East Antarctic Ice Sheet sensitivity under vulnerable conditions studied by combination of focused geophysical techniques

通过结合聚焦地球物理技术研究脆弱条件下东南部冰盖的敏感性

• 批准号: 522416134
• 负责人: Professor Dr. Karsten Gohl
• 金额: --
• 依托单位: Sektion Geophysik
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/522416134?language=en
• 关键词: East; Antarctic; Ice; Sheet; sensitivity

The long-standing paradigm that the East Antarctic Ice Sheet (EAIS) remains relatively stable, while only the marine-based West Antarctic Ice Sheet is vulnerable to the currently progressing climate change, has been challenged. The East Antarctic Ice Sheet around Denman Glacier in the Davis Sea sector of the southern Indian Ocean has recently been identified as potentially vulnerable to incursions of warm deep water. This is highly relevant for future climate and sea-level projections, because the potential ice mass loss of the Denman Glacier and connecting ice masses in its catchment hinterland would contribute to a sea-level rise of up to 1.5 to 2 m. Records of its behavior during past warm periods will provide constraints on this vulnerability. One of the basic data knowledge required for an assessment of past EAIS behavior is a mapping and analysis of the glacial-marine sediments on the continental shelf and rise as they represent archives of past ice sheet dynamics. Comprehensive shallow sub-surface hydroacoustic and high-resolution seismic to deep-basin seismic surveys on the continental shelf offshore Denman and neighboring outlet glaciers, to be acquired during RV Polarstern expedition PS141 in early 2024, will provide the key data of this project. The reconstructed seismic stratigraphy, linked to ocean drilling sites for chronostratigraphic control, will contain pattern of glacially transported sediments from erosion to deposition and, thus, enable a quantification of periods of major ice sheet advances and retreats. The combination of the different seismic recording setups will allow to image glacial structures at different depth at optimal resolution. In addition, the basement structures imaged by deep-basin seismics reveal tectonic lineaments and faults as well as former ice sheet grounding pinning points indicating possible extents of rift basins acting later as pathways for ice streams. The main work will be carried out by two PhD students, one at Kiel University and the other one at AWI, who will work very close together as the different hydroacoustic and seismic data sets complement each other. The reconstruction of glacial dynamics, in particular in past warm times, e.g. the Oligocene, Mid-Miocene, Pliocene warm periods as well as the last interglacials and retreat from the Last Glacial Maximum, will be used to feed the parameterization of paleo-ice sheet modelling simulations. The goal is to reveal the vulnerability of the East Antarctic Ice Sheet in warm periods in comparison to observations and models for the West Antarctic Ice Sheet. The results of this project will help lift the projections of the future behaviour of the East Antarctic Ice Sheet to a new level.

长期以来，人们一直认为南极东部冰盖相对稳定，而只有南极西部海洋冰盖易受当前不断发展的气候变化的影响，这一观点受到了挑战。南印度洋戴维斯海地区丹曼冰川周围的东南极冰盖最近被确定为可能容易受到温暖深水入侵的影响。这与未来的气候和海平面预测高度相关，因为丹曼冰川的潜在冰质量损失及其集水区腹地的连接冰团将导致海平面上升1.5至2米。它在过去暖期的行为记录将对这种脆弱性提供约束。评估过去EAIS行为所需的基本数据知识之一是绘制和分析大陆架上的冰川-海洋沉积物和上升，因为它们代表了过去冰盖动力学的档案。2024年初，北极星号PS141考察队将对登曼近海大陆架及其附近出海口冰川进行全面的浅层次水声和高分辨率地震至深盆地地震调查，为该项目提供关键数据。重建的地震地层学与海洋钻探地点相联系，以控制年代地层学，将包含冰川运输沉积物从侵蚀到沉积的模式，从而能够量化主要冰盖前进和后退的时期。不同地震记录装置的组合将允许在不同深度以最佳分辨率成像冰川结构。此外，深盆地地震成像的基底结构揭示了构造轮廓和断层，以及以前的冰盖接地固定点，表明裂谷盆地后来作为冰流通道的可能程度。主要工作将由两名博士生完成，一名来自基尔大学，另一名来自AWI，他们将密切合作，因为不同的水声和地震数据集相互补充。冰川动力学的重建，特别是在过去的温暖时期，如渐新世、中中新世、上新世的温暖期，以及末次间冰期和末次盛冰期的撤退，将用于古冰盖模拟模拟的参数化。目的是通过与南极西部冰盖的观测和模型进行比较，揭示南极东部冰盖在温暖期的脆弱性。这个项目的结果将有助于把对南极东部冰盖未来行为的预测提升到一个新的水平。