Indian Ocean warming from the peak of the Little Ice Age to the 21st century: Zanzibar Island, Western Indian Ocean (IndOC-W)

从小冰期高峰期到 21 世纪印度洋变暖：西印度洋桑给巴尔岛 (IndOC-W)

• 批准号: 468545267
• 负责人: Professorin Dr. Miriam Pfeiffer
• 金额: --
• 依托单位: Arbeitsgruppe Paläontologie - Historische Geologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/468545267?language=en
• 关键词: Indian; Ocean; warming; peak; Little

The Indian Ocean, which gathers one-third of the world’s population around its rim, has been warming faster than any other ocean basin during the 20th century and is strongly coupled to global mean temperatures. The mechanisms underlying this steady warming are not fully understood, in part due to uncertain/sparse historical temperature data, but the current rise in atmospheric CO2 clearly plays an important role. Indian Ocean warming affects the hydrology in the countries around its rim and threatens coral reef ecosystems, which experienced repeated thermal stress events that caused coral bleaching and mass mortality. These thermal stress events are caused by year-to-year modes of climate variability inherent in the Indo-Pacific. It is therefore vital to reconstruct Indian Ocean sea surface temperatures beyond the period influenced by anthropogenic forcing, in order to determine the onset of Indian Ocean warming and its relationship with global surface temperatures in the pre-industrial. Massive-growing tropical corals such as Porites form annual growth bands and preserve geochemical proxies of sea surface temperature (SST) and hydrology in their aragonite skeletons. Replicated, multi-core coral chronologies from the tropical Indian Ocean can provide SST reconstructions (including uncertainties) that extend over several centuries and can be used to evaluate historical temperature trends, the onset of anthropogenic warming and its impact on hydrology and coral growth. IndOC-W aims to analyse a large set of long-lived massive Porites corals from Zanzibar Island to establish the first multi-core Sr/Ca-SST reconstruction from the tropical Indian Ocean that covers more than 300 years and extends into the coldest interval of the Little Ice Age. In addition, we will measure coral δ18O in selected time windows to investigate the impact of extreme temperatures in the Indian Ocean on hydrology in equatorial East Africa. In addition, this study will be the first to assess the impact of past thermal stress events on trace element signatures in Porites skeletons by using a new LA-ICP-OES/MS technique that will be developed at Kiel University. In a companion project (IndOC-E), T. Felis will reconstruct eastern Indian Ocean temperature and hydrology using corals from the Andaman Sea. Results of IndOC-W and IndOC-E allow us to estimate (I) the basin-scale warming of the Indian Ocean from the Little Ice Age to the present and (II) spatial variations in warming rates relative to the basin mean. This is crucial to assess the impact of Indian Ocean warming on hydrology in the countries bordering the Indian Ocean and to validate climate model results. Our project significantly contributes to the overall scientific mission of the SPP 2299, namely to “understand the interaction between global climate change and modes of tropical climate variability, and their combined impact on coral reef ecosystems and tropical societies in a warming world.”

印度洋的边缘聚集了世界上三分之一的人口，在20世纪，它变暖的速度比其他任何海洋盆地都要快，并且与全球平均气温密切相关。这种稳定变暖背后的机制尚不完全清楚，部分原因是历史温度数据不确定/稀疏，但目前大气中二氧化碳的上升显然起着重要作用。印度洋变暖影响了其周边国家的水文，并威胁到珊瑚礁生态系统，这些生态系统经历了反复的热应激事件，导致珊瑚白化和大量死亡。这些热应力事件是由印度-太平洋固有的年度气候变化模式引起的。因此，重建受人为强迫影响时期之后的印度洋海面温度至关重要，以便确定工业化前印度洋变暖的开始及其与全球表面温度的关系。大量生长的热带珊瑚，如孔隙石，形成了年生长带，并在文石骨架中保存了海表温度和水文的地球化学指标。来自热带印度洋的复制的多核珊瑚年表可以提供几个世纪以来的海温重建（包括不确定性），并可用于评估历史温度趋势、人为变暖的开始及其对水文和珊瑚生长的影响。IndOC-W的目标是分析来自桑吉巴尔岛的大量长寿的Porites珊瑚，以建立第一个来自热带印度洋的多核Sr/Ca-SST重建，该重建覆盖了300多年，并延伸到小冰河期最冷的时期。此外，我们将在选定的时间窗内测量珊瑚δ18O，以研究印度洋极端温度对赤道东非水文的影响。此外，这项研究将首次使用基尔大学开发的新的LA-ICP-OES/MS技术来评估过去热应力事件对Porites骨架中微量元素特征的影响。在一个伙伴项目（IndOC-E）中，T. Felis将利用安达曼海的珊瑚重建东印度洋的温度和水文。IndOC-W和IndOC-E的结果使我们能够估计(I)从小冰期到现在印度洋的海盆尺度变暖，（II）相对于海盆平均变暖速率的空间变化。这对于评估印度洋变暖对印度洋沿岸国家水文的影响以及验证气候模型的结果至关重要。我们的项目对SPP 2299的整体科学使命做出了重大贡献，即“了解全球气候变化与热带气候变率模式之间的相互作用，以及它们在变暖世界中对珊瑚礁生态系统和热带社会的综合影响”。