From the last deglaciation to the Holocene, the Greenland Ice Core (GISP2) δ 18O records as well as the records of ice-rafted debris on the surface of the North Atlantic have revealed a succession of sudden cooling e...From the last deglaciation to the Holocene, the Greenland Ice Core (GISP2) δ 18O records as well as the records of ice-rafted debris on the surface of the North Atlantic have revealed a succession of sudden cooling events on the centennial to millennial scales. However, the temperature proxy records are rarely studied systematically and directly to ensure that this air temperature cooling pattern simultaneously existed in the East Asian Region, in addition to the repeated pattern occurring in the Greater Atlantic Region. A peat cellulose δ 18O temperature proxy record proximately existing for 14000 years was picked up from the Hani peat in Jilin Province, China. It suggests by comparison that the sudden cooling events, such as the Older Dryas, Inter-Allerφd, Younger Dryas, and nine ice-rafted debris events of the North Atlantic, are almost entirely reiterated in the temperature signals of Hani peat cellulose δ 18O. These cooling events show that the repeatedly occurring temperature cooling pattern not only appeared in the North Atlantic Region in the high latitudes, but also in the Northwest Pacific Region in the middle latitudes. The climate change events marking the start of the Holocene Epoch, the Holocene Megathermal, the "8.2 kyr" event, the "4.2 kyr" event, the Medieval Warm Period, and the Little Ice Age are further discussed. The sensitivity response of Hani peat cellulose δ 18O to the land surface temperature and the reason for the age accuracy of peat cellulose 14C are also discussed based on the characteristics of the peat bog environment.展开更多
全新世气候突变事件是全球变化研究的热点,但对其行为特征与动力学机制的认识仍存在不足。本文选取贵州董哥洞2支高分辨率、高精度定年的石笋(DX1和DA)δ^(18)O记录,分析小冰期和"8.2 ka BP"事件期间亚洲夏季风强度变化的结...全新世气候突变事件是全球变化研究的热点,但对其行为特征与动力学机制的认识仍存在不足。本文选取贵州董哥洞2支高分辨率、高精度定年的石笋(DX1和DA)δ^(18)O记录,分析小冰期和"8.2 ka BP"事件期间亚洲夏季风强度变化的结构特征与其驱动机制。通过两个突变事件的精细对比,发现两者在持续时间、振荡幅度和转型特征等方面均有很好的相似性,尤其是均显示出"两谷一峰"的结构性特征。北高纬地区淡水注入导致大西洋经向翻转流(AMOC)的减弱可能是触发"8.2 ka BP"事件的重要驱动力,这暗示具有相似结构特征的小冰期弱季风事件可能也响应于AMOC机制。将小冰期时期石笋δ^(18)O记录与指示AMOC变化的北大西洋放射性碳数据进行对比,发现两者具有相似的变化过程,这表明在早晚全新世不同气候背景条件下,AMOC仍能够通过影响南北半球温度梯度的变化而影响低纬热带辐合带位置的移动,进而调控千-百年尺度低纬季风区水文循环的时空变化。展开更多
基金Supported by National Natural Science Foundation of China (Grant Nos. 40573004, 40673069, 40231007)
文摘From the last deglaciation to the Holocene, the Greenland Ice Core (GISP2) δ 18O records as well as the records of ice-rafted debris on the surface of the North Atlantic have revealed a succession of sudden cooling events on the centennial to millennial scales. However, the temperature proxy records are rarely studied systematically and directly to ensure that this air temperature cooling pattern simultaneously existed in the East Asian Region, in addition to the repeated pattern occurring in the Greater Atlantic Region. A peat cellulose δ 18O temperature proxy record proximately existing for 14000 years was picked up from the Hani peat in Jilin Province, China. It suggests by comparison that the sudden cooling events, such as the Older Dryas, Inter-Allerφd, Younger Dryas, and nine ice-rafted debris events of the North Atlantic, are almost entirely reiterated in the temperature signals of Hani peat cellulose δ 18O. These cooling events show that the repeatedly occurring temperature cooling pattern not only appeared in the North Atlantic Region in the high latitudes, but also in the Northwest Pacific Region in the middle latitudes. The climate change events marking the start of the Holocene Epoch, the Holocene Megathermal, the "8.2 kyr" event, the "4.2 kyr" event, the Medieval Warm Period, and the Little Ice Age are further discussed. The sensitivity response of Hani peat cellulose δ 18O to the land surface temperature and the reason for the age accuracy of peat cellulose 14C are also discussed based on the characteristics of the peat bog environment.
文摘全新世气候突变事件是全球变化研究的热点,但对其行为特征与动力学机制的认识仍存在不足。本文选取贵州董哥洞2支高分辨率、高精度定年的石笋(DX1和DA)δ^(18)O记录,分析小冰期和"8.2 ka BP"事件期间亚洲夏季风强度变化的结构特征与其驱动机制。通过两个突变事件的精细对比,发现两者在持续时间、振荡幅度和转型特征等方面均有很好的相似性,尤其是均显示出"两谷一峰"的结构性特征。北高纬地区淡水注入导致大西洋经向翻转流(AMOC)的减弱可能是触发"8.2 ka BP"事件的重要驱动力,这暗示具有相似结构特征的小冰期弱季风事件可能也响应于AMOC机制。将小冰期时期石笋δ^(18)O记录与指示AMOC变化的北大西洋放射性碳数据进行对比,发现两者具有相似的变化过程,这表明在早晚全新世不同气候背景条件下,AMOC仍能够通过影响南北半球温度梯度的变化而影响低纬热带辐合带位置的移动,进而调控千-百年尺度低纬季风区水文循环的时空变化。
