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

作为地球上最温暖的水体，西太平洋暖池（WPWP）强烈影响厄尔尼诺南方涛动和亚洲-澳大利亚季风系统的动态，影响行星尺度大气环流，大气加热和热带水文。迄今为止，由于我们对WPWP过去变率的了解有限以及数据和模式模拟的相互矛盾的结果，热带太平洋气候对温室气体浓度和海平面上升的反应存在相当大的不确定性。（沉降率：~6 cm/kyr），在现今西太平洋水电站的西南边缘，首次获得了上中新统至上新世的半远洋演替序列（地点U1482，南纬15°3.32，东经120°26.10，水深：1 466米）。这个富含碳酸盐和粘土的序列提供了一个理想的档案，以记录不同气候背景状态下WPWP中的温度和降水变化，并更好地限制气候敏感性与辐射强迫（CO2和日射）的变化。利用高分辨率海洋温度和盐度重建的组合（根据主要是未改变的玻璃质浮游和中层水底栖有孔虫的氧同位素和Mg/Ca分析）和XRF扫描仪获得的季风径流记录，我们建议：1）在轨道时间尺度上监测与高纬度气候变化有关的西太平洋暖水区的空间范围变化; 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SST纬向梯度的变化，全球变冷和变暖事件; 4）评估中新世晚期和上新世早期气候逆转期间中间沃茨作为高纬度气候变化缓冲区的作用。我们的项目将集中在中新世晚期到上新世早期，它代表了地质学上最近的一个相对温暖的气候阶段，被认为是地球未来条件的潜在模拟。这段时间的特点是发生了几次基本的气候重组，这为探索比今天更温暖的地球上的气候-碳循环动力学以及研究WPWP变化对亚洲-澳大利亚季风系统演变和赤道太平洋纬向过程的影响提供了一个具有挑战性的机会（例如过去的厄尔尼诺状态），从而帮助指导模型并限制对气候变化和敏感性的预测。

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.