Validation of the Strontium-Uranium Thermometer Against Instrumental Records of Ocean Temperature

人为的二氧化碳排放正在改变地球的气候。然而，气候也在几十年到几千年的时间尺度上自然变化。确定这种变异性对于量化人类活动的影响和预测未来的变化至关重要。海洋表面温度(SST)在气候中起着重要作用，但仪器记录的时间太短，无法对自然变异性进行有力的评估。从珊瑚骨架产生的替代数据有可能填补这些空白，但产生冗长的记录需要使用在仪器时代之前生长的死亡菌落，而现有的地球化学SST替代数据不太适合这一点。一种新的温度计，锶-U，已经被开发出来，用于非生物珊瑚，但对SST的校准需要测试。该项目试图通过重建红海中部的记录，并与该地区受良好约束的观测海温进行比较，来验证SR-U。一个成功的结果将使科学界受益，因为它将打开全球非生物珊瑚档案馆，用于SST重建。改进的SST重建将为用于预测未来海洋和气候变化的相同数值模式提供目标。珊瑚与珊瑚之间的地球化学变异是从非生物珊瑚重建SST的主要障碍，而锶-U是基于对造成这种变异的过程的充分理解。该项目将从红海中部现有的Porites珊瑚岩芯产生过去50年的锶/钙和铀/钙数据，并应用大西洋物种的定标来重建SST记录。该地区船舶交通繁忙，意味着卫星前的观测记录受到很好的限制。此外，红海海温过去50年的特点是十年变化叠加在长期变暖趋势上，因此是对锶-U捕捉未知珊瑚变化和趋势能力的理想测试。其目的是验证概念，展示锶-铀作为一种工具的普遍应用，利用现代珊瑚和化石珊瑚重建准确的SST记录。

Anthropogenic CO2 emissions are changing Earth's climate. Yet climate also varies naturally on timescales of decades to millennia. Characterizing this variability is critical to both quantifying the anthropogenic influence and projecting future change. Sea surface temperature (SST) plays a major role in climate yet the instrumental record is too short to enable a robust evaluation of natural variability. Proxy data generated from coral skeletons have potential to fill these gaps but generation of lengthy records requires use of dead colonies that grew before the instrumental era, for which existing geochemical SST proxies are not well-suited. A new thermometer, Sr-U, has been developed for application to non-living corals but the calibration to SST requires testing. This project seeks to validate Sr-U by reconstructing a record for the central Red Sea and comparing against well-constrained observational SSTs for the region. A successful outcome will benefit the scientific community by opening the global archive of non-living corals for SST reconstructions. Improved SST reconstructions will provide a target for the same numerical models used to predict future oceanographic and climate change.Coral-to-coral geochemical variability is a major obstacle to SST reconstructions from non-living corals and Sr-U is based on a robust understanding of the processes that cause this variability. This project will generate Sr/Ca and U/Ca data for the last 50 years from an existing Porites coral core sampled in the central Red Sea and apply a calibration derived from Atlantic species to reconstruct the SST record. Heavy ship traffic in the region means the pre-satellite observational record is well-constrained. Additionally, Red Sea SSTs over the last 50 years are characterized by decadal variability superimposed on a long-term warming trend, and thus present an ideal test of the ability of Sr-U to capture both variability and trends in an unknown coral. The goal is a proof-of-concept, to demonstrate the universal application of Sr-U as a tool with which to reconstruct accurate SST records using modern and fossil corals alike.