Intermediate Water Records of Radiocarbon and Temperature Variability from the North Atlantic and Southern Ocean Using Deep-Sea Corals.

放射性碳是了解海洋环流和气候过去变化的一个成熟工具。然而，最近对中间水深（海平面以下约500至2，000米）的放射性碳的研究产生了从末次冰期最大期（LGM）到全新世过渡期间海洋行为的相互矛盾的说法。这个项目由加州理工学院的一位教授领导，试图通过使用北大西洋和南大洋的深海珊瑚化石产生过去30 000年新的中深度放射性碳记录来解决这个问题。这种方法相对于测量沉积物岩心中浮游生物的一个关键优势是有机会进行铀系年龄控制。此外，珊瑚化石样本有助于在冰川消融过渡的关键时期收集高分辨率的测量数据。对于一部分样本，将把代用温度数据（来自成团同位素）与放射性碳含量进行比较，以便更好地分辨中层和深层水团特征的变化。将使用简单的模型为数据分析的结果提供一个定量框架，这项研究将促进对海洋环流在冰川时间尺度上气候变化中的作用的理解。样本将通过正在开发的加州理工学院深海珊瑚数据库广泛提供，该数据库已被世界各地的科学家使用。研究人员将继续与NOSAMS（国家海洋科学质谱设施）合作，开发珊瑚和其他碳酸盐放射性碳年代测定的快速和廉价技术。研究人员还将继续为当地学校和组织以及更广泛的公众开展气候科学宣传工作。资金将支持一名女研究生。

Radiocarbon is a well-established tool for understanding past changes in ocean circulation and climate. However, recent studies of radiocarbon from intermediate water depths (~500 to 2,000 meters below sea level) have produced conflicting accounts of ocean behavior during the transition from the Last Glacial Maximum (LGM) to the Holocene. This project, led by a professor at the California Institute of Technology, seeks to resolve this problem by generating a new intermediate-depth radiocarbon record for the last 30,000 years using fossil deep-sea corals from the North Atlantic and Southern Oceans. A key advantage of this approach over measurements of plankton in sediment cores is the opportunity for uranium-series age control. Furthermore, fossil coral samples enable the collection of high-resolution measurements during key periods in the deglacial transition. For a subset of samples, proxy temperature data (from clumped isotopes) will be compared to radiocarbon content in order to better resolve changes in intermediate and deep water mass characteristics. Simple models will be used to provide a quantitative framework for the results of data analyses.This study will advance understanding of the role of ocean circulation in climate change on glacial time scales. Samples will be made broadly available through the developing CalTech deep-sea coral database, which is already in use by scientists from around the world. The investigator will continue collaboration with NOSAMS (National Ocean Sciences Mass Spectrometry Facility) to develop rapid and inexpensive techniques for radiocarbon dating of corals and other carbonates. The investigator will also continue ongoing climate science outreach efforts for local schools and organizations, as well as the broader public. Funding will support a female graduate student.