Evidence of abrupt climate change at 9.3 ka and 8.2 ka in the central Canadian Arctic: Connection to the North Atlantic and Atlantic Meridional Overturning Circulation
Evidence of abrupt climate change at 9.3 ka and 8.2 ka in the central Canadian Arctic: Connection to the North Atlantic and Atlantic Meridional Overturning Circulation
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DOI：
10.1130/abs/2017am-297240
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发表时间：
2019-09
影响因子：
4
通讯作者：
D. Porinchu;G. MacDonald;N. Rolland;K. Kremenetski;K. Moser;H. Seppä;K. Rühland
中科院分区：
文献类型：
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作者：
D. Porinchu;G. MacDonald;N. Rolland;K. Kremenetski;K. Moser;H. Seppä;K. Rühland
摘要：本研究提出了对从加拿大北极中部的一个小型苔原湖中恢复的全新世湖泊沉积物序列进行多代理分析的结果，并将该地区的气候变化与北大西洋联系起来。摇蚊和基于花粉的七月平均气温 (MJAT) 重建记录了 9.3 ka 和 8.2 ka 的显着偏差。相对于摇蚊推断的全新世长期平均值 9.4 °C，摇蚊推断的 7 月气温在 9.3 ka 时降低了 1.4 °C，在 8.2 ka 时降低了 1.7 °C。这些变冷事件也对应于禾本科（禾本科）的增加和桦木花粉的减少，反映了矮桦树覆盖密度的减少。包括需气附生植物和泥炭藓在内的几种硅藻类群的同时突然增加表明，由于潮湿条件，苔藓栖息地有所扩大。全新世早期 TK2 所证明的变冷的表现和时间与北大西洋中发现的突变气候事件一致，并且与北大西洋变冷和大西洋经向翻转环流 (AMOC) 减弱的间隔相一致。这项研究提高了我们对加拿大北极中部 9.3 ka 和 8.2 ka 事件的空间范围和震级的认识，为模拟气候系统对突发气候事件的响应的海洋大气耦合气候模型提供了基准，并为环北大西洋地区海洋-大气遥相关提供了见解。
Abstract This study presents the results of a multi-proxy analysis of a Holocene lacustrine sediment sequence recovered from a small tundra lake in the central Canadian Arctic and links climatic variations there to the North Atlantic. Chironomid and pollen-based reconstructions of mean July air temperature (MJAT) document notable deviations at 9.3 ka and 8.2 ka. Chironomid-inferred July air temperature is depressed by 1.4 °C at 9.3 ka and 1.7 °C at 8.2 ka relative to the long-term chironomid-inferred Holocene average of 9.4 °C. These cooling events also correspond to an increase in Gramineae (Poaceae) and a decrease in Betula pollen, reflecting a decrease in the density of dwarf birch cover. Concurrent, abrupt increases in several diatom taxa, including aerophilic epiphytes, and Sphagnum indicate an expansion of moss habitats as a result of wetter conditions. The expression and timing of the cooling evidenced at TK2 during the early Holocene is consistent with abrupt climate events identified in the North Atlantic and coincides with intervals of North Atlantic cooling and weakened Atlantic Meridional Overturning Circulation (AMOC). This research, which improves our understanding of the spatial extent and magnitude of the 9.3 ka and 8.2 ka events in the central Canadian Arctic, serves as a benchmark for coupled-ocean atmosphere climate models simulating the response of the climate system to abrupt climate events and provides insight in marine-atmosphere teleconnections in the circum-North Atlantic region.