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.

阿拉斯加布鲁克斯山脉以北地区的温度重建表明，末次冰期最高峰（LGM，26，500至19，000年前）比现在更温暖。全球气候模型对这一地区的模拟差异很大，有些人认为气候更温暖，有些人认为气候更寒冷。该地区几乎没有高分辨率的温度记录。因此，需要从末次盛冰期到现在的强有力的温度重建来测试气候模式的输出，并了解区域对气候强迫的敏感性。与模糊的温度历史相关联的是区域火灾历史的不确定性，正如在过去150年中意外发现的三次重大阿拉斯加苔原火灾所揭示的那样。这些火灾与传统观念相矛盾，即苔原生态系统很少燃烧，并激发一个关键问题：自LGM以来，气候变化，火灾和植被之间的关系是什么？ 该项目将利用从湖芯获得的记录，对该地区的温度进行仔细的重建。该项目将支持培训两名研究生，从而促进劳动力发展。 学生和他们的导师将利用布朗STEM外展办公室的活动，以K-12教室在普罗维登斯，RI，那里的教室人口主要是由代表性不足的少数民族在STEM领域。 该项目将在夏季期间将一名K-12教师带入实验室，并支持教师参加一次重要的区域科学会议。 该团队将参加Kaktovik海洋学计划，这是阿拉斯加Kaktovik Inupiat村为K-12学生举办的一个项目。收集的数据将被公开，并作为阿拉斯加冻土科学的参考。 最后，主要研究人员将扩大现有的项目博客成为一个专门的网站，为公众宣传有关该项目。PI将产生高分辨率，多代理记录的温度和火灾，因为末次盛冰期从沉积物芯的四湖在阿拉斯加北坡使用一套有机地球化学和传统的古生态代理。这些数据将对照完全耦合的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，并评估调节区域温度的潜在强迫和反馈。初步研究表明：（1）这些湖泊中烯酮的分布与初夏温度之间存在强的、可量化的关系，北极湖泊沉积物中植物叶蜡D/H比值记录了夏季平均温度;（2）湖泊沉积物中多环芳烃（PAH）记录了区域火灾历史; 3）多指标分析可以确定夏季早期、中期和平均温度的变化，并可以对季节温度变化的影响及其相关的反馈和强迫进行严格的检验。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火灾。研究地点位于图里克野外站北极长期生态研究（LTER）地点，该地点自1975年以来才开始提供连续的、具有战略重要性的监测数据。该研究将提供基本的高质量温度和火灾数据，将过去40年的仪器监测置于全新世和晚更新世的大背景下。