EAR-PF: Detecting dynamic topography in interglacial Caribbean sea level

大约12万年前的温暖期是地球全球气候最后一次比现在更温暖的时期，也是地球在更温暖的未来可能的样子的一个例子。在这段时间里，冰盖比现在小，导致平均海平面上升。海平面上升的地质证据包括构成佛罗里达群岛的珊瑚礁化石，以及加勒比海地区和其他地方的类似特征。然而，这些地质记录表明，在这个温暖时期达到的最高海平面在世界各地是不同的。本研究旨在揭示这一时期海平面空间变异的各种影响因素。特别是，本研究试图确定地幔动态地形的影响，即地幔流动对地球表面的变形，对海平面的影响。通过更好地约束影响海平面的不同因素，本研究将提高科学家对海平面变化的空间格局和冰盖对气候变化的敏感性的认识。这些进展将帮助科学家更好地预测气候变暖下未来的海平面。更广泛地说，这项研究将阐明南佛罗里达景观在12万年前温暖时期在浅海条件下形成的条件，以及它面临的持续和未来海平面上升的风险。该项目包括一个教育部分，以提高人们对人口稠密的迈阿密地区的地质历史和未来气候风险的认识，该地区将进行这项研究。海平面上升是一个全球迫切关注的问题，但无论是冰盖对变暖的敏感性，还是海平面变化的空间变化模式，都存在着很大的不确定性。对过去海平面变化的研究可以限制这两个组成部分。本项目旨在限制地幔动力地形对大加勒比地区12万年前末次间冰期海平面时空变化的影响。这是最近一次全球平均海平面高于现在，因此可以告诉科学家海平面如何在未来变暖的地球上变化。然而，过去和未来的海平面受到空间变化的固体地球变形的影响，包括由地幔流动引起的动态地形。为了提高对这一过程的科学认识，该项目将把数值模拟与地质海平面数据结合起来。该项目的第一个组成部分是开发高分辨率的全球地幔流动模型，以预测整个大加勒比地区动态地形变化的幅度和速率。第二部分是编制区域间冰期海平面指标综合数据集，揭示整个区域海平面的空间变化趋势。通过将这些数据与模拟结果和已发表的冰川均衡调整预测相结合进行统计反演，本项目将估算末次间冰期的动态地形变化及其对整个区域和全球平均海平面空间变异的贡献。这些结果将提高科学家对海平面变化的空间变异性以及冰盖和全球平均海平面对气候变化的敏感性的认识。该项目还包括一项公众教育活动，以提高人们对人口稠密的南佛罗里达景观的海洋起源的认识，该景观形成于最后一次间冰期，以及该地区海平面上升的危害。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The warm period ~120,000 years ago was the last time that Earth’s global climate was warmer than the present and is an example of what the Earth might look like in a warmer future. During this time, ice sheets were smaller than today, causing higher mean sea levels. Geologic evidence for higher sea levels includes the fossil coral reefs that make up the Florida Keys, and similar features throughout the Caribbean region and elsewhere. However, these geologic records indicate that the maximum sea level reached during this warm period was different in different places around the world. This study aims to unravel the various contributing factors to the spatial variability in sea level during this time. In particular, this research seeks to identify the influence of mantle dynamic topography, the deformation of Earth’s surface by the flow of Earth’s mantle, on sea level. By better constraining the different factors affecting sea level, this research will improve scientists’ understanding of spatial patterns of sea-level change and the sensitivity of ice sheets to climate change. These advances will help scientists better predict future sea levels under a warming climate. More broadly, this research will illuminate the conditions under which the South Florida landscape was formed under shallow marine conditions during the warm period 120,000 years ago, and the risks it faces from ongoing and future sea-level rise. This project includes an educational component to raise awareness of the geologic history and future climate risks the densely populated Miami region where this research will be performed.Sea-level rise is a globally pressing concern, but substantial uncertainty exists with both the sensitivity of ice sheets to warming and in the patterns of spatially variable sea-level change. Both components can be constrained by the study of past sea-level change. This project seeks to constrain the influence of mantle dynamic topography on spatio-temporal variations in sea level in the greater Caribbean region during the last interglacial period, ~120,000 years ago. This was the most recent time that global mean sea level was higher than present, and thus can inform scientists’ understanding of how sea level might change on a future warmer earth. However, past and future sea level are influenced by spatially variable solid earth deformation, including the dynamic topography resulting from mantle flow. To improve scientific understanding of this process, this project will combine numerical modeling with geologic sea-level data. The first component of the project is the development of high-resolution global models of mantle flow, which predict the magnitude and rate of change of dynamic topography across the greater Caribbean region. The second component is the compilation of a regionally comprehensive dataset of interglacial sea level indicators to reveal spatial trends in sea level across the region. By combining these data with modeling results and published glacial isostatic adjustment predictions in a statistical inversion, this project will estimate the dynamic topography change and its contribution to spatial variability in sea level across the region and global mean sea level at the last interglacial. These results will improve scientists’ understanding both of spatial variability in sea-level change and of the sensitivity of ice sheets and global mean sea level to changes in climate. This project also includes a public education campaign to increase awareness of the marine origins of the populous South Florida landscape, formed during the last interglacial period, and of the hazards of sea-level rise in the region.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.