Collaborative Research: Spatiotemporal observations of the demise of an ice sheet: Paleo perspectives from Baffin Bay, West Greenland.

由于大气和海洋变暖，格陵兰冰盖（GIS）今天正在萎缩。如果冰川完全融化，它所储存的淡水足以使海平面上升7.4米（24英尺）。因此，了解它对变暖的反应是很重要的。该项目将通过研究地理信息系统过去如何应对气候变暖来调查地理信息系统的脆弱性。在上一个冰河期结束时，大约2万年前，西部地理信息系统边缘进一步延伸到巴芬湾，在它现在的位置以西数百公里。到一万年前，冰缘已经大部分退回到现在的海岸线内。目前还不清楚是大气变暖、海洋变暖，还是两者兼而有之导致了这种退缩。作为该项目的一部分，沿着西格陵兰边缘研究的沉积物将确定冰川消融期间GIS退缩的时间、幅度和速度的区域变化。在相同的沉积物中记录的GIS变化和海洋变暖的相对时间，将提高我们对过去和未来大型冰盖行为的理解。该项目更广泛的影响包括支持一名博士后研究员，三名研究生和本科生研究人员。此外，该计划将支持制作一部以拟议的研究考察为基础的宣传影片。该项目还将促进以冰川消融为重点的高级本科课程的发展。为了实现这一目标，一次海洋学考察将使用海底和海底成像技术，并通过收集从上一个冰河时代结束到现在的沉积物岩心，研究西格陵兰岛的四个槽口扇系统（当GIS向近海扩展时，在那里沉积了大量沉积物）。沉积物记录中的生物、磁性、地球化学和物理性质将用于检验主要假设；海洋冰川底部不断上升的海洋温度是冰盖不稳定的主要驱动因素。该项目将确定：1)大西洋暖水沿西格陵兰边缘侵入的时间和范围；2)冰架退缩与海洋变化的阶段性；3)区域地质地貌和冰动力对冰缘退缩的影响。早期职业领导力（由资深导师支持）是这个项目的核心，有三位在美国的助理教授和一位博士后研究员指导船上的操作，并带头进行探险后的科学研究。一半的海上科学派对将是研究生和本科生。从巴芬湾获得的第一批美国沉积物岩心，以及美国设施和数据库中的岩心和数据档案，将为美国国家科学基金会提供多样化的高纬度研究机会，确保该项目的持续遗产。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。

The Greenland Ice Sheet (GIS) is shrinking today in response to the warming atmosphere and ocean. The GIS holds enough freshwater to raise sea level by 7.4 meters (24 feet) if it melted completely. Thus, understanding how it responds to warming is important. This project will investigate GIS vulnerability by studying how the GIS responded to climate warming in the past. At the end of the last ice age, about 20,000 years ago, the western GIS margin extended farther into Baffin Bay, hundreds of kilometers west of its present position. By 10,000 years ago, the ice margin had largely retreated to within the current coastline. It is unclear if a warming atmosphere, a warming ocean, or some combination of the two is responsible for the retreat. Sediments studied along the West Greenland margin as part of this project will establish regional variations in the timing, magnitude, and rate of GIS retreat during the deglaciation. The relative timing of GIS changes and ocean warming, recorded in the same sediments, will improve our understanding of the behavior of large ice sheets in the past and future. The project broader impacts include support for a postdoctoral researcher, three graduate students, and undergraduate researchers. In addition, the project will support production of an outreach film based on the proposed research expedition. The project also will facilitate development of an upper-level undergraduate course focused on the deglaciation. To accomplish this goal, an oceanographic expedition will study four West Greenland trough mouth fan systems (where the GIS deposited large volumes of sediment when it extended offshore) using seafloor and sub-seafloor imaging techniques and by collecting sediment cores spanning the end of the last ice age to present. Biological, magnetic, geochemical, and physical properties from the sediment records will be used to test the primary hypothesis; that increasing ocean temperature at the base of marine terminating glaciers is a major driver of ice-sheet instability. The project will establish: 1) the timing and extent of warm Atlantic water incursion along the west Greenland margin; 2) the phasing of ice margin retreat and ocean change; and 3) the influence of regional geology, geomorphology, and ice dynamics on ice-margin retreat. Early career leadership (supported by senior mentors) is at the heart of this project with three US-based assistant professors and one post-doctoral researcher directing shipboard operations and spearheading the post-expedition science. Half of the sea-going science party will be graduate and undergraduate students. Acquisition of the first US-based sediment cores from Baffin Bay and archival of the cores and data in US facilities and databases will provide diverse high-latitude research opportunities to the NSF community, ensuring the continuing legacy of this project.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.