CO2-CarbonCycle-Climate-Interactions (C4I)

CO2-碳循环-气候相互作用 (C4I)

基本信息

批准号：
NE/H017453/1
负责人：
Andy Ridgwell
金额：
$ 33.35万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH017453%2F1
关键词：
CO2 CarbonCycle Climate Interactions C4I

项目摘要

Oceans represent 70% of Earth's surface, supporting vast biodiversity and providing major food resources for humankind. Since the industrial revolution, the oceans have restricted the extent of global warming by taking up approximately 50% of the CO2 from fossil fuel burning and cement manufacture. CO2 forms carbonic acid when dissolved in seawater and lowers ambient pH in a phenomenon known as 'ocean acidification'. An important facet of ocean acidification is a decline in the concentration of carbonate ions in the ocean, a form of dissolved carbon that is depleted in the acidification reaction when CO2 is added to seawater. This is critical, because the shells and skeletons of many marine organisms are made of calcium carbonate (CaCO3) which dissolves at low carbonate ion concentrations (known as 'under-saturated' conditions). However, ecological thresholds of disruption may be crossed long before conditions of under-saturation actually occur and marine organisms' shells start dissolving around them, because calcium carbonate shells and skeletons will require more metabolic energy to maintain their thickness as carbonate ion concentrations fall. Experiments in the laboratory and field have already demonstrated this effect and find that calcifying algae called coccolithophorids generally produce less CaCO3 shell material in more acidic conditions. Slowing the rate of production of CaCO3 by algae living in the ocean surface may have a 'beneficial' impact by helping neutralize fossil fuel CO2, but a detrimental impact as ecosystems are disrupted. There may also be serious implications for the supply of organic detritus to organisms on the seafloor, as it is suspected that this food supply depends heavily on particles of CaCO3 to weigh down the fluffy organic matter and help it sink. Other impacts of ocean acidification may include changes in the amount and nutritional content of organic matter produced in the ocean, and loss of nutrients: converting nitrate to the powerful greenhouse gas nitrous oxide. How the ocean carbon cycle 'works' and whether CaCO3 particles are really important to weighting down fluffy organic matter as well as how exactly algae like coccolithophorids will respond to changing ocean chemistry are subject to significant uncertainties. This means that we would have no way of knowing whether a single computer model prediction for the future is correct or not. In this project we will tackle this question of uncertainty head-on - running out computer models of ocean carbon cycling and climate hundreds and hundreds of times to see what future impacts are possible and what are not. We will be greatly helped in this by using vast datasets describing what the modern ocean 'looks' like (in terms of the distributions of nutrients and patterns recorded in the sediments) to constrain the swarm of models so that they all agree on what the modern ocean looks like to begin with. The outcome of our work will firstly be a better understanding of the modern ocean carbon cycle, which is essential to get right before worrying about the future. We will also make predictions about the range of changes in ocean carbon and nutrient cycles we can expect in the future and how the ocean may affect the degree of future warming by emitting more or less greenhouse gases such as carbon dioxide and nitrous oxide.

海洋占地球表面的70％，支持广阔的生物多样性，并为人类提供主要的食物资源。自工业革命以来，海洋从化石燃料燃烧和水泥制造中占据了大约50％的二氧化碳，从而限制了全球变暖的程度。当溶解在海水中时，二氧化碳形成碳酸，并在一种称为“海洋酸化”的现象中降低环境pH。海洋酸化的一个重要方面是，海洋中碳酸盐离子浓度下降，海洋中溶解的碳的形式在酸化反应中耗尽的一种形式，当二氧化碳添加到海水中时。这很关键，因为许多海洋生物的贝壳和骨骼是由碳酸钙（CACO3）制成的，该钙溶解在低碳酸盐离子浓度（称为“饱和”疾病）。然而，破坏的生态阈值可能在不饱和条件实际发生之前很久就可以越过，并且海洋生物的贝壳开始溶解在它们周围，因为碳酸钙壳和骨骼需要更多的代谢能量以保持其厚度，以维持其厚度，因为碳酸盐离子离子浓度下降。实验室和田间的实验已经证明了这种作用，发现在更酸性的条件下，钙化藻类通常会产生较少的Caco3壳材料。通过帮助中和化石燃料二氧化碳二氧化碳的藻类降低了生活在海面的藻类的CACO3生产率可能会产生“有益”的影响，但是随着生态系统受到破坏，造成了不利影响。对于海底上的有机碎屑的供应也可能有严重的影响，因为怀疑这种食物的供应在很大程度上取决于Caco3的颗粒以权衡蓬松的有机物并帮助其下沉。海洋酸化的其他影响可能包括在海洋中产生的有机物的数量和营养含量的变化以及营养损失：将硝酸盐转化为强大的温室气氧化二氮。海洋碳循环如何“起作用”，以及CACO3颗粒是否对于减轻蓬松的有机物以及诸如Cococcolithophorids的藻类的确切藻类将如何响应变化的海洋化学响应，是否遭受重大的不确定性，这是否真的很重要。这意味着我们将无法知道对未来的单一计算机模型预测是否正确。在这个项目中，我们将解决这个不确定性的问题 - 耗尽了海洋碳循环和气候数百次的计算机模型，以查看未来的影响是可能的，什么是什么。通过使用大量数据集描述现代海洋的外观（就沉积物中记录的营养和图案的分布而言）来限制模型群，以使他们都同意现代海洋的外观，我们将在这方面得到极大帮助。我们工作的结果首先将是对现代海洋碳循环的更好理解，这对于在担心未来之前就至关重要。我们还将对我们未来可以期望的海洋碳和养分周期的变化范围进行预测，以及海洋如何通过发射或多或少或多或少的温室气体（例如二氧化碳和氧化二氮）来影响未来变暖的程度。