Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands.
Department of Earth Sciences, Royal Holloway, University of London, Egham, UK.
Sci Rep. 2019 Mar 7;9(1):3795. doi: 10.1038/s41598-019-40208-2.
A global Neogene cooling trend culminated ~7 million years ago with the onset of Greenland glaciation. Increased ocean-atmosphere interaction and low- to high-latitude circulation are thought to be key factors in reorganizing late Miocene global temperature and precipitation patterns, but the drivers of this reorganization have yet to be identified. Here, we present new information about the evolution of the Atlantic-Mediterranean gateway that generated Mediterranean overflow. We use sedimentary and palaeogeographic evidence to constrain the timing and dimensions of this gateway and document the initiation of a saline plume of water within the North Atlantic. Today, this saline jet entrains and transports Eastern North Atlantic water and its dissolved inorganic carbon into the interior of the ocean, contributing to the drawdown of CO and the sensitivity of the ocean to atmospheric changes. We show that during the Miocene this transport emerged simultaneously with gateway restriction and propose that the resulting interaction of ocean-surface and ocean-interior carbon inventories would have greatly enhanced ocean-atmosphere exchange, preconditioning the Earth System for late Miocene cooling.
全球中新世冷却趋势在大约 700 万年前达到顶峰，标志着格陵兰冰盖的开始形成。人们认为，海洋-大气相互作用的增加以及低纬到高纬的环流是重新组织中新世晚期全球温度和降水模式的关键因素，但这种重组的驱动因素尚未确定。在这里，我们提供了有关大西洋-地中海门户演化的新信息，该门户产生了地中海溢流水。我们利用沉积和古地理证据来限制这个门户的时间和范围，并记录北大西洋内盐水羽流的起始。今天，这个盐水射流会夹带和输送东北大西洋的水及其溶解的无机碳进入海洋内部，这有助于减少 CO 和海洋对大气变化的敏感性。我们表明，在中新世期间，这种输送与门户限制同时出现，并提出由此产生的海洋表面和海洋内部碳储量之间的相互作用将极大地增强海洋-大气交换，为中新世晚期的冷却做好地球系统的准备。
