(In)stability of glaciers and climate in volcanic landscapes of the Thwaites Glacier, Antarctica, and American Pacific Northwest

该学生将利用宇宙成因同位素开发新的测年工具，并将其应用于两个火山景观（南极洲和美国太平洋西北地区），以解决有关变暖世界中冰川过去和未来变化的重要和社会相关问题。首先，该学生将加入NERC-NSF国际思韦茨冰川合作项目（ITGC），这是一个英美联合的2500万美元研究项目，旨在显著提高我们对南极洲西部巨大的思韦茨冰川未来演变的理解，以及它在未来几十年和几个世纪对海平面变化的可能贡献。该项目将利用最先进的地球化学方法，对主要冰流附近和下面的火山峰收集的岩石样本进行研究，研究斯韦茨冰川过去的冰川变化。目标是：1)利用基性矿物中的宇宙成因放射性核素（例如be -10）开发新的地球化学测年工具；2)确定过去几千年来冰厚波动的时间和持续时间，这将通过在母项目“地质历史限制（GHC）”期间钻探的冰下基岩岩心的测量进行调查。其次，由于美国太平洋西北地区严重依赖高喀斯喀特山脉的积雪作为水资源，该学生将利用宇宙成因（传统的He-3、Cl-36和新开发的Be-10）在喀斯喀特山脉火山岩组成的冰碛上的表面暴露年龄，确定三个太平洋西北地区冰川的史前（1900年以前）范围。这些年龄将决定上个世纪冰川退缩的优先顺序，因为这种退缩反映了夏末积雪减少造成的总体负质量平衡，这反过来又为夏末积雪最近的减少提供了背景。然后，年龄数据将用于冰川模型模拟。研究结果将提供一个全新世晚期的视角，了解当前前所未有的冰川退缩是如何发生的，从而对喀斯喀特积雪减少的主要原因进行一个世纪尺度的测试。年龄数据将建立一个北美西部史前冰川变化的南北样带，以补充其他代理记录，这将检验关于北美西部晚全新世水文气候变化百年尺度模式的假设。结果将为测试区域气候和冰川模型提供一个新的目标，这些模型对于准确预测积雪和冰川变化是必要的。该学生将在太平洋西北地区（美国）进行实地工作，在伦敦帝国理工学院的宇宙实验室为宇宙形成同位素表面暴露定年开发方法和准备样品，并在澳大利亚ANSTO（澳大利亚）通过加速器质谱（AMS）进行测量。这是一个多学科项目，在现场、实验室和分析方法方面进行了重要的培训。对科学的热情对社会至关重要。

This studentship will develop new dating tools using cosmogenic isotopes and, in turn, apply them in two volcanic landscapes (Antarctica and Pacific Northwest, USA) to solve important and societally relevant problems concerning past and future changes to glaciers in a warming world.First, this student would join the NERC-NSF International Thwaites Glacier Collaboration, ITGC, which is a joint UK-US $25M research program aiming to significantly improve our understanding of the future evolution of the massive Thwaites Glacier in West Antarctica and its likely contribution to sea level change in the coming decades and centuries. The project will investigate past glacier changes of the Thwaites Glacier using state-of-the-art geochemical methods on rock samples collected from volcanic peaks next to and under major ice streams. Objectives are to: 1) develop new geochemical dating tools using cosmogenic radionuclides (e.g., Be-10) in mafic minerals, and 2) to determine the timing and duration of past fluctuations in ice thickness over several millennia, which will be investigated using measurements of subglacial bedrock cores drilled during the parent project, "Geological History Constraints (GHC)". Second, as the American Pacific Northwest relies heavily on the snowpack in the High Cascades as a water resource, this studentship will determine the age of prehistoric (pre-1900) extents of three Pacific Northwest glaciers, using cosmogenic (traditional He-3, Cl-36, and newly developed Be-10) surface exposure ages on moraines composed of volcanic rocks of the Cascades. These ages will determine precedence for retreat of the glaciers over the last century because such retreat reflects an overall negative mass balance due to reduced snowpack at the end of the summer, which will, in turn, provide context for recent declines in end-of-summer snowpack. The age data will then be implemented in glacier model simulations. Results will provide a late-Holocene view on how unprecedented current glacier retreat is, and consequently a century-scale test of primacy for Cascade snowpack decline. Age data will establish a north-south transect of western North American prehistoric glacier changes to complement other proxy records, which will test hypotheses on centennial-scale patterns in western North American late-Holocene hydroclimate change. Results will provide a novel target for testing regional climate and glacier models that are necessary for accurate future projections of snowpack and glacier changes.The student will conduct field work in the Pacific Northwest (USA), develop methods and prepare samples for cosmogenic isotope surface exposure dating in the CosmIC laboratory at Imperial College London, and conduct measurements by accelerator mass spectrometry (AMS) at ANSTO (Australia). This is a multidisciplinary project, with significant training in field, laboratory, and analytical methods. A passion for science that matters to society is critical.