Beyond Greenland: Extending the record of abrupt climate variability

格陵兰岛的冰芯记录对于我们理解千年尺度的气候变异性和所谓的“突然”气候变化至关重要(美国国家研究委员会关于突然气候变化的委员会将这种变化定义为气候系统在时间尺度上向不同模式的转变，其速度快于负责任的强迫，而且发生得如此迅速和出人意料，以至于人类或自然系统难以适应)。第一个长的格陵兰冰芯是在1966年钻探的，但直到1980年的S和90年的S，随着更多高质量的记录被创造出来，自然气候变化在亚千年时间尺度上可能的巨大程度才被充分认识到。例如，在上一次冰川时期的部分时间里，记录表明格陵兰上空的气温可能在几十年内上升高达16摄氏度。这些被称为Dansgaard-Oeschger振荡的温度变化被认为与海洋环流的变化有关。自从在冰芯记录中发现这种突然变化以来，古气候学家从各种气候档案中产生了大量记录，试图更多地了解气候突然变化的全球表现，并将格陵兰冰提供的记录延伸到现在之前的大约10万年。然而，仍然有许多悬而未决的问题，包括：突然的气候振荡与地球气候的长期变化(即大冰川周期)之间有什么联系？这种关系在中更新世转变(大约100万年前的一个时间间隔，当时冰川周期从~41kyr转变为~100kyr周期)之前成立吗？气候突变的幅度如何依赖于背景气候状态？气候突变和深海环流变化之间是否存在一致的关系？在这个项目中，我们将通过制作170万年前气候突变的第一个连续记录来解决这些问题。我们将构建北大西洋海面状况的长期替代记录，并用深海洋流变化的记录来补充这些记录。我们的项目符合国家科学研究中心‘地球系统科学’的科学主题，并与‘气候系统’主题相关。特别是，我们对突然变化、它与海洋环流的关系以及它随时间的演变的关注，解决了NERC面临的挑战，即“不断增加对推动全球变化的力量和反馈的了解”。通过实现我们的目标，我们将创造一个标志性的记录，为未来许多关于突然气候变化的研究提供基准。

Ice core records from Greenland have been pivotal in our understanding of millennial-scale climate variability and so-called 'abrupt' climate change (the US National Research Council Committee on Abrupt Climate Change defines such a change as a transition of the climate system into a different mode on a timescale that is faster than the responsible forcing and one that takes place so rapidly and unexpectedly that human or natural systems have difficulty adapting to it). The first long Greenland ice core was drilled in 1966 but it was not until the 1980's and '90's, as more high quality records were produced, that the magnitude of natural climate change possible on sub-millennial timescales was fully realised. For example, during parts of the last glacial period, the records suggest that temperatures over Greenland could rise by up to 16 degrees Celsius within decades. These temperature shifts, known as a Dansgaard-Oeschger oscillations, are thought to be associated with changes in ocean circulation.Since the discovery of such abrupt changes in the ice core record, paleoclimatologists have produced a huge array of records from various climate archives in their attempts to learn more about the global manifestation of abrupt climate change and to extend the records provided by Greenland ice, which typically reach back only to about 100 thousand years before present. However, many unanswered questions remain, including: What is the association between abrupt climate oscillations and longer term changes in Earth's climate (i.e. the great glacial cycles)? Did this relationship hold prior to the Mid Pleistocene Transition (an interval about 1 million years ago, when the glacial cycles changed from ~41kyr to ~100kyr periodicity)? How does the amplitude of abrupt climate variability depend on the background climate state? Is there a consistent relationship between abrupt climate shifts and changes in deep ocean circulation? Within this project we will address these questions by producing the first continuous record of abrupt climate variability stretching back 1.7 million years. We will construct long proxy records of sea surface conditions in the North Atlantic and supplement these with records of deep ocean current variability. Our project fits within the NERC science theme of 'earth system science' and is of relevance to the 'climate system' theme. In particular, our focus on abrupt change, its relation to ocean circulation and its evolution through time addresses NERC's challenge of 'increasing knowledge of the forces and feedbacks that drive global change'. By meeting our objectives we will have produced an iconic record that will provide a benchmark for many future studies on abrupt climate change.