| 摘要: |
| 频繁的千年尺度气候波动是冰期气候的典型特征。末次冰期时，南极和格陵兰在千年尺度呈现出反相位的温度变化：当格陵兰气候处于暖期时南极缓慢降温，当格陵兰处于冷期时南极缓慢升温。这种南北极遥相关现象被称为Bipolar Seesaw。Bipolar Seesaw对气候的影响是全球性的，并且Bipolar Seesaw背后的物理过程与冰期大气CO2浓度变化密切相关。因此，研究Bipolar Seesaw对于理解冰期气候的运行机制，探究大气CO2变化的控制因素，具有重要意义。目前学界对末次冰期Bipolar Seesaw现象的观测研究已较为全面，但Bipolar Seesaw的具体机制仍有众多问题未得到解决。本文综述了近年来国际上关于Bipolar Seesaw的研究进展，并归纳了Bipolar Seesaw未来的几个研究方向。 |
| 关键词: Bipolar Seesaw 冰期千年尺度气候事件 冰期千年尺度大气CO2变化 北大西洋经向翻转环流 |
| DOI：10.7515/JEE211004 |
| CSTR： |
| 分类号: |
| 基金项目:汕头大学科研基金（NTF 19003） |
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| The Bipolar Seesaw of the last glacial period: research progress and future directions |
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ZHENG Peisong, LAI Zhongping
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1. School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
2. Institute of Marine Sciences, Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China
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| Abstract: |
| Background, aim, and scope During the last glacial period, Greenland ice cores recorded 25 millennial-scale climate fluctuations called Dansgaarde-Oeschger events characterized by abrupt transitions (about decades) between relatively warm and cold climate states. During the cold and warm phase of the Dansgaarde-Oeschger events, the Antarctic gradually warms and cools respectively, leaving the “Antarctic isotope maximums” in isotope temperature archives. This anti-phase interhemispheric teleconnection is called the “Bipolar Seesaw” and is accompanied by the large-scale reorganization of global oceanic and atmospheric circulation and the variations in atmospheric carbon dioxide concentration. Currently, many problems of the Bipolar Seesaw are still unsolved. Thus, we here reviewed the researches of the Bipolar Seesaw to constrain the progress, problems, and future research directions. Materials and methods We focused on the researches of the recent two decades and reviewed the observational characteristics of the Bipolar Seesaw, the mechanism of Dansgaarde-Oeschger events and the Antarctic isotope maximums, and the connections between Bipolar Seesaw and millennial-scale atmospheric carbon dioxide concentrations. Results Even though the observational characteristics (e. g. the timing of each event, the lag of bipolar signal transfer) of the Bipolar Seesaw of the last glacial period is already well studied. We outlined the following issues: the mechanism of the Dansgaarde-Oeschger events, the dynamical processes that link the Dansgaarde-Oeschger events and the Antarctic isotope maximums, and the cause for the connections between millennial-scale atmospheric carbon dioxide changes and the Bipolar Seesaw. Discussion We discussed the following issues: the challenges for the current hypotheses of the Dansgaarde-Oeschger events. The contribution of deep-ocean heat release for the Antarctic isotope maximums. And the inconsistency between millennial-scale atmospheric CO2 and the Antarctic temperature behavior. Conclusions Thus, despite the progress of the observations of the Bipolar Seesaw, we listed many aspects of the Bipolar Seesaw for further investigations in order to solve the puzzles behind. Recommendations and perspectives We suggest that further investigation could focus on the following directions: (1) To identify and date the Bipolar Seesaw before the last glacial period. (2) To investigate whether the Dansgaarde-Oeschger events are caused by local freshwater forcing or the oscillation of Atlantic meridional overturning circulation between different modes which could relate to a remote control. (3) To quantify the contribution of the heat release from the deep Southern Ocean to the Antarctic isotope maximums. (4) To investigate the causes for the different Antarctic temperature and atmospheric carbon dioxide behavior at the millennial scale. (5) To test the connections between millennial-scale climate events of the north Pacific and north Atlantic. |
| Key words: Bipolar Seesaw glacial millennial-scale climate event glacial millennial-scale atmospheric CO2
changes Atlantic Meridional Overturning Circulation |
