Collaborative Research: Unraveling North American Ice-Sheet Dynamics and Regional Sea-Level Change along the U.S. Mid-Atlantic over the Last Glacial Cycle

合作研究：揭示末次冰期期间北美冰盖动力学和美国大西洋中部沿线区域海平面变化

• 批准号: 2244721
• 负责人: Christopher Hein
• 金额: $ 29.95万
• 依托单位: College of William & Mary Virginia Institute of Marine Science
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2244721&HistoricalAwards=false
• 关键词: Collaborative; Research; Unraveling; North; American

Rising sea levels impact coastal ecosystems and communities around the world. One of the most important factors influencing sea level rise locally is the vertical movement of the land surface. These adjustments can be caused by the growth and decay of glaciers and ice sheets which are often located thousands of kilometers away. A better understanding of this ice-land interaction—termed glacial isostatic adjustment—can improve predictions of future sea-level rise. This study will map and date shoreline deposits along the Eastern Shore of Virginia that were formed over the last ~120,000 years. The focus is on times when sea level was near to, or higher than present. These data will inform modeling of glacial isostatic adjustment and ice-sheet changes to better quantify the history of global ice sheet growth and decay. This research will address questions surrounding past regional sea-level and ice-sheet changes over the last glacial period. The work may also improve projections of the effect of glacial isostatic adjustment on regional sea-level rise into the future. Additionally, this project will support collaboration between the scientists and the non-profit Barrier Islands Center in Machipongo, Virginia. The collaboration will combine the geological results from the science team with local community knowledge of the region. This work will develop museum exhibits focused on the geology and physical history of the Virginia Eastern Shore. Global variations in ice volume through the last glacial cycle are a direct and sensitive measure of ice age climate change. However, regional (relative) sea level is controlled by a suite of local factors, primary among which is glacial isostatic adjustment. Significant uncertainty in the history of sea-level changes during the last glacial cycle—and the role of glacial isostatic adjustment in those—highlights the need for high-quality and well-dated sea-level markers across the ice-sheet growth phase (120,000 to 26,000 years ago). Mid-field sea-level observations (along the peripheral bulge of ice sheets) have the potential to bridge gaps in understanding between global sea level and local continental ice-sheet behavior, since relative sea level at these locations is sensitive to changes in the volume and extent in nearby ice sheets, as well as globally averaged sea-level changes. Focusing on the mid-field Eastern Shore of Virginia (USA), this study will first analyze high-resolution topographic and subsurface mapping data, assign indicative meanings to associated preserved Pleistocene coastal deposits, and develop a comprehensive geochronology to create a robust local, mid-field sea-level record over the period of growth of the last ice sheet. We will then perform state-of-the-art sea-level simulations using a range of possible ice-loading histories, which span the range of uncertainty on global mean sea level and ice-sheet geometries in order to gain insight into North American ice-sheet dynamics over this time period. In doing so, this study will better quantify the history of global ice sheet growth and decay and improve understanding of linkages between climate forcings and ice-sheet dynamics, with associated impacts on global eustatic, and mid-field relative sea level. Furthermore, this work will support the career development of 2 PhD students and an early-career PI, and mentor two undergraduate student research projects. The project will enable a collaboration with the non-profit Barrier Islands Center to engage the local community to share experiential knowledge to help create a museum exhibit.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.

海平面上升影响世界各地的沿海生态系统和社区，影响当地海平面上升的最重要因素之一是陆地表面的垂直运动，这些变化通常是由冰川和冰盖的生长和衰退引起的。更好地了解这种冰地相互作用（称为冰川均衡调整）可以改善对未来海平面上升的预测。这项研究将绘制弗吉尼亚东海岸沿线形成的海岸线沉积物的地图和日期。最后的〜120,000 年。这些数据将为冰川均衡调整和冰盖变化建模提供信息，以更好地量化全球冰盖生长和衰退的历史。该项目将解决有关上一个冰川时期过去区域海平面和冰盖变化的问题，这项工作还可能改善冰川均衡调整对未来区域海平面上升影响的预测，此外，该项目还将支持之间的合作。科学家们和弗吉尼亚州马奇蓬戈的非营利性屏障群岛中心的合作将把科学团队的地质成果与当地社区的知识结合起来，这项工作将开发专注于弗吉尼亚州地质和自然历史的博物馆展品。东海岸：最后一个冰川周期的全球冰量变化是冰期气候变化的直接而敏感的衡量标准，然而，区域（相对）海平面受一系列当地因素控制，其中主要是冰川均衡调整。重要的上一次冰川周期期间海平面变化历史的不确定性，以及冰川均衡调整在其中的作用，凸显了在整个冰盖生长阶段（120,000到26,000 年前）中场海平面观测（沿着冰盖的外围隆起）有可能弥合全球海平面和当地大陆冰盖行为之间的理解差距，因为相对而言。这些地点的海平面对附近冰盖的体积和范围的变化以及全球平均海平面变化很敏感，本研究将首先分析弗吉尼亚州东海岸的中场。我们将利用高分辨率地形和地下测绘数据，为相关保存的更新世沿海沉积物赋予指示意义，并开发全面的地质年代学，以创建最后一个冰盖生长期间的可靠的当地中场海平面记录。然后执行使用一系列可能的冰加载历史进行最先进的海平面模拟，涵盖全球平均海平面和冰盖几何形状的不确定性范围，以便深入了解北美冰盖动态在此期间，这项研究将更好地量化全球冰盖生长和衰退的历史，并增进对气候强迫和冰盖动态之间联系的理解，以及对全球海平面上升和中场相对海平面的相关影响。 .此外，这项工作将支持职业发展该项目将与非营利性屏障群岛中心合作，吸引当地社区分享经验知识，帮助创建博物馆展览。授予 NSF 的法定使命，并通过评估反映使用基金会的智力优点和更广泛的影响审查标准，被认为值得支持。