Collaborative Research: Reconstructing Pacific Trade Wind Variability-- Extending and Replicating a Promising New Coral Proxy

2000年至2014年间，尽管大气中的温室气体持续增加，但全球地表变暖明显放缓。气候模型和观察都表明，变暖的放缓或“中断”可能（至少部分）归因于热带太平洋的强劲信风。这些强风将热量输送到次表层海洋，留下更少的热量来温暖大气。由于风力强度在十年到十年的时间尺度上变化（与太平洋的自然变化有关），过去100年中其他加速和减缓变暖的时期可能与热带信风的这些变化有关。因此，在未来十年，当周期逆转，信风再次减弱时，变暖可能会加速。然而，我们对全球气温和热带太平洋风强度之间的联系的理解迄今为止一直受到历史风观测不足的限制。该项目将利用活珊瑚和化石珊瑚骨架中捕获的热带太平洋风变化的化学指纹，调查过去世纪和前工业化时代的风变化及其与全球气温的联系。该研究还将扩展这种新型风档案的应用，为将此类记录扩展到其他地点和时间段提供关键基础。 这些热带太平洋风强度的自然档案在最近的过去有可能大大提高我们对风的变化对全球气候变化率的影响的理解。该项目还将通过支持两名早期职业女性科学家，一名少数民族博士后研究员和两名本科生，共同开发促进种族，性别和LGBTQ多样性，公平和包容性的计划，为扩大科学的参与和多样性做出贡献。热带太平洋珊瑚记录大大提高了我们的海洋对气候强迫在过去一千年的变化的反应的理解，但我们的理解相关的大气响应仍然有限的（往往是间接和/或远程）水文代理解释的不确定性。该项目利用现有的现代和化石珊瑚芯和一个有前途的新珊瑚代用品，调查热带太平洋信风在自然和人为强迫变化中的变化。该项目将在塔拉瓦环礁建立西风异常和珊瑚骨骼Mn/Ca的开创性研究基础上，校准和扩展这一新的替代物，并将其扩展到各个地点（塔拉瓦、基里蒂马蒂、布塔里塔里和帕尔米拉）和时间段（世纪和小冰期/工业化前）。初步结果表明，珊瑚Mn/Ca从Kiritimati和Butaritari捕获西风在1997/98年厄尔尼诺事件期间在这些网站上观察到，支持风的变化和珊瑚Mn/Ca之间的因果关系，在环礁与西向泻湖，从而扩展Mn/Ca为基础的贸易风重建跨越空间和时间的潜力。该项目将利用赤道太平洋西部和中部的重叠现代珊瑚和化石珊瑚，对20世纪世纪和小冰期（LIA）至工业化前时期（1400- 1850 CE）的太平洋信风强度进行首次稳健、良好复制和定量重建。该项目还奠定了珊瑚锰/钙为基础的贸易风重建扩展到其他网站和时间段通过探索这种新的代理的优势和局限性的基础。这种信风重建有可能大大提高我们的理解信风的变化及其对全球气候变化的影响，以应对自然和人为强迫。

Global surface warming markedly slowed between 2000 and 2014 despite a continued increase in greenhouse gases in the atmosphere. Both climate models and observations suggest that this slowdown or "hiatus" in warming may be attributed (at least in part) to strong trade-winds in the tropical Pacific. These strong winds transport heat into the subsurface ocean, leaving less heat to warm the atmosphere. Because wind strength changes on a decade-to-decade timescale (associated with natural variability in the Pacific), other periods of both accelerated and reduced warming over the last 100 years are likely tied to these changes in tropical trade-winds. Thus, warming will likely accelerate in the coming decade(s) when the cycle reverses and trade-winds weaken once again. However, our understanding of the link between global air temperatures and tropical Pacific wind strength to date has been limited by the scarcity of historical wind observations. This project will utilize the chemical fingerprints of changes in tropical Pacific winds captured in the skeleton of living and fossil corals to investigate past wind variability - and its link to global air temperatures - across the past century and preindustrial era. The research will also extend the application of this novel wind archive, providing key groundwork for such records to be extended to additional sites and time periods. These natural archives of tropical Pacific wind strength over the recent past have the potential to dramatically improve our understanding of the impact of wind variability on the rate of global climate change. This project will also contribute to broadening participation and diversity in science by supporting two early career female scientists, a minority postdoctoral researcher and two undergraduates, who will together develop programs to promote race, gender, and LGBTQ diversity, equity and inclusion at Boston University. Tropical Pacific coral records have dramatically improved our understanding of the oceanic response to changes in climate forcing over the past millennium, but our understanding of the associated atmospheric response remains limited by uncertainties in the interpretation of (often indirect and/or remote) hydrological proxies. This project leverages existing modern and fossil coral cores and a promising new coral proxy to investigate tropical Pacific trade wind variability across changes in natural and anthropogenic forcing. Building off pioneering studies linking westerly wind anomalies and coral skeletal Mn/Ca at Tarawa Atoll, the project will calibrate and extend this new proxy across sites (Tarawa, Kiritimati, Butaritari, and Palmyra) and time periods (20th century and Little Ice Age/preindustrial). Initial results demonstrate that coral Mn/Ca from Kiritimati and Butaritari capture the westerly winds observed at these sites during the 1997/98 El Niño event, supporting the causal link between wind variability and coral Mn/Ca at atolls with west-facing lagoons, and thus the potential for extending Mn/Ca-based trade-wind reconstructions across space and time. This project will produce the first robust, well-replicated, and quantitative reconstructions of Pacific trade wind strength spanning the 20th century and Little Ice Age (LIA) to preindustrial period (1400-1850CE) using overlapping modern and fossil corals from the western and central equatorial Pacific. This project also lays the foundation for coral Mn/Ca-based trade-wind reconstructions to be expanded to other sites and time periods by exploring the strengths and limitations of this novel proxy. Such trade-wind reconstructions have the potential to dramatically improve our understanding of trade-wind variability and its impact on global climate change in response to both natural and anthropogenic forcings.