Collaborative Research: Assessing the Global Climate Response to Melting of the Antarctic Ice Sheet

合作研究：评估全球气候对南极冰盖融化的反应

• 批准号: 1443347
• 负责人: Alan Condron
• 金额: $ 69.27万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1443347&HistoricalAwards=false
• 关键词: Collaborative; Research; Assessing; Global; Climate

There is compelling historical evidence that the West Antarctic Ice Sheet (WAIS) is vulnerable to rapid retreat and collapse. Recent observations, compared to observations made 20-30 years before, indicate that both ice shelves (thick ice with ocean below) and land ice (thick ice with land below), are now melting at a much faster rate. Some numerical models suggest that significant ice retreat may begin within many of our lifetimes, starting with the abrupt collapse of Pine Island and Thwaites Glaciers in the next 50 years. This may be followed by retreat of much of the WAIS and then the collapse of parts of the East Antarctic ice sheet (EAIS). This research project will assess the extent to which global ocean circulation and climate will be impacted if enormous volumes of fresh water and ice flow into the Southern Ocean. It will establish whether a rapid collapse of WAIS in the near-future poses any significant threat to the stability of modern-day climate and human society. This is a topic that has so far received little attention as most prior research has focused on the response of climate to melting the Greenland ice sheet. Yet model simulations predict that the volumes of fresh water and ice released from Antarctica in the next few centuries could be up at least ten-times larger than from Greenland. The Intellectual Merit of this project stems from its ability to establish a link between the physical Antarctic system (ice sheet dynamics, fresh water discharge and iceberg calving) and global climate. The PIs (Principal Investigators) will assess the sensitivity of ocean circulation and climate to increased ice sheet melt using a combination of ocean, iceberg, ice sheet and climate models. Results from this study will help identify areas of the ice sheet that are vulnerable to collapse and also regions of the ocean where a significant freshening will have a considerable impact on climate, and serve to guide the deployment of an observational monitoring system capable of warning us when ice and fresh water discharge start to approach levels capable of disrupting ocean circulation and global climate. This project will support and train two graduate students, and each PI will be involved with local primary and secondary schools, making presentations, mentoring science fair projects, and contributing to curriculum development. A novel, web-based, interactive, cryosphere learning tool will be developed to help make school children more aware of the importance of the Polar Regions in global climate, and this software will be introduced to science teachers at a half day workshop organized by the UMass STEM Education Institute. Recent numerical simulations using a continental ice sheet/shelf model show the potential for more rapid and greater Antarctic ice sheet retreat in the next 50-300 years (under the full range of IPCC RCP (Intergovernmental Panel on Climate Change, Representative Concentration Pathways) future warming scenarios) than previously projected. Exactly how the release of enormous volumes of ice and fresh water to the Southern Ocean will impact global ocean circulation and climate has yet to be accurately assessed. This is in part because previous model simulations were too coarse to accurately resolve narrow coastal boundary currents, shelf breaks, fronts, and mesoscale eddies that are all very important for realistically simulating fresh water transport in the ocean. In this award, future projections of fresh water discharge and iceberg calving from Antarctic will be used to force a high resolution eddy-resolving ocean model (MITgcm) coupled to a new iceberg module and a fully-coupled global climate model (CCSM4). High resolution ocean/iceberg simulations will determine the role of mesoscale eddies in freshwater transport and give new insight into how fresh water is advected to far-field locations, including deep water formation sites in the North Atlantic. These simulations will provide detailed information about subsurface temperatures and changes in ocean circulation close to the ice front and grounding line. An accompanying set of fully coupled climate model simulations (NCAR CCSM4) will identify multidecadal-to-centennial changes in the climate system triggered by increased high-latitude Southern Ocean freshwater forcing. Particular attention will be given to changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC), wind stress, sea ice formation, and global temperatures. In doing so, this project will more accurately determine whether abrupt and potentially catastrophic changes in global climate are likely to be triggered by changes in the Antarctic system in the near-future.

有令人信服的历史证据表明，南极冰盖（WAIS）容易撤退和倒塌。与在20 - 30年前进行的观察相比，最近的观察结果表明，冰架（下面是海洋的厚冰）和陆上冰（厚厚的冰（厚厚的冰层），现在都以更快的速度融化。一些数值模型表明，从我们的许多生命中开始，大量的冰撤退可能会开始，从未来50年的派恩岛和Thwaites冰川突然崩溃开始。随后可能是大部分婚姻的撤退，然后是南极冰盖（EAIS）部分的倒塌。该研究项目将评估如果大量淡水和冰流入南大洋，全球海洋循环和气候将在多大程度上受到影响。它将确定WAIS在近事件中的迅速崩溃是否会对现代气候和人类社会的稳定构成任何重大威胁。到目前为止，这个话题很少受到关注，因为大多数先前的研究都集中在气候对融化格陵兰冰盖的反应上。然而，模型模拟预测，在接下来的几个世纪中，从南极洲释放的淡水和冰块可能比格陵兰大十倍。该项目的智力优点源于其在物理南极系统（冰盖动态，淡水排放和冰山产犊）和全球气候之间建立联系的能力。 PI（主要研究人员）将使用海洋，冰山，冰盖和气候模型的组合评估海洋循环和气候对增加冰盖融化的敏感性。这项研究的结果将有助于识别冰盖的区域，这些区域容易崩溃，并且在海洋的区域中，重大的新鲜度将对气候产生重大影响，并有助于指导在冰和淡水排放开始接近能够破坏海洋循环和全球气候水平的观察性监测系统时的部署。该项目将支持和培训两名研究生，每个PI将与当地的中小学有关，进行演讲，指导科学公平项目以及为课程发展做出贡献。将开发一种基于网络的新型，基于网络的互动，冰圈学习工具，以帮助学童更加了解全球气候中极地地区的重要性，并且该软件将在UMass STEM教育研究所组织的半天工作坊中介绍给科学教师。使用大陆冰盖/架子模型的最新数值模拟显示，在接下来的50 - 300年中（在IPCC RCP的完整范围内（气候变化，代表性浓度途径，代表性浓度途径）中，有可能更快，更大的南极冰盖撤退（在整个IPCC RCP范围内）比以前所预测的。确切地说，向南洋释放大量冰和淡水将如何影响全球海洋循环和气候。这部分是因为以前的模型模拟太粗糙，无法准确解决狭窄的沿海边界电流，架子断裂，前部和中尺度涡流，这些涡流对于实际模拟海洋中的淡水运输非常重要。在此奖项中，未来对南极的淡水排放和冰山产犊的预测将用于迫使高分辨率分辨率分辨率的海洋模型（MITGCM）与新的冰山模块和完全耦合的全球气候模型（CCSM4）耦合。高分辨率的海洋/冰山模拟将决定中尺度涡流在淡水运输中的作用，并为如何将淡水提供给远场地点，包括北大西洋上的深水地层。这些模拟将提供有关地下温度以及靠近冰面和接地线的海洋循环变化的详细信息。随附的一组完全耦合的气候模型模拟（NCAR CCSM4）将在气候系统中确定多年次数到宁静的变化，这是由增加南部海洋淡水强迫升高而触发的。特别注意大西洋子午倾覆循环（AMOC），风应力，海冰形成和全球温度的变化。这样一来，该项目将更准确地确定全球气候中突然和潜在的灾难性变化是否可能是由于近未景点中南极系统的变化而触发的。