| 摘要: |
| 5.0 ka BP前后全球普遍经历了一次快速的降温事件，对世界范围内很多地区的环境产生了显著影响。本文利用公开发表的有高精度年代控制的、高分辨率石笋和湖沼沉积记录，系统回顾了5 ka BP气候事件在我国不同地区的降雨表现。这次气候事件在我国季风区不同区域都有记录，其中在季风区北方和青藏高原地区记录的最为清楚，体现为显著的干旱。事件起始于5.6 — 5.5 ka BP，在5.0 ka BP左右达到峰值，其后快速回升。5 ka BP气候事件对我国新石器文化的发展产生了重要影响。太阳辐射减少导致的赤道辐合带南移和大西洋经向翻转环流减弱导致的亚洲夏季风减弱可能驱动了此次气候事件。然而，不同地区、特别是南方地区的不同记录在此次事件的表现形式和开始时间有所差异。云南和湖北的泥炭记录显示此次事件为突变事件，发生于4.7 — 4.9 ka BP，不同于其他地质记录的渐变状态。未来还需加强在南方地区，特别是华东地区重建涵盖5 ka BP气候事件的有绝对定年的高分辨率可靠降雨记录。进一步厘清这些记录的差异是由于不同气候代用指标和记录分辨率的不同以及测年误差导致的，还是对气候事件的响应存在着区域差异。 |
| 关键词: 5 ka BP事件 降雨表现 文化影响 中国季风区 |
| DOI：10.7515/JEE201605003 |
| CSTR： |
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| 基金项目:科技部全球变化专项（2013CB955902）；国家自然科学基金项目（41372192，41290254）；中国科学院西部之光项目；陕西省青年科技新星项目（2015KJXX-57） |
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| 5 ka BP event in monsoonal China |
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LI Dong, TAN Liangcheng, AN Zhisheng1,2,3
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1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of
Sciences, Xi’an,710061, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an 710054, China
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| Abstract: |
| Background, aim, and scope A lot of studies suggested the Holocene climate change had played an important role in the evolution of the Neolithic cultures around the world. During the Holocene, there were a series of abrupt climate changes. One of the abrupt events occurred around ~5 ka BP, which significantly changed the environment of many regions over the world. Because this event occurred before the dawn of civilization, it had caused important influences on human society. In this paper, we reviewed the recently published high-resolution, absolutely-dated speleothem and limnological records from different regions of monsoonal China, which had recorded hydrological changes during the 5 ka BP event period. We further discussed its impacts on the Neolithic culture of China, as well as the driving mechanisms. Materials and methods We divided the monsoonal China into Northeast China, North China, Central China, East China, South China, Southwest China and the Tibetan Plateau. We compared the hydrological changes in different regions of monsoonal China, by using recent published high-resolution, absoluted dated records. Results We suggested the monsoonal China, from the north to the south, had experienced dry climate during this event. The dry event was most significantly recorded in North China, Northeast China and Tibetan Plateau. It began at 5.6 — 5.5 ka BP, reaching to the driest at ~5.0 ka BP, and then the precipitation rapidly recovered. Stalagmite record from Central China also showed similar result with North China. There was also cold and dry climate in Southwest China during the period of 5.5 — 4.8 ka BP. In South China, notably dry climate was observed in 5.5 — 5.0 ka BP. It seems there was imprint of 5 ka BP event in East China, although it’s hard to determine the exact timing, because of low resolutions and poor age controls of the published records. The extreme dry climate had played an important role on the evolution of Chinese Neolithic culture. The reduction of solar irradiance might cause the southward migration of ITCZ during the 5 ka BP event. Meanwhile, reduced AMOC during this event might weaken the Asian summer monsoon. The common effects of these two aspects might significantly reduce the monsoon precipitation in China. Discussion Despite the similarities, some discrepancies were observed on the existed records in southern China. Peat records from Xihu in Southwest China and Dajiuhu in Central China show an abrupt and strongly dry event in 4.7— 4.9 ka BP. This is different from other geological records which show gradually decreasing precipitation from 5.6— 5.5 ka BP, with the driest time at 5.0 ka BP. Further studies are needed to clarify whether these discrepancies were caused by dating errors and resolutions of different proxies or different regional responses to the 5 ka BP event. Conclusions The monsoonal China had experienced notably dry climate during the 5 ka BP event. The extreme dry climate had played an important role on the evolution of Chinese Neolithic culture. The reduction of solar irradiance might cause the southward migration of ITCZ, and reduce the AMOC, weakening the Asian summer monsoon. Ultimately, those factors had caused the reduction of monsoon precipitation in China.Recommendations and perspectives It is crucial to build reliable precipitation records covering the 5 ka BP event period with high resolution and absolute dates in southern China. In addition, the impacts of this event on the evolution of Neolithic culture in different regions of monsoonal China need to be further discussed. |
| Key words: 5 ka BP event hydrological changes culture impacts monsoonal China |
