Doctoral Dissertation Research: A Comparison of the Holocene Extents of the Greenland Ice Sheet in Western and Eastern Greenland

北极目前比地球上其他地方变暖得更快，格陵兰冰盖对这种变暖的反应是许多当前研究的焦点。到2100年，格陵兰冰盖对全球海平面上升的贡献的模型预测从4.5厘米到17厘米不等。该项目将通过记录过去温暖时期，特别是最近间冰期(全新世，距今11650年)的冰盖边缘，帮助理解格陵兰冰盖对未来气候变暖的可能反应。这项研究将集中在格陵兰岛西部的Kangerlussuaq地区(北纬67.0度，西经50.7度)，在那里，全新世冰缘范围的记录以突出的、保存完好的冰河脊带为标志。通过使用宇宙源核素铍-10进行表面暴露测年，初步确定了冰雹的年龄，证明了准确测定康格鲁斯苏阿克附近冰雹的年龄的能力。来自一组冰川的结果表明，格陵兰冰盖在大约6500年前到公元1850年历史进步达到顶峰之间，比现在要小。该项目将结合详细的地貌测绘和冰雹地表暴露测年，编制康格鲁斯苏亚克附近格陵兰冰盖边缘波动的年表。冰盖边缘的波动将与全新世的日照、海洋环流和地表气温记录进行比较，以检查可能影响格陵兰东部全新世冰盖范围波动的可能气候机制。这些波动的时间和空间连续性将为格陵兰冰盖如何应对未来的气候变化提供洞察。这项研究将在格陵兰的康格尔卢斯苏阿克地区产生第一个直接确定冰缘年代的年代学。来自格陵兰冰盖的冰芯记录了冰盖上的温度、沙尘和其他大气条件，但没有提供有关冰盖敏感边缘如何变化的信息。结合来自格陵兰东部的数据，这一来自格陵兰西部的新记录将提供一个地理上广泛的、空间上的冰缘波动比较，这将有助于测试导致冰盖变化的气候机制的假说。作为博士论文研究改进奖，该奖项还将为有前途的学生建立强大的独立研究生涯提供支持。

The Arctic is currently warming more rapidly than other locations on the planet and the response of the Greenland Ice Sheet to this warming is a focus of many current studies. Model projections of the contribution of the Greenland Ice Sheet to global sea level rise range from 4.5 to 17 cm by 2100. This project will help to understand the possible response of the Greenland Ice Sheet to future warming by developing records of the ice sheet margin during past warm times particularly during recent interglacial period (the Holocene Epoch, 11,650 years B.P. to present). The research will focus on the Kangerlussuaq region (67.0N, 50.7W) in western Greenland where a record of ice margin extents during the Holocene is marked by belts of prominent, well-preserved moraine ridges. Preliminary ages of moraines, determined by surface-exposure dating using the cosmogenic nuclide Beryllium-10, demonstrate the ability to date precisely the moraines near Kangerlussuaq. Results from one set of moraines, the ?Orkendalen moraines?, located just outboard of (and in some places adjacent to) the historical moraines, indicate that the Greenland Ice Sheet was smaller than at present between ~6,500 years ago and the historical advance culminating in A.D. 1850. The project will develop a chronology of the Greenland Ice Sheet margin fluctuations near Kangerlussuaq using a combination of detailed geomorphic mapping and surface-exposure dating of moraines. Ice sheet margin fluctuations will be compared with Holocene records of insolation, ocean circulation and surface air temperatures to examine the possible climate mechanisms that may have influenced the fluctuations of Holocene ice extent in eastern Greenland. The timing and spatial continuity of these fluctuations will provide insight into how the Greenland Ice Sheet will respond to future climate changes. This research will produce the first directly dated ice margin chronology in the Kangerlussuaq region in Greenland. Ice cores from the Greenland Ice Sheet register temperature, dustiness and other atmospheric conditions over the ice sheet, but do not provide information on how the sensitive margins of the ice sheet have changed. Combined with data from eastern Greenland, this new record from western Greenland will provide a geographically broad, spatial comparison of ice margin fluctuations that will be useful for testing hypotheses of climate mechanisms that cause ice sheet variability.As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.