Collaborative Research: P2C2--Constraints on Last Interglacial and Late Holocene Global Mean Sea Level and Fingerprinting Polar Ice Mass Flux from Broadly Distributed Coastal Caves

该项目旨在增进对全球平均海平面(GMSL)的了解，并确定冰盖和冰川对全球平均海平面变化的相对贡献。研究人员将利用保存在洞穴沉积物中的地质记录，从多个地点(地中海、尤卡坦半岛、菲律宾海)重建过去130.000年的大冰川历史，并研究过去温暖气候期间的海平面高地。由于世界上三分之一以上的人口生活在海岸线地区，评估该地区对未来海平面上升的脆弱性具有社会意义，需要了解过去海平面波动的幅度、速度和驱动因素，以便结合当前的趋势。这将通过海岸线矿物学记录提供的直接海平面估计来实现，即在部分淹没的洞穴上形成的海平面上的洞穴潜水过度生长。洞穴潜水过度生长(POS)是冰期关键时期，包括中上新世暖期、最后间冰期(LIG)和全新世晚期期间当地海平面变化的精确和准确的指标。该项目旨在分析现有的POS档案，并将其扩展到包括几个有希望的洞穴遗址。科学目标被概括在几个核心研究问题中：1)从LIG到全新世晚期，GMSL的时间变化是什么，GMSL峰值和全球变暖开始之间的相位是什么；2)主要极地冰盖对这种变化的相对贡献是什么，是否有半球遥相关的证据？以及3)相对于整个晚全新世GMSL的记录，GMSL的上升和加速异常程度如何？研究人员将开发一条几乎连续的GMSL曲线，用于气候变暖间隔，该曲线来自与最先进的统计和地球物理模型相关的高时间和垂直分辨率的POS观测。这些观测包括U系列年代学、高分辨率碳和氧稳定同位素分析以及矿物学和岩石学分析，以限制海平面高峰期的时间和持续时间。此外，冰川均衡调整(GIA)的数值模拟将用于修正GMSL记录，使其不受GIA的影响。潜在的更广泛的影响(包括更多的知识和更好地了解海平面上升的程度和驱动因素)。这对不同的科学界研究海平面、冰盖、地球气候和固体地球性质之间的关键关系具有直接意义。此外，新开发的知识将具有广泛的社会相关性，因为它可能使沿海社区、利益攸关方和政策制定者受益。该项目将为南佛罗里达大学、新墨西哥州大学和哈佛大学的研究生和本科生提供教育和研究培训，他们将参与跨学科研究的许多方面。此外，这项研究的结果将通过在各个项目机构的教学进行交流。研究人员将通过同行评议的出版物和在国内和国际会议上的介绍，与相关科学界传播项目成果。研究结果还将通过公开演讲、科普文章和媒体报道向更广泛的公众传播。将为所研究的洞穴的外联活动编写教育材料，包括水下图像和视频。在这个项目中收集的数据将被公之于众。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to advance the knowledge of global mean sea level (GMSL) and characterize the relative contribution of ice sheets and glaciers to GMSL variations. The researchers will use geological records preserved in cave deposits to reconstruct the GMSL history over the last 130.000 years from multiple locations (Mediterranean Sea, Yucatan Peninsula, Philippine Sea), and to study sea-level high stands during past warm climates. With over one third of the world’s population living within coastline regions, assessing the regional vulnerability to future-sea level rise is of societal relevance and requires an understanding of the magnitude, rate, and drivers of past sea level fluctuations to put current trends in context. This will be achieved by direct sea level estimates provided by coastline mineralogical records, namely phreatic overgrowth on speleothems which form at sea level on partly submerged caves.Phreatic overgrowths on speleothems (POS) are precise and accurate indicators of local sea level changes during critical periods of the ice age, including the Mid-Pliocene Warm period, the Last Interglacial (LIG) and the Late Holocene. This project aims to analyze existing POS archives and to expand this archive to include several promising cave sites. The scientific goals are encapsulated in several core research questions: 1) What is the temporal variability of GMSL from the LIG to the Late Holocene and what is the phasing between peak GMSL and the initiation of global scale warming; 2) What are the relative contributions of the major polar ice sheets to this variability and is there evidence of hemispheric teleconnections?; and 3) to what extent is the GMSL rise and acceleration anomalous relative to the record of GMSL across the Late Holocene? The researchers will develop a near continuous GMSL curve for climate warm intervals derived from high temporally and vertically well resolved POS observations linked to state of the art statistical and geophysical modelling. The observations include U-series chronologies, high-resolution stable isotope analyses of C and O, and mineralogical and petrographical analyses to constrain timing and duration of peak sea-level high stands. Additionally, numerical simulations of Glacial Isostatic Adjustment (GIA) will be used to correct GMSL record from the impact of GIA. The potential Broader Impacts (include a greater knowledge and a better understanding of the magnitude and drivers of sea level rise. This has direct implication for different scientific communities investigating key relationships between sea level, ice sheets, Earth’s climate, and properties of the solid earth. Further, the newly developed knowledge will be of a broad societal relevance as it will potentially benefit coastal communities, stakeholders, and policy makers. This project will provide education and research training for graduate and undergraduate students at the universities of South Florida, New Mexico and Harvard who will be involved in many aspects of the interdisciplinary research. Additionally, the results of this research will be communicated through teaching at the various project institutions. The researchers will disseminate the project findings with the relevant scientific communities via peer-reviewed publication and presentation at national and international conferences. The research finding will be also disseminated to the broader public through public presentations, popular science articles and media coverage. Educational material will be developed for outreach activities at the studied caves, including underwater images and videos. The data collected during this project will be made publicly accessible.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.