过去2000年亚热带西太平洋水文气候变化的年际分辨率记录

Paleoclimate reconstructions of the past two millennia are scientific basis for understanding natural climate variability and assessing historical position and attribution of late 20th-century global warming. And, it is essential for decadal to centennial climate prediction. However, the scarcity of marine proxy data at sufficiently long and high temporal resolution hampers the accurate evaluating of range, rate, cycle and causes of climatic variations on a global-scale over the last two millennia. Based on alkenone and pollen, geochemistry proxy records from a marine core MD05-2907 recovered off northeast of Taiwan, the specific purposes of this project are to reconstruct sub-decadal resolution time series of sea surface temperature (SST) and continental precipitation in the Western Subtropical Pacific for the past two millennia. In particular, it is also aimed to explore the feature of hydrological climate variations on decadal to multidecadal timescales and identify similarities and differences between climate statuses during the Current Warm Periods and historical Warm Periods (the Roman Warm Period and the Medieval Warm Period) documented in marine archive. Then, the underlying internal dynamical mechanisms associated with Asian Monsoon, ITCZ and ENSO, which responsible for the regional climate variations, will be investigated based on comparing the time series to representative high-resolution paleoclimate records all over the world. This study is crucial to enrich high-resolution proxy records from the tropical and subtropical marine realm, and will be helpful to relieve the uncertainties in the current understanding of climate variation over the last two millennia.

过去2000年气候变化历史的重建是认识气候自然变化规律、评估20世纪全球增暖地位和归因的科学基础,对预测未来数十至数百年的气候变化有重要意义；然而高分辨率、长时间海洋记录的缺乏极大地阻碍了对过去2000年全球规模的气候变化幅度、速率、周期及原因的准确评价。本研究以位于台湾东北部海区的MD05-2907岩心为材料，分别利用UK′37和孢粉、地球化学等代用指标，重建过去2000年亚热带西太平洋十年以下分辨率的海表温度和大陆降水序列；揭示区域水文气候十年-年代际变化特征，辨识海洋记录中20世纪暖期与历史暖期（罗马暖期和中世纪暖期）区域气候的异同；对比全球已有的高分辨率典型记录，分析过去2000年与亚洲季风、ITCZ和ENSO等关联的区域气候变化的内部动力机制。以期充实热带、亚热带高分辨海洋记录，减少对过去2000年气候变化认识的不确定性。

高分辨率、长时间海洋记录的缺乏极大地阻碍了对过去2000年全球规模气候变化的准确重建。台湾东北部及邻近海域是北半球高纬大气环流与热带太平洋大气环流的交汇区，其水文气候变化对高-低纬的气候变化都非常敏感。项目以该海区的MD05-2907岩心为材料，利用现代器测资料以及多种古气候代用指标，研究了过去2000年来台湾东北部及邻近海域多种时间尺度的气候变化特征。发现了台湾东北部海洋沉积物δ13Corg 记录的的休斯效应以及19世纪末期以来史无前例地增强的ENSO活动；揭示了现代暖期区域SST 的季节与年际异常及其东亚冬季风、ENSO的联系；重建了过去2000年区域降水的年际-百年尺度变化特征和过程，阐述了过去2000年区域降水与热带太平洋和北半球高纬大气环流的联系。研究成果对于认识历史时期的气候变率、评估20世纪全球变化的原因以及对未来气候变化趋势的准确预测将有重要意义。