Collaborative Research: Climatic Instability in Interior Alaska from the isotopic record of Late Quaternary ground ice

劳森OPP-0714060智慧价值：14C测年冰缘冰楔生长间隔和d18O剖面的初步结果表明，阿拉斯加北极的最后一次冰川气候具有千年尺度的变化特征。这些突如其来的事件的特点是冰楔交替生长，在距今45,000到20,000年的时间间隔内至少有7个融化期。冰楔d18O值随着冰龄的减少而减小，表明在寒冷宜人的气候中逐渐变冷。这些千禧年尺度的冰楔生长/融化事件是北半球冰柱和格陵兰冰明显的9个暖丹斯加德/奥施格事件(冰柱3-11)的北极表现，这一假设得到了评估。为了验证这一假设，冰楔的年代将由14摄氏度的被困有机物质确定，并通过生成d18O和dd时间序列来估计古气候条件，d18O和dd时间序列是冬季气温的替代。如果这一假设是正确的，它将表明格陵兰岛和环北大西洋地区强烈表现的千年尺度的突然和严重的气候变化具有半球的空间指纹，并突出了永久冻土区在千年时间尺度上对全球气候变化的敏感性。这项研究将利用阿拉斯加费尔班克斯附近的寒冷地区研究CRREL永久冻土隧道中第四纪多年冻土的独特地面冰记录，在受控和工程实验室(CRREL)的环境条件下，允许在零度以下的温度下进行精确采样，并对沉积物和冰及其沉积和热史进行详细和严格的分析。广泛的影响：由于缺乏来自北极和永久冻土区的古气候数据，这项工作将记录北极气候对全球气候变化的敏感性。从北极环境中获得的上一次冰川时期的数据很少，可以用来校准全球气候模型，因此限制了科学家预测未来与人为全球变暖有关的气候变化的能力。然而，全球变暖的影响已经在北极地区得到了记录，那里的土著文化、村庄和生活方式将受到气候大变化或快速变化的严重影响。对冰楔和地面冰的详细稳定同位素分析将为北极非冰川地区提供高分辨率的替代数据源，填补我们在理解全球气候中冰-海洋-大气相互作用方面的一个重要数据空白。研究将是一项合作努力，支持达特茅斯学院和内华达大学拉斯维加斯分校的本科生和研究生。

ABSTRACTLawsonOPP-0714060Intellectual Merit : Preliminary results of 14C-dated periglacial ice wedge growth intervals and d18O profiles suggest that the last glacial climate in Arctic Alaska was characterized by millennial-scale variability. These abrupt events are characterized by alternating ice wedge growth and at least seven thaw periods over the interval of 45,000 to 20,000 yrs BP. A decrease in ice wedge d18O values with decreasing ice age indicates gradual cooling during cold stadial climates. The hypothesis that these millennial-scale ice-wedge growth/thaw events are arctic manifestations of northern hemisphere stadials and the nine warm Dansgaard/Oeschger events (stadials 3-11) evident in Greenland Ice is evaluated. To test the hypothesis, ice wedges will be dated by 14C of entrapped organic material, and paleoclimate conditions estimated via the generation of d18O and dD time series, a proxy for winter air temperature. If the hypothesis is correct, it will indicate that the abrupt and severe millennial-scale climate changes strongly manifested in Greenland and the circum-North Atlantic have a hemispheric spatial fingerprint, and highlight the sensitivity of permafrost areas to global climate change on millennial time scales. This research will utilize the unique ground ice record in the Quaternary age permafrost in the Cold Regions Research CRREL Permafrost Tunnel near Fairbanks, Alaska, under controlled and Engineering Lab (CRREL) environmental conditions that allow precise sampling in subfreezing temperatures linked to a detailed and rigorous analysis of the sediments and ice and their sedimentary and thermal history.Broader Impacts: Due to a paucity of paleoclimatic data from Arctic and permafrost regions, this work will document the sensitivity of Arctic climate to global climate changes. Few data from the last glacial period are available from Arctic environments to calibrate global climate models, thus limiting scientists' ability to predict future climate change associated with anthropogenic global warming. Yet the effects of global warming are already documented in Arctic regions where native cultures, villages and ways of life will be severely affected by large or rapid changes in climate. The detailed stable isotopic analyses of ice wedges and ground ice will provide a high resolution proxy data source for unglaciated regions of the Arctic, filling an important data gap in our understanding of ice-ocean-atmosphere interactions in global climate. Research will be a collaborative effort, supporting undergraduate and graduate students at Dartmouth College and University of Nevada-Las Vegas..