Testing smaller-than-present configurations of the Antarctic Ice Sheet using a novel integration of geochronology

使用地质年代学的新颖整合来测试比现在更小的南极冰盖构造

• 批准号: NE/T011963/1
• 负责人: David Small
• 金额: $ 83.3万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT011963%2F1
• 关键词: Testing; smaller; than; present; configurations

The Antarctic Ice Sheets (East Antarctica and West Antarctica) hold enough fresh water to raise global sea levels by over 60 m. Even a partial collapse of the West Antarctic Ice Sheet, by far the smaller of the two, could raise sea level by 2-3 m displacing many millions of people and forcing them to find new places to live inland. It is known that the Antarctic Ice Sheets are losing mass at an increased rate meaning they are heading to a configuration that is smaller than present. To understand how such a configuration is reached it is vital to understand ice sheet behavior at times in the past when they were smaller than present.Computer models of ice sheet behaviour are capable of making predictions but require observations for validation and improvement. One way of doing this is to test whether the models accurately reproduce behaviours observed in reality. The limited areas of Antarctica that are not ice covered have yielded vital information on past ice sheet extents but can only inform on larger than present ice sheet configurations. To understand smaller than present configurations this proposal will access rock that is now covered by ice. This rock retains measureable properties that record when it was last uncovered by the ice sheet allowing the timing and duration of these events to be determined. This project will collect sub-glacial samples from a key region of West Antarctica, the Weddell Sea. In this area recent work using radar has identified internal structures within the ice sheet that suggests it has undergone recent change. Specifically, the data is consistent with the ice sheet having expanded over the last few hundreds of years following a period of time where it was smaller than present. Understanding the current state of the ice sheet and the process that control its behaviour is key to making predictions about how it will respond to human induced global warming. I will use a portable drill system to drill through ice close to present day mountains that protrude above the ice sheet. Over the course of two Antarctic field seasons the drill will be used to collect a series of sub-glacial rock cores that will be returned to laboratories where a novel combination of geochronological methods will be employed to establish if the rock has previously been exposed due to the ice sheet being smaller. By combining different techniques I will improve the constraints that can be obtained; thus not only can it be established if the ice sheet was smaller in the past but also when, and for how long, this was the case. I will then use the new data to evaluate computer models of ice sheet behaviour. These models use combinations of parameter values, representing processes that occur in reality, to produce simulations of ice sheet behaviour through time. By exploring a range a different parameter values large collections of simulations (ensembles) define a range of potential ice sheet simulations that may or may not closely reflect reality. The new geological data is a product of the actual ice sheets behaviour and can be used to sieve out model simulations that are far from reality. Remaining simulations can be scored according to how closely they match the geological data. In this way I will determine what parameters (i.e. what processes) are key to controlling ice sheet behaviour. In this way my project will bring about a step-change in our understanding of processes that control ice sheet behaviour on short geological timescales. Furthermore, the refined ice sheet history and model parameter ranges identified in this project will improve future modelling efforts and lead to more precise predictions of future ice sheet behaviour and associated sea level rise.

南极冰原（东南极洲和西南极洲）拥有足够的淡水，可以使全球海平面上升60多米。南极西部冰原是两个冰原中较小的一个，即使它的部分崩塌，也可能使海平面上升2-3米，使数百万人流离失所，并迫使他们在内陆寻找新的居住地。众所周知，南极冰盖正在以更快的速度失去质量，这意味着它们正在走向一个比现在更小的结构。为了理解这种构造是如何形成的，了解过去冰盖比现在小的时候的行为是至关重要的。冰盖行为的计算机模型能够做出预测，但需要观察来验证和改进。一种方法是测试模型是否能准确再现现实中观察到的行为。南极洲有限的未被冰覆盖的地区提供了关于过去冰盖范围的重要信息，但只能提供比现在更大的冰盖结构的信息。为了了解比现在更小的构造，这个提议将进入现在被冰覆盖的岩石。这种岩石保留了可测量的属性，记录了它最后一次被冰盖覆盖的时间，从而确定了这些事件的时间和持续时间。该项目将从西南极洲的一个关键地区威德尔海收集冰下样本。在这个地区，最近使用雷达的工作已经确定了冰盖的内部结构，表明它最近经历了变化。具体来说，这些数据与冰盖在过去几百年里的扩张是一致的，而在过去的一段时间里，冰盖比现在小。了解冰盖的现状和控制其行为的过程，是预测它将如何应对人类引起的全球变暖的关键。我将使用便携式钻孔系统在靠近现今突出在冰盖之上的山脉的冰层上钻孔。在两个南极野外季节的过程中，该钻头将用于收集一系列冰下岩芯，这些岩芯将被送回实验室，在那里将采用一种新的地质年代学方法组合来确定岩石是否因冰盖较小而先前暴露。通过结合不同的技术，我将改进可以获得的约束条件；因此，不仅可以确定过去的冰盖是否更小，而且可以确定这种情况何时发生以及持续了多长时间。然后，我将使用这些新数据来评估冰原行为的计算机模型。这些模型使用代表现实中发生的过程的参数值的组合来模拟冰盖随时间的行为。通过探索不同参数值的范围，大量模拟集合（集合）定义了可能或可能不密切反映现实的潜在冰盖模拟范围。新的地质数据是实际冰盖行为的产物，可以用来筛除与现实相距甚远的模型模拟。剩下的模拟可以根据它们与地质数据的匹配程度来打分。通过这种方式，我将确定哪些参数（即哪些过程）是控制冰盖行为的关键。通过这种方式，我的项目将使我们对在短地质时间尺度上控制冰盖行为的过程的理解发生阶段性的变化。此外，在本项目中确定的精细化的冰盖历史和模式参数范围将改进未来的建模工作，并对未来冰盖行为和相关的海平面上升进行更精确的预测。

项目成果

Investigating the roles of relative sea-level change and glacio-isostatic adjustment on the retreat of a marine based ice stream in NW Scotland

研究相对海平面变化和冰川均衡调整对苏格兰西北部海洋冰流退缩的作用

• DOI: 10.1016/j.quascirev.2021.107366
• 发表时间: 2022
• 期刊: Quaternary Science Reviews
• 影响因子: 4
• 作者: Simms A

Supplementary material to "Erosion rates in a wet, temperate climate derived from rock luminescence techniques"

补充材料

• DOI: 10.5194/gchron-2021-5-supplement
• 发表时间: 2021
• 作者: Smedley R

Ice-free valleys in the Neptune Range of the Pensacola Mountains, Antarctica: glacial geomorphology, geochronology and potential as palaeoenvironmental archives

南极洲彭萨科拉山脉海王星山脉的无冰山谷：冰川地貌、地质年代学和作为古环境档案的潜力

• DOI: 10.1017/s0954102021000237
• 发表时间: 2021
• 期刊: Antarctic Science
• 影响因子: 1.6
• 作者: Small D

An ensemble of Antarctic deglacial simulations constrained by geological observations

受地质观测限制的南极冰消模拟集合

• DOI: 10.1016/j.quascirev.2022.107800
• 发表时间: 2022
• 期刊: Quaternary Science Reviews
• 影响因子: 4
• 作者: Pittard M

Erosion rates in a wet, temperate climate derived from rock luminescence techniques

来自岩石发光技术的湿润温带气候中的侵蚀率

• DOI: 10.5194/gchron-3-525-2021
• 发表时间: 2021
• 期刊: Geochronology
• 作者: Smedley R