IODP Expedition 363 Objective Research: Evolution of the Indo-Pacific warm pool and deep Pacific circulation during major global climate transitions since the latest Miocene

由于世界海洋吸收、储存和释放热量和碳的能力巨大，研究海洋在全球气候变化和全球碳循环中的作用至关重要。印度-太平洋暖池是世界上最大的表层非常温暖的海洋温度群-S海洋和大气的最大能量和水分来源；因此，它与大气环流、降雨模式和全球气候密切相关。在表层海洋之下是深海太平洋，这是世界上最大的盆地？S海洋，具有巨大的碳和热量储存能力。因此，它在碳循环、热量传输和全球气候变化中发挥着关键作用。尽管对现代气候条件的研究清楚地表明，全球变暖和太平洋深海是气候系统的重要组成部分，但对于这些地区如何应对和参与长期的全球气候变化，特别是在全球变暖的情况下，仍有许多不清楚的地方。为了探讨这些话题，这个项目聚焦于过去的地质时代，当时全球气候与今天有很大的不同。该项目将涉及UCSC的一名博士后学者和至少十名本科生，从而为早期职业科学家和寻求STEM领域培训的本科生提供关键的培训和指导。将特别关注本科生参与原创研究和招募不同的研究团队。本项目将调查上新世早期暖期和向更新世寒冷冰期气候的过渡。这一时间间隔(600万年前)对我们对暖期和重大长期气候过渡期间气候行为的理解提供了有价值的测试。为此，2016年10月6日至12月8日，国际海洋发现计划363(IODP Exp 363)在IPWP地区的9个地点采集了约7公里的沉积物。作为与其他IODP Exp 363船上科学家的国际合作努力的一部分，该项目将实现IODP Exp 363的两个主要目标。首先，为了检验即使在全球气候发生重大变化时IPWP是稳定的零假设，将生成几个IPWP站点(U1482/3和U1488)过去6个月的浮游有孔虫表面和次表层镁/钙温度估计。这些地点之间的比较，以及与其他温度替代测量的比较，对于评估替代偏差、温跃层的作用以及印度洋-太平洋贯穿流对IPWP演变的影响至关重要。其次，为了验证在中新世末期和上新世暖期存在北太平洋深水形成的观点，将在西太平洋的两个站点(U1488和U1489)产生海底有孔虫同位素记录。与太平洋其他地方公布的海底同位素数据进行比较，并与建模模拟进行比较，将把这些新的测量结果放在全球范围内。这些数据也将对开发高分辨率年龄模型至关重要，为其他研究岩心的研究人员提供了一个关键框架。总体而言，该项目的成果将与其他考察队363名科学家以及海洋和气候模型师产生的数据结合在一起，以便从机制上更深入地了解印度洋-太平洋区域在全球气候进程中的作用。此外，它还将确定北太平洋深水是否在过去的暖期形成并对全球热量输送做出了贡献。

Because of the enormous capacity of the world?s oceans to absorb, store, and release heat and carbon, it is critically important to study the role of the oceans in global climate change and in the global carbon cycle. The Indo-Pacific warm pool (IPWP) is the largest mass of very warm surface ocean temperatures (≥28˚C) of the world?s oceans and the biggest source of energy and moisture to the atmosphere; as such, it is intimately linked to atmospheric circulation, rainfall patterns, and global climate. Beneath the surface ocean is the deep Pacific, which is the largest basin of the world?s ocean with enormous capacity to store carbon and heat. Thus, it plays a critical role in the carbon cycle, in heat transport, and in global climate change. Although it is clear from studies of modern conditions that the IPWP and the deep Pacific are crucial components of the climate system, there is a lot that is not understood about how these regions respond to, and participate in, long term global climate change especially in a warming world. To probe these topics, this project is focused on past geological epochs when global climate was dramatically different than today. This project will involve a post-doctoral scholar and at least ten undergraduates at UCSC, thereby providing critical training and mentoring for an early career scientist and for undergraduates seeking training in STEM fields. There will be special attention placed on undergraduates being involved in original research and in recruiting a diverse team of researchers.This project will investigate the early Pliocene warm period and the transition to the cold Ice Age climate of the Pleistocene. This time interval (6 ? 0 million years ago) provides valuable tests of our understanding of the behavior of the climate during warm periods and during major long-term climate transitions. To this end, from Oct. 6 to Dec. 8, 2016, the International Ocean Discovery Program Expedition 363 (IODP Exp 363) recovered ~7 km of sediment from nine sites in the IPWP region. As part of an international collaborative effort with other IODP Exp 363 shipboard scientists, this project will achieve two of the primary objectives of IODP Exp 363. First, to test the null hypothesis that the IPWP was stable even while there were major changes in global climate, planktonic foraminifera surface and subsurface Mg/Ca-temperature estimates covering the last 6 myrs at several IPWP sites (U1482/3 and U1488) will be generated. Comparison between these sites, and comparison to other temperature proxy measurements will be critical for evaluating proxy biases, the role of the thermocline, and the influence of the Indo-Pacific Throughflow, on the evolution of the IPWP. Second, to test the idea that there was North Pacific deep water formation in the latest Miocene and warm Pliocene period, benthic foraminifera isotope records at two West Pacific sites (U1488 and U1489) will be generated. Comparison to published benthic isotope data from elsewhere in the Pacific, and to modeling simulations, will put these new measurements into a global context. These data will also be critical to the development of high-resolution age models, providing a key framework for other researchers working on the cores. Overall, the results of this project will be combined with data being generated by other Expedition 363 scientists, and with ocean and climate modelers, in order to achieve a deeper mechanistic understanding of the role of the Indo-Pacific region in global climate processes. In addition, it will determine if North Pacific deep water formed and contributed to global heat transport during past periods of warmth.