Modeled Export of Ancient, Thick Sea Ice from the Arctic, and its Role in Abrupt Climate Change

模拟北极古代厚海冰的输出及其在气候突变中的作用

• 批准号: 1855918
• 负责人: Alan Condron
• 金额: $ 12.67万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-15 至 2020-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1855918&HistoricalAwards=false
• 关键词: Modeled; Export; Ancient; Thick; Sea

NontechnicalThis research will address fundamental questions regarding both paleo-climate and paleo-circulation of the ocean by identifying what may have triggered past abrupt climate change. In the late nineteenth century, Sir George Nares came across 15-18 m thick, immobile, ice extending 480 km off the northern Ellesmere coast. The characteristics of the ice were very different from the 2-3 m thick ice now circulating the Arctic Ocean. Similar accounts from other arctic explorers from this time provided insight into what must surely have been a far thicker and more persistent ice cover over the Arctic Ocean during full glacial conditions than we see today. Indeed, low biological productivity and extremely low, or absent, sediment deposition in the Arctic during glacial periods suggest that parts of the central and western Arctic Ocean were covered by very thick, perennial ice. This research will explore how such ice could have covered much of the Arctic Ocean during glacial periods, how thick it could have been, and whether its eventual mobilization and demise could have produced freshwater output to the North Atlantic large enough to weaken the deep water formation and trigger abrupt climate cooling. Using a suite of sophisticated, high-resolution, coupled numerical model experiments, this group will address these questions and highlight the connection between changes in the Arctic hydrological cycle and global climate.Each investigator has a serious commitment to education and public outreach, and the project will support and train a graduate student who will work with the investigators in all aspects of the research. Each investigator has been involved with local primary and secondary schools, either by making presentations, hiring students for the summer, mentoring science fair projects, or contributing to curriculum development. They will contribute to the on-going middle and high school science teacher training activities by developing a web-based, interactive, sea ice-learning tool to teach school children about the mechanisms behind sea ice formation and how ice will change as the arctic climate warms. In addition, well-developed relationships with local community organizations will help promote public understanding of abrupt climate change. The idea of thick sea ice in the Arctic has a remarkable ability to capture the public imagination in much the same way as it did in the Victorian period when explorers returned from the Arctic with tales of thick impenetrable ice, conveying the concept of the important role that the Arctic plays in global climate.TechnicalThe intellectual merit of this project stems from its ability to establish a link between the physical arctic system (circulation, sea ice, icebergs) and global climate. Numerical models have recently shown that freshwater sourced from the Arctic is twice as effective at disrupting climate than freshwater released from more southerly sources, but to the present the subject of freshwater and abrupt climate change has been dominated by discussion of meltwater floods emanating from glacial lake outbursts. Determining whether the export of sea ice and associated superimposed ice from the Arctic to the North Atlantic could supply enough freshwater to the Nordic Seas to cause the Earth's climate to cool will provide new insight into the mechanisms that trigger abrupt climate change. By quantifying the sensitivity of Atlantic meridional overturning circulation to arctic freshwater forcing the researchers will also be able to better examine whether changes in the arctic hydrological cycle in the near future (from sea ice melt and freshwater export from the Beaufort Gyre) pose a threat to the stability of modern-day climate and human society. In addition, the numerical model developed for this project will resolve ocean circulation, sea ice, and iceberg transport at a resolution approx. 0.17 degrees (ca. 19 km), 5-10 times higher than that of existing paleo-climate models, and have the capability of simulating narrow coastal boundary currents, shelf-breaks, and frontal zones important for freshwater transport along the continental margins, and other features not captured by the current generation of paleo-climate models.

非技术这项研究将通过识别过去可能引发的气候变化可能引发的是对海洋的古气候和古循环的基本问题。在十九世纪后期，乔治·纳雷斯爵士（Sir George Nares）遇到了15-18 m厚，不动，冰，距离北埃尔斯米尔海岸480公里。冰的特征与现在循环北极海的2-3 m厚的冰非常不同。从那时起，其他北极探险家的类似说明就可以洞悉肯定在整个冰川状况下在北极海洋上比我们今天看到的要厚得多，更持久的冰盖。实际上，在冰川期间，北极的低生物生产力，极低或不存在的沉积物沉积表明，中西部和西部北极海洋的一部分被非常厚的多年生冰覆盖。这项研究将探讨在冰川时期，这种冰如何覆盖大部分北极海洋，它的厚度是多么厚，以及它最终的动员和灭亡是否可以在北大西洋上产生淡水产量，足以削弱深水形成和触发突然的气候冷却。该组将使用一套精致的，高分辨率的数值模型实验，将解决这些问题，并强调北极水文周期的变化与全球气候的变化之间的联系。east研究者对教育和公众的宣传有一个认真的承诺，该项目将支持并培训研究研究人员在研究各个方面的研究生。每个研究者都通过进行演讲，聘请夏季的学生，指导科学博览会项目或为课程开发做出贡献，参与当地的中小学。他们将通过开发一种基于网络的，互动的，海冰学习工具来教育学生有关海冰形成背后的机制以及随着北极气候的温暖，冰的变化将如何变化，从而为正在进行的中学和高中科学教师培训活动做出贡献。此外，与当地社区组织的发展良好的关系将有助于促进公众对突然气候变化的理解。北极中厚海冰的想法具有出色的能力，可以与维多利亚时代的探险者以厚实的冰冰的故事从北极回来时，以与维多利亚时代的方式捕捉公众的想象力相同，从而使北极在全球气候中发挥着重要作用的重要作用的概念，这是在全球气候中发挥的。全球气候。最近已经显示，来自北极的淡水在破坏气候的有效性是从更南方释放的淡水造成的两倍，但是对于目前，淡水和突然的气候变化的主题源于对冰川洪水从冰川湖爆发中散发出的融合水洪水的讨论。确定从北极向北大西洋的海冰和相关叠加的冰的出口是否可以向北欧海洋提供足够的淡水，以使地球的气候冷却，从而为触发突然的气候变化的机制提供新的见解。通过量化大西洋子午倾斜循环对北极淡水的敏感性，迫使研究人员还将能够更好地检查在不久的将来的北极水文周期的变化（从Beaufort Gyre出口和淡水出口）是否对现代气候和人类社会的稳定构成威胁。此外，为该项目开发的数值模型将以大约分辨率解决海洋循环，海冰和冰山传输。 0.17度（约19公里），比现有的古气候模型高5-10倍，并且具有模拟狭窄的沿海边界电流，货架断裂和额叶区域的能力，对于沿着大陆边缘的淡水运输至关重要，以及当前一代古气候模型未捕获的其他特征。