Collaborative Research: P2C2 - Reconstructing rates and sources of sea-level change over the last ~150 thousand years from a new coral database

合作研究：P2C2 - 从新的珊瑚数据库重建过去约 15 万年海平面变化的速率和来源

• 批准号: 1702684
• 负责人: Jerry Mitrovica
• 金额: $ 6.81万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-15 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1702684&HistoricalAwards=false
• 关键词: Collaborative; Research; P2C2; Reconstructing; rates

COLLABORATIVE RESEARCH: RECONSTRUCTING RATES AND SOURCES OF SEA LEVEL CHANGE OVER THE LAST ~150 THOUSAND YEARS FROM A NEW CORAL DATABASE Future sea level rise, driven by shrinking land ice and ocean warming, threatens coastal populations, economic activity, infrastructure, and ecosystems around the world. Data on past sea level positions are critical for understanding how sensitive sea level and ice sheets are to temperature change. Paleo-sea level records come from several different sources. For time periods older than about 4000 years, some of the records with the best vertical resolution and most precise ages come from coral reefs, which grow at distinctive elevation ranges with respect to mean sea level.During the Last Interglacial stage, about 125,000 years ago, global average sea-surface temperature peaked around its current level, while analyses of corals and other proxies indicate global mean sea level peaked about 6-9 m higher than today. This magnitude of sea level rise - implying considerably smaller ice sheets in Greenland and West Antarctica - hints at the long-term commitment current warming has imparted to future sea level rise. The researchers in this project will use the coral sea level database to better understand rates of sea level and ice-sheet change over time, and how these rates relate to changes in the global climate. The knowledge gained will contribute to work by this team and others in the research community on future sea level projections. The project will provide a graduate student and a postdoctoral researcher with interdisciplinary training in oceanography, geology, geophysics and statistics. It will also synthesize a global reconstruction of sea-level over the last 150,000 years, and associated numerical methods for producing this reconstruction, that can be broadly used by the research community. This project focuses on four basic questions: (1) How much did global mean sea level vary over time, and how do local, relative sea levels vary in space, over this time period? (2) How fast did global mean sea level change during the last 150,000 years, and what was the relationship between changes in sea level and changes in temperature? (3) Can the spatial patterns of sea level change be used to separate the contributions of different ice sheets to global mean sea level change? (4) How does global mean sea level reconstructed using corals compare to other continuous records of sea level and climate change? To address these questions, the researchers will: (1) develop emulators of geophysical models of glacio-isostatic adjustment and mantle dynamic topography in order to estimate the contribution of different ice sheets to sea level change, (2) refine the history of seawater uranium isotope compositions that are important to interpreting accurate ages from U-Th-dated corals, and (3) incorporate ecological data about the relationship between coral growth position and sea level into a spatio-temporal statistical framework that links together the coral database and the geophysical models. The application of these techniques to the coral database for the last 150,000 years will provide a uniquely high-precision, continuous record of global mean sea level variability over this time period. This reconstruction will enable a more precise estimate of the magnitude of global mean sea level variability and rates of global mean sea level change, and should allow discrimination between global mean sea level contributions from North American and Arctic sources and those from Antarctic sources. These reconstructions will provide data with which to test the ice sheet models used to project future changes in addition to supporting the career development of a postdoctoral scholar and the training of a Ph.D. student.

合作研究：从一个新的珊瑚数据库重建过去~ 15万年海平面变化的速率和来源未来海平面上升，由陆地冰萎缩和海洋变暖驱动，威胁着世界各地的沿海人口，经济活动，基础设施和生态系统。过去海平面位置的数据对于了解海平面和冰盖对温度变化的敏感程度至关重要。古海平面记录来自几个不同的来源。对于4000年以上的时间段，一些具有最佳垂直分辨率和最精确年龄的记录来自珊瑚礁，珊瑚礁生长在相对于平均海平面的独特海拔范围内。在大约125，000年前的末次间冰期，全球平均海面温度达到目前水平的峰值，而对珊瑚和其他代用品的分析表明，全球平均海平面最高时比今天高出约6-9米。海平面上升的幅度--这意味着格陵兰岛和南极洲西部的冰盖要小得多--暗示了当前变暖对未来海平面上升的长期影响。该项目的研究人员将利用珊瑚海平面数据库更好地了解海平面和冰盖随时间的变化率，以及这些变化率与全球气候变化的关系。所获得的知识将有助于该小组和研究界其他人在未来海平面预测方面的工作。该项目将为一名研究生和一名博士后研究员提供海洋学、地质学、海洋物理学和统计学方面的跨学科培训。它还将综合过去15万年来全球海平面的重建，以及用于产生这种重建的相关数值方法，这些方法可以被研究界广泛使用。该项目主要关注四个基本问题：（1）全球平均海平面随时间变化的程度，以及在这段时间内，局部相对海平面在空间上的变化情况？(2)在过去的15万年里，全球平均海平面变化的速度有多快，海平面变化与温度变化之间的关系是什么？(3)海平面变化的空间格局能否用来区分不同冰盖对全球平均海平面变化的贡献？(4)使用珊瑚重建的全球平均海平面与其他海平面和气候变化的连续记录相比如何？为了解决这些问题，研究人员将：（1）开发冰川均衡调整和地幔动态地形地球物理模型的仿真器，以估计不同冰盖对海平面变化的贡献，（2）完善海水铀同位素组成的历史，这对解释U-Th定年珊瑚的准确年龄很重要，及（3）把珊瑚生长位置与海平面之间关系的生态数据纳入一个时空统计框架，把珊瑚数据库和地球物理模型连接起来。将这些技术应用于过去15万年的珊瑚数据库，将提供这一时期全球平均海平面变化的独特的高精度连续记录。这一重建将能够更精确地估计全球平均海平面变化的幅度和全球平均海平面变化率，并应能够区分北美和北极来源与南极来源对全球平均海平面的贡献。这些重建将提供数据来测试用于预测未来变化的冰盖模型，此外还将支持博士后学者的职业发展和博士的培训。学生.