Changes in ocean circulation and the global carbon cycle during the last interglacial-glacial transition: Marine Isotope Stage 5a to 4

末次间冰期-冰期过渡期间海洋环流和全球碳循环的变化：海洋同位素阶段 5a 至 4

• 批准号: NE/F002734/1
• 负责人: Stephen Barker
• 金额: $ 53.8万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF002734%2F1
• 关键词: Changes; ocean; circulation; global; carbon

The last glacial period was punctuated by repeated, high-amplitude millennial-scale shifts in northern hemisphere climate known as Dansgaard-Oeschger (D-O) oscillations. These events were characterised by the extremely rapid alternation between cold and warmer conditions with temperature increases over Greenland and NW Europe sometimes exceeding 10 degrees Celsius within a few decades. The discovery of D-O oscillations has provided a major stimulus for climate research and fuelled debate over the possible nature of climate change in the future, yet very little is known about the origin of these events. Ocean circulation is a fundamental component of Earth's climate system. Changes in circulation are known to be associated with major shifts in global climate, including glacial-interglacial transitions as well as more rapid events such as D-O oscillations. The transition from the last interglacial period (similar to today) to full glacial conditions, around 75,000 years ago, saw a large build-up of continental ice sheets and a decrease in atmospheric CO2. This period also saw the first appearance of D-O climate variability, suggesting that a critical threshold, between the relative stability of the last interglacial and the instability of glacial times, had been crossed. However, fundamental uncertainties currently exist concerning the role of ocean circulation within the evolving climate system and its apparent threshold behaviour at this time. This project will investigate changes in Atlantic Ocean circulation and their role in global climate change during the MIS 5a/4 transition. The project will improve our understanding of the links between ocean circulation and climate change and will therefore inform scientists working in related fields and potentially policy makers. Palaeoclimate reconstructions will be made on each of five sediment cores taken from the North Atlantic, covering both east and west basins in intermediate and deep waters. Proxies for nutrient distribution and carbon chemistry will be used to reconstruct the evolving deep ocean chemical structure during MIS 5a/4 while dynamical palaeocirculation proxies will enable assessment of physical changes in bottom current speed and mass volume transport. Direct temporal correlation of the reconstructions with records from ice cores and absolutely dated cave deposits will enable the development of extremely robust age models, vital for investigation of potential leads and lags between the reconstructed changes and other climate relevant parameters such as ice volume and atmospheric CO2. A further circulation proxy record will be produced from a core from the Atlantic/Indian sector of the Southern Ocean. This will provide unambiguous evidence for the relative timing between changes in ocean circulation and the global carbon cycle. The data produced as part of this project will provide critical constraints for differentiating between key physical and chemical changes in Earth's climate system during the transition to full glacial conditions and the onset of glacial climate instability.

末次冰期被北方半球气候反复的、高振幅的千年尺度变化所打断，这种变化被称为Dansgaard-Oeschger（D-O）振荡。这些事件的特征是寒冷和温暖条件之间的快速交替，格陵兰和西北欧的温度在几十年内有时超过10摄氏度。D-O振荡的发现为气候研究提供了重大刺激，并引发了关于未来气候变化可能性质的辩论，但对这些事件的起源知之甚少。海洋环流是地球气候系统的基本组成部分。已知环流的变化与全球气候的重大变化有关，包括冰川-间冰期过渡以及更快速的事件，如D-O振荡。从最后一个间冰期（类似于今天）到大约75，000年前的完全冰川条件的过渡，看到了大陆冰盖的大量积累和大气中二氧化碳的减少。这一时期也是D-O气候变率的首次出现，表明末次间冰期的相对稳定性和冰期的不稳定性之间的临界阈值已经被跨越。然而，目前关于海洋环流在不断演变的气候系统中的作用及其此时的明显阈值行为存在根本的不确定性。该项目将调查在MIS 5a/4过渡期间大西洋环流的变化及其在全球气候变化中的作用。该项目将提高我们对海洋环流与气候变化之间联系的认识，从而为相关领域的科学家和潜在的决策者提供信息。将对取自北大西洋的五个沉积物岩心中的每一个进行古气候重建，这五个沉积物岩心覆盖了中、深水沃茨的东西两个盆地。营养物分布和碳化学代用指标将用于重建MIS 5a/4期间不断演变的深海化学结构，而动力学古环流代用指标将有助于评估底流速度和质量体积运输的物理变化。重建与冰芯记录和绝对定年洞穴沉积物的直接时间相关性将使非常强大的年龄模型的发展，对于调查重建的变化和其他气候相关参数（如冰量和大气CO2）之间的潜在线索和滞后至关重要。将从南大洋大西洋/印度洋部分的一个岩芯中制作进一步的环流代用记录。这将为海洋环流和全球碳循环变化之间的相对时间提供明确的证据。作为这一项目的一部分而产生的数据将提供关键的制约因素，以区分地球气候系统在向完全冰川条件过渡期间和冰川气候不稳定开始期间的主要物理和化学变化。

项目成果

Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions

• DOI: 10.1002/palo.20025
• 发表时间: 2013-06
• 期刊: Paleoceanography
• 作者: D. Thornalley;S. Barker;Julia Becker;I. Hall;G. Knorr

Millennial atmospheric CO2 changes linked to ocean ventilation modes over past 150,000 years

• DOI: 10.1038/s41561-023-01297-x
• 发表时间: 2023-10
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: J. Yu;R. F. Anderson;Z. Jin;X. Ji;D. Thornalley;L. Wu;N. Thouveny;Y. Cai;L. Tan

Timing of the descent into the last Ice Age determined by the bipolar seesaw

• DOI: 10.1002/2014pa002623
• 发表时间: 2014-06-01
• 期刊: PALEOCEANOGRAPHY
• 作者: Barker, Stephen;Diz, Paula
• 通讯作者: Diz, Paula

Linkages between rapid climate variability and deep-sea benthic foraminifera in the deep Subantarctic South Atlantic during the last 95 kyr

• DOI: 10.1002/2015pa002784
• 发表时间: 2015-06
• 期刊: Paleoceanography
• 作者: P. Diz;S. Barker

Evidence of silicic acid leakage to the tropical Atlantic via Antarctic Intermediate Water during Marine Isotope Stage 4

海洋同位素第四阶段期间硅酸通过南极中层水泄漏到热带大西洋的证据

• DOI: 10.1002/palo.20030
• 发表时间: 2013
• 期刊: Paleoceanography
• 作者: Griffiths J