CO2 and climate change: deciphering the role of the high-latitude oceans

二氧化碳与气候变化：解读高纬度海洋的作用

基本信息

批准号：
MR/W013835/1
负责人：
Graeme MacGilchrist
金额：
$ 118.46万
依托单位：
University of St Andrews
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2022
资助国家：
英国
起止时间：
2022 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=MR%2FW013835%2F1
关键词：
CO2 climate change deciphering role

项目摘要

With every ton of carbon injected to the atmosphere, humanity makes a commitment to long term changes in climate. The severity of that commitment will depend on how Earth's carbon sinks, that remove carbon from the atmosphere, are themselves altered by the ensuing climatic shifts.The role of the ocean is critical: CO2 dissolves in seawater, allowing the ocean to take up about 30% of the CO2 emitted to date. The future trajectory of atmospheric CO2 - and climate - is thus critically dependent on the behaviour of the ocean CO2 sink.High latitude regions are particularly important, as cooling of surface water allows more CO2 to dissolve (similar to CO2 bubbles in a cold fizzy drink). Cooling also increases density, allowing CO2-laden water to sink and be stored in the ocean's abyss.However, high latitude mixing can also bring CO2 back up to the surface. Depending on the speed at which this CO2 is removed by photosynthesis, and the degree to which it is capped by sea ice, the high latitude oceans may act either as a CO2 source, or a CO2 sink.At present, these processes are not well represented in the computer models used to predict CO2 change in the future. For example, most models misrepresent the seasonal cycle of CO2 uptake and release in the Southern Ocean. They also tend to predict that the ocean will continue to absorb CO2 like a simple sponge, but from the geological record we know that the ocean can switch from a carbon sink to a carbon source with surprising speed.It is therefore critically important that we improve simulation of fundamental processes in the ocean carbon cycle and understand the dynamic ways in which oceanic CO2 has changed in the past and could change in the future. These are the core aims of this proposal.To achieve this, I will harness insights from paleo data alongside new developments in carbon cycle modelling. Pairing these approaches will allow us to answer major questions about Earth's past, such as the causes of ice age CO2 change, and to use paleo observations to help test and improve the oceanographic tools used to predict our future.Firstly, I will examine biases in state-of-the-art carbon cycle models by evaluating how carbon is stored within oceanic layers known as watermasses. Watermass analysis has been one of the most successful tools in oceanography but has been used surprisingly little to study the ocean carbon cycle. It also lends itself well to paleo data, to test how carbon was stored in the ice age ocean.Secondly, I will develop new ways of simulating processes of carbon uptake at high latitudes. The complexity and fine spatial scales involved make this challenging for global models. Here, I will use "idealised" approaches which focus on the most essential processes and regions. Specific targets include the spinning circulation of the North Atlantic and the complex interactions in the Southern Ocean, and these will be compared to records of rapid deglacial CO2 change from these regions. A long term aim is to apply novel mathematical approaches to make a new style of model of global ocean carbon.Thirdly, I will bring together these new insights to create efficient models of the global ocean carbon cycle and its interaction with climate. I will harness them to examine the causes of ice age CO2 change, and trajectories of CO2 uptake in the future.This work will provide oceanographers, climate scientists, and paleoceanographers with a new toolkit for examining major CO2 change. I have positioned myself at the nexus of these fields, and the complementary expertise available at St Andrews, coupled with that of a leading group of project partners, will allow me to undertake the bold, interdisciplinary work needed for a step change in our understanding of the ocean carbon cycle. The reach and impact of this work will be extended directly to policymakers by creation of user-friendly models of future CO2 trajectories and their impact on climate.

每向大气中注入一吨碳，人类就对气候的长期变化做出了承诺。这一承诺的严重程度将取决于地球碳汇（从大气中去除碳）本身如何因随后的气候变化而改变。海洋的作用至关重要：二氧化碳溶解在海水中，使海洋吸收约 30迄今为止排放的二氧化碳的百分比。因此，大气二氧化碳和气候的未来轨迹很大程度上取决于海洋二氧化碳汇的行为。高纬度地区尤其重要，因为地表水的冷却可以使更多的二氧化碳溶解（类似于冷碳酸饮料中的二氧化碳气泡））。冷却也会增加密度，使富含二氧化碳的水下沉并储存在海洋的深渊中。然而，高纬度的混合也会将二氧化碳带回表面。根据光合作用去除二氧化碳的速度以及被海冰覆盖的程度，高纬度海洋可能充当二氧化碳源或二氧化碳汇。目前，这些过程并不顺利代表用于预测未来二氧化碳变化的计算机模型。例如，大多数模型歪曲了南大洋二氧化碳吸收和释放的季节性周期。他们还倾向于预测海洋将像简单的海绵一样继续吸收二氧化碳，但从地质记录中我们知道海洋可以以惊人的速度从碳汇转变为碳源。因此，我们改进模拟海洋碳循环的基本过程，了解海洋二氧化碳在过去和未来可能发生变化的动态方式。这些是该提案的核心目标。为了实现这一目标，我将利用古数据的见解以及碳循环建模的新发展。将这些方法结合起来将使我们能够回答有关地球过去的重大问题，例如冰河时代二氧化碳变化的原因，并利用古观测来帮助测试和改进用于预测我们未来的海洋学工具。首先，我将检查以下方面的偏差：通过评估碳在被称为水团的海洋层中的储存方式，建立最先进的碳循环模型。水体分析一直是海洋学中最成功的工具之一，但令人惊讶的是，它很少用于研究海洋碳循环。它还非常适合古数据，以测试冰河时代海洋中碳的储存方式。其次，我将开发模拟高纬度地区碳吸收过程的新方法。所涉及的复杂性和精细的空间尺度使全球模型面临挑战。在这里，我将使用“理想化”的方法，重点关注最重要的流程和区域。具体目标包括北大西洋的旋转环流和南大洋的复杂相互作用，这些目标将与这些地区冰消期二氧化碳快速变化的记录进行比较。长期目标是应用新颖的数学方法建立一种新型的全球海洋碳模型。第三，我将汇集这些新见解，创建全球海洋碳循环及其与气候相互作用的有效模型。我将利用它们来研究冰河时期二氧化碳变化的原因以及未来二氧化碳吸收的轨迹。这项工作将为海洋学家、气候科学家和古海洋学家提供一个新的工具包来研究二氧化碳的主要变化。我将自己定位于这些领域的结合点，圣安德鲁斯提供的互补专业知识，再加上项目合作伙伴领导小组的专业知识，将使我能够开展大胆的跨学科工作，以逐步改变我们对以下领域的理解：海洋碳循环。通过创建未来二氧化碳轨迹及其对气候影响的用户友好模型，这项工作的范围和影响将直接扩展到政策制定者。