Environmental and Climate History Off NorthEast Greenland (ECHONEG)

拟议的项目旨在以前所未有的时间分辨率(几十年至百年)重建第四纪晚期(最后13万年)格陵兰东北部的环境变异性。研究海域位于北冰洋西部，北纬81-82°，西经7-9°，是北冰洋向北欧输出淡水和海冰的主要输出区。西部的这种寒冷和低盐度的外流，以及与东部相对温暖、含盐的大西洋水向北平流形成强烈对比的海洋条件，为形成致密的近地表水团提供了海洋条件，这些水团最终下沉到深处，并最终驱动大西洋经向翻转环流(AMOC)。数值模拟实验和海洋地质研究表明，这一系统对淡水扰动高度敏感，在上一次冰期-间冰期循环中已数次减弱(或停止)。该项目的目标是重建北极淡水输出和海冰覆盖率的可变性，它们与大西洋水平流的可变性的关系，AMOC减弱和极端淡水输出事件的潜在联系(例如，在较年轻的仙女木间期)，以及第四纪晚期格陵兰北部冰川的可变性。为此，提出了一种多重代理方法，利用沉积学、微古生物学、同位素和有机地球化学方法，对2015年夏季从东北格陵兰大陆边缘和陆架获得的两个长而大体积的沉积物岩芯进行了调查。前期工作(包括14C测年)揭示了可以达到十年到百年尺度的分辨率，这远远好于该地区早期的研究。预期结果是关于一个与全球气候迅速密切互动的地区的冰覆盖、淡水出口、盐度、温度、层化、初级生产力和陆上冰川变化的详细数据。它们将大大提高我们对北极陆地-海洋-冰-气候相互作用及其后果的理解，例如，在过去150年里北极急剧变暖的趋势中。

The proposed project aims at a reconstruction of environmental variability off and in Northeast Greenland during the Late Quaternary (last 130,000 years) at a yet unprecedented temporal resolution (decades to centennials). The research area at ca. 81-82°N, 7-9°W in the western Fram Strait is the main export region for freshwater and sea ice from the Arctic Ocean to the Nordic Seas. This cold and low-saline outflow in the West and the strong contrast to the relatively warm, saline northward advection of Atlantic Water in the East provide oceanic conditions that allow for the formation of dense near-surface water masses which eventually sink to depth and eventually drive the Atlantic meridional overturning circulation (AMOC). Numerical modelling experiments and marine geological research have shown that this system is highly sensitive to freshwater perturbations and has been weakened (or halted) several times in the last glacial-interglacial cycle. It is currently under threat due to enhanced freshwater outflow from the Arctic, including meltwater from the Greenland ice sheet.The goals of the project are to reconstruct the variability of Arctic freshwater export and sea ice coverage, their relation to the variability of Atlantic Water advection, the potential linkages of AMOC weakenings and extreme freshwater export events (e.g., during the Younger Dryas interval), and the variability of glaciation on North Greenland during the Late Quaternary. To do this, a multiproxy approach is proposed to investigate two long, large volume sediment cores obtained in summer 2015 from the NE Greenland continental margin and the shelf, applying sedimentological, micropaleontological, isotopical and organic-geochemical methods. Preliminary work (incl. 14C datings) has revealed that a decadal- to centennial-scale resolution can be reached, which is by far better than in earlier studies in the area. Expected results are detailed data on the variability of ice coverage, freshwater export, salinity, temperature, stratification, primary productivity and onshore glaciation in an area that is interacting quickly and closely with global climate. They will significantly improve our understanding of Arctic land-ocean-ice-climate interactions and their consequences, e.g., in the dramatic Arctic warming trend in the last 150 years.