文章标题：Abrupt ice-age shifts in southern westerly winds and Antarctic climate forced from the north

文章作者：Christo Buizert, Michael Sigl, Mirko Severi, Bradley R. Markle, Justin J. Wettstein, Joseph R. McConnell, Joel B. Pedro, Harald Sodemann, Kumiko Goto-Azuma, Kenji Kawamura, Shuji Fujita, Hideaki Motoyama, Motohiro Hirabayashi, Ryu Uemura, Barbara Stenni, Frédéric Parrenin, Feng He, T. J. Fudge & Eric J. Steig

DOI:https://doi.org/10.1038/s41586-018-0727-5

原文链接：https://www.nature.com/articles/s41586-018-072

内容提要：南半球的中纬度西风在全球气候系统中通过影响南大洋上升流、深海的碳交换、阿古拉斯泄漏（将印度洋海水输送到大西洋）以及南极冰盖的大概稳定性在全球气候系统中发挥核心作用。南半球西风的经向变化发生已被假设与热带辐合区证据充分的变化同时响应Dansgaard-Oeschger（DO）事件（即上一个冰河时代突然的北大西洋气候变化事件）。南半球大气环流对DO循环的全面响应及其对南极温度的影响仍不清楚。本文使用通过火山标记的五个同步冰芯来表明南极温度对DO循环的响应，这可以被理解为两种模式的叠加：滞后于北半球气候约200年的空间均匀海洋“双极跷跷板”模式，以及与北半球突发事件同步的空间异质大气模式。大气模式的温度异常类似于与当前南方环形模式变化相关的温度异常，而不是太平洋-南美模式。此外，氘过量记录表明南半球西风的纬向连贯迁移经过了与北半球气候同相的所有海洋盆地。本研究提供了一个简单的概念框架，用于理解突然的北半球气候变化所引起的环南极温度变化。文章提供了南半球西风突然变化的观测证据，这些变化先前已记录了全球海洋环流和大气二氧化碳的各种后果。这些耦合的变化突出了应从全球视角研究DO周期，而不仅仅局限于北大西洋。

论文摘要：The mid-latitude westerly winds of the Southern Hemisphere play a central role in the global climate system via Southern Ocean upwelling1, carbon exchange with the deep ocean2, Agulhas leakage (transport of Indian Ocean waters into the Atlantic)3 and possibly Antarctic ice-sheet stability4. Meridional shifts of the Southern Hemisphere westerly winds have been hypothesized to occur5,6 in parallel with the well-documented shifts of the intertropical convergence zone7 in response to Dansgaard–Oeschger (DO) events— abrupt North Atlantic climate change events of the last ice age. Shifting moisture pathways to West Antarctica8 are consistent with this view but may represent a Pacific teleconnection pattern forced from the tropics9. The full response of the Southern Hemisphere atmospheric circulation to the DO cycle and its impact on Antarctic temperature remain unclear10. Here we use five ice cores synchronized via volcanic markers to show that the Antarctic temperature response to the DO cycle can be understood as the superposition of two modes: a spatially homogeneous oceanic ‘bipolar seesaw’ mode that lags behind Northern Hemisphere climate by about 200 years, and a spatially heterogeneous atmospheric mode that is synchronous with abrupt events in the Northern Hemisphere. Temperature anomalies of the atmospheric mode are similar to those associated with present-day Southern Annular Mode variability, rather than the Pacific–South American pattern. Moreover, deuterium-excess records suggest a zonally coherent migration of the Southern Hemisphere westerly winds over all ocean basins in phase with Northern Hemisphere climate. Our work provides a simple conceptual framework for understanding circum-Antarctic temperature variations forced by abrupt Northern Hemisphere climate change. We provide observational evidence of abrupt shifts in the Southern Hemisphere westerly winds, which have previously documented1,2,3 ramifications for global ocean circulation and atmospheric carbon dioxide. These coupled changes highlight the necessity of a global, rather than a purely North Atlantic, perspective on the DO cycle.

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