GEO ICE - Benchmark Geological Records for the Response of the West Antarctic Ice Sheet to Near Future Temperature

GEO ICE - 南极西部冰盖对近期温度响应的基准地质记录

基本信息

批准号：
NE/W000172/1
负责人：
Tina Van De Flierdt
金额：
$ 82.85万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2022
资助国家：
英国
起止时间：
2022 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FW000172%2F1
关键词：
GEO ICE Benchmark Geological Records

项目摘要

The Paris Agreement presents humanity with an ambitious and critical goal: to keep global warming well below 2 degrees above pre-industrial levels. All 197 countries have signed up, and 189 have formally approved it. But there is no doubt that these targets present a massive challenge, and a certain amount of environmental change is already inevitable. We know that sea level will rise 10s of centimetres over the next several decades, displacing many millions of people living in low lying coastal areas. But we don't yet know just how much more our seas will rise through the coming centuries. Will our efforts to curb emissions stop the collapse of Antarctica's ice shelves and loss of the West Antarctic Ice Sheet? Under which conditions does collapse occur? And which part of the ice sheet will react first? Computer models yield conflicting results on these questions, partly because they simulate the past (and our future) using different environmental conditions and model physics. To figure out which of these are right, we need to obtain observational data from the geological past to test the models. Our project will embark in a detective story to provide some long-searched for evidence. We will exploit two geological records to reconstruct West Antarctic Ice Sheet history under temperatures only slightly elevated above modern levels (i.e. late Pleistocene interglacials). The first of these records comes from a recent ship-based drilling campaign (International Ocean Discovery Program Expedition 374) that recovered mud and sand from the Ross Sea, an area right next to the West Antarctic Ice Sheet. The second record will be retrieved from an ice shelf-based drilling rig that will recover the first extended record of sub-seafloor mud and sand from far beneath the Ross Ice Shelf, at a location where the West Antarctic ice sheet detaches from the seafloor and starts to float into the Ross Sea (Siple Coast drilling). For our first work package, we will analyse the chemical composition of mud, sand and organic particles to reconstruct critical environmental conditions. Firstly, the mud and sand will uncover where on the continent the pieces of rocks came from. Knowledge of the location of erosion can then tell us in turn whether the West Antarctic Ice Sheet melted during past times when temperatures were just a little bit warmer than today, or not. Secondly, the chemical composition of organic particles in the same samples will reveal prevailing ocean temperatures at the time of deposition. Thirdly, the presence/absence of certain types of marine algae will tell us whether floating ice was present or not. The combination of the three different sets of data will help us unravel where geographically ice melting started in West Antarctica.For our second work package, we will utilise our new data to test coupled ice sheet-climate models, which are also used to predict future sea level. Assessing how well these models perform in simulating the geological past is a key way of determining how accurate their projections of the future are. In detail we will test two such models, called PSUICE3D and BISICLES. We will analyse existing model simulations that led to collapse of the West Antarctic Ice Sheet during past warm times, and perform new simulations using a more realistic environmental framework constrained by our new data. The comparison of predicted places of ice retreat and modelled places of ice retreat has never been realised before and will allow us to pinpoint which parts of Antarctica are most vulnerable to moderate levels of global warming, providing vital information towards mitigation and adaptation of sea level rise for settlements in coastal areas around the globe.

《巴黎协定》向人类提出了一个雄心勃勃且重要的目标：将全球变暖控制在远低于工业化前水平 2 度的范围内。 197个国家全部签署，189个国家正式批准。但毫无疑问，这些目标提出了巨大的挑战，一定程度的环境变化已经不可避免。我们知道，未来几十年海平面将上升数十厘米，使生活在低洼沿海地区的数百万人流离失所。但我们还不知道在接下来的几个世纪里我们的海平面将会上升多少。我们遏制排放的努力能否阻止南极洲冰架的崩塌和南极西部冰盖的消失？什么情况下会发生塌陷？冰盖的哪一部分会首先发生反应？计算机模型在这些问题上产生了相互矛盾的结果，部分原因是它们使用不同的环境条件和模型物理学来模拟过去（和我们的未来）。为了弄清楚哪一个是正确的，我们需要从过去的地质中获取观测数据来测试模型。我们的项目将从一个侦探故事开始，以提供一些长期寻找的证据。我们将利用两项地质记录来重建西南极冰盖在温度仅略高于现代水平（即晚更新世间冰期）的情况下的历史。第一个记录来自最近的一次船基钻探活动（国际海洋发现计划第 374 次探险），该活动从紧邻西南极冰盖的罗斯海回收了泥和沙。第二个记录将从基于冰架的钻机中获取，该钻机将从罗斯冰架下方深处恢复第一个海底泥浆和沙子的长期记录，该位置是南极西部冰盖与海底分离的位置，开始漂浮到罗斯海（Siple Coast 钻探）。对于我们的第一个工作包，我们将分析泥浆、沙子和有机颗粒的化学成分，以重建关键的环境条件。首先，泥土和沙子将揭示大陆上岩石碎片的来源。了解侵蚀位置可以反过来告诉我们，西南极冰盖是否在过去温度比现在稍高一点的时期融化了。其次，同一样本中有机颗粒的化学成分将揭示沉积时的主要海洋温度。第三，某些类型的海藻的存在/不存在将告诉我们浮冰是否存在。三组不同数据的结合将帮助我们解开南极洲西部冰融化开始的地理位置。对于我们的第二个工作包，我们将利用我们的新数据来测试耦合的冰盖气候模型，该模型也用于预测未来海平面。评估这些模型在模拟过去地质方面的表现是确定其对未来预测准确程度的关键方法。我们将详细测试两个这样的模型，称为 PSUICE3D 和 BISICLES。我们将分析过去温暖时期导致南极西部冰盖崩塌的现有模型模拟，并使用受新数据约束的更现实的环境框架进行新的模拟。预测的冰退缩地点与模拟的冰退退地点之间的比较以前从未实现过，这将使我们能够查明南极洲的哪些地区最容易受到中等程度的全球变暖的影响，为缓解和适应海平面上升提供重要信息全球沿海地区的定居点。