Climate response to orbital forcing during the Eocene deglaciated, high temperature, high CO2 state: New records from Sites 1210, 1258 & 1267

在过去的150年里，人类已经将大气中的二氧化碳浓度从280 ppmv（百万分之一）增加到380 ppmv。根据南极冰芯中气泡的著名记录，我们知道这个人为价值比过去80万年里地球上看到的任何东西都要高得多。按照中国和印度工业化的速度，到本世纪末，大气中的二氧化碳浓度预计将达到750，甚至1000 ppmv。自始新世（大约5000万年前）以来，地球上从未出现过这种浓度，当时地球比现在温暖得多，冰川也少（见2008年6月21日《新科学家》封面故事）。这些引人注目的观察结果意味着我们必须提高对这些古代地质气候稳定性的认识。在过去，这是不可能以我们提出的方式实现的，因为这项工作所需的各种地质材料（来自海洋深处的年代久远、保存完好、未受干扰的沉积物）是不可获得的。然而，英国是一个主要的国际合作科学计划的一部分，该计划被称为（综合）海洋钻探计划或(I)ODP。在ODP的最后一个阶段(I)，它发起了一项在海底钻孔的大型运动，以回收这种工作所需的始新世沉积物。我们每个人都积极参与了这次活动（参见第一部分，我们的“业绩记录”）。我们的提案寻求资金，利用这些最近恢复的(I)ODP沉积物来研究“始新世温室”期间的自然气候变化。具体来说，我们想了解在这种冰川消融、高温、高二氧化碳水平的状态下，气候对地球绕太阳轨道的敏感性。我们计划通过将现有的化学技术应用于针尖大小的有孔虫化石，生成表层和深海的古气候记录，这种化石被称为有孔虫，它们的壳是由碳酸钙制成的。我们工作的一个关键方面将是确定不同半球、纬度和海洋的温度和碳循环行为的节律波动。我们的工作有可能找到新的方法：1)解决关于在其他地质时间间隔存在大量冰盖的持续争论。2)测试当地（表层海洋出口生产）与全球（深海“酸度”）对海底CaCO3埋藏的控制。

In the past 150 years mankind has increased the level of atmospheric carbon dioxide in the atmosphere from 280 parts per million by volume (ppmv) to 380 ppmv. We know that this anthropogenic value is much higher than anything seen on Earth in the last 800 thousand years from the famous records of air bubbles trapped in layers of ice cored in Antarctica. At the rate at which China and India are industrializing, by the end of this century, the concentration of CO2 in the atmosphere is predicted to reach 750, perhaps 1000 ppmv. These sorts of concentrations have not been seen on Earth since the Eocene (about 50 million years ago) when our planet was much warmer and less glaciated than today (see cover story, New Scientist, 21 June, 2008). These remarkable observations mean that we must improve our understanding of the stability of these ancient geological climates. In the past this would not have been possible in the way that we propose because the sorts of geological materials required for this work (well-dated, well-preserved and undisturbed sediments from the depths of the oceans) were not available. However, the UK is part of a major international collaborative science program called the (Integrated)Ocean Drilling Program or (I)ODP. In its last phase of operation (I)ODP instigated a major campaign of drilling holes in the sea floor to retrieve the sorts of Eocene sediments required for this sort of work. Each of us was heavily involved in this campaign (see Part I, our 'track records'). Our proposal seeks funding to study natural climate variability during this 'Eocene greenhouse' interval using these recently recovered (I)ODP sediments. Specifically, we want to understand the sensitivity of climate to Earth's orbit of the Sun under this deglaciated, high temperature, high CO2 level state. We plan to generate palaeoclimate records for the surface and deep ocean by applying established chemical techniques to pin-head sized fossils called foraminifera that make their shells from calcium carbonate. A key aspect of our work will be to determine the rhythmic fluctuations in temperature and carbon cycle behaviour across different hemispheres, latitudes and oceans. Our work has the potential to identify novel methods to: 1) Tackle ongoing debate over the existence of substantial ice sheets during other intervals of geologic time. 2) Test for local (surface ocean export production) versus global (deep ocean 'acidity') control on the burial of CaCO3 at the sea floor.