Ice shelves in a warming world: Filchner Ice Shelf system, Antarctica

我们的星球正在变暖，这是不可否认的。最近温室气体浓度的增加导致大气和海洋变暖，冰雪总量减少，海平面上升约3毫米/年。尽管未来气温上升的精确速度可能不确定，但毫无疑问，它会增加。为了应对气候变暖，南极冰盖的大面积可能变得不稳定，导致冰的突然和永久性损失。事实上，对于一个研究相对较好的地区，阿蒙森海域，这可能已经在进行中。然而，我们对这些过程、崩塌的可能性和对海平面的潜在影响的了解仍然很差，特别是在威德尔地区非常不同的气候状况下。这个项目的目的是研究在不久的将来这个面积占南极洲五分之一的地区将会发生什么情况，以及到本世纪结束时这里的变化可能对全球海平面产生的影响。我们的目标是分三个阶段：我们将研究和了解南极洲重要的威德尔地区的大气、海洋和冰盖之间的复杂关系，该地区包括费尔希纳冰架及其集水盆地。我们将确定大气如何决定海洋条件，以及这些条件又如何决定冰架底部的融化。在精心设计的实地活动中，我们将收集数据，以改进模型的工作方式，并验证其结果。第一阶段将产生一个模型系统，详细描述当前正在发生的物理过程，通过使用系统中的自然变化，我们将确定每个关联过程对变化的敏感性。下一步是用21世纪预期的大气和海洋特性的最佳估计来强制我们模拟系统的边界。然后，我们将能够确定冰架下面的海洋条件将如何变化，以及冰架底部的融化速度。随着融化速度的变化，冰架的几何形状也会发生变化：我们将确定大陆冰流的速度如何响应这些变化，以及它对海平面上升的影响。在最后阶段，我们将扩大研究范围，从我们的大范围，但仍然是区域性的区域，到全球范围。前两个步骤中使用的模型（大气、海洋和冰）是高分辨率、最先进但区域有限的模型。我们将与我们的项目合作伙伴气象局哈德利中心（MO）合作，将我们对过程及其敏感性的更好理解纳入下一代全球地球系统预测模型。最后，我们将评估我们预测的可靠性。这将首先通过确保不同区域模型之间的一致性来实现，这些模型既在项目内部运行，也由我们在德国阿尔弗雷德·韦格纳研究所的项目合作伙伴运行。然后，我们将使用新一代MO耦合气候模式的有限集合来量化我们预测南极冰盖对海平面变化的贡献的不确定性。南极冰盖对海平面上升的未来贡献仍然是预算中约束最少的部分。该项目汇集了极地气象学、海洋学、冰-海相互作用、冰川学和模型不确定性方面的社区领先专家，将在预测未来海平面变化方面提供最大的单一改进。新的观测和数据是必不可少的，但代价高昂。AWI和NERC将分担物流负担，而不是使用昂贵的商用基础设施，从而为项目提供卓越的价值。

That our planet is warming is undeniable. Recent increases in greenhouse gas concentrations have seen an associated warming of the atmosphere and oceans, a reduction in the total amount of snow and ice and a rise in sea level of approximately 3 mm/year. Although the precise rate of future temperature rise may be uncertain, there is little doubt that it will increase. In response to a warmer climate, large areas of the Antarctic Ice Sheet could become unstable, resulting in sudden and permanent loss of ice. Indeed for one relatively well-studied region, the Amundsen Sea Sector, this may already be underway. However, our understanding of the processes, the likelihood of collapse and the potential impact on sea-level remains poor, especially in the very different climatic regime of the Weddell Sector. This project aims to address what will happen in the near-future to a region that spans one fifth of Antarctica and the impact changes here could have on global sea-level by the end of this century. We aim to do this in three stages:We will study and understand the intricate relationships between the atmosphere, the ocean and the ice sheet in the important Weddell sector of Antarctica, which contains Filchner Ice Shelf and its catchment basins. We will determine how the atmosphere determines the ocean conditions, and how these in turn determine the melting at the base of the ice shelf. In a carefully designed field campaign we will collect data both to improve the way the models work, and also to validate their results. This first stage will yield a system of models that gives a detailed representation of the physical processes currently at work, and by using the natural variability in the system we will determine the sensitivity to change of each linked process.The next step is to force the boundaries of our modelled system with the best available estimate of the atmospheric and oceanographic properties expected over the 21st century. We will then be in a position to determine how the ocean conditions beneath the ice shelf will change, together with the rate of melting at the ice shelf base. As the melt rate changes, so will the ice shelf geometry: we will determine how the rate of ice flow from the continent responds to these changes, and its impact on sea-level rise.In the final stage we will widen the scope of the study from our large, yet still regional area, to a global context. The models to be used in the first two steps, (atmosphere, ocean and ice) are high resolution, state-of-the-art but limited-area models. We will work with our Project Partner, the Met Office Hadley Centre (MO), to incorporate our improved understanding of processes and their sensitivities within the next generation of global earth-system predictive models. Finally, we will assess the reliability of our predictions. This will be done first by ensuring consistency between the different regional models, run both within the project and by our project partners at the Alfred Wegener Institute in Germany. We will then use a limited ensemble of runs of the new generation of MO coupled climate models to quantify the uncertainty in our predictions of the contribution of the Antarctic Ice Sheet to sea level change.The future contribution of the Antarctic Ice Sheet to sea level rise remains the least well constrained component in the budget. By bringing together from across the community leading experts in polar meteorology, oceanography, ice-ocean interaction, glaciology and model uncertainty, this project will provide the largest single improvement in the prediction of future sea level change. New observations and data are essential, but expensive. Rather than using costly commercially-available infrastructure, AWI and NERC will share the logistic burden with the project delivering excellent value as a result.