Collaborative Research: A Continuous 60,000 Year Sediment Record Documenting Abrupt to Precession-Scale Climate Change and Ecosystem Response at Fish Lake UT, Upper CO River Basin

在过去的几十年里，全球干旱严重程度和野火强度的增加引起了人们对气候变化在人类一生中如何影响人类、生态系统和水资源的认识的关注。美国西部干旱地区人口的快速增长，加上普遍的干旱、森林温度压力、昆虫爆发和前所未有的野火，对人类和经济产生了负面影响，并将注意力集中在提高我们对这些有价值和独特的生态系统的气候压力增加的控制和长期后果的理解。这个跨学科项目将把21世纪北美西部的干旱和极端火灾季节置于一个更长期的背景下，作为确定气候变化和生态系统响应可能的未来情景的一种手段。本研究将使用从科罗拉多河上游流域的一个源湖收集的长而连续的沉积物湖泊记录来调查过去的降水和温度变化，以及这些变化对植被、野火、森林干扰和冰川的影响，并特别关注过去在与人类相关的时间尺度上发生的快速气候变化时期。这是可能的，因为在过去的6万年里，鱼湖沉积物的高堆积率约为18.5米，产生了60英尺高的泥浆，其中包含花粉、木炭、虫子部位、鱼骨和其他化石，除了沉积物本身和它保存的分子化石外，研究人员还可以研究这些化石。建议的工作包括x射线荧光（XRF）和CT岩心扫描，以识别突变沉积物边界并以尽可能高的分辨率表征沉积物剖面。利用叶蜡δ - 2h（长链和短链）和手旋体δ - 18o等水同位素示踪剂研究降水和蒸发的变化。分子化石，如支链甘油二烷基甘油四醚（brGDGTs）将被用作估计过去夏季温度的方法。景观和水生生态系统的响应将通过花粉、木炭、多环芳烃（PAHs）、生物源二氧化硅、有机碳、氮和稳定同位素进行研究。鱼类湖高原的流域侵蚀和冰川活动将通过扫描XRF，粒度，有机质，生物硅和体积密度进行新的细节研究。2014年发现的一个11米长的岩心，通过陆地大型化石和木炭的210Pb和AMS 14C的辐射测定方法、温度年代学和古地磁测量，成功地确定了测年时间。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。

Over the last several decades increased drought severity and wildfire intensity around the globe has drawn attention to a need for an improved understanding of how climate change over a human lifetime impacts people, ecosystems, and water resources. Rapid population growth in the arid western US combined with pervasive drought, temperature stress on forests, insect outbreaks, and unprecedented wildfires has negatively impacted people and the economy and focused attention on the need to improve our understanding of the controls and long-term consequences of increased climate stress on these valuable and unique ecosystems. This interdisciplinary project will place the 21st century drought and extreme fire seasons in western North America into a longer-term context as a means to identify likely future scenarios for climate change and ecosystem response. This research will use a long and continuous sediment lake record collected from a headwater lake in the upper Colorado River Basin to investigate past variations in precipitation and temperature, and the impacts these changes had on vegetation, wildfire, forest disturbance, and glaciation with special attention paid to periods of rapid climate change that has happened in the past over timescales relevant to people. This is possible because of the high accumulation rate of Fish Lake sediments of about 18.5 meters over the last 60,000 years producing a 60 foot high section of mud containing things like pollen, charcoal, bug parts, fish bones, and other fossils for researchers to study in addition to the sediment itself and the molecular fossils it preserves. The proposed work includes X-ray Fluorescence (XRF) and CT core scanning to identify abrupt sediment boundaries and characterize the sediment profiles at the highest possible resolution. Changes in precipitation and evaporation will be investigated by water isotope tracers, including leaf wax delta-2H (long and short chain) and chironomid delta-18O. Molecular fossils such as branched glycerol dialkyl glycerol tetraethers (brGDGTs) will be used as way to estimate past summer temperatures through time. Landscape and aquatic ecosystem responses will be studies by using pollen, charcoal, polycyclic aromatic hydrocarbons (PAHs), biogenic silica, and organic carbon, nitrogen and stable isotopes. Watershed erosion and glacial activity of the Fish Lake Plateau will be investigated in new detail with scanning XRF, grainsize, organic matter, biogenic silica, and bulk density. Successful dating of an 11-m long core recovered in 2014 has been demonstrated by radiometric methods, including 210Pb and AMS 14C of terrestrial macrofossils and charcoal, by tephrochronology, and by paleomagnetic measurements.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.