于西地中海4.2ka(Bond Event 3)附近的潜在气候异常，百年尺度的冬季最大雨量通常与过去5000年来“湿与凉”和“干与暖”交替的总体模式是同步的。
Abstract. Gerard C. Bond established a Holocene series of North Atlantic ice-rafted debris events based on quartz and haematite-stained grains recovered from subpolar North Atlantic marine cores. These so-called “Bond events” document nine large-scale and multi-centennial North Atlantic cooling phases that might be linked to a reduced thermohaline circulation. Regardless of the high prominence of the Holocene North Atlantic ice-rafted debris record, there are critical scientific comments on the study: the Holocene Bond curve has not yet been replicated in other marine archives of the North Atlantic and there exist only very few palaeoclimatic studies that indicate all individual Bond events in their own record. Therefore, evidence of consistent hydro-climatic teleconnections between the subpolar North Atlantic and distant regions is not clear. In this context, the Western Mediterranean region presents key hydro-climatic sites for the reconstruction of a teleconnection with the subpolar North Atlantic. In particular, variability in Western Mediterranean winter precipitation might be the result of atmosphere–ocean coupled processes in the outer-tropical North Atlantic realm. Based on an improved Holocene δ18O record from Lake Sidi Ali (Middle Atlas, Morocco), we correlate Western Mediterranean precipitation anomalies with North Atlantic Bond events to identify a probable teleconnection between Western Mediterranean winter rains and subpolar North Atlantic cooling phases. Our data show a noticeable similarity between Western Mediterranean winter rain minima and Bond events during the Early Holocene and an opposite pattern during the Late Holocene. There is evidence of an enduring hydro-climatic change in the overall Atlantic atmosphere–ocean system and the response to external forcing during the Middle Holocene. Regarding a potential climatic anomaly around 4.2 ka (Bond event 3) in the Western Mediterranean, a centennial-scale winter rain maximum is generally in-phase with the overall pattern of alternating “wet and cool” and “dry and warm” intervals during the last 5000 years.