Collaborative Research: Ice sheet sensitivity in a changing Arctic system - using ice sheet observations and modeling to test the stable Greenland Ice Sheet hypothesis

合作研究：不断变化的北极系统中的冰盖敏感性——利用冰盖观测和建模来检验稳定的格陵兰冰盖假说

• 批准号: 1503281
• 负责人: Eric Steig
• 金额: $ 45.81万
• 依托单位: University of Washington
• 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 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1503281&HistoricalAwards=false
• 关键词: Collaborative; Research; Ice; sheet; sensitivity

NontechnicalThere is enough water in the Greenland Ice Sheet (GrIS) that, were it to melt, it would raise sea level in most coastal cities significantly with huge consequences for society. In the face of accelerated ice sheet contribution to sea level rise, it remains uncertain how the GrIS will adjust to a warming Arctic, declining sea ice and related changing precipitation patterns. This is a concern, given that future sea level rise is strongly dependent on the GrIS response to arctic change. The scientific community is currently undecided between a model of a dynamic GrIS that becomes greatly reduced during warm periods and a model where it is relatively stable, even through periods warmer than today. This proposal addresses the idea that increased arctic precipitation offsets GrIS mass loss during times of elevated temperature. The researchers will test this by contributing significant new information on arctic system change and related GrIS dynamics during past and ongoing warm periods, and employing an ice sheet modeling effort synthesizing all new data aimed at both past and future GrIS simulations. The researchers explicitly combine multiple scientific disciplines to provide a better understanding of how key arctic system components such as precipitation, temperature, sea-ice cover and GrIS mass balance are interconnected. The results will be of fundamental relevance to the fates of the arctic system, the GrIS and global sea level rise.This project will train six graduate students and one post-doctoral researcher. The cross-cutting research program is paralleled by the scope of the outreach plan, to develop a variety of deliverables, including development of an iBook and public outreach events. In addition the team will participate in public outreach events in Buffalo and New York City, where the public and scientists interact in a casual setting. Finally, this work has synergies with ongoing missions at NASA and other programs within the NSF.TechnicalDue to recent advances in numerical ice sheet models and new sub-ice topography of Greenland, combined with finely-tuned field approaches and geochronologic techniques, the time is ripe for a coordinated, cross-disciplinary effort focusing on cryosphere variability in a warming Arctic; the Greenland Ice Sheet (GrIS) and sea ice constitute the largest, and most critical components of the arctic cryosphere. The hypothesis that increased arctic precipitation can counterbalance GrIS mass loss during times of elevated temperatures stems from recent findings suggesting that it may be more stable than expected during interglacials. The researchers will: generate new GrIS margin reconstructions during and since the mid-Holocene Thermal Maximum (9,000 to 5,000 years ago), with a powerful approach that combines lake sediment stratigraphy with new sub-ice topography and novel high-sensitivity cosmogenic isotope methods; develop new Holocene climate reconstructions of moisture, temperature and sea ice conditions from lake and ocean sediments and an advanced synthesis of existing arctic ice core and other paleoclimate data; and employ state-of-the-art numerical ice sheet modeling fueled by ice margin and climate reconstructions to test a range of climatic and dynamic controls on GrIS change. If the idea is supported, then it would suggest a relatively stable GrIS during warm periods. If, however, this project provides evidence that the GrIS retreated considerably during the warmer-than-present mid-Holocene and in turn, that the GrIS has reacted more sensitively to temperature than to precipitation change, the results would support a tightly coupled ice sheet size-temperature link and in turn, a much greater near-term GrIS contribution to sea level rise. Either result will be of fundamental relevance to the fates of the arctic system, the GrIS and global sea level rise.

非技术性格陵兰冰原（GrIS）中有足够的水，如果融化，大多数沿海城市的海平面将显着上升，对社会造成巨大影响。面对冰盖对海平面上升的加速贡献，GrIS 将如何适应北极变暖、海冰减少以及相关降水模式的变化仍不确定。鉴于未来海平面上升很大程度上取决于 GrIS 对北极变化的反应，这是一个令人担忧的问题。科学界目前尚未决定是在温暖时期大大减少的动态 GrIS 模型还是即使在比现在更温暖的时期也相对稳定的模型。该提案提出了北极降水量增加抵消了气温升高期间 GrIS 质量损失的想法。研究人员将通过提供有关过去和当前温暖时期北极系统变化和相关 GrIS 动态的重要新信息来测试这一点，并采用冰盖建模工作综合针对过去和未来 GrIS 模拟的所有新数据。研究人员明确地将多个科学学科结合起来，以便更好地了解降水、温度、海冰覆盖和 GrIS 质量平衡等关键的北极系统组成部分如何相互关联。研究结果将对北极系统、GrIS和全球海平面上升的命运产生根本性影响。该项目将培养六名研究生和一名博士后研究员。跨领域研究计划与外展计划的范围并行，以开发各种可交付成果，包括开发 iBook 和公共外展活动。此外，该团队还将参加在布法罗和纽约市举行的公共外展活动，公众和科学家将在轻松的环境中互动。最后，这项工作与 NASA 正在进行的任务和 NSF 内的其他项目具有协同作用。技术由于数值冰盖模型和格陵兰岛新的冰下地形的最新进展，再加上微调的现场方法和地质年代学技术，时间是协调一致的跨学科努力的时机已经成熟，重点关注北极变暖中冰冻圈的变化；格陵兰冰盖（GrIS）和海冰构成了北极冰冻圈最大、最关键的组成部分。北极降水量增加可以抵消气温升高期间 GrIS 质量损失的假设源于最近的研究结果，表明在间冰期期间它可能比预期更稳定。研究人员将：采用将湖泊沉积物地层学与新的冰下地形和新颖的高灵敏度宇宙成因同位素方法相结合的强大方法，在全新世中期热最大值（9,000至5,000年前）期间和之后生成新的GrIS边缘重建；根据湖泊和海洋沉积物对水分、温度和海冰条件进行新的全新世气候重建，并对现有的北极冰芯和其他古气候数据进行高级综合；并采用由冰缘和气候重建推动的最先进的数值冰盖模型来测试对 GrIS 变化的一系列气候和动态控制。如果这个想法得到支持，那么这将表明温暖时期的 GrIS 相对稳定。然而，如果该项目提供证据表明 GrIS 在比现在更温暖的全新世中期大幅后退，反过来，GrIS 对温度的反应比对降水变化的反应更敏感，那么结果将支持紧密耦合的冰盖尺寸与温度的联系，反过来，近期 GrIS 对海平面上升的贡献更大。这两种结果都将对北极系统、GrIS 和全球海平面上升的命运产生根本性影响。