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; 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.

海平面的上升影响了世界各地的教练生态系统和社区。影响海平面上升的最重要因素之一是陆地表面的垂直运动。这些调整可能是由于冰川和冰盖的生长和腐烂引起的，这些冰川和冰盖通常位于数千公里之外。更好地理解这种冰原的互动 - 冰川等静态调整 - 可以改善对未来海平面上升的预测。这项研究将在弗吉尼亚州东岸沿着过去〜120，000年形成。重点是海平面接近或高于现在的时间。这些数据将为冰川等静止调整和冰盖变化的建模提供信息，以更好地量化全球冰盖生长和衰减的历史。这项研究将解决围绕过去的地区海平面和冰盖变化的问题。这项工作还可以改善冰川等静止调整对未来地区海平面上升的影响。此外，该项目将支持弗吉尼亚州Machipongo的科学家与非营利性障碍岛中心之间的合作。该合作将将科学团队的地质结果与该地区的当地社区知识相结合。这项工作将开发博物馆展览，重点是弗吉尼亚州东海岸的地质和物理历史。在最后一个冰川周期中，整个冰量的全球变化是对冰期气候变化的直接和敏感的测量。但是，区域（相对）海平面受到一系列局部因素的控制，其中主要是冰川等静态调整。在最后一个冰川周期中，海平面变化的历史上的重大不确定性以及冰川等静态调整的作用 - 高光是整个冰层增长阶段（120,000至26，000年前）对高质量和良好的海平面标记的需求。中场海平面的观察（沿着外围冰盖的外围球）有可能弥合全球海平面和局部连续冰原行为之间的理解差距，因为这些位置的相对海平面对附近冰盖的体积和范围的变化敏感，以及全球平均的海平面变化。该研究着眼于弗吉尼亚州（美国）的中场东岸，将首先分析高分辨率地形图和地下映射数据，将指示性含义分配给相关的保留的更新世沿海沉积物，并开发全面的地球人工学，以创造出色的本地，中场海平面的稳健地位，在最后一个冰计划的增长期间。然后，我们将使用一系列可能的冰载历史进行最新的海平面模拟，这些模拟涵盖了全球平均海平面和冰盖几何形状的不确定性范围，以便在这段时间内深入了解北美冰盖动态。在此过程中，这项研究将更好地量化全球冰盖生长和衰减的历史，并提高对气候强迫和冰盖动态之间联系的理解，并对全球eustatic和中场相对海平面产生相关的影响。此外，这项工作将支持2名博士学位学生和一个早期职业生涯的职业发展，并指导两个本科生研究项目。该项目将与非营利性障碍岛中心合作，以吸引当地社区分享专业知识，以帮助创建博物馆展览。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响审查标准来评估被认为是宝贵的支持。