青藏高原巴松措年纹层记录的200年以来气候环境演化

全球气候变暖自上世纪末期出现停滞，而青藏高原尤其是其东南部地区仍存在明显的升温趋势，该区域过去200年高分辨率气候环境演化及其对全球变化的响应有待深入研究。本项目选择青藏高原东南部的巴松措，利用年纹层计年、210Pb/137Cs及AMS 14C测年结果，建立可靠的沉积物年代序列；在对湖泊现代沉积物季节性监测分析的基础上，结合沉积物岩芯年纹层的结构及组成特征，揭示年纹层的形成机制及纹层厚度的气候环境指示意义；利用年纹层厚度及年分辨率的气候代用指标（粒度、有机碳含量、矿物及元素组成等）探讨年纹层的形成过程及沉积环境特征；并通过孢粉记录重建区域的植被演化过程；在此基础上，建立巴松措地区过去200年以来的年分辨率气候环境演化序列。通过对比分析，探讨青藏高原东南部地区气候环境对全球气候变化的响应模式，为充分理解青藏高原东南部地区年分辨率的古气候演化模式、夏季风演化过程以及相应的驱动机制提供科学依据。

A Global Warming Hiatus, i.e. a period of relatively little change in globally averaged surface temperatures, began in the end of last century (ca. 1998 A.D.). However, an obviously warming trend was observed from the Tibetan Plateau especially the southeastern Tibetan Plateau (SETP) during this period. The responding process of regional climate and environment changes to global climate change during the past 200 years needs further investigation. We choose Lake Basom Tso in SETP as our study area. Varve counting, 210Pb/137Cs dating as well as AMS 14C dating will be used to establish the age-depth model for the sediment core recovered from the lake center. The mechanism of the varve formation and the palaeoclimatic indication of varve thickness will be investigated through seasonal monitoring on the modern sedimentation process. Subsequently, the varve thickness and sedimentary proxies, i.e. grain size, Total Organic Carbon content (TOC), mineral and element compositions, will be used to trace the environmental changes during the varve formation. The fossil pollen record will be interpreted in terms of changes in the regional vegetation. Finally, the climate-vegetation variations in Lake Basom Tso region during the past 200 years will be reconstructed at an annual resolution, which will be compared with regional and global records, as well as simulation results, in order to investigate the responding mechanisms of the climate changes over SETP to global warming. This project could provide further insights to the annual scale variations of past climate and vegetation changes over the SETP, the variation of Asian Summer Monsoon during the recent past, as well as the underlying drivers.