Collaborative Research: Reconciling conflicting Arctic temperature and fire reconstructions using multi-proxy records from lake sediments north of the Brooks Range, Alaska

合作研究：使用阿拉斯加布鲁克斯山脉以北湖泊沉积物的多代理记录来协调相互矛盾的北极温度和火灾重建

• 批准号: 1504069
• 负责人: Carrie Morrill
• 金额: $ 4.94万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1504069&HistoricalAwards=false
• 关键词: Collaborative; Research; Reconciling; conflicting; Arctic

Temperature reconstructions from the region north of the Brooks Range in Alaska suggest a warmer-than-present Last Glacial Maximum (LGM, 26,500 to 19,000 years ago). Global climate models differ strongly in their simulations of this region, with some suggesting a warmer and others a colder climate. There are virtually no high-resolution temperature records from this region. Robust temperature reconstructions spanning the LGM to present are therefore needed to test the outputs from climate models and to understand regional sensitivity to climate forcing. Associated with the ambiguous temperature history is uncertainty in the regional fire history, as revealed by the unexpected discovery of three major Alaskan tundra fires in last 150 years. These fires contradict the conventional notion that tundra ecosystems rarely, if ever, burn and stimulate a key question: What are the relationships between climate change, fire, and vegetation since the LGM? This project will develop careful reconstructions of temperatures in the region using records obtained from lake cores. The resulting data will then be compared with a variety of climate model outputs.The project will contribute to workforce development by supporting the training of two graduate students. The students and their mentors will leverage activities of the Brown STEM Outreach Office to K-12 classrooms in Providence, RI, where the classroom population is composed largely of under-represented minorities in the STEM fields. The project will entrain a K-12 teacher into the laboratory during the summer and support the teacher's participation in a major regional science meeting. The team will participate in the Kaktovik Oceanography Program, a project in the Inupiat village of Kaktovik, Alaska for K-12 students. The data collected will be made public and serve as a reference for Alaskan tundra science. Finally, the principal investigators will expand an existing project blog into a dedicated website for public outreach concerning the project.The PIs will generate high resolution, multiproxy records of temperature and fire since the LGM from sediment cores of four lakes on the North Slope of Alaska using a suite of organic geochemical and traditional paleoecological proxies. These data will be tested against predictions from fully coupled climate models to evaluate the ability of IPCC-grade models to simulate past temperature changes, and to evaluate potential forcings and feedbacks that regulate regional temperatures. The work is built upon initial studies that indicate that: 1) strong, quantifiable relationships exist between alkenone distributions and early summer temperature in these lakes, and plant leaf wax D/H ratios in Arctic lake sediments record mean summer temperatures; 2) polycyclic aromatic hydrocarbons (PAH) in lake sediments record the regional fire history; and 3) multiproxy analysis can determine temperature changes in early, middle and mean summer temperatures and will permit critical examination on the impacts of seasonal temperature change and its associated feedbacks and forcing. The PAH approach complements charcoal records and allows detection of paleo-fires across a broader regional scale. Study sites are located within the Toolik Field Station Arctic Long Term Ecological Research (LTER) site, which only began to provide continuous, strategically important monitoring data since 1975. The study will provide fundamental, high quality temperature and fire data, placing the past 40 years of instrumental monitoring in the grand context of the Holocene and late Pleistocene.

来自阿拉斯加布鲁克斯范围以北地区的温度重建表明，最高冰期的最高速度比最高含量高（LGM，26,500至19，000年前）。全球气候模型在对该地区的模拟中有很大差异，其中一些暗示着温暖的气候，而另一些则是气候更冷的气候。该区域几乎没有高分辨率的温度记录。因此，需要跨LGM的稳健温度重建来测试气候模型中的输出，并了解区域对气候强迫的敏感性。与含糊的温度历史相关的是区域火灾历史上的不确定性，这是由于过去150年中三大阿拉斯加苔原大火的意外发现所揭示的。这些大火与传统观念相矛盾，即苔原生态系统很少（如果有的话）燃烧和刺激一个关键问题：自LGM以来气候变化，火和植被之间有什么关系？ 该项目将使用从湖泊岩心获得的记录进行仔细的温度重建。然后，将将所得数据与各种气候模型输出进行比较。该项目将通过支持两名研究生的培训来为劳动力发展做出贡献。 学生及其导师将利用棕色STEM外展办公室的活动到RI的Providence的K-12教室，那里的课堂人口主要由STEM领域中代表性不足的少数群体组成。 该项目将在夏季将K-12老师纳入实验室，并支持教师参加大型区域科学会议。 该团队将参加Kaktovik Oceanography计划，这是一个在阿拉斯加的Inupiat村庄的Kaktovik村庄的项目。收集的数据将公开，并作为阿拉斯加苔原科学的参考。 最后，首席研究人员将将现有的项目博客扩展到专门的网站，以供有关该项目的公众推广。PIS将使用一套有机地球学和传统的古生物学特有的套件来产生高分辨率，温度和火灾记录，因为LGM来自阿拉斯加北坡的四个湖泊的沉积物核心。这些数据将通过完全耦合气候模型的预测进行测试，以评估IPCC级模型模拟过去温度变化的能力，并评估可能调节区域温度的潜在强度和反馈。这项工作建立在最初的研究基础上，表明：1）这些湖泊中的烯酮分布和夏季早期温度之间存在牢固的可量化关系，以及北极湖沉积物中植物叶蜡D/H比植物叶D/h比率记录了平均夏季温度； 2）湖沉积物中的多环芳烃（PAH）记录了区域火史； 3）多Xy分析可以确定早期，中和平均夏季温度的温度变化，并将允许对季节性温度变化及其相关反馈和强迫的影响进行严格的检查。 PAH方法补充了木炭记录，并允许在更广泛的区域范围内检测古呼吸。研究地点位于Toolik野战站北极长期生态研究（LTER）地点内，该地点仅开始提供自1975年以来的连续，具有战略意义的监测数据。该研究将提供基本的，高质量的温度和火灾数据，将过去40年的工具监测放置在全新世和晚期的宏伟环境中。