High-resolution, quantitative records of temperature and effective precipitation for the past 25kyr from Lake Qinghai

该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。青藏高原位于地球大陆海拔最高的地方，以其特殊的季风气候而闻名。它是对全球气候变化最敏感的地区之一。该地区的高分辨率、定量和长期的古气候记录对于我们理解区域和全球季风变化的控制机制都是非常有价值的。该区域现有的记录因其持续时间短(例如树轮)、多种影响因素(例如高海拔冰芯、花粉、碳酸盐湖Del-18O)和性质(例如沉积岩相)而受到阻碍。这笔赠款将从国际大陆钻探计划最近采集的青海湖沉积物岩芯中重建过去25,000年来十年至百年尺度的温度和有效降水记录。青海湖沉积物中含有烯烃生物标志物，这为定量研究陆相古气候提供了机会。本研究利用青海湖沉积物中陆生和水生生物标志物的烯酮分布和化合物特有的氢同位素比值，独立地重建温度、盐度和水文平衡。它还分离出湖泊沉积物中的个别木质素酚，用于放射性碳测年，以获得可靠的年代学。该小组假设，过去25,000年来青海湖周围温度和降水变化的幅度、时序性、突发性和周期性对关键气候强迫因素如太阳辐射、太阳活动和温室气体表现出异常敏感，并显示出与北大西洋和热带过程的明显联系。与建模人员的密切合作将使这一全面的古气候数据集与模拟结果进行变革性的合成，以揭示气候变化的潜在驱动机制。国际研究人员小组指定PI负责青海湖的有机地球化学研究。他的工作代表了美国参与青海钻探项目，该项目从一个具有重要战略意义的大陆地区获得了高质量的古气候记录。这项研究促进了多学科方法(有机地球化学、同位素地球化学和古气候学)来研究突出的气候问题，并允许对学生进行跨学科培训。PI通过每年指导几篇本科生高级论文，展示了他为本科生提供尖端研究经验的承诺。该项目通过布朗大学正在进行的NSF GK-12教育计划，促进研究生参与普罗维登斯公立学校的科学教学，并促进普罗维登斯学校教师参与研究。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The Qinghai-Tibetan Plateau occupies the highest elevation on the continental Earth and is renowned for its extraordinary monsoonal climate. It is among the most sensitive regions to global climate change. High resolution, quantitative and long term paleoclimate records from this region are extremely valuable to our understanding of the mechanisms controlling monsoon variability, both regionally and globally. Existing records in the region are hampered by their short duration (e.g., tree rings), multiple influencing factors (e.g., high-altitude ice cores, pollen, lake carbonate del-18O), and qualitative nature (e.g., sediment lithofacies). This grant will reconstruct decadal to centennial scale records of temperature and effective precipitation for the past 25,000 years from the recently recovered sediment cores of Lake Qinghai by the International Continental Drilling Program. Lake Qinghai sediments are rare in that they contain alkenone biomarkers, providing an opportunity for quantitative continental paleoclimate research. This study uses alkenone distributions and compound-specific H isotope ratios of terrestrial and aquatic biomarkers in Lake Qinghai sediments to independently reconstruct temperature, salinity and hydrological balance. It also isolates individual lignin phenols in lake sediments for radiocarbon dating to obtain a robust chronology. The group hypothesize that the amplitude, timing, abruptness and periodicity of temperature and precipitation changes around Lake Qinghai for the past 25,000 yrs display exceptional sensitivity to key climate forcing factors such as insolation, solar activities and greenhouse gases, and show clear linkages to North Atlantic and tropical processes. Close collaboration with modelers will permit transformative synthesis of this comprehensive paleoclimate data set with modeling outcomes to unravel the underlying driving mechanisms of climatic variations.The PI was designated to be in charge of organic geochemical studies for Lake Qinghai by an international group of reserchers. His work represents the United States' participation in the Qinghai drilling project, which obtained high quality paleoclimate records from a strategically important continental region. This study promotes multidisciplinary approaches (organic geochemistry, isotope geochemistry and paleoclimatology) to studying prominent climatic problems, and allows cross-discipline training of students. The PI has demonstrated his commitment to provide cutting edge research experience to undergraduate students by supervising on several under-graduate senior theses per year. This project facilitates participation of graduate students in teaching science in Providence public schools and involvement of Providence school teachers in research through the ongoing NSF GK-12 Education Program at Brown University.