Five million years of Antarctic Circumpolar Current strength variability-猫眼课题宝

DOI：

10.1038/s41586-024-07143-3

发表时间：

2024-03

期刊：

Nature

影响因子：

64.8

通讯作者：

中科院分区：

综合性期刊1区

文献类型：

作者：

Frank Lamy;Gisela Winckler;H. Arz;Jesse R Farmer;J. Gottschalk;L. Lembke‐Jene;Jennifer L Middleton;Michèlle van der Does;Ralf Tiedemann;C.A. Alvarez Zarikian;C. Basak;A. Brombacher;L. Dumm;Oliver Esper;L. Herbert;Shinya Iwasaki;G. Kreps;V. Lawson;Li Lo;E. Malinverno;A. Martínez-García;Elisabeth Michel;S. Moretti;Christopher M Moy;A. Ravelo;C. Riesselman;M. Saavedra‐Pellitero;H. Sadatzki;Inah Seo;Raj K Singh;Rebecca A. Smith;A. Souza;Joseph S. Stoner;María H. Toyos;Igor M Venancio P de Oliveira;Sui Wan;Shuzhuang Wu;Xiangyu Zhao

南极绕极流(ACC)代表着世界上最大的洋流系统，影响着全球海洋环流、气候和南极冰盖的稳定性。今天，ACC的动力学受大气强迫、海洋密度梯度和涡旋活动的控制。尽管在更新世冰期-间冰期旋回中，古海洋重建显示出ACC位置和强度的区域异质性，但ACC的长期演化鲜为人知。在这里，我们记录了南太平洋沉积物岩芯中ACC强度的变化。我们发现，自530万年前(Ma)以来，与全球变冷和全球冰量增加形成对比的是，ACC流量没有线性的长期趋势。( )相反，我们观察到了一百万年时间尺度上的逆转，从上新世全球冷却期间ACC强度增加到随后随着更新世早期进一步冷却而下降。ACC体制的这一转变与南大洋的重新配置相吻合，这改变了ACC对大气和海洋强迫的敏感性。我们发现ACC强度的变化与40万年的偏心周期密切相关，可能起源于南太平洋急流与热带太平洋温度变率有关的岁差变化的调制。冰川时期较弱的ACC流、赤道前移的蛋白石沉积和大气中二氧化碳的减少之间的持久联系首先出现在中更新世过渡期(MPT)。最强的ACC流发生在上更新世-更新世比现在温暖的时段，这提供了未来气候变暖可能增加ACC流的证据。

The Antarctic Circumpolar Current (ACC) represents the world’s largest ocean-current system and affects global ocean circulation, climate and Antarctic ice-sheet stability, –. Today, ACC dynamics are controlled by atmospheric forcing, oceanic density gradients and eddy activity. Whereas palaeoceanographic reconstructions exhibit regional heterogeneity in ACC position and strength over Pleistocene glacial–interglacial cycles, , –, the long-term evolution of the ACC is poorly known. Here we document changes in ACC strength from sediment cores in the Pacific Southern Ocean. We find no linear long-term trend in ACC flow since 5.3 million years ago (Ma), in contrast to global cooling and increasing global ice volume. Instead, we observe a reversal on a million-year timescale, from increasing ACC strength during Pliocene global cooling to a subsequent decrease with further Early Pleistocene cooling. This shift in the ACC regime coincided with a Southern Ocean reconfiguration that altered the sensitivity of the ACC to atmospheric and oceanic forcings, –. We find ACC strength changes to be closely linked to 400,000-year eccentricity cycles, probably originating from modulation of precessional changes in the South Pacific jet stream linked to tropical Pacific temperature variability. A persistent link between weaker ACC flow, equatorward-shifted opal deposition and reduced atmospheric CO2during glacial periods first emerged during the Mid-Pleistocene Transition (MPT). The strongest ACC flow occurred during warmer-than-present intervals of the Plio-Pleistocene, providing evidence of potentially increasing ACC flow with future climate warming.

Five million years of Antarctic Circumpolar Current strength variability

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