Sub-annual climate variability during the last deglaciation: New views from coralline biogeochemistry

如果我们回到大约18000年前，我们几乎认不出我们的星球。当时，北方许多人口稠密的地区都是冰冻的荒原：纽约和柏林都被冰川覆盖，伦敦和巴黎后来建立的地方也是永久冰冻的。然而，没过多久，这些冰块就开始融化。海洋被淡水淹没，导致海平面上升，改变了海洋环流的模式。在这个提议中我们想回答的问题是，这种环流模式的变化对地球气候有什么影响？问题是，对我们气候的直接测量（例如温度）只能追溯到过去的几百年，因此这些信息必须从所谓的代理或“替代品”中重建。珊瑚是特别有用的替代物，因为它们可以准确地确定年代，而且它们的化学成分反映了一些重要的环境参数，例如它们生长的水温。在这里，我们建议从大溪地岛的珊瑚骨骼的化学成分的变化，是20 000年和10 000年的年龄之间的记录。独特的是，我们将使用新的激光技术，使我们能够获得极高分辨率的记录（几天到几个月）。这意味着我们将能够捕捉到可能影响地球从冰川向温暖条件过渡的短期事件。

If we travelled back in time some 18 000 years, we would hardly recognise our planet. Many parts of the Northern Hemisphere that are densely populated today were frozen wastes: glaciers covered the cities of New York and Berlin, and the ground where London and Paris would become established was permanently frozen. Not long after however, this ice began to melt. The oceans were flooded with fresh water, causing sea level to rise and changing the pattern of ocean circulation. The question that we want to answer in this proposal, is what effect did this change in the pattern of circulation have on Earth's climate? The problem is that direct measurements of our climate (for example, temperature) extend back no further than the past few hundred years, so such information must instead be reconstructed from so-called proxies, or 'substitutes'. Corals are particularly useful proxies, because they can be accurately dated and their chemical composition reflects a number of important environmental parameters, such as the temperature of the water in which they grew. Here, we propose to obtain records of the variation in the chemical composition of coral skeletons from Tahiti that are between 20 000 and 10 000 years old. What is unique, is that we will use new laser technology that enables us to obtain records at extremely high resolution (a few days to a few months). This means that we will be able to capture the short-term events that can influence the transition from glacial to warmer conditions on Earth.