Age model, radiocarbon dates and dinoflagellate cyst measurements from sediment core DA06-139G

A marine sediment core from Vaigat in Disko Bugt, West Greenland, has been analysed in terms of lithology, dinoflagellate cysts and foraminifera in order to evaluate the influence of oceanographic variability on West Greenland glacier stability. The data show that during the past 5200 years the Atlantic foraminiferal abundance in the subsurface waters of the West Greenland Current (WGC) episodically increased, indicating periods of increases in the inflow of subsurface warm Atlantic water at 2000 - 1500 cal. yr BP and 1300 cal. yr BP as well as periods of less pronounced increased bottom-water temperatures around 4700 - 4000 cal. yr BP, 3100 - 2800, 2600, 1000 - 800, 500 - 400, and at 200 cal. yr. The sedimentological and dinoflagellate cyst data indicate that these episodes with enhanced advection of Irminger Sea-derived waters are accompanied by increased iceberg rafting, which we link to increased iceberg calving in relation to destabilization of the Jakobshavn Isbrae. The long-term trend in the data documents the end of a late-Holocene Thermal Maximum between 5200 and 4300 cal. yr BP and a final onset of the Neoglaciation at 3500 cal. yr BP. Increased responses of the iceberg rafting after 3500 cal. yr BP, reflects a westward/seaward advance of the glacier margin in relation to onset of Neoglaciation and a development of the glacier into a floating tongue after 2000 cal. yr BP. A comparison of our record with a record from the eastern North Atlantic indicates that a NAO-like anomaly pattern between subsurface waters in West Greenland and atmospheric temperature in the Eastern North Atlantic may have been operating during most of the late Holocene. However, during the past 1000 years the NAO signal may have weakened as some other mode of climate variability overprints the anti-phase climate signal in this region.

对西格陵兰迪斯科湾瓦伊加特海域的一处海洋沉积岩芯（marine sediment core）开展了岩性、沟鞭藻囊孢（dinoflagellate cysts）及有孔虫（foraminifera）分析，以评估海洋环流变率对西格陵兰冰川稳定性的影响。数据显示，在过去5200年间，西格陵兰洋流（West Greenland Current, WGC）次表层水体中的大西洋型有孔虫丰度呈间歇性升高，指示出两次暖大西洋次表层水流入侵增强的时段：2000~1500 cal. yr BP与1300 cal. yr BP，同时还存在多段底层水温小幅升高的时期，分别为约4700~4000 cal. yr BP、3100~2800 cal. yr BP、2600 cal. yr BP、1000~800 cal. yr BP、500~400 cal. yr BP及200 cal. yr BP。沉积学与沟鞭藻囊孢数据表明，这些伊尔明厄海（Irminger Sea）源水平流增强的时段，均伴随冰山筏运通量升高，我们将其归因于雅各布港冰川（Jakobshavn Isbrae）失稳所引发的冰山崩解加剧。数据的长期趋势记录了全新世晚期热盛期（late-Holocene Thermal Maximum）于5200~4300 cal. yr BP间结束，以及新冰期（Neoglaciation）于3500 cal. yr BP最终启动。3500 cal. yr BP后冰山筏运响应增强，反映出伴随新冰期启动的冰川前缘向西侧/海盆方向推进，以及2000 cal. yr BP后冰川发育为浮冰舌的过程。将本研究记录与北大西洋东部的相关记录对比后发现，西格陵兰次表层水体与北大西洋东部大气温度间的类北大西洋涛动（North Atlantic Oscillation, NAO）异常模态，可能在全新世晚期的大部分时段均存在。然而在过去1000年间，北大西洋涛动信号或已有所减弱，这是由于其他气候变率模态叠加掩盖了该区域的反相位气候信号。