EAGER: 1500 Years of Indian Summer Monsoon Variabilty Reconstructed from High-Resolution Tibetan Lake Sediments

EAGER：利用高分辨率西藏湖泊沉积物重建 1500 年印度夏季季风变化

• 批准号: 1023547
• 负责人: Lonnie Thompson
• 金额: $ 5.21万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1023547&HistoricalAwards=false
• 关键词: EAGER; 1500; Years; Indian; Summer

This EAGER grant investigates Indian summer monsoon dynamics during the last 1500 years using lake sediments from the Tibetan Plateau. Specifically, they examine if and how radiative variability impacted the monsoon during the following target events: the Medieval Climate Anomaly (AD 900 to 1300), Little Ice Age (AD 1400 to 1800), and current warm period. This research targets small alpine (~400 m diameter) lakes in the Nyainqentanglha Mountains, which are located at the southeastern edge of the Tibetan Plateau. This region is ideal because monsoon moisture is transported over the Nyainqentanglha Mountains from the Bay of Bengal before entering the Tibetan Plateau. As such, the hydrologic balance of lakes in this region should be highly sensitive to changes in the strength of the monsoon. This project provides valuable information about monsoon variability that can be used to explore how and why this system changes through time. The results of this study will aid efforts to understand how the monsoon, which sustains sensitive ecosystems and over 1 billion people, may respond to future warming trends driven by anthropogenic increases in radiative forcing from greenhouse gases (i.e. CO2).The analytical efforts will be focused on the highest quality sediment, and reconstructs monsoon rainfall using oxygen isotopes (d18O) measured on authigenic or biogenic CaCO3 where possible, or geochemical indicators of erosion and sediment flux calculations if the bedrock geology precludes the preservation of CaCO3 in lake sediments. The results will be synthesized with ice core and tree ring records from the Tibetan Plateau and Himalaya and speleothem records from western China in order to a develop regional perspective monsoon variability and assess how it compares with East Asian monsoon variability during the targeted events. Despite the potential for significant discovery, this research faces many field-based and analytical challenges that make it high risk. Most importantly, age models of sufficient temporal resolution that are needed to make detailed statements about monsoon variability are notoriously difficult in this region. However, the principal investigators have considerable experience working with similar lake systems in comparable environments in the high Andes of tropical South America. From this work, they have successfully developed techniques sediment dating. Intellectual Merit of the Proposed ActivityThis research directly addresses the P2C2 research objectives to understand the response of monsoon systems to climate change and to determine the sensitivity of these systems to abrupt changes in radiative forcing, particularly during past warm intervals. This research provides sub-decadally resolved records of monsoon variability that allow for a detailed analysis of how this monsoon system responded to changes in radiative forcing during the past 1500 years, which will improve forecasts of monsoon variability in response to warming trends.Broader Impacts of the Proposed ActivityThis research will benefit the more than 1 billion people who depend on the monsoon for their livelihood. The information about monsoon dynamics and their relationship with radiative forcing will be beneficial for forecasting and preparing for future variability in this system as a result of rising global temperatures from anthropogenic increases in greenhouse gases. With an improved understanding of monsoon variability, effective water management strategies can be developed to cope with potential future water shortages and/or increased monsoonal variability.

这项渴望的赠款使用藏族高原的湖泊沉积物在过去1500年中调查了印度夏季季风动态。具体而言，他们检查了在以下目标事件中辐射变异的影响以及如何影响季风：中世纪的气候异常（公元900至1300年），很少的冰河时代（1400至1800年）和当前的温暖时期。这项研究针对的是位于藏族高原东南边缘的Nyainqentanglha山脉的小高山（直径约400 m）湖泊。该地区是理想的选择，因为季风水分在进入藏族高原之前从孟加拉湾的Nyainqentanglha山上运输。因此，该地区湖泊的水文平衡应对季风强度的变化高度敏感。该项目提供了有关季风可变性的有价值的信息，可用于探索该系统如何随着时间的流逝而变化。这项研究的结果将有助于努力了解如何维持敏感的生态系统和超过10亿人的季风，可能会响应未来的变暖趋势，这是由于人为增加的辐射强迫驱动的温暖趋势（即CO2）（即CO2）（即，分析努力都将重点放在氧气降压的范围内，并重新构建了孔子量，并重新建立了孔子（grountors）（grounders），并重新建造了孔子（grountors）（grounders）（grounders）（grounders）（Recondig）（均可降雨）。生物caco3在可能的情况下，或地球化学指标侵蚀和沉积物通量计算，如果基岩地质排除了在湖水沉积物中的CACO3的保存。结果将与来自西藏高原和喜马拉雅山的冰核和树环记录合成，并从中国西部进行了史密特姆记录，以发展区域透视季季的差异，并评估其在目标事件期间与东亚季风变异性的比较。尽管有重大发现的潜力，但这项研究仍面临许多基于现场和分析的挑战，使其风险很高。最重要的是，在该区域中，需要对季风变异的详细陈述所需的足够时间分辨率的年龄模型在该地区很难。但是，在热带南美高的安第斯山脉的可比环境中，主要研究人员在与类似的湖泊系统中有丰富的经验。从这项工作中，他们成功地开发了沉积物约会。拟议活动的智力优点这一研究直接解决了P2C2研究目标，以了解季风系统对气候变化的反应，并确定这些系统对突出强迫突然变化的敏感性，尤其是在过去的温暖间隔中。这项研究提供了季风可变性的子宫副本的记录，可以详细分析该季风系统如何应对过去1500年中辐射强迫的变化，这将提高季风变异性的预测，以响应变暖趋势。对拟议活动的影响，这项活动的研究将使超过10亿人对他们依赖于他们的Liveli的人受益于10亿人，这将使他们受益于10亿人。有关季风动态及其与辐射强迫的关系的信息将有益于预测和准备该系统的未来变异性，这是由于温室气体的人为增加的全球温度升高而导致的。随着对季风可变性的了解，可以制定有效的水管理策略来应对潜在的未来水短缺和/或增加季风变异性。