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.

关于新金元气候的关键争议集中在中新世晚期的模棱两可的太平洋中是否存在永久性厄尔尼诺现象。由于人为的全球变暖项目预测到2100年的平均温度最高为4°C，因此了解中新世晚期气候系统至关重要，该气候平均比今天温暖4.5°C。调查中新世温暖的厄尔尼诺现象状况的存在可以为未来气候的发展提供关键信息。当温暖的海水地表水延伸到赤道太平洋时，现代的厄尔尼诺尼诺会导致全球降水和温度异常，这是由于赤道太平洋在推动全球大气循环，降水，热传输和碳循环中的重要作用。延长的厄尔尼诺现象可能具有严重的，宽度，全球后果，并有可能引发中新世晚期观察到的全球干旱的增加。该拟议项目的主要科学目标是测试中新世晚期El Nino-Nino样条件在6.5和9.7.7.7 MA.7.7 MA之间存在于6.5和9.7 MA之间。为了解决这一问题，我提出，通过在空前的前所未有的冰川间 - 冰期分辨率下，通过在6.0-9.0-9.7 ma之间产生高分辨率的同位型（混合层和热量线）稳定的同位素记录，通过产生高分辨率的底栖（混合层和热跃层）稳定的稳定的同位素记录，以使用36.-9.7 mA的稳定速度来重建水柱结构和西部太平洋温暖池（WPWP）的变化，使用了36.7 ma，i1 i1 i1 i1 i。将冰川间 - 冰分分辨率的新的WPWP记录与东部赤道太平洋记录进行比较将允许彼此区分短期和长期变化。因此，我们可以测试中新世晚期ElNiño样条件的真实范围，以进行测试和表征〜6.5 MA过渡到LaNiña样条件的性质。高分辨率底栖层学将用于开发天文年龄模型，并提供新的U1488记录与来自东部等效太平洋站点U1337和U1338和U1338的现有天文调整的记录之间的牢固相关性（IODPExp。320/321）。该项目最终可能会解决中新世晚期永久性的厄尔尼诺辩论，并显着促进我们对比现在更暖的气候期间主导的厄尔尼诺现象所带来的全球后果的理解。