Multicentury records of ENSO and rainfall in corals from northern Australia

该项目整合了全球环境变化的两个基本问题：热带气候变化和珊瑚礁活力。通过研究大堡礁北部偏远地区的珊瑚礁气候和珊瑚生长的历史，这项研究将说明该地区的气候在过去200多年里是如何变化的，以及珊瑚的生长是如何变化的。这个地区的珊瑚可以存活几个世纪，从上到下的长寿命珊瑚群的岩心显示了珊瑚在这段时间内的生长速度。珊瑚的骨骼化学可以追踪珊瑚生长的环境条件（温度、盐度、沉积）。因为珊瑚以每年一厘米或更多的速度生长，岩心可以以几周到几个月的规模取样，以确定短期（季节性）和长期（世纪）的生长和环境趋势。该项目利用了已经从澳大利亚北部回收的岩心，那里的温度和盐度与El Niño系统的状态密切相关。El Niño影响着世界各地的气候。这项研究将帮助气候科学家了解随着世界变暖，厄尔尼诺Niño是如何变化的，以及最近的强厄尔尼诺Niño事件是不寻常的，还是在自然行为的范围内。通过将气候记录与同一核心的珊瑚生长历史联系起来，该项目将帮助珊瑚生态学家从季节到世纪的时间尺度上看到气候变化与珊瑚生长速度之间的联系。这项研究包括与澳大利亚海洋科学研究所（AIMS）合作，该研究所为澳大利亚政府提供珊瑚礁管理和保护方面的建议。通过在AIMS度过一个夏天，研究生将获得有关珊瑚健康，生长和保护问题的高级经验，这些问题对于管理美国和国外的珊瑚礁至关重要。项目参与者将在亚利桑那大学从事跨学科的气候研究，包括气候模型分析、厄尔尼诺Niño的全球影响，并通过生物圈-2的公开演讲向更广泛的受众交流他们的工作。该项目的具体目标包括：-对珊瑚进行多世纪分季节测量&amp；#948；18O和Sr/Ca来定义该地区温度和盐度的自然变率及其与区域气候的关系；-提取El Niño和澳大利亚季风降雨的季节性特定历史，与其他记录进行比较，并评估长期变异性；-比较地球化学历史与发光和生长带性质，以评估作为环境变化代用物的一致性和敏感性；-利用珊瑚的多元资料，评估环境变化（海温、海温和沉积）与珊瑚生长（伸展、钙化）之间的关系；-将记录纳入更广泛的热带变率分析，例如长期变化和趋势、大尺度模式、多代理综合以及与GCM模拟的比较。这个项目代表了气候和珊瑚研究的重大进展。尽管珊瑚古气候学的历史悠久，但这将是第一次在亚季节、多世纪尺度上整合地球化学和生长带特征。多种古气候代理将产生广泛有用的El Niño和季风降雨重建，并揭示环境变化如何影响珊瑚生长。这些结果将纳入大规模综合，以提高对长期热带变率的认识。作为AIMS以科学为基础的保护使命的一部分，所有结果将与珊瑚礁管理者和其他利益相关者公开分享，并在亚利桑那州向通过亚利桑那大学生物圈-2的数千名游客展示。

This project integrates two fundamental issues of global environmental change, tropical climate variations and coral reef vitality. By developing linked histories of reef climate and coral growth on the remote northern Great Barrier Reef, this research will illustrate how the region's climate has changed over the past 200+ years and how coral growth has varied in response. Corals in this region can survive for centuries, and a core from the top to the bottom of a long-lived coral colony reveals annual banding that documents the rate of coral growth over that time. The coral's skeletal chemistry tracks the environmental conditions (temperature, salinity, sedimentation) under which the coral grew. Because the corals grow at a rate of a centimeter or more each year, cores can be sampled at a scale of weeks to months to determine short-term (seasonal) as well as long-term (century) trends in growth and environment. The project takes advantage of cores already recovered from northern Australia, where temperature and salinity are closely tied to the state of the El Niño system. El Niño influences climate around the world. This research will help climate scientists understand how El Niño is changing as the world warms and whether recent strong El Niño events are unusual or within the range of natural behavior. By linking the climate record to a history of coral growth from the same core, this project will help coral ecologists to see the connections between climate variations and coral growth rates from seasonal to century time scales. The research includes collaboration with the Australian Institute of Marine Sciences (AIMS), which advises the Australian government on reef management and conservation. By spending a summer at AIMS, a graduate student will receive high-level experience in issues of coral health, growth, and conservation that are critical for managing reefs here in the US as well as abroad. Project participants will engage in interdisciplinary climate research at the University of Arizona, including climate model analysis, the global impacts of El Niño, and communicating their work to a broader audience through public presentations at Biosphere-2. The specific goals of this project include the following:- Use multicentury, subseasonal measurements of coral δ18O and Sr/Ca to define the natural variability of temperature and salinity in this region, and their relationship to regional climate; - Extract seasonally specific histories of El Niño and Australian monsoon rainfall to compare with other records and evaluate for long-term variability; - Compare geochemical histories with luminescent and growth band properties to evaluate agreement and sensitivity as proxies for environmental change; - Use the multivariate information from corals to assess relationships among environmental variations (SST, SSS, and sedimentation) and coral growth (extension, calcification); - Incorporate records into broader analyses of tropical variability, e.g. long-term variations and trends, large-scale patterns, multiproxy syntheses, and comparisons to GCM simulations. This project represents a major advance in climate and coral studies. Despite the long history of coral paleoclimatology, this will be the first integration of geochemical and growth-band characteristics at a subseasonal, multicentury scale. Multiple paleoclimate proxies will yield broadly useful reconstructions of El Niño and monsoon rainfall and reveal how environmental changes influence coral growth. These results will be incorporated into large-scale syntheses to improve understanding of long-term tropical variability. All results will be publically shared with reef managers and other stakeholders, as part of the AIMS mission of science-based conservation, and presented in Arizona to the thousands of visitors that pass through the University of Arizona's Biosphere-2.