Collaborative Research:RUI:P2C2: Extending Key Records of Holocene Climate Change and Glacier Fluctuations in the North Pacific Region Using Subfossil Wood from Southeastern Alaska

该项目旨在建立一个数千年的树木年轮年表，从阿拉斯加东南部冰川退缩暴露的亚化石树木到精确的日历日期全新世冰川波动，并将它们与气候季节性的新记录进行比较。几千年的树木年轮年表将用于扩展春季和夏季温度的重建，并通过分析树木年轮中的创伤树脂导管来建立冬季风暴的新记录。冬季风暴重建与阿留申低压系统（AL）的强度有关，其分析有可能改变对北太平洋冷季海洋-大气变率的认识。该项目的具体目标是：1)生成2000年来冬季AL和夏季温度变化的记录，以确定它们如何响应过去的气候强迫。2)利用树木年代学精确测定了过去4000年7个陆端冰川和2个潮汐冰川的进退时间。3)验证阿拉斯加南部沿海全新世冰川最广泛的推进发生在夏季气温较低（融化减少）与AL增强（降雪增加）同时发生的假设。潜在的更广泛的影响包括收集对时间敏感的埋藏木材档案，这些档案将可供科学界进行多学科调查。该项目将产生春夏温度、冬季风暴和冰川推进/退缩的新重建，以更好地了解气候-冰川物质平衡的动态和千年时间尺度的北太平洋年代际变化。该项目将为四名本科生提供培训，作为他们本科论文的一部分，包括实地考察、数据分析和结果展示。研究人员将通过在冰川湾国家公园进行两次演讲来进行公众宣传。此外，还将与霍纳印第安人协会和霍纳原生森林伙伴关系合作，在霍纳阿拉斯加土著村举办一次树木年代学讲习班，目的是让学生学习以收集和分析树木年轮记录为中心的技能技术。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to develop a multi-millennial, tree-ring chronology from subfossil trees exposed by retreating glaciers in Southeast Alaska to precisely calendar-date Holocene glacier fluctuations and compare them with a new record of climate seasonality. The multi-millennial tree-ring chronology will be used to extend reconstructions of spring and summer temperatures and build new records of winter storminess by analyzing traumatic resin ducts in annual tree rings. The winter storminess reconstruction is related to the strength of the Aleutian Low-pressure system (AL) and its analysis has the potential to transform the understanding of cold season ocean-atmospheric variability in the North Pacific. Specific goals of this project are to: 1) Generate 2,000-year-long records of wintertime AL along with summer temperature variability to determine how they responded to past climate forcing. 2) Use dendrochronology to precisely date when seven land-terminating and two tidewater glaciers advanced and retreated during the last 4000. 3) Test the hypothesis that the most extensive Holocene glacier advances in south coastal Alaska occurred when cooler summer air temperatures (reduced melt) coincided with a strengthened AL (increased snowfall). The potential Broader Impacts include the collection of time-sensitive archives of buried wood that would be available to the scientific communities for multi-disciplinary investigations. The project will generate new reconstructions of spring-summer temperature, winter storminess and glacier advance/retreats to better understand the dynamics of climate-glacier mass balance and the North Pacific decadal variability at millennial time scales. This project will provide training for four undergraduate students as part of their undergraduate thesis including field work, data analysis and presentation of the results. The researchers will engage in public outreach by giving two talks at Glacier Bay National Park. In addition, a dendrochronology workshop in partnership with the Hoonah Indian Association and the Hoonah Native Forest Partnership will be organized in the Native Alaskan Village of Hoonah with the goal of engaging students in skill-based technique centered on the collection and analysis of tree-ring records.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.