Collaborative Research:Extracting Multi-century Low-latitude Sea Surface Temperatures from Coral Skeletons Using Replicated Records of Annual Growth: Method Refinement&Applicat

过去1000年全球气温的替代重建为理解最近的变暖趋势提供了一个背景，并允许更好地估计人为(温室气体)强迫对全球气候变化的贡献。大部分来自高纬度树木年轮记录的数据表明，20世纪末是上个千年最温暖的时期。然而，与这些估计相关的不确定性是显著的，特别是在被称为中世纪变暖的时期，该时期在约700年前结束。地球表面的温度变化？S最接近于全球热带地区的温度变化，那里75%是海洋；然而，来自低纬海洋的跨越过去1000年的数据集很少。为了改进全球温度重建和减少不确定性，迫切需要来自低纬海洋的良好复制的海表面温度记录。巨大的长寿珊瑚就像树上的生长轮一样，以每年一次的方式附生着碳酸钙骨骼，有可能提供这一信息。PIS最近应用了一种重建年度SST的方法，该方法利用了珊瑚骨骼生长与水温之间已证明的关系。在由3个珊瑚物种产生的多个记录中，珊瑚生长在年际和更长的时间尺度上捕获了仪器记录中SST变异性的50%-60%。将该方法应用于从巴哈马采集的长约440年的缓慢生长的珊瑚，表明SST在现代AD1550的误差范围内，小冰期SSTs比今天低约1℃，并且在过去50年的SSTs中存在着强烈的人为信号。PIS将在这项初步工作的基础上，重点改进从珊瑚生长记录中提取SST的方法，并将其应用于生成低纬大西洋和太平洋长达数世纪的替代SST记录。通过对完整珊瑚岩芯进行三维CAT扫描获得的数据相对快速和便宜，能够从每个地点的多个菌落产生许多不同长度的记录，并利用树状年代学中应用的技术，提供足够的数据，对重建的SSTs提供现实的误差估计。资金将支持3名PI，一名博士后研究科学家，一名博士生，以及一名本科生的研究经验。

Proxy reconstructions of global temperatures over the past 1000 years provide a context for understanding recent warming trends and allow better estimates of the contribution of anthropogenic (greenhouse gas) forcing to global climate change. Data compiled mostly from high latitude tree ring records suggest that the late 20th century was the warmest period of the last millennium. Nevertheless, the uncertainties associated with these estimates are significant, especially during the period known as the Medieval Warming which ended ~700 years ago. Temperature changes at the earth?s surface follow most closely those of the global tropics, which are 75% ocean; yet few datasets that span the last 1000 years exist from the low latitude oceans. In order to improve global temperature reconstructions and to reduce uncertainties, well-replicated records of sea surface temperature (SST) from the low-latitude oceans are urgently needed. Massive long-lived corals, which accrete calcium carbonate skeleton in annual bands like growth rings on a tree, have the potential to provide this information. The PIs have recently applied a method of reconstructing annual SST that takes advantage of the demonstrated relationship between the skeletal growth of corals and water temperature. In multiple records generated from 3 coral species, coral growth captures between 50-60% of the SST variability in the instrumental record, on interannual and longer timescales. Applying the method to a ~440-year long slow-growing coral collected from the Bahamas suggests that SSTs were within error of modern ~ AD1550, that Little Ice Age SSTs were about 1ºC cooler than today and that there is a strong anthropogenic signal in the SSTs of the last 50 years. The PIs will build on this initial work, focusing on refining the method of extracting SST from coral growth records and applying it to generate multi-century long proxy SST records for the low-latitude Atlantic and Pacific Oceans. Data acquisition by 3-D CAT scanning of intact coral cores is relatively rapid and inexpensive, enabling generation of many records of varying lengths from multiple colonies at each site, and, using techniques applied in dendrochronology, provide enough data to provide realistic error estimates on reconstructed SSTs. Funding will support 3 PIs, a post-doctoral research scientist, a PhD student, and research experience for an undergraduate.