Marine Test of the Sensitivity of Ice Streams Entering Baffin Bay to Ocean Warming from LGM through Deglaciation, with an Emphasis on Central West Greenland Ice Streams

该研究将通过研究末次盛冰期（LGM）和全新世早期流入巴芬湾的冰流的行为来评估海洋变暖对过去冰盖动力学的影响。这项研究将为理解冰盖对过去暖期的响应提供一个新的背景，特别是在LGM之后的Bølling/Allerod间冰期，该间冰期是海平面快速上升和气候突变的主要原因。在LGM，格陵兰冰原（GIS）是三个大冰原之一，最终通过大而快速流动的冰流进入巴芬湾。该项目将通过对西格陵兰大陆斜坡现有（2008年和2009年）沉积物岩心的多代理分析，研究巴芬湾过去的历史、动力学和冰盖与海洋的相互作用，以及海洋变暖在冰盖消亡中的作用。这一提议的数据将用于模拟冰流的淡水通量，并将提供关于格陵兰冰盖在过去海平面上升中所起作用的新信息，因为LGM冰盖开始减少高达4.6米的海平面当量。该研究将利用有孔虫动物群、沉积物矿物学、稳定同位素分析、冰山漂流碎屑地层学（IRD）和可见漫反射光谱数据来验证三个假设：2.由于西格陵兰洋流引起的海洋变暖的存在或不存在，GIS的西缘在间冰期上升，在间冰期后退。2 .冰山漂流物（IRD）的峰值产生于两个不同的过程：近端IRD产生于GIS从陆架边缘撤退，而远端IRD产生于巴芬湾北部的洛伦潮冰盖和因努特冰盖/西北格陵兰边缘的崩塌。沿着西格陵兰边缘的暖水平流导致巴芬湾北部冰山和极地前沿海冰的加速融化，沿着西格陵兰边缘形成了一个IRD带，它保存了海洋变暖条件下冰盖排放事件的记录。由于现代气候变暖，地理信息系统的质量正在下降。它储存的淡水足以使全球海平面上升6.5米，这使得它对气候变暖的敏感性成为一个主要的社会问题。预计地理信息系统对过去变暖的敏感性和响应（这是本项目的重点）将有助于限制对地理信息系统未来演变的预测。

The proposed research will evaluate how ocean warming contributed to past ice sheet dynamics through study of the Last Glacial Maximum (LGM) through early Holocene behavior of ice streams draining into Baffin Bay. This research will provide a new context for understanding ice sheet response to past warm periods, in particular, the Bølling/Allerod interstadial period, which hosted rapid sea level rise and abrupt climate warming after the LGM. At the LGM the Greenland Ice Sheet (GIS) was one of three large ice sheets terminating via large, fast flowing ice streams into Baffin Bay. This project willstudy the past history, dynamics, and ice-sheet ocean interactions in Baffin Bay, and the role of ocean warming in ice sheet demise, via multi-proxy analysis of existing (2008 and 2009) sediment cores from the West Greenland continental slope. Data from this proposal will be used to model freshwater flux from the ice streams, and will provide new information on what role the Greenland Ice Sheet played in past sea-level rise as the LGM ice sheet began to shed as much as 4.6 m of sea level equivalent. The research will test three hypotheses using foraminiferal faunas, sediment mineralogy, stable isotope analyses, stratigraphy of iceberg rafted detritus (IRD), and visible diffuse spectral reflectance data:1. The western margin of the GIS advanced during stadials and retreated during interstadials inresponse to the presence or absence of ocean warming via the West Greenland Current.2. Peaks of ice-berg rafted material (IRD) result from two distinct processes: Proximal IRD isderived from retreat of the GIS off the shelf edge, whereas distal IRD results from collapse of theLaurentide Ice Sheet and Innutian Ice Sheet/NW Greenland margins in northern Baffin Bay.3. Advection of warm water along the West Greenland margin causes enhanced melting ofnorthern Baffin Bay icebergs and sea ice at the polar front, forming an IRD belt along the W.Greenland margin, which preserves a record of ice sheet-discharge events under conditions ofocean warming. The GIS is losing mass in response to modern warming. It stores enough fresh water to raise global sea level by 6.5 m, making its sensitivity to warming a major societal concern. It is anticipated that the sensitivity and response of the GIS to past warming, which are the foci of this project, will help constrain projections of the future evolution of the GIS.