The Antarctic Ice Sheet Large Ensemble (AISLENS) Project: Assessing the Role of Climate Variability in Past and Future Ice Sheet Mass Loss

对未来海平面上升预测的不确定性部分来自冰盖融化，冰盖附近海洋和大气温度的不可预测变化的影响。利用最先进的建模技术，南极冰盖大集合(AISLENS)项目将估计最近过去和未来几个世纪这种气候变化可能导致的南极冰盖融化的范围。AISLENS项目还将通过向更广泛的气候和冰川学社区提供开放产品的模拟输出来促进研究。该项目将支持一名早期职业教师，以及一名研究生、博士后研究员和本科生的跨学科培训。作为该项目的一部分，还将开设“海平面上升和海岸工程”本科课程，将地球科学和土木工程专业的学生聚集在一个跨学科的环境中，并促进他们在海平面科学和海岸适应方面的教育。这项研究将在美国东南部的地理环境中进行，这是美国最容易受到海平面上升影响的地区。拟议中的研究的主要目标是了解和量化内部气候变化在推动南极冰盖最近过去和未来的冰消退中所起的作用。AISLENS项目将包括对1950年至2300年南极冰盖演变的数百次模拟，这些模拟是由于气候的现实变化而被迫进行的，包括海洋和大气温度波动造成的降雪和融化。南极气候强迫的合理实现将通过随机模拟能量亿级地球系统模型(E3SM)在过去和未来排放情景下的输出而产生。这些对气候变化的认识将被用来迫使MAS奥尔巴尼陆地冰(马里)模型，一个最先进的南极冰盖冰流模型。在这个项目中，将使用AISLENS进行不确定性和归因分析。在不确定性分析中，将对南极冰盖未来演变模拟中的集合扩散演变进行系统分解，以确定气候变异性的哪些时间和空间尺度对未来冰盖投影的不确定性贡献最大。在归属分析中，将把对最近南极冰损失的一系列卫星观测与AISLENS模拟的涵盖最近过去的南极冰损失内部变率的包络进行比较。这一分析将为最近的观测结果提供背景，表明南极气候强迫的显著可变性，并为对观测到的冰盖变化进行强有力的统计推断研究提供可能的途径。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Uncertainty in projections of future sea level rise comes, in part, from ice-sheet melting under the influence of unpredictable variations in ocean and atmospheric temperature near ice sheets. Using state-of-the-art modeling techniques, the Antarctic Ice Sheet Large Ensemble (AISLENS) Project will estimate the range of possible Antarctic Ice Sheet melt during the recent past and over the next several centuries that could result from such climate variations. The AISLENS Project will also facilitate research by providing modeling output as an open product to the broader climate and glaciology communities. The project will support an early career faculty member, and interdisciplinary training for a graduate student, postdoctoral fellow and undergraduate student. As a part of this project, an undergraduate course on "Sea Level Rise and Coastal Engineering" will be also developed, bringing together Earth Science and Civil Engineering students in an interdisciplinary setting and contributing to their education in sea level science and coastal adaptation. This will be done in the geographic context of the Southeastern US, the region of most concentrated vulnerability to sea-level rise in the US.The primary goal of the proposed research is to understand and quantify the role of internal climate variability in driving ice loss from the Antarctic Ice Sheet over the recent past and into the future. The AISLENS Project will encompass hundreds of simulations of Antarctic ice sheet evolution from 1950 to 2300 forced by realistic variations in climate, including snowfall and melt from fluctuating oceanic and atmospheric temperatures. Plausible realizations of Antarctic climate forcing will be generated from stochastic emulation of output from the Energy Exascale Earth System Model (E3SM) under past and future emissions scenarios. These realizations of variable climate will be used to force the MPAS Albany Land Ice (MALI) model, a state-of-the-art model of ice flow in the Antarctic Ice Sheet. In this project, AISLENS will be used to conduct uncertainty and attribution analyses. In the uncertainty analysis, the evolution of ensemble spread in simulations of the future evolution of the Antarctic Ice Sheet will be systematically decomposed to determine which temporal and spatial scales of climate variability contribute the most to future ice-sheet projection uncertainty. In the attribution analysis, a range of satellite-based observations of recent Antarctic ice loss will be compared to the envelope of internal variability of Antarctic ice loss simulated in AISLENS simulations encompassing the recent past. This analysis will provide context to recent observations indicating significant variability of Antarctic climate forcing and provide a possible path forward for conducting robust statistical inference studies for observed ice-sheet changes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.