Transient temperature asymmetry between hemispheres in the Palaeogene Atlantic Ocean
Transient temperature asymmetry between hemispheres in the Palaeogene Atlantic Ocean
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DOI：
10.1038/s41561-018-0182-9
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发表时间：
2018-07
影响因子：
18.3
通讯作者：
Zhonghui Liu;Yuxin He;Yiqing Jiang;Huanye Wang;Weiguo Liu;S. Bohaty;P. Wilson
中科院分区：
文献类型：
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作者：
Zhonghui Liu;Yuxin He;Yiqing Jiang;Huanye Wang;Weiguo Liu;S. Bohaty;P. Wilson
在距今约4000万年至2300万年(Ma)的古近纪晚期，地球从温暖的非冰川气候状态过渡到南极的大片动态冰盖。这种转变在很大程度上是从深海氧同位素记录中推断出来的，因为来自独立温度代理的记录很少。在这里，我们展示了2500万年来北大西洋表面温度变化的基于烯酮的记录。我们长期的温度记录表明，在始新世中期达到峰值(~29 °C)，总体缓慢下降到始新世/渐新世过渡(Eot，~34 Ma)，并在渐中新世期间出现高幅度变化(~28~24 °C)。该记录的整体结构与深海记录相似，但也有明显的异常。我们没有发现北大西洋表面冷却的证据，这与南极洲首次变得足够冷，足以维持大冰盖，亚南极水域大幅冷却时的EOT直接重合。因此，EOT期间的表层海洋冷却在两个半球之间具有很强的不对称性。北大西洋与南部高纬度的这种瞬时热脱钩表明，南极冰川引发了海洋环流驱动的热量输送的变化，并影响了远场气候响应。
During the Late Palaeogene between ~40 and 23 million years ago (Ma), Earth transitioned from a warm non-glaciated climate state and developed large dynamic ice sheets on Antarctica. This transition is largely inferred from the deep-sea oxygen isotope record because records from independent temperature proxies are sparse. Here we present a 25-million-year-long alkenone-based record of surface temperature change from the North Atlantic Ocean. Our long temperature record documents peak warmth (~29 °C) during the middle Eocene, a slow overall decline to the Eocene/Oligocene transition (EOT, ~34 Ma) and high-amplitude variability (between ~28 and 24 °C) during the Oligo–Miocene. The overall structure of the record is similar to that of the deep-sea record, but a distinct anomaly is also evident. We find no evidence of surface cooling in the North Atlantic directly coinciding with the EOT when Antarctica first became cold enough to sustain large ice sheets and subantarctic waters cooled substantially. Surface ocean cooling during the EOT was therefore strongly asymmetric between hemispheres. This transient thermal decoupling of the North Atlantic Ocean from the southern high latitudes suggests that Antarctic glaciation triggered changes in ocean circulation-driven heat transport and influenced the far-field climate response.