Integrative Study of Marine Ice Sheet Stability and Subglacial Life Habitats in W Antarctica - Lake and Ice Stream Subglacial Access Research Drilling (LISSARD)

Abstract: The LISSARD project (Lake and Ice Stream Subglacial Access Research Drilling) is one of three research components of the WISSARD integrative initiative (Whillans Ice Stream Subglacial Access Research Drilling) that is being funded by the Antarctic Integrated System Science Program of NSF's Office of Polar Programs, Antarctic Division. The overarching scientific objective of WISSARD is to assess the role of water beneath a West Antarctic ice stream in interlinked glaciological, geological, microbiological, geochemical, and oceanographic systems. The LISSARD component of WISSARD focuses on the role of active subglacial lakes in determining how fast the West Antarctic ice sheet loses mass to the global ocean and influences global sea level changes. The importance of Antarctic subglacial lakes has only been recently recognized, and the lakes have been identified as high priority targets for scientific investigations because of their unknown contributions to ice sheet stability under future global warming scenarios. LISSARD has several primary science goals: A) To provide an observational basis for improving treatments of subglacial hydrological and mechanical processes in models of ice sheet mass balance and stability; B) To reconstruct the past history of ice stream stability by analyzing archives of past basal water and ice flow variability contained in subglacial sediments, porewater, lake water, and basal accreted ice; C) To provide background understanding of subglacial lake environments to benefit RAGES and GBASE (the other two components of the WISSARD project); and D) To synthesize data and concepts developed as part of this project to determine whether subglacial lakes play an important role in (de)stabilizing Antarctic ice sheets. We propose an unprecedented synthesis of approaches to studying ice sheet processes, including: (1) satellite remote sensing, (2) surface geophysics, (3) borehole observations and measurements and, (4) basal and subglacial sampling.
The latest report of the Intergovernmental Panel on Climate Change recognized that the greatest uncertainties in assessing future global sea-level change stem from a poor understanding of ice sheet dynamics and ice sheet vulnerability to oceanic and atmospheric warming. Disintegration of the WAIS (West Antarctic Ice Sheet) alone would contribute 3-5 m to global sea-level rise, making WAIS a focus of scientific concern due to its potential susceptibility to internal or ocean-driven instability. The overall WISSARD project will test the overarching hypothesis that active water drainage connects various subglacial environments and exerts major control on ice sheet flow, geochemistry, metabolic and phylogenetic diversity, and biogeochemical transformations.
Societal Relevance: Global warming, melting of ice sheets and consequential sea-level rise are of high societal relevance. Science Resource Development: After a 9-year hiatus WISSARD will provide the US-science community with a renewed capability to access and study sub-ice sheet environments. Developing this technological infrastructure will benefit the broader science community and assets will be accessible for future use through the NSF-OPP drilling contractor. Furthermore, these projects will pioneer an approach implementing recommendations from the National Research Council committee on Principles of Environmental Stewardship for the Exploration and Study of Subglacial Environments (2007). Education and Outreach (E/O): These activities are grouped into four categories: i) increasing student participation in polar research by fully integrating them in our research programs; ii) introducing new investigators to the polar sciences by incorporating promising young investigators in our programs, iii) promotion of K-12 teaching and learning programs by incorporating various teachers and NSTA programs, and iv) reaching a larger public audience through such venues as popular science magazines, museum based activities and videography and documentary films. In summary, WISSARD will promote scientific exploration of Antarctica by conveying to the public the excitement of accessing and studying what may be some of the last unexplored aquatic environments on Earth, and which represent a potential analogue for extraterrestrial life habitats on Europa and Mars.

摘要：LISSARD项目（Lake and Ice Stream Subglacial Access Research Drilling，湖泊与冰流冰下通道研究钻探计划）是WISSARD综合计划（Whillans Ice Stream Subglacial Access Research Drilling，威兰斯冰流冰下通道研究钻探计划）的三个研究组成部分之一，该计划由美国国家科学基金会（National Science Foundation, NSF）极地项目办公室南极分部的南极综合系统科学计划资助。WISSARD的核心科学目标是评估西南极冰流下方水体在相互关联的冰川学、地质学、微生物学、地球化学与海洋学系统中所扮演的角色。WISSARD下属的LISSARD项目聚焦于活跃冰下湖泊在决定西南极冰盖向全球海洋流失冰量的速率，以及影响全球海平面变化方面所发挥的作用。南极冰下湖泊的重要性直到近年才被学界认知，这些湖泊被列为科学研究的高优先级目标，因为在未来全球变暖情景下，它们对冰盖稳定性的影响尚不明确。LISSARD拥有四项核心科学目标：A) 为改进冰盖质量平衡与稳定性模型中的冰下水文与机械过程表征提供观测依据；B) 通过分析冰下沉积物、孔隙水、湖水以及底部增生冰中记录的基底水体与冰流变化历史档案，重建冰流稳定性的演化历史；C) 为理解冰下湖泊环境提供基础背景知识，以惠及WISSARD计划的另外两个组成部分RAGES与GBASE；D) 整合本项目产生的数据与研究理念，判断冰下湖泊在南极冰盖的（去）稳定化过程中是否发挥了关键作用。本项目提出了一种前所未有的冰盖过程研究方法整合方案，具体包括：(1) 卫星遥感技术；(2) 地表地球物理探测；(3) 钻孔观测与测量；以及(4) 基底与冰下采样。政府间气候变化专门委员会（Intergovernmental Panel on Climate Change, IPCC）最新报告指出，评估未来全球海平面变化时面临的最大不确定性源于对冰盖动力学机制，以及冰盖对海洋与大气变暖的脆弱性认知不足。仅西南极冰盖（West Antarctic Ice Sheet，简称WAIS）的崩塌就会导致全球海平面上升3至5米，加之其内部或海洋驱动的不稳定性风险极高，因此西南极冰盖成为学界关注的焦点。WISSARD整体计划将验证这一核心假说：活跃的水体排水过程连接了不同的冰下环境，并对冰盖流动、地球化学特征、代谢与系统发育多样性，以及生物地球化学转化过程起到关键调控作用。社会相关性：全球变暖、冰盖消融及其引发的海平面上升与社会福祉高度相关。科研资源建设：在中断9年后，WISSARD计划将为美国科学界提供全新的冰下环境探测与研究能力。本项目开发的技术基础设施将惠及更广泛的科研共同体，相关设备可通过NSF-OPP钻探承包商向未来的科研工作开放使用。此外，本系列项目将率先践行美国国家研究委员会2007年发布的《冰下环境勘探与研究环境管理原则》委员会提出的相关建议。教育与公众参与（Education and Outreach, E/O）：相关活动分为四大类别：i) 让学生深度融入本研究项目，提升其参与极地研究的积极性；ii) 吸纳具有潜力的青年研究者加入本项目，向其普及极地科学研究知识；iii) 联合各类教师与美国国家科学教师协会（National Science Teachers Association, NSTA）项目，推广K-12阶段的科教教学活动；iv) 通过科普杂志、博物馆科普活动、影像制作与纪录片等渠道，面向更广泛的公众开展科普传播。总而言之，WISSARD计划将通过向公众传递探索与研究地球上可能尚存的最后一批未被开发的水生环境之一的兴奋感，推动南极科学勘探进程——这些冰下湖泊同时也可作为木卫二与火星上地外生命栖息地的潜在类比研究对象。