The centennial-scale response of the Indian monsoon to Holocene climate change: a high-resolution lacustrine isotope record from Peiku Co, Tibet

了解印度夏季风(ISM)过去的变化对于了解整个季风系统及其与气候系统其他部分的关系至关重要。尽管现有的仪器数据和替代证据表明，ISM在亚十年到千年的时间尺度上发生了变化，但我们仍然对季风环流如何控制亚洲大陆上空的长期湿度知之甚少。虽然海洋和石笋替代记录提供了ISM变化的框架，但它们几乎没有揭示大陆季风区内的水文条件，那里的人口是最重要的。尽管如此，这些记录显示了ISM中十年至百年尺度的气候振荡，与北大西洋环流的变化、热带海洋温度的显著扰动以及西太平洋暖池中类似ENSO的行为是同步的，这可能是由于太阳输出的变化所致。但是，目前还不清楚季风是对高纬度遥相关做出反应，还是通过类似ENSO的机制在启动和/或放大热带气候突变方面发挥主要作用。因此，ISM仪器前的古气候记录是理解季风变率起源的关键。我将调查ISM在过去15,000卡的可变性。通过对西藏南部培库错沉积物中介形类的高分辨率同位素和微量元素研究，发现了西藏南部北库的介形类。Peiku Co提供了过去湿度变化信息的最佳档案之一，因为它位于ISM降雨的边缘，因此对季风强度的变化很敏感。这一古气候记录将被用来评估ISM行为的变化，并调查不同强迫因素和更广泛的气候遥相关的相对重要性。

Knowledge of the past variations in the Indian summer monsoon (ISM) is essential for understanding the monsoon system as a whole and its relationship to other parts of the climate system. Despite existing instrumental data and proxy evidence for variations in the ISM at sub-decadal to millennial timescales, we still have a poor understanding of how monsoon circulation has controlled long-term moisture over the Asian landmass. While marine and stalagmite proxy records have provided a framework of variations in the ISM, they reveal little about the hydrological conditions within the continental monsoon domain, where the human population is foremost. Even so, these records show decadal- to century-scale climate oscillations in the ISM that are concurrent with N. Atlantic ocean circulation changes, significant perturbations in tropical ocean temperatures and ENSO-like behaviour in the western Pacific warm pool, potentially forced by variations in solar output. But, it is unclear whether the monsoon responds to high-latitude teleconnections, or plays a primary role in initiating and/or amplifying abrupt climate changes from the tropics via ENSO-like mechanisms. Consequently, pre-instrumental palaeoclimate records of the ISM are key to understanding the origin of monsoon variability. I will investigate ISM variability over the past 15,000 cal. years through a high-resolution isotopic and trace element study of ostracods from sediments in Lake Peiku Co, southern Tibet. Peiku Co offers one of the best archives of information of past moisture changes as it lies at the edge of ISM rains and is therefore sensitive to changes in monsoon intensity. This palaeoclimatic record will be used to evaluate changes in the behaviour of the ISM and to investigate the relative importance of different forcing factors and wider climatic teleconnections.