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.

长期以来的范式认为，东南极冰盖（EAIS）保持相对稳定，而只有海洋西南极冰盖容易受到当前气候变化的影响，这一范式已受到挑战。最近发现，南印度洋戴维斯海区登曼冰川周围的东南极冰盖可能容易受到温暖深水的入侵。这与未来气候和海平面预测高度相关，因为登曼冰川潜在的冰量损失及其流域腹地的连接冰量将导致海平面上升高达 1.5 至 2 m。其在过去温暖时期的行为记录将为该漏洞提供限制。评估过去的 EAIS 行为所需的基本数据知识之一是对大陆架和海隆上的冰川海洋沉积物进行绘图和分析，因为它们代表了过去冰盖动态的档案。将于 2024 年初 RV Polarstern 探险 PS141 期间对 Denman 近海大陆架和邻近的出口冰川进行全面的浅层地下水声和高分辨率地震到深盆地震调查，这将为该项目提供关键数据。重建的地震地层学与用于年代地层控制的海洋钻探地点相关联，将包含冰川输送的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。不同地震记录设置的组合将允许以最佳分辨率对不同深度的冰川结构进行成像。此外，深盆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钉扎点，表明裂谷盆地的可能范围后来成为冰流的通道。主要工作将由两名博士生完成，一名在基尔大学，另一名在 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，例如渐新世、中中新世、上新世温暖期以及末次间冰期和末次盛冰期的退缩将用于古冰盖建模模拟的参数化。目标是与南极西部冰盖的观测和模型相比，揭示温暖时期东南极冰盖的脆弱性。该项目的结果将有助于将东南极冰盖未来行为的预测提升到一个新的水平。