Across the middle Miocene, Earth's climate underwent a major cooling and expansion of the Antarctic ice sheet. However, the associated response and development of the tropical climate system is not fully understood, in part because this is influenced by both global climate and also low‐latitude tectonic gateways and paleoceanography. Here we use combined δ¹⁸O and Mg/Ca of planktic foraminifera to reconstruct the thermal history and changes in hydrology from the Indo‐Pacific region from 16.5 to 11.5 Ma. During the warmth of the early middle Miocene, our records indicate a dynamic ocean‐atmosphere system in the Indo‐Pacific region, with episodes of saltier and warmer tropical surface waters associated with high pCO₂ and retreat of the Antarctic ice sheet. We show that across the Middle Miocene Climate Transition (MMCT) surface ocean temperatures in the Indo‐Pacific cooled by ~2°C, synchronous with the advance of the Antarctic ice sheet. The associated cooling in the Southern Ocean appears to have started earlier and was stronger. Further, we show that western Pacific Ocean warmed and eastern tropical Indian Ocean freshened following the MMCT, likely caused by the constriction of the Indonesian Seaway and reduced connectivity between the Pacific and Indian Oceans following Antarctic glaciation. The MMCT therefore represented a key phase in the evolution of the West Pacific Warm Pool and associated tropical climate dynamics.

中文翻译：

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在中新世中期气候变迁中启动西太平洋暖池？

在中新世中期，地球的气候经历了南极冰原的主要冷却和膨胀。但是，对热带气候系统的相关响应和发展还没有完全了解，部分原因是这受到全球气候以及低纬度构造通道和古海洋学的影响。这里，我们使用结合δ ¹⁸ O和浮游有孔虫重建热历史和变化水文从印度太平洋地区16.5至11.5马的镁/钙。在中新世中期初期，我们的记录表明，印度太平洋地区的海洋-大气系统活跃，伴随着较高的p CO ₂的盐分和温暖的热带地表水出现和南极冰原撤退。我们发现，在中新世中期气候变迁（MMCT）中，与南极冰盖的推进同步，印度太平洋中的海洋温度降低了约2°C。与之相关的南大洋的降温似乎较早开始，并且强度更大。此外，我们显示，MMCT后，西太平洋变暖，东部热带印度洋变新，这可能是由于印度尼西亚海道的收缩以及南极冰期后太平洋与印度洋之间的连通性降低所致。因此，MMCT代表了西太平洋暖池及相关热带气候动态演变的关键阶段。