Climate interconnections of the Pliocene greenhouse

由于持续的温室气体排放，全球变暖已经比工业化前的水平高出1摄氏度。极地地区正在失去冰块，海洋正在变暖，减少了海洋的混合和深海的通风，限制了海洋生态系统的氧气供应。这些相互关联的变化是全球相关的，但最紧迫的是研究区域因素在哪里使系统容易缺氧。一个关键的目标是将古气候记录回溯到足够远的时间，以吸取上一次由二氧化碳引起的持续全球变暖和南极冰盖退缩的大间隔：上新世（约300万至500万年前）的教训。我们将研究阿拉伯海，它具有全球海洋中最厚的氧气最小带，因为(i)它在北印度洋的死角位置意味着富含氧气的冷水团只能从南部（南极来源）供应，（ii）强烈的西南印度夏季季风推动了一个极其多产的上升流供养的生态系统，通过水柱和深度氧气消耗从有机物质中产生的强降雨。我们将研究过去全球变暖、南极冰量、季风环流强度和海洋氧合（通风）之间的关系。

Global warming has already reached 1C above the pre-industrial level because of ongoing greenhouse gas emissions. The polar regions are losing ice mass and the ocean is warming, reducing oceanic mixing and ventilation of deep waters, limiting oxygen supply to marine ecosystems. These interconnecting changes are relevant globally but most acute and urgent to study where regional factors predispose the system towards anoxia. A key objective is to extend palaeoclimate records back in time far enough to learn the lessons of the last great interval of sustained CO2-induced global warmth and Antarctic ice sheet retreat: the Pliocene (~3 to 5 million years ago). We will study the Arabian Sea which features the thickest oxygen minimum zone in the global ocean because (i) its cul-de-sac location in the northern Indian Ocean means that cold oxygen-rich water masses can only be supplied from the south (Antarctic-sourced) and (ii) strong southwest Indian summer monsoon winds drive an extremely productive upwelling-fed ecosystem, with intense rain out of organic matter through the water column and oxygen consumption at depth. We will investigate the relationships between past changes in global warmth, Antarctic ice volume, monsoon circulation strength and oxygenation (ventilation) of the ocean.