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

这个学生项目将使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（南极洲和太平洋西北部，美国），以解决重要的和社会相关的问题，过去和未来的变化，冰川在一个变暖的世界。首先，这名学生将加入nerc-国家科学基金会国际思韦茨冰川合作，ITGC，这是一个英国和美国联合的2500万美元的研究计划，旨在大大提高我们对南极洲西部巨大的斯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，对从主要冰流附近和冰流下的火山峰收集的岩石样本进行研究，以调查思韦茨冰川过去的冰川变化。目标是：1）开发新的地球化学测年工具，使用宇宙成因放射性核素（例如，Be-10）在镁铁质矿物中，以及2）确定数千年来冰厚度过去波动的时间和持续时间，这将使用在母项目“地质历史约束（GHC）”期间钻取的冰下基岩岩心的测量结果进行调查。第二，由于美国太平洋西北部在很大程度上依赖于积雪在高瀑布作为水资源，这个学生将确定史前（前1900年）的三个太平洋西北冰川的范围，使用宇宙成因（传统的He-3，Cl-36，和新开发的Be-10）冰碛的表面暴露年龄组成的瀑布的火山岩。这些年龄将决定冰川在上个世纪退缩的优先顺序，因为这种退缩反映了由于夏末积雪减少而导致的总体负质量平衡，这反过来又为最近夏末积雪减少提供了背景。年龄数据将在冰川模型模拟中得到应用。研究结果将提供一个全新世晚期的观点，如何前所未有的当前冰川退缩，因此一个世纪规模的测试的首要级联积雪下降。年龄数据将建立北美西部史前冰川变化的南北横断面，以补充其他代理记录，这将测试北美西部全新世晚期水文气候变化百年尺度模式的假设。研究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未来积雪和冰川变化是必要的。该学生将在太平洋西北部（美国）进行实地考察，在伦敦帝国理工学院的CosmIC实验室开发方法并制备用于宇宙成因同位素表面暴露测年的样品，并在ANSTO（澳大利亚）通过加速器质谱（AMS）进行测量。这是一个多学科的项目，在现场，实验室和分析方法的重要培训。对社会重要的科学的热情至关重要。

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.