侯梅1,3,
郑洪波4,
葛全胜1
1. 中国科学院地理科学与资源研究所, 中国科学院陆地表层格局与模拟重点实验室, 北京 100101
2. 中国科学院青藏高原地球科学卓越创新中心, 北京 100101
3. 中国科学院大学, 北京 100049
4. 云南大学地球系统科学研究中心, 云南 昆明 650091
基金项目: 国家自然科学基金面上项目（批准号：41672176和41172154）和国家重点基础研究发展计划项目（批准号：2015CB953800）共同资助
详细信息
作者简介: 吴文祥, 男, 51岁, 研究员, 气候变化影响与适应研究, E-mail:wuwx@igsnrr.ac.cn
中图分类号: P534.63+2;P532 收稿日期:2018-11-05
修回日期:2019-01-15
刊出日期:2019-03-30
Environmental expressions of 7.5~7.0 cal. ka B.P. climate event in China and its dynamic mechanisms
Wu Wenxiang1,2,,Hou Mei1,3,
Zheng Hongbo4,
Ge Quansheng1
1. Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101
2. CAS Center for Excellence in Tibetan Plateau Earth Science, Beijing 100101
3. University of Chinese Academy of Sciences, Beijing 100049
4. Research Center for Earth System Science, Yunnan University, Kunming 650091, Yunnan
MSC: P534.63+2;P532
--> Received Date: 05 November 2018
Revised Date: 15 January 2019
Publish Date: 30 March 2019
摘要
摘要:识别全新世气候事件、阐明其区域环境表现特征、揭示其驱动机制是理解气候系统变化行为、预测未来气候变化以及弄清考古学文化转变动因的关键，具有重要的科学价值和现实意义。随着高分辨率全新世古气候重建的进展，7.5~7.0 cal.ka B. P.事件逐渐被揭示，但到目前为止仍缺乏针对该气候事件各种类型证据的系统收集、对比以及对其产生动力机制的分析。本文基于中国26条古气候记录，系统总结了这一气候事件在中国地区的环境表现。结果显示，7.5~7.0 cal.ka B. P.气候事件在中国多个地区都有明显的反映，整体表现为温度下降、夏季风强度减弱。与全球其他地区的古气候记录对比显示7.5~7.0 cal.ka B. P.气候事件可能具有全球性的特征。与驱动因子系列对比发现该气候事件发生在北半球夏季太阳辐射逐渐减少、太阳活动减弱、火山活动频发、劳伦泰德冰盖快速融化期间，表明这4种因素在7.5~7.0 cal.ka B. P.气候事件发生过程中发挥了作用。未来需要更多测年准确、分辨率高的古气候记录定量-半定量刻画该气候事件的变化幅度、起止时间以及区域差异，同时结合古气候模拟揭示7.5~7.0 cal.ka B. P.气候事件产生的动力机制。
关键词: 中国/
全新世/
7.5~7.0 cal.ka B. P.气候事件/
夏季风强度/
驱动机制
Abstract:Identification of Holocene climate events and their regional environmental expressions, exploration of their temporal and spatial characteristics, and investigation of the dynamic mechanisms behind them are important for understanding climate system, forecasting future climate changes and interpreting the cultural transformations. With the advances in Holocene paleoclimate reconstructions, one climate event at 7.5~7.0 cal. ka B.P. is increasingly recognized but lack a systematic review. In this paper, we review paleoclimate evidences from 26 sites covering most of China to detect 7.5~7.0 cal.ka B.P. climate event, including 24 well-dated and highly-resolved paleoclimate time series together with 2 lower-quality paleoclimate records.
The widely distributed proxy records clearly show decreased temperature during 7.5~7.0 cal.ka B.P. over most areas of China. However precipitation indicators show pronounced spatial differences in different parts of China, with drier conditions in the Tibetan Plateau and in Northern China, and probably wetter conditions in the middle Yangtze River region. This spatial pattern of precipitation variation could be attributed to the behavior of a reduced summer monsoon intensity associated with decreased temperature during 7.5~7.0 cal.ka B.P. climate event. There are some discrepancies in terms of onset timing, duration and magnitude of this climate event from site to site. It is difficult to clarify whether these discrepancies are caused by the dating errors, the sensitivity of climate proxies, or their different regional responses. Comparison with various proxy records from other parts of the world indicate that the 7.5~7.0 cal.ka B.P. is of global scale. Such climatic anomaly is characterized by cooling and wetter conditions in north-central Europe and North America and South America monsoon domain, widespread drying around the tropical Africa, the Indian monsoon domain and the Mediterranean.
The close correspondence in timing between solar irradiance minima, strong volcanic eruptions, meltwater flux into the North Atlantic, orbitally-induced decrease in solar insolation, and 7.5~7.0 cal.ka B.P. climate event suggests possible causal links. Of all the potential climate forcing mechanisms, solar activity and meltwater flux seem to play more important role in the southward migration of the Intertropical Convergence Zone and the slowing of North Atlantic Thermohaline Overrunning, triggering weakening of the Asian summer monsoon. In the future, more quantitative reconstructions and precisely-dated and highly-resolved climate records are needed to describe the magnitude, duration, and regional differences of 7.5~7.0 cal.ka B.P. climate event, and paleoclimate simulations should be incorporated to elucidate the relative contributions of these four forcing factors
Key words:China/
Holocene/
7.5~7.0 cal.ka B.P. climate event/
summer monsoon/
causal mechanisms
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