Rethinking Antarctic Sea Level Projections (RASP)

重新思考南极海平面预测 (RASP)

• 批准号: NE/Y001451/1
• 负责人: Christopher Yit Sen Bull
• 金额: $ 102.65万
• 依托单位: Northumbria University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY001451%2F1
• 关键词: Rethinking; Antarctic; Sea; Level; Projections; Rethinking; Antarctic; Sea; Level; Projections

One major consequence of global warming is the rising of sea levels that threaten coastal communities, ecosystems and industries worldwide. Since the beginning of the industrial revolution, global sea-levels have risen by about 20cm, largely through four components: the expansion of warming ocean waters, the melting of glaciers and the thinning of the Antarctic and Greenland ice sheets. In the recent 2021 report from the International Panel on Climate Change summarising the physical understanding of the Earth System, it is emphasised that future ice loss of the Antarctic Ice Sheet is the most uncertain of the four components above. Computer simulations suggest that the Antarctic Ice Sheet could slightly lower sea level or, more likely, raise sea level by more than 50 cm by 2100. Antarctica is particularly relevant for the UK, since northern hemisphere sea level responds over proportionately to ice loss in Antarctica, due to a reduction of the local gravitational pull. Furthermore, a research briefing for UK parliament (POSTnote 555) discusses that 50 cm of local sea level rise would make about 200 km of UK coastal flood defences vulnerable to failure. Further commissioned research suggests that by 2080, higher end sea-level estimates cause yearly damages in the UK that are £540m higher than those expected for the lower end estimates. Clearly, there is an urgent need to reduce uncertainty in sea-level projections for UK coastal planning. In the project "Rethinking Antarctic Sea-level Projections" (RASP), we propose a new approach to better understand and constrain the uncertainty for the Antarctic component.One reason why the future evolution of the Antarctic Ice Sheet is so uncertain is a gap in the scientific understanding, and thus representation in computer models, of how the surrounding Southern Ocean melts the Antarctic Ice Sheet in the future. Warmer ocean waters are found offshore of the Antarctic continent in the deeper, open ocean. In some regions, they already access the continental shelf and reach the ice, causing high melting. This is for example the case in the Amundsen Sea, where the bulk of Antarctica's ice loss is observed. Other regions, such as the Weddell Sea, are currently protected by colder waters. If, and how, those warm water masses access the continental shelf is dependent on a complex interaction of regional climate drivers such as winds, precipitation and air temperatures. But how important these different climate drivers will be for ice loss in the different Antarctic regions in the future, is unclear. We here propose to answer this question using a numerical model that represents the relevant Southern Ocean processes. Importantly, it will include the continental shelf and the ice-shelf cavities where the ice is in contact with the ocean in Antarctica. This gives us the unique opportunity to make a suite of targeted numerical experiments to identify the most relevant of those regional climate drivers, and how they interact. Using this novel understanding, we can then bridge the gap between the far-field, open ocean and the vicinity of the ice sheet. We will use a numerical ice flow model to make Antarctic future projections. This model represents how the changes in the atmosphere and ocean-driven melting affect the ice flow in Antarctica, and thereby lead to sea-level rise. We will run a range of experiments testing for uncertainties in future changes in the atmosphere and ocean, as well as uncertainties in the model physics. In particular, we can map out how much each climate driver contributes to the uncertainty in Antarctic sea-level projections. Thereby, we can fill the knowledge gap in the physical links between the Southern Ocean and the Antarctic Ice Sheet, and how much each link will contribute to sea-level rise over the coming decades to centuries.

全球变暖的一个主要结果是海平面上升，威胁到全球沿海社区，生态系统和行业。自工业革命开始以来，全球海平面已经上升了约20厘米，主要通过四个组成部分：变暖海水的扩展，冰川的融化以及南极和格陵兰冰片的变薄。在国际气候变化小组的最新一份报告中，总结了对地球系统的物理理解，强调，南极冰盖的未来冰丢失是上述四个组成部分中最不确定的。计算机模拟表明，南极冰盖的海平面可能会略低，或者更有可能在2100年将海平面提高超过50 cm。由于北半球海平面对南极的冰损失的响应，由于局部引力的减少，南极洲尤其与英国相关。此外，英国议会的研究简报（Post Note 555）讨论了50厘米的当地海平面上升将使大约200公里的英国沿海洪水防御危害失败。进一步委托的研究表明，到2080年，高端海平面估计值在英国导致年度损失比低端估计的预期高5.4亿英镑。显然，迫切需要减少英国沿海规划的海平面项目的不确定性。 In the project "Rethinking Antarctic Sea-level Projections" (RASP), we propose a new approach to better understand and constrain the uncertainty for the Antarctic component.One reason why the future evolution of the Antarctic Ice Sheet is so uncertain is a gap in the scientific understanding, and thus representation in computer models, of how the surrounding Southern Ocean melts the Antarctic Ice Sheet in the future.在较深的开阔海洋中发现了温暖的海水在南极大陆的海上。在某些地区，他们已经进入连续的架子并到达冰，从而导致高融化。例如，在Amundsen海中，观察到大部分南极冰损失的情况。其他地区，例如韦德尔海，目前受到较冷水的保护。如果以及如何进入连续架子的温水质量，则取决于区域气候驱动因素（例如风，精度和空气温度）的复杂相互作用。但是，这些不同的气候驱动因素对未来不同南极地区的冰损的重要性尚不清楚。我们在这里建议使用代表相关南部海洋过程的数值模型来回答这个问题。重要的是，它将包括连续的架子和与南极洲海洋接触的冰架腔。这为我们提供了独特的机会，可以制作一套有针对性的数值实验，以确定这些区域气候驱动因素的最相关，以及它们如何相互作用。然后，使用这种新颖的理解，我们可以弥合远场，开阔海洋和冰盖附近之间的缝隙。我们将使用数值冰流模型来制定南极的未来项目。该模型代表了大气和海洋驱动熔化的变化如何影响南极的冰流，从而导致海平面上升。我们将在大气和海洋的未来变化以及模型物理学的不确定性中进行一系列实验测试。特别是，我们可以绘制每个气候驱动因素有助于南极海平面预测的不确定性。因此，我们可以填补南大洋与南极冰盖之间物理联系的知识差距，以及在未来几十年到几个世纪以来，每个连接将有助于海平面上升。