Climate and environmental change in the Andaman Sea since the late Little Ice Age: Sea surface temperature, hydroclimate, and coral response to thermal stress in the northeastern Indian Ocean (IndOC-E)

该项目通过在与社会相关的时间尺度上量化从仪器前时期到21世纪初的变暖期间的气候和环境变化，有助于更好地了解变暖世界中热带海洋气候变率及其对珊瑚礁生态系统的影响。这些都是“热带气候变率和珊瑚礁”优先方案（SPP 2299）的主要目标。该项目将通过分析浅水珊瑚骨骼中的同位素和地球化学指标，以超高分辨率重建小冰期晚期以来印度洋东北部的海洋气候和环境变化。建议以每月分辨率从南安达曼海（泰国）的Porites珊瑚中生成19世纪初（甚至18世纪初）的海面温度，水文（水文气候）和珊瑚对热应力的响应的重建。一个由于内波降温的缓和作用而不受海洋热浪强烈影响的地点将提供基于Sr/Ca和18O成对测量的海面温度和水文（水文气候）的代理记录。另一个受热浪影响不减的地点将根据Sr/Ca、18O、Mg/Ca、13C和生长模式测量的异常特征，提供珊瑚对热应激事件响应的代理记录。重建将能够研究不同El Niño的相互作用、印度洋偶极子、火山爆发和大振幅内波在调节小冰河期晚期以来安达曼海温度和水文的变动性和极端方面的相互作用，并对珊瑚生长、恢复力和亚洲季风水文极端产生影响。此外，将探讨历史海表温度产品对稀疏观测或方法变化时间间隔的验证，热带印度洋温度在19世纪早期出现的显著冷间隔，以及重建印度洋偶极子事件的潜力。重建将能够探索安达曼海珊瑚在过去几个世纪中是否暴露于热应激事件，以及由过去极端的印度洋东北部变暖（如1877/78年非常强烈的El Niño事件）导致的生态记忆是否导致近几十年热诱导应激事件中更高的温度耐受性。与一个配套项目一起，将在盆地东北和西部边缘研究小冰期晚期以来印度洋变暖和年际变率、盆地尺度差异以及与全球变暖和热带太平洋年际变率的关系。

This project contributes towards a better understanding of tropical marine climate variability and its impact on coral reef ecosystems in a warming world, by quantifying climatic and environmental changes during the warming from the pre-instrumental period to the early 21st century on timescales relevant for society. These are major aims of the Priority Programme “Tropical Climate Variability and Coral Reefs” (SPP 2299). The project will reconstruct marine climate and environmental change in the northeastern Indian Ocean since the late Little Ice Age at ultra-high resolution, by analysing isotopic and geochemical proxies in shallow-water coral skeletons. It is proposed to generate reconstructions of sea surface temperature, hydrology (hydroclimate), and coral response to thermal stress back to the early 1800s (or even early 1700s) at monthly resolution from Porites corals of the southern Andaman Sea (Thailand). A site not strongly affected by marine heatwaves because of the mitigating effect of cooling by internal waves will provide proxy records of sea surface temperature and hydrology (hydroclimate), based on paired measurements of Sr/Ca and 18O. Another site experiencing the unabated influence of heatwaves will provide a proxy record of coral response to thermal stress events, based on anomalous signatures in measurements of Sr/Ca, 18O, Mg/Ca, 13C, and growth patterns. The reconstructions will enable to study the interplay of different El Niño flavours, the Indian Ocean Dipole, volcanic eruptions, and large amplitude internal waves in modulating variability and extremes of Andaman Sea temperatures and hydrology since the late Little Ice Age, with implications for coral growth, resilience, and Asian monsoon hydrological extremes. Furthermore, the validation of historical sea surface temperature products for time intervals of sparse observations or method changes, the occurrence of a prominent early 19th century cold interval in tropical Indian Ocean temperature, and the potential for reconstructing Indian Ocean Dipole events will be explored. The reconstructions will enable to explore if Andaman Sea corals were exposed to thermal stress events during past centuries and if ecological memory, resulting from extreme northeastern Indian Ocean warmings of the past such as the very strong 1877/78 El Niño event, lead to higher temperature tolerance during thermally-induced stress events of recent decades. Together with a companion project, Indian Ocean warming and interannual variability since the late Little Ice Age, basin-scale differences, and relationships with global warming and tropical Pacific interannual variability will be studied at the basin’s northeastern and western rim.