Resolving contradictory hypotheses concerning prolonged late Miocene El Niño-like conditions using the first high-resolution equatorial Pacific climate records

使用第一份高分辨率赤道太平洋气候记录解决有关长期晚中新世厄尔尼诺现象的矛盾假设

• 批准号: 408101468
• 负责人: Dr. Thomas Westerhold
• 金额: --
• 依托单位: College of Earth, Ocean, and Atmospheric Sciences
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/408101468?language=en
• 关键词: Resolving; contradictory; hypotheses; concerning; prolonged

A key dispute concerning Neogene climate centres on whether or not permanent El Niño-like conditions existed in the equatorial Pacific during the Late Miocene. Because anthropogenic global warming projections predict an up to 4°C mean temperature increase by 2100, it is of utmost importance to understand the late Miocene climate system, which was on average 4.5 °C warmer than today. Investigating the existence of permanent El Niño-like conditions during the warm late Miocene can provide critical information for the development of future climate. A modern El Niño, when warm sea surface waters extend far across the equatorial Pacific, causes global precipitation and temperature anomalies, due to the important role of the equatorial Pacific Ocean in driving global atmospheric circulation, precipitation, heat transport and carbon cycling. Prolonged El Niño-like conditions may have had serious, widespread, global consequences and potentially triggered the increase in global aridity observed during the late Miocene.The main scientific goal of this proposed project is to test the hypothesis that permanent late Miocene El Nino-like conditions existed in the equatorial Pacific between 6.5 and 9.7 Ma. To resolve this, I propose reconstructing changes in the water column structure and thermocline depth of the Western Pacific Warm Pool (WPWP), at unprecedented glacial-interglacial resolution, by generating high-resolution benthic and planktonic (mixed layer and thermocline) stable isotope records between 6.0-9.7 Ma, using recently recovered sediments from Site U1488 (IODP Expedition 363). Comparing the new WPWP records at glacial-interglacial resolution with eastern equatorial Pacific records will allow short- and long-term changes to be distinguished from each other. We can thereby test the true extent of late Miocene El Niño-like conditions to be tested and characterise the nature of the ~6.5 Ma transition to La Niña-like conditions. The high-resolution benthic stratigraphy will be used to develop an astronomical age model and to provide a robust correlation between the new U1488 records and existing astronomically tuned records from eastern equatorial Pacific Sites U1337 and U1338 (IODP Exp. 320/321). This project may ultimately resolve the late Miocene permanent El Niño debate and significantly advance our understanding of the global consequences of dominant El Niño conditions during climates warmer than the present.

关于新近纪气候的一个关键争议集中在晚中新世期间赤道太平洋是否存在永久的厄尔尼诺样条件。由于人为全球变暖预测预测到2100年平均气温将上升4°C，因此了解晚中新世气候系统至关重要，该系统平均比今天高4.5 °C。调查在温暖的晚中新世期间是否存在永久性的厄尔尼诺现象，可以为未来气候的发展提供关键信息。现代厄尔尼诺现象，当温暖的海面沃茨延伸到赤道太平洋，造成全球降水和温度异常，因为赤道太平洋在推动全球大气环流、降水、热量输送和碳循环方面发挥着重要作用。长时间的类似厄尔尼诺现象的情况可能产生严重的、广泛的全球性后果，并可能引发中新世晚期观测到的全球干旱增加，这一拟议项目的主要科学目标是检验这样一种假设，即在6.5至9.7 Ma之间，赤道太平洋存在永久性的中新世晚期类似厄尔尼诺现象的情况。为了解决这个问题，我建议重建的水柱结构和温跃层深度的西太平洋暖池（WPWP）的变化，在前所未有的冰川间冰期的分辨率，通过产生高分辨率的底栖和浮游（混合层和温跃层）稳定同位素记录6.0-9.7马之间，使用最近恢复的沉积物从站点U1488（IODP远征363）。比较新的WPWP记录在冰川间冰期的分辨率与赤道东太平洋的记录将允许短期和长期的变化，以区分彼此。因此，我们可以测试晚中新世厄尔尼诺条件的真实程度进行测试，并验证~6.5 Ma过渡到拉尼娜条件的性质。高分辨率海底地层学将用于建立天文年龄模型，并提供新的U1488记录与东赤道太平洋站点U1337和U1338（IODP Exp. 320/321）。该项目可能最终解决中新世晚期永久性厄尔尼诺的争论，并大大促进我们对气候比现在温暖的主导厄尔尼诺条件的全球后果的理解。