Impact of Western Pacific Warm Pool variability on regional and global climate evolution during the late Miocene and early Pliocene

中新世晚期和上新世早期西太平洋暖池变率对区域和全球气候演变的影响

• 批准号: 387857866
• 负责人: Dr. Ann Holbourn
• 金额: --
• 依托单位: Institut für Geowissenschaften
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/387857866?language=en
• 关键词: Impact; Western; Pacific; Warm; Pool

As the warmest water body on the planet, the Western Pacific Warm Pool (WPWP) strongly influences the dynamics of the El Niño Southern Oscillation and the Asian-Australian monsoon system, affecting planetary-scale atmospheric circulation, atmospheric heating, and tropical hydrology. To date, there is considerable uncertainty regarding the response of the tropical Pacific climate to rising greenhouse gas concentrations and sea level due to our limited understanding of the WPWP past variability and conflicting results from data and model simulations.During IODP Expedition 363, an extended (sedimentation rate: ~6 cm/kyr), undisturbed upper Miocene to lower Pliocene hemipelagic succession was retrieved for the first time at the southwestern edge of the present day WPWP (Site U1482, 15°3.32 S, 120°26.10 E, water depth: 1466 m). This carbonate- and clay-rich sequence provides an ideal archive to document temperature and precipitation variations in the WPWP under different climate background states and to better constrain climate sensitivity in relation to changes in radiative forcing (CO2 and insolation). Using a combination of high-resolution ocean temperatures and salinity reconstructions (based on oxygen isotope and Mg/Ca analyses of mainly unaltered, glassy planktonic and intermediate water benthic foraminifers) and XRF-scanner derived monsoonal runoff records, we propose: 1) to monitor variations in the spatial extent of the WPWP in relation to high-latitude climate change on orbital timescales; 2) to investigate the relationships between changes in the Equator-to-pole temperature gradient and the long-term evolution of the Australian monsoon; 3) to assess changes in the zonal SST gradient of the tropical Pacific Ocean during intense, global cooling and warming episodes and 4) to evaluate the role of intermediate waters as a buffer of high-latitude climate variations during late Miocene and early Pliocene climate reversals.Our project will focus on the late Miocene to early Pliocene period, which represents a geologically recent, relatively warm climate phase that is considered a potential analog of future conditions on Earth. This interval was marked by several episodes of fundamental climate re-organization, offering a challenging opportunity to explore climate-carbon cycle dynamics on a warmer-than-today Earth as well as to investigate the impact of WPWP variations on the evolution of the Asian-Australian monsoon system and on zonal equatorial Pacific processes (e.g. past El Niño state) and, thus, to help guide models and constrain predictions of climate change and sensitivity.

作为地球上最温暖的水体，西太平洋暖池(WPWP)强烈影响着厄尔尼诺南方涛动和亚澳季风系统的动态，影响着行星尺度的大气环流、大气加热和热带水文。到目前为止，热带太平洋气候对温室气体浓度和海平面上升的响应仍存在相当大的不确定性，这是因为我们对WPWP过去的变异性以及来自数据和模式模拟的相互矛盾的结果的了解。在IODP考察期间，首次在现今WPWP的西南边缘(U1482站，15°3.32 S，120°26.10 E，水深1466m)恢复了一个延长的(沉积速率：~6 cm/Kyr)上中新世至上新世下部的半深海演替。这一富含碳酸盐和粘土的序列为记录不同气候背景状态下WPWP的温度和降水变化提供了理想的档案，并更好地限制了与辐射强迫(二氧化碳和太阳辐射)变化有关的气候敏感性。利用高分辨率海洋温度和盐度重建(基于主要未改变的玻璃浮游和中水有孔虫的氧同位素和镁/钙分析)和XRF扫描仪获取的季风径流记录，我们建议：1)监测WPWP在轨道时间尺度上与高纬度气候变化的空间范围变化；2)研究赤道-极地温度梯度变化与澳大利亚季风长期演变之间的关系；3)评估热带太平洋在强烈的全球变冷和变暖期间热带太平洋纬向海温梯度的变化，以及4)评估中新世晚期和上新世早期作为高纬度气候变化缓冲的作用。我们的项目将集中于晚中新世至上新世早期，这是一个地质上最近的、相对温暖的气候阶段，被认为是地球未来条件的潜在类比。这一间隔的特点是发生了几次基本的气候重组，这为探索比今天温暖的地球上的气候-碳循环动力学以及调查全球变暖对亚洲-澳大利亚季风系统的演变和对赤道太平洋纬向过程(例如过去的厄尔尼诺状态)的影响提供了一个具有挑战性的机会，从而有助于指导气候变化模型和限制气候变化和敏感性的预测。