Marine Evidence for GIS Stability and History of Jakobshavn Isbrae, West Greenland, from the LGM to Holocene

智力优势：主要研究人员将重建格陵兰岛西部Jakobshavns Isbrae （JAKIB）的晚第四纪-全新世行为，JAKIB是现代格陵兰冰盖（GIS）最大的冰流之一。从末次盛冰期（LGM）到现在的时期将被研究，因为它涉及到冰盖物质平衡的最近大规模变化，这是大陆架沉积物中保存最好的时期，也是格陵兰冰芯中古气候最高分辨率代用记录可用的时期。考虑到冰流的规模及其相关流域的大小，该调查将提供关于晚第四纪-全新世的行为和GIS主要区域的稳定性的信息。这项研究将有助于评估冰川消融与内部和外部环境控制之间的联系，例如流入的大西洋水的影响，并将有助于建立地理信息系统未来可能行为的模型。主要研究人员将参加2007年夏末英国科考船詹姆斯·克拉克·罗斯爵士前往西格陵兰岛的一次研究巡航，并与英国同事合作进行巡航后的跨学科实验室工作和建模项目。在地球物理数据的基础上，从陆架边缘和沿陆架槽延伸到Disko Bugt内现代冰缘近端和远端地点的样带，将获得年代准确、高分辨率的沉积物记录。假设1：冰川覆盖范围和西格陵兰洋流与地理信息系统之间的相互作用记录在有孔虫动物群、矿物学变化以及沉积物的Sm和Nd同位素组成中。假设2：西格陵兰洋流从LGM到全新世在强度、流动路径和水团组成上发生了变化。这些变化已经并将继续在冰盖的行为中发挥关键作用。更广泛的影响：本研究的基本原理是确定最近（最近~ 100年）观测到的地理信息系统质量平衡的变化是否反映了冰盖动态的自然变率，还是与人为引起的气候变暖有关。解决这个问题的关键是了解自LGM以来的冰盖行为，包括格陵兰岛附近过去与今天一样温暖甚至更温暖的时期，比如全新世中期的最佳时期。这项研究将对格陵兰冰原在LGM西部边缘的时间和范围以及JAKIB冰流在冰川消融期间的行为做出新的发现，这些新信息将为古海洋学家、气候和海平面建模者提供信息。这个项目是一项国际努力。它将资助一名美国博士生和两名本科生。它将涉及科罗拉多大学和英国之间的国际学生交流。获得的数据将被存入NOAA古气候数据库。

Intellectual Merit: The Principal Investigators will reconstruct the Late Quaternary-Holocene behavior of Jakobshavns Isbrae (JAKIB) in western Greenland, one of the largest ice streams draining the modern Greenland Ice Sheet (GIS). The period from the Last Glacial Maximum (LGM) to the present will be studied because it involves the most recent large scale change in the mass-balance of the ice sheet, it is the period that will be best preserved in continental shelf sediments, and it is the period for which the highest resolution proxy records of paleo-climate from the Greenland ice cores are available. Given the scale of this ice stream and the size of its associated drainage basin, the investigation will provide information on the Late-Quaternary-Holocene behavior and stability of a major area of the GIS. This research will allow assessment of the links between deglaciation and internal and external environmental controls, such as the influence of inflowing Atlantic Water, and will facilitate modeling of the likely future behavior of the GIS. The Principal Investigators will participate in a research cruise of the British Research Vessel, Sir James Clark Ross, to West Greenland in the late summer of 2007 and collaborate with British colleagues on the post-cruise, interdisciplinary program of laboratory work and modeling. Well-dated, high-resolution sediment records from a transect of sites extending from the shelf edge and along the shelf trough, to sites within Disko Bugt both proximal and distal to the modern ice margin will be acquired on the basis of geophysical data. The hypotheses to test using these cores are:Hypothesis 1: Glacier ice extent and interactions between the West Greenland Currentand the GIS are recorded in the foraminiferal faunas, mineralogical variations, and Sm and Nd isotopic compositions of the sediments.Hypothesis 2: The West Greenland Current has changed in strength, flowpath andwatermass composition from the LGM through the Holocene. These variations haveplayed and continue to play a key role in ice-sheet behavior.Broader Impacts: The underlying rationale for this research is to determine if recent(last ~ 100 yr) observed changes to the mass balance of the GIS reflect natural variabilityin ice sheet dynamics, or if they relate to anthropogenically-induced climate warming.Key to resolving this is an understanding of ice sheet behavior since the LGM andincluding periods in the past near Greenland that were as warm or, even warmer thantoday, such as the middle Holocene optimum. This research will make new discoveriesconcerning the timing and extent of the Greenland Ice Sheet at the LGM on its westernmargin, and the behavior of the JAKIB ice stream during deglaciation, new informationthat will inform paleoceanographers and climate and sea-level modelers. This project is an international effort. It will support a U.S. PhD student, and two undergraduate students. It will involve international student exchanges between the University of Colorado and the United Kingdom. The data acquired will be lodged in the NOAA Paleoclimate Database.