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) 目前正在缩小。 GIS 拥有足够的淡水，如果完全融化，可使海平面上升 7.4 米（24 英尺）。因此，了解它如何应对变暖非常重要。该项目将通过研究 GIS 过去如何应对气候变暖来调查 GIS 的脆弱性。在大约 20,000 年前的最后一个冰河时代末期，GIS 西部边缘进一步延伸到巴芬湾，距其当前位置以西数百公里。到一万年前，冰缘已大部分退缩到现在的海岸线范围内。目前尚不清楚气候变暖、海洋变暖或两者的某种结合是导致退却的原因。作为该项目的一部分，对西格陵兰边缘的沉积物进行研究，将确定冰川消退期间 GIS 退缩的时间、幅度和速率的区域差异。在相同沉积物中记录的 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对一名博士后研究员、三名研究生和本科生研究人员的支持。此外，该项目还将支持根据拟议的研究考察制作一部外展电影。该项目还将促进专注于冰消融的高年级本科课程的开发。 为了实现这一目标，海洋学考察将利用海底和海底成像技术，并收集上一个冰河时代末期至今的沉积物岩芯，研究四个西格陵兰岛槽口扇系统（GIS 在向近海延伸时沉积了大量沉积物）。沉积物记录中的生物、磁性、地球化学和物理特性将用于检验主要假设；海洋终止冰川底部海洋温度的升高是冰盖不稳定的主要驱动因素。该项目将确定：1）大西洋暖水沿格陵兰岛西缘入侵的时间和范围； 2）冰缘退缩和海洋变化的阶段性； 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（由高级导师支持）是该项目的核心，由三名驻美国的助理教授和一名博士后研究员指导船上操作并带头进行探险后科学。出海科学队伍的一半将是研究生和本科生。从巴芬湾获取第一个美国沉积岩芯，并将岩芯和数据存档在美国设施和数据库中，将为 NSF 社区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 NSF 的法定使命，并通过使用基金会的智力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.