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

这项拟议的研究将通过研究流入巴芬湾的冰流的早期全新世行为，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新的背景，特别是在末次盛冰期之后发生海平面迅速上升和气候突然变暖的Bölling/Allerod间歇期。在LGM上，格陵兰冰盖(GIS)是通过快速流动的大型冰流进入巴芬湾的三个大冰盖之一。该项目将研究巴芬湾过去的历史、动力学和冰盖海洋相互作用，以及海洋变暖在冰盖消亡中的作用，通过对西格陵兰大陆斜坡现有的(2008和2009年)沉积岩芯进行多代理分析。这项提议的数据将用于模拟来自冰流的淡水通量，并将提供新的信息，说明格陵兰冰盖在过去的海平面上升中扮演了什么角色，因为末次冰盖开始下降多达4.6米当量的海平面。这项研究将利用有孔虫动物群、沉积物矿物学、稳定同位素分析、冰山排碎屑地层学(IRD)和可见的漫反射光谱数据来检验三个假说：1.地理信息系统的西缘在基准期进退，在基准期对通过西格陵兰海流的海洋变暖的存在或不存在做出反应。冰山浮筏物质(IRD)的峰值来自两个不同的过程：近端IRD来自于地理信息系统从陆架边缘撤退，而远端IRD来自巴芬湾北部Laurentide冰盖和Innutian冰盖/格陵兰西北边缘的坍塌。西格陵兰边缘暖水平流导致巴芬湾北部冰山和极锋海冰融化加剧，形成沿西格陵兰边缘的IRD带，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，地理信息系统正在失去质量。它储存的淡水足以使全球海平面上升6.5米，这使得它对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反应将有助于限制对地理信息系统未来演变的预测，这是该项目的重点。

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.