INTRIGUED: INvestigating The Role of the North Pacific In Glacial and Deglacial CO2 and Climate

感兴趣：研究北太平洋在冰期和冰消期二氧化碳和气候中的作用

基本信息

批准号：
NE/N011716/1
负责人：
James Rae
金额：
$ 64.46万
依托单位：
University of St Andrews
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FN011716%2F1
关键词：
INTRIGUED INvestigating Role North Pacific

项目摘要

The geological record offers an invaluable window into the different ways earth's climate can operate. The most recent large-scale changes in earth's climate, prior to modern climate change, were the Pleistocene glacial cycles, which feature growth and disintegration of large ice sheets, rapid shifts in major rain belts, and abrupt changes in ocean circulation. Changes in atmospheric CO2 concentrations, reconstructed from air bubbles in ice cores, are intimately linked with these ice age climate events. Indeed the close coupling of CO2 and temperature over glacial-interglacial cycles has become an iconic image in climate science, a poster child for the importance of CO2 in climate, and the natural template against which to compare current man-made CO2 rise. However despite the high profile of glacial-interglacial CO2 change, we still don't fully understand its cause. The leading hypotheses for glacial CO2 change involve increased CO2 uptake by the ocean during ice ages, which is vented to the atmosphere during deglaciation. However despite decades of work these hypotheses have had few direct tests, due to a lack of data on CO2 storage in the glacial ocean. One of the most glaring holes in our understanding of ice age CO2 and climate change is the behaviour of the Pacific. This basin contains half of global ocean volume, and ~30 times more CO2 than the atmosphere, and so its behaviour will have global impact. It has also recently been suggested that the North Pacific may play an active role in deglacial CO2 rise, with local deep water formation helping to release CO2 from the deep ocean to the atmosphere. If correct, this hypothesis provides a new view of Earth's climate system, with deep water able to form in each high latitude basin in the recent past, and the North Pacific potentially playing a pivotal role in deglaciation. However few data exist to test either the long-standing ideas on the Pacific's role in glacial CO2 storage, nor the more recent hypothesis that North Pacific deep water contributed to rapid deglacial CO2 rise. Given the size of the Pacific CO2 reservoir, our lack of knowledge on its behaviour is a major barrier to a full understanding of glacial-interglacial CO2 change and the climate of the ice ages. This proposal aims to transform our understanding of ice age CO2 and climate change, by investigating how the deep North Pacific stored CO2 during ice ages, and released it back to the atmosphere during deglaciations. We will use cutting-edge geochemical measurements of boron isotopes in microfossil shells (which record the behaviour of CO2 in seawater) and radiocarbon (which records how recently deep waters left the surface ocean), on recently collected samples from deep ocean sediment cores. By comparing these new records to other published data, we will be able to distinguish between different mechanisms of CO2 storage in the deep Pacific, and to test the extent of North Pacific deep water formation and CO2 release during the last deglaciation. We will also improve the techniques used to make boron isotope measurements, and add new constraints on the relationship between boron isotopes and seawater CO2 chemistry, which will help other groups using this technique to study CO2 change. To help us understand more about the mechanisms of changes in CO2 and ocean circulation, and provide synergy with scientists in other related disciplines, we will compare our data to results from earth system models, and collaborate with experts on nutrient cycling and climate dynamics. Our project will ultimately improve understanding of CO2 exchange between the ocean and the atmosphere, which is an important factor for predicting the path of future climate change.

地质记录为了解地球气候的不同运作方式提供了宝贵的窗口。在现代气候变化之前，地球气候最近发生的大规模变化是更新世冰川循环，其特点是大冰盖的生长和崩解、主要雨带的快速变化以及海洋环流的突然变化。由冰芯中的气泡重建的大气二氧化碳浓度的变化与这些冰河时代的气候事件密切相关。事实上，冰期-间冰期循环中二氧化碳与温度的紧密耦合已成为气候科学中的标志性图像、二氧化碳在气候中重要性的典型代表，以及用于比较当前人为二氧化碳上升的自然模板。然而，尽管冰期-间冰期二氧化碳变化引人注目，但我们仍然不完全了解其原因。关于冰川二氧化碳变化的主要假设涉及冰河时期海洋吸收的二氧化碳增加，这些二氧化碳在冰消期期间排放到大气中。然而，尽管经过数十年的研究，由于缺乏冰川海洋二氧化碳储存的数据，这些假设几乎没有经过直接检验。我们对冰河时代二氧化碳和气候变化的理解中最明显的漏洞之一是太平洋的行为。该盆地的海洋体积占全球一半，二氧化碳含量是大气的约30倍，因此其行为将对全球产生影响。最近也有人提出，北太平洋可能在冰消期二氧化碳上升中发挥积极作用，当地深水形成有助于将二氧化碳从深海释放到大气中。如果正确的话，这一假设为地球气候系统提供了一个新的视角，在最近的过去，深水能够在每个高纬度盆地中形成，而北太平洋可能在冰消过程中发挥关键作用。然而，很少有数据可以检验关于太平洋在冰川二氧化碳储存中的作用的长期观点，也没有检验北太平洋深水导致冰消二氧化碳快速上升的最新假设。考虑到太平洋二氧化碳库的规模，我们对其行为缺乏了解是充分了解冰期-间冰期二氧化碳变化和冰河时代气候的主要障碍。该提案旨在通过研究北太平洋深处如何在冰河时期储存二氧化碳，并在冰消期将其释放回大气中，从而改变我们对冰河时期二氧化碳和气候变化的理解。我们将对最近从深海沉积物核心收集的样本使用微化石壳中硼同位素（记录海水中二氧化碳的行为）和放射性碳（记录深水离开海洋表层的时间）的尖端地球化学测量。通过将这些新记录与其他已发布的数据进行比较，我们将能够区分太平洋深部二氧化碳储存的不同机制，并测试末次冰消期间北太平洋深水形成和二氧化碳释放的程度。我们还将改进用于硼同位素测量的技术，并对硼同位素和海水二氧化碳化学之间的关系添加新的约束，这将有助于其他小组使用该技术研究二氧化碳变化。为了帮助我们更多地了解二氧化碳和海洋环流的变化机制，并与其他相关学科的科学家进行协同，我们将把我们的数据与地球系统模型的结果进行比较，并与营养循环和气候动力学方面的专家合作。我们的项目最终将增进对海洋和大气之间二氧化碳交换的了解，这是预测未来气候变化路径的重要因素。