东亚新仙女木事件的行为特征与环境效应：中高纬湖泊记录

The Younger Dryas (YD) event was defined as an abrupt, dramatic cooling event occurring in the North Atlantic region during the last period of global warming in the geological past. This extremely cooling event was thought to have exerted profound influence on atmospheric circulation and terrestrial ecosystem; however, its behavior and consequence in eastern Asia remain unclear. In this project, Hulun Lake located in the high-middle latitude was selected as a research target. A sediment core extracted from the central part of the lake will be dated using AMS 14C and 230Th techniques to establish the age-depth model, and analyzed for multidisciplinary proxies of grain-size distribution, elements and stable isotopes of authigenic carbonate and sedimentary organic matter and pollen assemblages to generate high-resolution time series of variations in the hydrology and vegetation of the lake region and quantitatively reconstruct the history of changes in the regional temperature and precipitation during the period from the last deglacial to the postglacial. Based on these results, we aim at 1) identifying the YD event recorded by Hulun Lake; 2) determining the timing and duration of the YD event; 3) estimating the variability and magnitude of the proxies during the initiation and termination of the YD event; 4) revealing the response of the hydrology and vegetation in the lake region to the abrupt cooling reversal and the subsequent rapid warming recovery occurring in the northern high latitudes during the global warming period; and 5) exploring the dynamic links between centennial- and decadal-scale changes in the climate and environment of the East Asian monsoon region and ocean–atmosphere interactions in the high and low latitudes. Studies on the YD event registered by Hulun Lake would provide valuable insights into copping with possible extreme climate events under future global warming scenarios.

新仙女木（YD）事件是最近一次全球增温期北大西洋发生的突然、剧烈降温事件。这一极端冷事件对大气环流模式和陆地生态格局产生了深刻影响，然而迄今为止，YD事件在东亚的行为特征及环境效应仍不清楚。本项目选择中高纬湖泊呼伦湖为研究对象，利用14C和230Th定年技术，构建沉积岩芯年代模型；通过沉积物粒度组成、碳酸盐和有机质元素及同位素地球化学、孢粉组合等多学科交叉研究，建立末次冰消期至冰后期湖区水文和植被变化的高分辨率代用序列，定量恢复区域温度和降水量变化历史。在此基础上，辨识呼伦湖记录的YD事件，确定YD事件的发生时限和持续时间，估算其起始期和终结期代用指标的变率和变幅，揭示湖区水文和植被对全球增温过程中北半球高纬急剧转冷和快速回暖的响应方式，探讨东亚季风区百年－十年尺度气候环境变化与高、低纬海－气相互作用的动力关联。呼伦湖YD事件记录研究将为应对未来全球变暖背景下的极端气候事件提供重要启示。

本项目选取东亚中高纬代表性湖泊呼伦湖和达里湖为研究对象，开展了湖泊岩芯的高分辨率、多指标综合研究，建立末次冰消期至冰后期湖区水文和植被变化的高分辨率代用序列，定量恢复了区域温度变化历史，取得了以下重要成果：（1）湖泊自生碳酸盐元素、稳定同位素和团簇同位素分析发现东亚夏季风边缘区Younger Dryas事件期间气候寒冷，Bølling–Allerød暖期至Younger Dryas转折期区域降温幅度达6℃。（2）末次冰消期呼伦湖区高分辨率植被演替过程表明，Younger Dryas事件期间研究区周围山地发育耐寒针叶林和亚高山草甸，湖盆区域生态环境恶化，生长藜科为主的荒漠草原、植被盖度低。（3）Younger Dryas事件源自北大西洋地区，其气候信号通过大气环流自高纬向低纬传输，进而影响东亚夏季风边缘区气候变化。上述成果为全面认识Younger Dryas事件在东亚的行为特征与环境效应积累了关键数据，为应对未来全球变暖背景下的极端气候事件提供了重要启示。