Effects of acidification and warming on long-term ocean carbon cycling constrained by observations

酸化和变暖对长期海洋碳循环的影响受到观测的限制

• 批准号: 1416700
• 负责人: Andreas Schmittner
• 金额: $ 25.98万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1416700&HistoricalAwards=false
• 关键词: Effects; acidification; warming; long; term

The chemical changes associated with ocean acidification will make it more difficult for important marine species (such as coccolithophores, foraminifera, and pteropods) to build their calcium carbonate (CaCO3) body parts, and existing CaCO3 will dissolve more easily. Thus acidification will likely decrease the production of CaCO3 in the future ocean. Warmer temperatures, on the other hand, lead to faster metabolic rates, which will likely increase primary and CaCO3 production. Faster warming of surface waters than deeper waters leads to increased stratification and less nutrient input into the sunlit surface ocean (photic zone). This may cause shifts in plankton species composition favoring coccolithophores and thus increasing CaCO3 production. Any change in CaCO3 production may also affect organic carbon fluxes from the surface to the deep ocean due to the aggregation and association of CaCO3 with organic particles. This research examines the relative importance of these effects on future global CaCO3 production and carbon cycling on long time scales (hundreds to thousands of years) using an improved model calibrated with existing observations. CaCO3 production increases atmospheric CO2, thus its future evolution may be an important feedback on climate. The sign and uncertainty of this feedback will be evaluated.An existing global model of ocean biogeochemical cycles suitable for millennial time scale simulations will be improved by adding a process based formulation of particle aggregation and sinking. The model will consider two mineral forms of CaCO3, calcite and aragonite, as well as opal, terrigenous, and organic matter as components of the aggregates. A global dataset of particulate organic carbon (POC) will be created by analyzing and calibrating large volume filtration measurements, bottle, transmissometer and satellite data including error estimates. This dataset, together with a large array of existing other global-scale biogeochemical observations will be used to calibrate the model and estimate uncertain parameters as well as different structural formulations of (a) the effect of ocean acidification on the production of CaCO3 and (b) particle aggregation. A Bayesian data assimilation scheme, designed to quantify three hypothetic mechanisms regarding the control of the rain ratio (CaCO3 over POC export from the euphotic zone), will be applied. Probabilistic projections will be carried out to quantify the effect of each mechanism on long term ocean carbon cycling and its feedback on atmospheric CO2 concentrations. The ability of the existing observations to constrain the projections will be evaluated. The project aims to lead to a better, more quantitative understanding of multi-variable processes that control global cycling of CaCO3 and carbon in the ocean and their coupling. Improving ocean biogeochemical cycling in a widely used Earth System Model of intermediate complexity will enhance infrastructure for research and education. The improved model will be made publicly available and benefit future research of long-term carbon cycle processes such as studies of anthropogenic effects or paleoclimate. The global POC dataset will also be made publicly available. A 3-day workshop for K-12 educators will be organized with climate change and ocean acidification as its main topics. Society may benefit from the outcome of this project through an improved assessment (including uncertainties) of the effects of anthropogenic carbon emissions on ocean biogeochemical cycles.

与海洋酸化相关的化学变化将使重要的海洋物种（例如cococolithophores，有孔虫和翼足）更难建造其碳酸钙（CACO3）身体部位，并且现有的CACO3将更容易溶解。因此，酸化可能会减少未来海洋中CACO3的产生。另一方面，温度较高会导致代谢率更快，这可能会增加原发性和CACO3的产生。地表水的变暖比更深的水更快地导致分层增加，而对阳光表面海洋（光学区）的养分输入却更少。这可能会导致有利于球虫的浮游物种组成的变化，从而增加了CACO3的产生。由于CaCO3与有机颗粒的聚集和关联，CACO3产生的任何变化也可能影响从表面到深海的有机碳通量。这项研究研究了这些影响对未来全球CACO3生产的相对重要性，并使用现有观察结果校准的改进模型在长期尺度（数百年）上长期尺度（数百年）循环。 CACO3产生增加了大气二氧化碳，因此其未来的进化可能是对气候的重要反馈。将评估此反馈的符号和不确定性。现有的海洋生物地球化学循环的全球模型将通过添加基于过程的粒子聚集和下沉的表述来改善适合千禧一代的时间尺度模拟。该模型将将两种矿物形式的Caco3，方解石和后者以及蛋白石，地质和有机物视为骨料的组成部分。通过分析和校准大量量过滤测量，瓶子，透射仪和卫星数据（包括错误估计值），将创建一个颗粒有机碳（POC）的全局数据集。该数据集以及一系列现有的其他全球尺度生物地球化学观察结果将用于校准模型并估算不确定的参数以及（a）海洋酸化对CACO3和（b）粒子聚集的影响的不同结构公式。将采用贝叶斯数据同化方案，旨在量化有关降雨比的控制的三种假设机制（POC3上的CACO3从兴奋区出口）。将进行概率投影，以量化每种机制对长期海洋循环的影响及其对大气二氧化碳浓度的反馈。将评估现有观察限制预测的能力。该项目的目的是对控制CACO3和碳在海洋及其耦合的全球循环的多变量过程中有更好的定量理解。在广泛使用的地球系统模型中，改善海洋生物地球化学循环将增强研究和教育的基础设施。改进的模型将公开获得，并有益于对长期碳循环过程的未来研究，例如人为效应或古气候的研究。全球POC数据集也将公开可用。将为K-12教育者举办的为期3天的研讨会，以气候变化和海洋酸化为主要主题。通过改进人为碳排放对海洋生物地球化学周期的影响的评估（包括不确定性），社会可能会从该项目的结果中受益。